Exhibit 4.1

WHEN RECORDED
MAIL TO:

Executed in 35 Counterparts, No. 35

SUPPLEMENTAL INDENTURE

DATED FEBRUARY 1, 2004

UNION ELECTRIC COMPANY

TO

THE BANK OF NEW YORK,
AS TRUSTEE

(SUPPLEMENTAL TO THE INDENTURE OF MORTGAGE AND DEED OF
TRUST DATED JUNE 15, 1937, AS AMENDED, EXECUTED BY

UNION ELECTRIC COMPANY
TO THE BANK OF NEW YORK, AS TRUSTEE)

First Mortgage Bonds, Environmental Improvement Series 2004A (1998A Bonds)

This instrument was prepared by Steven R. Sullivan, Senior Vice President Governmental/Regulatory Policy, General Counsel and Secretary of Union Electric Company, 1901 Chouteau Avenue, St. Louis, Missouri 63103, (314) 554-2098.

SUPPLEMENTAL INDENTURE, dated the 1st day of February, Two thousand and four (2004) made by and between UNION ELECTRIC COMPANY, a corporation organized and existing under the laws of the State of Missouri (hereinafter called the "Company"), party of the first part, and The Bank of New York (successor trustee to Bank of America, National Association, formerly Boatmen's Trust Company), a bank existing under the laws of the State of New York (hereinafter called the "Trustee"), as Trustee under the Indenture of Mortgage and Deed of Trust dated June 15, 1937, hereinafter mentioned, party of the second part:

WHEREAS, the Company has heretofore executed and delivered to the Trustee its Indenture of Mortgage and Deed of Trust, dated June 15, 1937, as amended May 1, 1941, April 1, 1971, February 1, 1974, July 7, 1980, February 1, 2000 and August 15, 2002 (said Indenture of Mortgage and Deed of Trust as so amended, being hereinafter referred to as the "Original Indenture"), to secure the payment of the principal of and the interest (and premium, if any) on all bonds at any time issued and outstanding thereunder, and indentures supplemental thereto dated June 15, 1937, May 1, 1941, March 17, 1942, April 13, 1945, April 27, 1945, October 1, 1945, April 11, 1947, April 13, 1949, September 13, 1950, December 1, 1950, September 20, 1951, May 1, 1952, March 1, 1954, May 1, 1955, August 31, 1955, April 1, 1956, July 1, 1956, August 1, 1957, February 1, 1958, March 1, 1958, November 5, 1958, March 16, 1959, June 24, 1959, December 11, 1959, August 17, 1960, September 1, 1960, October 24, 1960, June 30, 1961, July 1, 1961, August 9, 1962, September 30, 1963, November 1, 1963, March 12, 1965, April 1, 1965, April 14, 1966, May 1, 1966, February 17, 1967, March 1, 1967, February 19, 1968, March 15, 1968, August 21, 1968, April 7, 1969, May 1, 1969, September 12, 1969, October 1, 1969, March 26, 1970, April 1, 1970, June 12, 1970, January 1, 1971, April 1, 1971, September 15, 1971, December 3, 1973, February 1, 1974, April 25, 1974, February 3, 1975, March 1, 1975, June 11, 1975, May 12, 1976, August 16, 1976, April 26, 1977, October 15, 1977, November 7, 1977, December 1, 1977, August 1, 1978, October 12, 1979, November 1, 1979, July 7, 1980, August 1, 1980, August 20, 1980, February 1, 1981, October 8, 1981, August 27, 1982, September 1, 1982, December 15, 1982, March 1, 1983, June 21, 1984, December 12, 1984, June 11, 1985, March 1, 1986, May 1, 1986, May 1, 1990, December 1, 1991, December 4, 1991, January 1, 1992, September 30, 1992, October 1, 1992, December 1, 1992, February 1, 1993, February 18, 1993, May 1, 1993, August 1, 1993, October 1, 1993, January 1, 1994, February 1, 2000, August 15, 2002, March 5, 2003, April 1, 2003, July 15, 2003 and October 1, 2003, respectively, have heretofore been entered into between the Company and the Trustee; and

WHEREAS, Bonds have heretofore been issued by the Company under the Original Indenture as follows:

(1) $80,000,000 principal amount of First Mortgage and Collateral Trust Bonds, 3-3/4% Series due 1962, all of which have been redeemed prior to the date of the execution hereof;

(2) $90,000,000 principal amount of First Mortgage and Collateral Trust Bonds, 3-3/8% Series due 1971, which are described in the Supplemental Indenture dated

May 1, 1941 (hereinafter called the "Supplemental Indenture of May 1, 1941"), all of which have been paid at maturity prior to the date of the execution hereof;

(3) $13,000,000 principal amount of First Mortgage and Collateral Trust Bonds, 2-3/4% Series due 1975 (herein called the "Bonds of 1975 Series"), which are described in the Supplemental Indenture dated October 1, 1945 (hereinafter called the "Supplemental Indenture of October 1, 1945"), all of which have been paid at maturity prior to the date of the execution hereof;

(4) $25,000,000 principal amount of First Mortgage and Collateral Trust Bonds, 2-7/8% Series due 1980 (herein called the "Bonds of 1980 Series"), which are described in the Supplemental Indenture dated December 1, 1950 (hereinafter called the "Supplemental Indenture of December 1, 1950"), all of which have been paid at maturity prior to the date of the execution hereof;

(5) $30,000,000 principal amount of First Mortgage and Collateral Trust Bonds, 3-1/4% Series due 1982 (herein called the "Bonds of 1982 Series"), which are described in the Supplemental Indenture dated May 1, 1952 (hereinafter called the "Supplemental Indenture of May 1, 1952"), all of which have been paid at maturity prior to the date of the execution hereof;

(6) $40,000,000 principal amount of First Mortgage Bonds, 3-3/4% Series due 1986 (herein called the "Bonds of 1986 Series"), which are described in the Supplemental Indenture dated July 1, 1956 (hereinafter called the "Supplemental Indenture of July 1, 1956"), all of which have been paid at maturity prior to the date of the execution hereof;

(7) $35,000,000 principal amount of First Mortgage Bonds, 4-3/8% Series due 1988 (herein called the "Bonds of 1988 Series"), which are described in the Supplemental Indenture dated March 1, 1958 (hereinafter called the "Supplemental Indenture of March 1, 1958"), all of which have been paid at maturity prior to the date of the execution hereof;

(8) $50,000,000 principal amount of First Mortgage Bonds, 4-3/4% Series due 1990 (herein called the "Bonds of 1990 Series"), which are described in the Supplemental Indenture dated September 1, 1960 (hereinafter called the "Supplemental Indenture of September 1, 1960"), all of which have been paid at maturity prior to the date of the execution hereof;

(9) $30,000,000 principal amount of First Mortgage Bonds, 4-3/4% Series due 1991 (herein called the "Bonds of 1991 Series"), which are described in the Supplemental Indenture dated July 1, 1961 (hereinafter called the "Supplemental Indenture of July 1, 1961"), all of which have been paid at maturity prior to the date of the execution hereof;

(10) $30,000,000 principal amount of First Mortgage Bonds, 4-1/2% Series due 1993 (herein called the "Bonds of 1993 Series"), which are described in the

Supplemental Indenture dated November 1, 1963 (hereinafter called the "Supplemental Indenture of November 1, 1963"), all of which have been redeemed prior to the date of the execution hereof;

(11) $35,000,000 principal amount of First Mortgage Bonds, 4-1/2% Series due 1995 (herein called the "Bonds of 1995 Series"), which are described in the Supplemental Indenture dated April 1, 1965 (hereinafter called the "Supplemental Indenture of April 1, 1965"), all of which have been paid at maturity prior to the date of the execution hereof;

(12) $30,000,000 principal amount of First Mortgage Bonds, 5-1/2% Series due 1996 (herein called the "Bonds of 1996 Series"), which are described in the Supplemental Indenture dated May 1, 1966 (hereinafter called the "Supplemental Indenture of May 1, 1966"), all of which have been paid at maturity prior to the date of the execution hereof;

(13) $40,000,000 principal amount of First Mortgage Bonds, 5-1/2% Series due 1997 (herein called the "Bonds of 1997 Series"), which are described in the Supplemental Indenture dated March 1, 1967 (hereinafter called the "Supplemental Indenture of March 1, 1967"), all of which have been paid at maturity prior to the date of the execution hereof;

(14) $50,000,000 principal amount of First Mortgage Bonds, 7% Series due 1998 (herein called the "Bonds of 1998 Series"), which are described in the Supplemental Indenture dated March 15, 1968 (hereinafter called the "Supplemental Indenture of March 15, 1968"), all of which have been redeemed prior to the date of the execution hereof;

(15) $35,000,000 principal amount of First Mortgage Bonds, 7-3/8% Series due 1999 (herein called the "Bonds of May 1999 Series"), which are described in the Supplemental Indenture dated May 1, 1969 (hereinafter called the "Supplemental Indenture of May 1, 1969"), all of which have been redeemed prior to the date of the execution hereof;

(16) $40,000,000 principal amount of First Mortgage Bonds, 8-1/4% Series due 1999 (herein called the "Bonds of October 1999 Series"), which are described in the Supplemental Indenture dated October 1, 1969 (hereinafter called the "Supplemental Indenture of October 1, 1969"), all of which have been redeemed prior to the date of the execution hereof;

(17) $100,000,000 principal amount of First Mortgage Bonds, 9.95% Series due 1999 (herein called the "Bonds of November 1999 Series"), which are described in the Supplemental Indenture dated November 1, 1979 (hereinafter called the "Supplemental Indenture of November 1, 1979"), all of which have been redeemed prior to the date of the execution hereof;

(18) $60,000,000 principal amount of First Mortgage Bonds, 9% Series due 2000 (herein called the "Bonds of 2000 Series"), which are described in the Supplemental Indenture dated April 1, 1970 (hereinafter called the "Supplemental Indenture of April 1, 1970"), all of which have been redeemed prior to the date of the execution hereof;

(19) $50,000,000 principal amount of First Mortgage Bonds, 7-7/8% Series due 2001 (herein called the "Bonds of January 2001 Series"), which are described in the Supplemental Indenture dated January 1, 1971 (hereinafter called the "Supplemental Indenture of January 1, 1971"), all of which have been redeemed prior to the date of the execution hereof;

(20) $50,000,000 principal amount of First Mortgage Bonds, 7 5/8% Series due 2001 (herein called the "Bonds of April 2001 Series"), which are described in the Supplemental Indenture dated April 1, 1971 (hereinafter called the "Supplemental Indenture of April 1, 1971"), all of which have been redeemed prior to the date of the execution hereof;

(21) $60,000,000 principal amount of First Mortgage Bonds, 8 1/8% Series due 2001 (herein called the "Bonds of October 2001 Series"), which are described in the Supplemental Indenture dated September 15, 1971 (hereinafter called the "Supplemental Indenture of September 15, 1971"), all of which have been redeemed prior to the date of the execution hereof;

(22) $70,000,000 principal amount of First Mortgage Bonds, 8-3/8% Series due 2004 (herein called the "Bonds of 2004 Series"), which are described in the Supplemental Indenture dated February 1, 1974 (hereinafter called the "Supplemental Indenture of February 1, 1974"), all of which have been redeemed prior to the date of the execution hereof;

(23) $70,000,000 principal amount of First Mortgage Bonds, 10-1/2% Series due 2005 (herein called the "Bonds of 2005 Series"), which are described in the Supplemental Indenture dated March 1, 1975 (hereinafter called the "Supplemental Indenture of March 1, 1975"), all of which have been redeemed prior to the date of the execution hereof;

(24) $70,000,000 principal amount of First Mortgage Bonds, 8-7/8% Series due 2006 (herein called the "Bonds of 2006 Series"), which are described in the Supplemental Indenture dated August 16, 1976 (hereinafter called the "Supplemental Indenture of August 16, 1976"), all of which have been redeemed prior to the date of the execution hereof;

(25) $27,085,000 principal amount of First Mortgage Bonds, 5.80% Environmental Improvement Series 1977, which are described in the Supplemental Indenture dated October 15, 1977 (hereinafter called the "Supplemental Indenture of October 15, 1977"), all of which have been redeemed prior to the date of the execution hereof;

(26) $60,000,000 principal amount of First Mortgage Bonds, 8 5/8% Series due 2007 (herein called the "Bonds of 2007 Series"), which are described in the Supplemental Indenture dated December 1, 1977 (hereinafter called the "Supplemental Indenture of December 1, 1977"), all of which have been redeemed prior to the date of the execution hereof;

(27) $55,000,000 principal amount of First Mortgage Bonds, 9.35% Series due 2008 (herein called the "Bonds of 2008 Series"), which are described in the Supplemental Indenture dated August 1, 1978 (hereinafter called the "Supplemental Indenture of August 1, 1978"), all of which have been redeemed prior to the date of the execution hereof;

(28) $60,000,000 principal amount of First Mortgage Bonds, Environmental Improvement Series 1980, which are described in the Supplemental Indenture dated August 1, 1980 (hereinafter called the "Supplemental Indenture of August 1, 1980"), all of which have been redeemed prior to the date of the execution hereof;

(29) $150,000,000 principal amount of First Mortgage Bonds, 15-3/8% Series due 1991 (herein called the "Bonds of February 1991 Series"), which are described in the Supplemental Indenture dated February 1, 1981 (hereinafter called the "Supplemental Indenture of February 1, 1981"), all of which have been redeemed prior to the date of the execution hereof;

(30) $125,000,000 principal amount of First Mortgage Bonds, 15% Series due 1992 (herein called the "Bonds of 1992 Series"), which are described in the Supplemental Indenture dated September 1, 1982 (hereinafter called the "Supplemental Indenture of September 1, 1982"), all of which have been redeemed prior to the date of the execution hereof;

(31) $100,000,000 principal amount of First Mortgage Bonds, 13% Series due 2013 (herein called the "Bonds of 2013 Series"), which are described in the Supplemental Indenture dated March 1, 1983 (hereinafter called the "Supplemental Indenture of March 1, 1983"), all of which have been redeemed prior to the date of the execution hereof;

(32) $100,000,000 principal amount of First Mortgage Bonds, 9-3/8% Series due 2016 (herein called the "Bonds of 2016 Series"), which are described in the Supplemental Indenture dated March 1, 1986 (hereinafter called the "Supplemental Indenture of March 1, 1986"), all of which have been redeemed prior to the date of the execution hereof;

(33) $100,000,000 principal amount of First Mortgage Bonds, 8-7/8% Series due 1996 (herein called the "Bonds of 1996 Series"), which are described in the Supplemental Indenture dated May 1, 1986 (hereinafter called the "Supplemental Indenture of May 1, 1986"), all of which have been redeemed prior to the date of the execution hereof;

(34) $60,000,000 principal amount of First Mortgage Bonds, Environmental Improvement Series 1990A, which are described in the Supplemental Indenture dated May 1, 1990 (hereinafter called the "Supplemental Indenture of May 1, 1990"), all of which have been redeemed prior to the date of the execution hereof;

(35) $125,000,000 principal amount of First Mortgage Bonds, 8-3/4% Series due 2021 (herein called the "Bonds of 2021 Series"), which are described in the Supplemental Indenture dated December 1, 1991 (hereinafter called the "Supplemental Indenture of December 1, 1991"), all of which have been redeemed prior to the date of the execution hereof;

(36) $75,000,000 principal amount of First Mortgage Bonds, 8.33% Series due 2002 (herein called the "Bonds of 2002 Series"), which are described in the Supplemental Indenture dated December 4, 1991 (hereinafter called the "Supplemental Indenture of December 4, 1991"), all of which have been paid at maturity prior to the date of the execution hereof;

(37) $100,000,000 principal amount of First Mortgage Bonds, 7.65% Series due 2003 (herein called the "Bonds of 2003 Series"), which are described in the Supplemental Indenture dated January 1, 1992 (hereinafter called the "Supplemental Indenture of January 1, 1992"), all of which have been paid at maturity prior to the date of the execution hereof;

(38) $204,000,000 aggregate principal amount of First Mortgage Bonds, consisting of $100,000,000 principal amount of 6-3/4% Series due 1999 and $104,000,000 principal amount of 8-1/4% Series due 2022 (herein called the "Bonds of 1999 Series" and "Bonds of 2022 Series", respectively), which are described in the Supplemental Indenture dated October 1, 1992 (hereinafter called the "Supplemental Indenture of October 1, 1992"), of which the Bonds of 1999 Series have been paid at maturity prior to the date of execution hereof and the Bonds of 2022 Series have been redeemed prior to the date of the execution hereof;

(39) $170,000,000 aggregate principal amount of First Mortgage Bonds, consisting of $85,000,000 principal amount of 7-3/8% Series due 2004 and $85,000,000 principal amount of 8% Series due 2022 (herein called the "Bonds of December 2004 Series" and "Bonds of December 2022 Series", respectively, which are described in the Supplemental Indenture dated December 1, 1992, (hereinafter called the "Supplemental Indenture of December 1, 1992"), of which the Bonds of December 2022 Series have been redeemed prior to the date of the execution hereof and the Bonds of December 2004 Series are outstanding at the date of the execution hereof;

(40) $188,000,000 principal amount of First Mortgage Bonds, 6-7/8% Series due 2004 (herein called the "Bonds of August 2004 Series"), which are described in the Supplemental Indenture dated February 1, 1993 (hereinafter called the "Supplemental Indenture of February 1, 1993"), all of which are outstanding at the date of the execution hereof;

(41) $148,000,000 principal amount of First Mortgage Bonds, 6-3/4% Series due 2008 (herein called the "Bonds of May 2008 Series"), which are described in the Supplemental Indenture dated May 1, 1993 (hereinafter called the "Supplemental Indenture of May 1, 1993"), all of which are outstanding at the date of the execution hereof;

(42) $75,000,000 principal amount of First Mortgage Bonds, 7.15% Series due 2023 (herein called the "Bonds of 2023 Series"), which are described in the Supplemental Indenture dated August 1, 1993 (hereinafter called the "Supplemental Indenture of August 1, 1993"), all of which have been redeemed prior to the date of the execution hereof;

(43) $44,000,000 principal amount of First Mortgage Bonds, Environmental Improvement Series 1993 (herein called the "Bonds of 2028 Series"), which are described in the Supplemental Indenture dated October 1, 1993 (hereinafter called the "Supplemental Indenture of October 1, 1993"), all of which are outstanding at the date of the execution hereof;

(44) $100,000,000 principal amount of First Mortgage Bonds, 7% Series due 2024 (herein called the "Bonds of 2024 Series"), which are described in the Supplemental Indenture dated January 1, 1994 (hereinafter called the "Supplemental Indenture of January 1, 1994"), all of which are outstanding at the date of the execution hereof;

(45) $173,000,000 principal amount of First Mortgage Bonds, Senior Notes Series AA (herein called the "Bonds of 2012 Series"), which are described in the Supplemental Indenture dated August 15, 2002 (hereinafter called the "Supplemental Indenture of August 15, 2002"), all of which are outstanding at the date of the execution hereof;

(46) $184,000,000 principal amount of First Mortgage Bonds, Senior Notes Series BB (herein called the "Bonds of 2034 Series"), which are described in the Supplemental Indenture dated March 5, 2003 (hereinafter called the "Supplemental Indenture of March 5, 2003"), all of which are outstanding at the date of the execution hereof;

(47) $114,000,000 principal amount of First Mortgage Bonds, Senior Notes Series CC (herein called the "Bonds of 2015 Series"), which are described in the Supplemental Indenture dated April 1, 2003 (hereinafter called the "Supplemental Indenture of April 1, 2003"), all of which are outstanding at the date of the execution hereof;

(48) $200,000,000 principal amount of First Mortgage Bonds, Senior Notes Series DD (herein called the "Bonds of 2018 Series"), which are described in the Supplemental Indenture dated July 15, 2003 (hereinafter called the "Supplemental Indenture of July 15, 2003"), all of which are outstanding at the date of the execution hereof; and

(49) $200,000,000 principal amount of First Mortgage Bonds, Senior Notes Series EE (herein called the "Bonds of 2013 Series"), which are described in the Supplemental Indenture dated October 1, 2003 (hereinafter called the "Supplemental Indenture of October 1, 2003"), all of which are outstanding at the date of the execution hereof; and

WHEREAS, the following Bonds will be issued by the Company pursuant to this Supplemental Indenture or pursuant to a separate Supplemental Indenture each dated February 1, 2004 and each series of such Bonds will be outstanding upon the authentication by the Trustee of such Bonds:

(A) $60,000,000 principal amount of First Mortgage Bonds, Environmental Improvement Series 2004A (1998A Bonds) (herein called the "New Bonds"), which are described in this Supplemental Indenture dated February 1, 2004 (hereinafter called "this Supplemental Indenture" or the "Supplemental Indenture of February 1, 2004 (2004A)"), all of which will be outstanding upon the authentication by the Trustee of the New Bonds;

(B) $50,000,000 principal amount of First Mortgage Bonds, Environmental Improvement Series 2004B (1998B Bonds) (herein called the "Bonds of 2033 (Series 1998B)"), which are described in the Supplemental Indenture dated February 1, 2004 (hereinafter called the "Supplemental Indenture of February 1, 2004 (2004B)"), all of which will be outstanding upon the authentication by the Trustee of the Bonds of 2033 (Series 1998B); and

(C) $50,000,000 principal amount of First Mortgage Bonds, Environmental Improvement Series 2004C (1998C Bonds) (herein called the "Bonds of 2033 (Series 1998C)"), which are described in the Supplemental Indenture dated February 1, 2004 (hereinafter called the "Supplemental Indenture of February 1, 2004 (2004C)"), all of which will be outstanding upon the authentication by the Trustee of the Bonds of 2033 (Series 1998C);

and

WHEREAS, the Company on August 31, 1955 acquired all of the properties of Union Electric Power Company, the Subsidiary as defined in Article I of the Original Indenture, upon the dissolution of the Subsidiary; the Company, by Supplemental Indenture dated August 31, 1955, conveyed all of the properties so acquired (other than property of the character defined as excepted property in the granting clauses of the Original Indenture) to the Trustee upon the terms and trusts in the Original Indenture and the indentures supplemental thereto set forth for the equal and proportionate benefit and security of all present and future holders of the Bonds and coupons issued and to be issued thereunder, all the shares of stock of the Subsidiary were released from the lien of the Original Indenture; and the Company became entitled to change the general designation of the Bonds so as to omit the words "and Collateral Trust"; and

WHEREAS, the Articles of Incorporation of the Company were duly amended on April 23, 1956, to change its corporate name from "Union Electric Company of Missouri" to "Union Electric Company"; and

WHEREAS, the Articles of Agreement of the Trustee were duly amended effective on January 4, 1982 to change its corporate name from "St. Louis Union Trust Company" to "Centerre Trust Company of St. Louis", and further amended on December 9, 1988, to change its corporate name from "Centerre Trust Company of St. Louis" to "Boatmen's Trust Company"; and

WHEREAS, that on March 13, 1998, Boatmen's Trust Company merged into NationsBank, National Association and effective July 5, 1999, changed its name to Bank of America, National Association; and

WHEREAS, that on February 1, 2000, The Bank of New York, as transferee of the corporate trust business of Bank of America, National Association (formerly known as Boatmen's Trust Company), Trustee under the Original Indenture, became successor Trustee under the Original Indenture; and

WHEREAS, the Company is entitled at this time to have authenticated and delivered additional Bonds on the basis of property additions upon compliance with and pursuant to the provisions of Article III, Section 4 of the Original Indenture; and

WHEREAS, the Company has entered into a Loan Agreement dated as of September 1, 1998 (the "Original Loan Agreement") with the State Environmental Improvement and Energy Resources Authority of the State of Missouri (the "Authority") pursuant to which the Authority agreed to issue $60,000,000 aggregate principal amount of its Environmental Improvement Revenue Refunding Bonds (Union Electric Company Project) Series 1998A (the "Authority Bonds"), all of which are presently outstanding and loan the proceeds thereof to the Company; and

WHEREAS, the Authority Bonds were issued pursuant to an Indenture of Trust dated as of September 1, 1998 (the "Original Authority Bond Indenture") between the Authority and UMB Bank & Trust, N.A., as successor to State Street Bank and Trust Company of Missouri, N.A., as trustee (the "Authority Bond Trustee"); and

WHEREAS, the Company has determined it to be necessary and desirable to further secure rights of the owners of the Authority Bonds to the payment of principal and interest on the Authority Bonds by obtaining a Financial Guaranty Insurance Policy with respect to the Authority Bonds (the "Authority Bond Insurance Policy") from MBIA Insurance Corporation and in furtherance thereof
(i) the Authority and the Authority Bond Trustee will enter into an Amended and Restated Indenture of Trust dated as of February 1, 2004 (the "Authority Bond Indenture") which amends and restates the Original Authority Bond Indenture, and
(ii) the Authority and the Company will enter into the First Amendment to Loan Agreement dated as of February 1, 2004 (the "First Amendment to Loan Agreement"), which amends the Original Loan

Agreement (the Original Loan Agreement as so amended is referred to herein as the "Agreement"); and

WHEREAS, in connection with obtaining the Authority Bond Insurance Policy, the Company desires by this Supplemental Indenture to provide for the issuance to the Authority Bond Trustee of a new series of Bonds under the Original Indenture as security for the Company's obligations under the Agreement with respect to the payment of the Authority Bonds, to have the designation provided in Article I, Section 1 hereof (herein called the "New Bonds"), and the Original Indenture provides that certain terms and provisions, as determined by the Board of Directors of the Company, of the Bonds of any particular series may be expressed in and provided by the execution of an appropriate supplemental indenture; and

WHEREAS, the Original Indenture provides that the Company and the Trustee may enter into indentures supplemental to the Original Indenture specifically to convey, transfer and assign to the Trustee and to subject to the lien of the Original Indenture additional properties acquired by the Company; and

WHEREAS, the Company, in the exercise of the powers and authority conferred upon and reserved to it under the provisions of the Original Indenture and pursuant to appropriate resolutions of the Board of Directors, has duly resolved and determined to make, execute and deliver to the Trustee a Supplemental Indenture in the form hereof for the purposes herein provided; and

WHEREAS, all conditions and requirements necessary to make this Supplemental Indenture a valid, binding and legal instrument have been done, performed and fulfilled and the execution and delivery hereof have been in all respects duly authorized;

NOW, THEREFORE, THIS INDENTURE WITNESSETH:

That, in consideration of the premises and of the mutual covenants herein contained and of the acceptance of this trust by the Trustee and of the sum of One Dollar duly paid by the Trustee to the Company at or before the time of the execution of this Supplemental Indenture, and of other valuable considerations, the receipt whereof is hereby acknowledged, and in order further to secure the payment of the principal of and interest (and premium, if any) on all Bonds at any time issued and outstanding under the Original Indenture, according to their tenor and effect, and to secure the Company's obligations under the Agreement with respect to the payment of the Authority Bonds, the Company has executed and delivered this Supplemental Indenture and has granted, bargained, sold, warranted, aliened, remised, released, conveyed, assigned, transferred, mortgaged, pledged, set over and confirmed and by these presents does grant, bargain, sell, warrant, alien, remise, release, convey, assign, transfer, mortgage, pledge, set over and confirm unto The Bank of New York, as Trustee, and to its successors in trust under the Original Indenture forever, all and singular the following described properties (in addition to all other properties heretofore subjected to the lien of the Original Indenture and not heretofore released from the lien thereof) - that is to say:

FIRST

ALL power houses, plants, buildings and other structures, dams, dam sites, substations, heating plants, gas works, holders and tanks, together with all and singular the electric, heating, gas and mechanical appliances appurtenant thereto of every nature whatsoever, now owned by the Company, including all and singular the machinery, engines, boilers, furnaces, generators, dynamos, turbines and motors, and all and every character of mechanical appliance for generating or producing electricity, steam, gas and other agencies for light, heat, cold, or power or other purposes, and all transmission and distribution systems used for the transmission and distribution of electricity, steam, gas and other agencies for light, heat, cold or power or any other purpose whatsoever, whether underground or overhead, surface or otherwise, now owned by the Company, including all poles, towers, posts, wires, cables, conduits, manholes, mains, pipes, tubes, drains, furnaces, switchboards, transformers, conductors, insulators, supports, meters, lamps, fuses, junction boxes, regulator stations, and other electric, steam and gas fixtures and apparatus; all of the aforementioned property being located in the City of St. Louis, the counties of Adair, Audrain, Benton, Bollinger, Boone, Butler, Caldwell, Callaway, Camden, Cape Girardeau, Clark, Clay, Clinton, Cole, Cooper, Crawford, Daviess, Dunklin, Franklin, Gasconade, Howard, Iron, Jefferson, Knox, Lewis, Lincoln, Livingston, Macon, Madison, Maries, Marion, Miller, Mississippi, Moniteau, Montgomery, Morgan, New Madrid, Osage, Pemiscot, Perry, Pettis, Phelps, Pike, Pulaski, Ralls, Randolph, Ray, Reynolds, Ripley, St. Charles, St. Francois, Ste. Genevieve, St. Louis, Saline, Schuyler, Scott, Stoddard, Warren, Washington, and Wayne, Missouri, the counties of Adams, Alexander, Calhoun, Franklin, Hancock, Henderson, Jackson, Jersey, Macoupin, Madison, Massac, Monroe, Perry, Pike, Pulaski, St. Clair, Union, and Washington, Illinois, and the counties of Des Moines, Henry, Johnson, Lee, and Washington, Iowa, upon real estate owned by the Company, or occupied by it under rights to so occupy, which real estate is described in the Indenture of Mortgage and Deed of Trust dated June 15, 1937, in the Supplemental Indentures dated May 1, 1941, March 17, 1942, April 13, 1945, April 27, 1945, October 1, 1945, April 11, 1947, April 13, 1949, September 13, 1950, December 1, 1950, September 20, 1951, May 1, 1952, March 1, 1954, May 1, 1955, August 31, 1955, April 1, 1956, July 1, 1956, August 1, 1957, February 1, 1958, March 1, 1958, November 5, 1958, March 16, 1959, June 24, 1959, December 11, 1959, August 17, 1960, September 1, 1960, October 24, 1960, June 30, 1961, July 1, 1961, August 9, 1962, September 30, 1963, November 1, 1963, March 12, 1965, April 1, 1965, April 14, 1966, May 1, 1966, February 17, 1967, March 1, 1967, February 19, 1968, March 15, 1968, August 21, 1968, April 7, 1969, May 1, 1969, September 12, 1969, October 1, 1969, March 26, 1970, April 1, 1970, June 12, 1970, January 1, 1971, April 1, 1971, September 15, 1971, December 3, 1973, February 1, 1974, April 25, 1974, February 3, 1975, March 1, 1975, June 11, 1975, May 12, 1976, August 16, 1976, April 26, 1977, October 15, 1977, November 7, 1977, December 1, 1977, August 1, 1978, October 12, 1979, November 1, 1979, July 7, 1980, August 1, 1980, August 20, 1980, February 1, 1981, October 8, 1981, August 27, 1982, September 1, 1982, December 15, 1982, March 1, 1983, June 21, 1984, December 12, 1984, June 11, 1985, March 1, 1986, May 1, 1986, May 1, 1990, December 1, 1991, December 4, 1991, January 1, 1992, September 30, 1992, October 1, 1992, December 1, 1992, February 1, 1993, February 18, 1993, May 1, 1993, August 1, 1993, October 1, 1993, January 1, 1994, February 1, 2000, August 15, 2002, March 5, 2003, April 1, 2003, July 15, 2003, October 1, 2003 and in this Supplemental Indenture and the seven other Supplemental Indentures each dated

February 1, 2004, or attached to or connected with such real estate or transmission or distribution systems of the Company leading from or into such real estate.

SECOND

ALSO, (except as in the Original Indenture expressly excepted) all franchises and all permits, ordinances, easements, privileges, immunities and licenses, all rights to construct, maintain and operate overhead, surface and underground systems for the distribution and transmission of electricity, steam, gas or other agencies for the supply to itself or others of light, heat, cold or power, all rights-of-way, all waters, water rights and flowage rights and all grants and consents, now owned or, subject to the provisions of Article XII of the Original Indenture, which it may hereafter acquire.

ALSO, (except as in the Original Indenture expressly excepted) all inventions, patent rights and licenses of every kind now owned by the Company or, subject to the provisions of Article XII of the Original Indenture, which it may hereafter acquire.

THIRD

ALSO, subject to the provisions of Article XII of the Original Indenture, all other property, real, personal and mixed (except as therein or herein expressly excepted) of every nature and kind and wheresoever situated now or hereafter possessed by or belonging to the Company, or to which it is now, or may at any time hereafter be, in any manner entitled at law or in equity.

TO HAVE AND TO HOLD all said properties, real, personal and mixed, mortgaged, pledged and conveyed by the Company as aforesaid, or intended so to be, unto the Trustee and its successors and assigns forever;

SUBJECT, HOWEVER, to the exceptions and reservations and matters hereinabove recited, to existing leases, to existing liens upon rights of way for transmission or distribution line purposes, as defined in Article I of the Original Indenture, and any extensions thereof, and subject to existing easements for streets, alleys, highways, rights-of-way and railroad purposes over, upon and across certain of the property hereinbefore described, and subject also to all the terms, conditions, agreements, covenants, exceptions and reservations expressed or provided in the deeds or other instruments respectively under and by virtue of which the Company acquired the properties hereinabove described, and to undetermined liens and charges, if any, incidental to construction or other existing permitted liens as defined in Article I of the Original Indenture;

IN TRUST, NEVERTHELESS, upon the terms and trusts in the Original Indenture and the indentures supplemental thereto, including this Supplemental Indenture, set forth, for the equal and proportionate benefit and security of all present and future holders of the Bonds and coupons issued and to be issued thereunder, or any of them, without preference of any of said Bonds and coupons of any particular series over the Bonds and coupons of any other series, by reason of priority in the time of the issue, sale or negotiation thereof, or by reason of the purpose of issue

or otherwise howsoever, except as otherwise provided in Section 2 of Article IV of the Original Indenture.

AND IT IS HEREBY COVENANTED, DECLARED AND AGREED, by and between the parties hereto, for the benefit of those who shall hold the Bonds and coupons, or any of them to be issued under the Original Indenture, as follows:

ARTICLE I

DESCRIPTION OF THE NEW BONDS

Section 1.1. There is hereby created a new series of Bonds to be executed, authenticated and delivered under and secured by the Original Indenture which shall, subject to the provisions of Section 1 of Article II of the Original Indenture, be designated as "First Mortgage Bonds, Environmental Improvement Series 2004A (1998A Bonds)" (the "New Bonds") of the Company. The New Bonds shall be executed, authenticated and delivered in accordance with the provisions of, and shall in all respects be subject to all of the terms, conditions and covenants of, the Original Indenture and shall be issued to, and registered in the name of, the Authority Bond Trustee under the Authority Bond Indenture to secure any and all obligations of the Company under the Agreement with respect to the payment of the Authority Bonds.

The New Bonds shall mature, subject to prior redemption, on September 1, 2033, and shall bear interest at the same rate or rates of interest as the Authority Bonds which, in turn, shall be determined by the methods set forth in the Authority Bond Indenture, which provides for an Auction Rate, a Daily Rate, a Weekly Rate, a Commercial Paper Rate or a Long-Term Interest Rate (each as defined in the Authority Bonds Indenture). Reference is made to the provisions of the Authority Bond Indenture concerning the methods by which such interest rates are determined, and the means by which the method of determining such interest rates may be changed, and such provisions are included in this Supplemental Indenture as if fully set forth herein. Interest on the New Bonds is payable on the same dates as interest on the Authority Bonds is paid, until the principal sum of the New Bonds is paid in full. The New Bonds shall be payable as to principal and interest in any coin or currency of the United States of America which at the time of payment is legal tender for public and private debts, and shall be payable, in immediately available funds, at the office of the Authority Bond Trustee.

Section 1.2. The New Bonds shall not be assignable or transferable except as permitted or required by Section 12.13 of the Authority Bond Indenture. Any such transfer shall be effected at the principal office or place of business of the Trustee under the Original Indenture. The New Bonds are exchangeable for the New Bonds of other denominations, as in the Original Indenture provided, except that payment of a service charge therefor will not be required by the Company.

Notwithstanding the provisions of Section 6 of Article II of the Original Indenture, the New Bonds shall be dated their date of authentication and shall bear interest from the interest payment date to which interest on the New Bonds has been paid next preceding the date thereof,

unless such date is an interest payment date to which interest has been paid, in which case they shall bear interest from the date thereof.

Upon any payment of the principal of and interest on, all or any portion of the Authority Bonds, whether at maturity or otherwise or upon provision for the payment thereof having been made in accordance with Section 7.01 of the Authority Bond Indenture, the New Bonds in a principal amount equal to the principal amount of such Authority Bonds shall, to the extent of such payment of principal and interest, be deemed paid and the obligation of the Company thereunder to make such payment shall be discharged to such extent and, in the case of the payment of principal, such New Bonds shall be surrendered to the Company for cancellation as provided in and subject to the terms of Section 7.04 of the Authority Bond Indenture. The Trustee may at any time and all times conclusively assume that the obligation of the Company under the Agreement to make payments with respect to the principal of and interest on the Authority Bonds, so far as such payments at the time have become due, has been fully satisfied and discharged pursuant to the foregoing sentence unless and until the Trustee shall have received a written notice from the Authority Bond Trustee signed by one of its officers stating (i) the timely payment of principal or interest on, the Authority Bonds has not been made, (ii) that the Company is in arrears as to the payments required to be made by it to the Authority Bond Trustee pursuant to the Agreement, and (iii) the amount of the arrearage.

Section 1.3. The New Bonds and the Trustee's certificate on the New Bonds shall be substantially in the following forms respectively:

                           [Form of Face of New Bond]

No. ____                                                          $________

                               Ill. C. C. No. 6314

NOTWITHSTANDING ANY PROVISIONS HEREOF OR IN THE ORIGINAL INDENTURE THIS BOND IS
NOT ASSIGNABLE OR TRANSFERABLE EXCEPT AS PERMITTED OR REQUIRED BY SECTION

12.13 OF THE AMENDED AND RESTATED INDENTURE OF TRUST DATED AS OF FEBRUARY 1, 2004, BETWEEN THE STATE ENVIRONMENTAL IMPROVEMENT AND ENERGY RESOURCES AUTHORITY OF THE STATE OF MISSOURI AND UMB BANK & TRUST, N.A., AS SUCCESSOR TO STATE STREET BANK AND TRUST COMPANY OF MISSOURI, N.A., AS TRUSTEE

UNION ELECTRIC COMPANY
(Incorporated under the laws of the State of Missouri)

First Mortgage Bonds, Environmental Improvement Series 2004A (1998A Bonds)

Illinois Commerce Commission Identification No. 6314

UNION ELECTRIC COMPANY, a corporation organized and existing under the laws of the State of Missouri (hereinafter called the "Company," which term shall include any successor corporation as defined in the Amended Indenture referred to on the reverse hereof), for value received, hereby promises to pay to UMB Bank & Trust, N.A., as successor to State Street Bank and Trust Company of Missouri, N.A., as trustee under the Authority Bond Indenture hereinafter referred to, or registered assigns, the sum of _________________________ Dollars, on the 1st day of September, 2033, subject to prior redemption, in any coin or currency of the United States of America which at the time of payment is legal tender for public and private debts, and to pay interest thereon, in like coin or currency, at the same rate or rates of interest as the Authority Bonds (as determined in accordance with the Authority Bond Indenture referred to below), but in no event shall the interest rate on this Bond exceed twelve percent (12%) per annum. Interest on overdue principal premium, if any, and, to the extent permitted by law, on overdue interest, shall be payable at the interest rate payable on the Authority Bonds. Interest on this Bond is payable on the same dates as interest on the Authority Bonds, or, if this Bond shall be duly called for redemption, until the redemption date, or if the Company shall default in the payment of the principal hereof, until the Company's obligation to pay principal shall be discharged as provided in the Amended Indenture is paid, until the principal sum is paid in full. The principal of, and interest on, this Bond are payable, in immediately available funds, at the office of the Authority Bond Trustee hereinafter referred to.

Under an Indenture of Trust dated as of September 1, 1998, as amended and restated by the Amended and Restated Indenture of Trust dated as of February 1, 2004 (as so amended and restated, the "Authority Bond Indenture") between the State Environmental Improvement and Energy Resources Authority of the State of Missouri (the "Authority") and UMB Bank & Trust, N.A., as successor to State Street Bank and Trust Company of Missouri, N.A., as trustee (the "Authority Bond Trustee"), the Authority has issued its Environmental Improvement Revenue

Refunding Bonds (Union Electric Company Project) Series 1998A in the aggregate principal amount of $60,000,000 (the "Authority Bonds"). The Company has agreed to pay the principal of and interest on the Authority Bonds pursuant to a Loan Agreement dated as of September 1, 1998, as supplemented and amended by the First Amendment to Loan Agreement dated as of February 1, 2004 (as so amended, the "Agreement") between the Company and the Authority. Pursuant to the Granting Clause of the Authority Bond Indenture, this Bond is issued to the Authority Bond Trustee to secure any and all obligations of the Company under the Agreement with respect to payment of the Authority Bonds. Payment of principal of, or interest on, the Authority Bonds shall constitute payments on this Bond as further provided herein and in the Supplemental Indenture dated February 1, 2004 pursuant to which this Bond has been issued (the "Supplemental Indenture").

Upon any payment of the principal of, and interest on, all or any portion of the Authority Bonds, whether at maturity or otherwise or upon provision for the payment thereof having been made in accordance with Section 7.01 of the Authority Bond Indenture, a principal amount of this Bond equal to the principal amount of such Authority Bonds shall, to the extent of such payment of principal and interest, be deemed paid and the obligation of the Company thereunder to make such payment shall be discharged to such extent and, in the case of the payment of principal, such Bonds shall be surrendered to the Company for cancellation as provided in Section 7.04 of the Authority Bond Indenture. The Trustee (as hereinafter defined) may at any time and all times conclusively assume that the obligation of the Company to make payments under the Agreement with respect to the principal of, and interest on, the Authority Bonds, so far as such payments at the time have become due, has been fully satisfied and discharged pursuant to the foregoing sentence unless and until the Trustee shall have received a written notice from the Authority Bond Trustee signed by one of its officers stating (i) that timely payment of principal of, or interest on, the Authority Bonds has not been made, (ii) that the Company is in arrears as to the payments required to be made by it to the Authority Bond Trustee pursuant to the Agreement, and (iii) the amount of the arrearage.

This Bond shall not be entitled to any benefit under the Amended Indenture or any indenture supplemental thereto, or become valid or obligatory for any purpose, until The Bank of New York, the Trustee under the Amended Indenture, or a successor trustee thereto under the Amended Indenture, or an agent therefor, shall have signed the form of certificate endorsed hereon.

The provisions of this Bond are continued on the reverse hereof and such continued provisions shall for all purposes have the same effect as though fully set forth at this place.

IN WITNESS WHEREOF, Union Electric Company has caused this Bond to be signed in its name by its Chairman of the Board or President or a Vice President by manual signature or a facsimile thereof, and its corporate seal (or a facsimile thereof) to be hereto affixed and attested by its Secretary or an Assistant Secretary by manual signature or a facsimile thereof.

Dated,
UNION ELECTRIC COMPANY,

[CORPORATE SEAL]

Attest:

[FORM OF TRUSTEE'S CERTIFICATE]

This Bond is one of the Bonds, of the series designated therein, described in the within-mentioned Amended Indenture and Supplemental Indenture of February 1, 2004.

THE BANK OF NEW YORK, as Trustee

[FORM OF REVERSE OF NEW BOND]

This Bond is one of a duly authorized issue of Bonds of the Company (herein called the "Bonds"), limited to an aggregate principal amount of $60,000,000, of the series hereinafter specified, all issued under and equally secured by the Indenture of Mortgage and Deed of Trust, dated June 15, 1937, executed by the Company to The Bank of New York (successor trustee to Bank of America, National Association, formerly Boatmen's Trust Company), as trustee (herein called the "Trustee"), as amended by indentures supplemental thereto dated May 1, 1941, April 1, 1971, February 1, 1974, July 7, 1980, February 1, 2000 and August 15, 2002, between the Company and the Trustee (said mortgage and deed of trust, as so amended, being herein called the "Amended Indenture"), to which Amended Indenture and all indentures supplemental thereto reference is hereby made for a description of the properties mortgaged and pledged, the nature and extent of the security, the rights of the bearers or registered owners of the Bonds and of the Trustee in respect thereto, and the terms and conditions upon which the Bonds are, and are to be, secured. To the extent permitted by, and as provided in, the Amended Indenture, modifications or alterations of the Amended Indenture, or of any indenture supplemental thereto, and of the rights and obligations of the Company and of the holders of the Bonds may be made with the consent of the Company by an affirmative vote of not less than 60% in amount of the Bonds entitled to vote then outstanding, at a meeting of Bondholders called and held as provided in the Amended Indenture, and by an affirmative vote of not less than 60% in amount of the

Bonds of any series entitled to vote then outstanding and affected by such modification or alteration, in case one or more but less than all of the series of Bonds then outstanding under the Amended Indenture are so affected. Additionally, the Company may amend the Amended Indenture, as supplemented, by an appropriate written consent of not less than 60% in aggregate principal amount of the Bonds outstanding (and, if the rights of one or more, but less than all, series of Bonds then outstanding are to be affected by action taken pursuant to such consent, then also by consent of the holders of at least 60% in principal amount of each series of Bonds so to be affected and outstanding hereunder) without a meeting of such Bondholders. No such modification or alteration shall be made which will affect the terms of payment of the principal of, or interest on, this Bond, which are unconditional. The Bonds may be issued in series, for various principal sums, may mature at different times, may bear interest at different rates and may otherwise vary as in the Amended Indenture provided. This Bond is one of a series designated as the "First Mortgage Bonds, Environmental Improvement Series 2004A (1998A Bonds)" (herein called the "Bonds of this Series") of the Company, issued under and secured by the Amended Indenture and described in the indenture (hereinafter called the "Supplemental Indenture") dated February 1, 2004, between the Company and the Trustee, supplemental to the Amended Indenture.

The Bonds of this Series are not entitled to the benefit of any improvement, maintenance or analogous fund.

This Bond is, subject to the provisions of the Amended Indenture, subject to redemption in the amounts, at the times, at the prices and under the circumstances under which the Authority Bonds are subject to redemption under the same terms and circumstances set forth in the Authority Bond Indenture for the redemption of the Authority Bonds.

This Bond is also subject to mandatory redemption at the principal amount hereof plus accrued interest to the date fixed for redemption if the Trustee or the Company is notified that an "Event of Default" under the Authority Bond Indenture has occurred and is continuing and the Authority Bond Trustee has declared the principal amount of all Authority Bonds then outstanding due and payable in accordance with the Authority Bond Indenture.

The Company may, by notice to the Trustee at least 60 days prior to any date on which any principal amount is due on this Bond, elect to receive a credit in respect of such principal payment (a) for any Bonds of this Series then due which have been redeemed prior to such principal payment date or otherwise acquired and delivered to the Trustee for cancellation by said Trustee prior to the giving of such notice, or (b) for any Authority Bonds which have been purchased, delivered for cancellation or previously redeemed, which in each case have not theretofore been applied as a credit against such principal payment. Each Bond with respect to which the Company elects to receive a credit will be credited by the Trustee at 100% of the principal amount thereof against such principal payment, provided further that in the case of a credit with respect to any Authority Bonds, the principal amount thereof shall be established by an officers' certificate (as defined in the Amended Indenture) concurred in by the Authority Bond Trustee, included with the above-mentioned notice to the Trustee. The principal amount of Bonds to be paid on the due date of such principal payment will be reduced by the amount of any such credit or credits in respect of Bonds previously redeemed or delivered as provided above.

Upon cancellation in full or in part of any of the Authority Bonds (or provision for payment thereof having been made in accordance with the provisions of the Authority Bond Indenture) and payment of all fees and charges of the trustee thereunder, such trustee shall deliver to the Trustee, for cancellation a corresponding amount of Bonds remaining in its possession.

Such redemption in every case shall be effected upon notice delivered by the Company at least 60 days prior to the date of redemption, to the registered owner of the Bonds at its address as the same shall appear on the transfer register of the Company, all subject to the conditions of, and as more fully set forth in, the Amended Indenture and Supplemental Indenture.

In case an event of default, as defined in the Amended Indenture, shall occur, the principal of all the bonds at any such time outstanding under the Amended Indenture may be declared or may become due and payable, upon the conditions and in the manner and with the effect provided in the Amended Indenture. The Amended Indenture provides that such declaration may in certain events be waived by the holders of a majority in principal amount of the bonds outstanding.

This Bond shall not be assignable or transferable except as permitted or required by Section 12.13 of the Authority Bond Indenture. This Bond is exchangeable by the registered owner hereof, in person or by duly authorized attorney, on the books of the Company to be kept for that purpose at the office of the Company in the City of St. Louis, Missouri, upon surrender and cancellation of this Bond and on presentation of a duly executed written instrument of transfer, and thereupon a new Bond or Bonds of the same series, of the same aggregate principal amount and in authorized denominations will be issued to the transferee or transferees in exchange herefor, without payment of any charge other than stamp taxes and other governmental charges incident thereto; and this Bond with or without others of like series, may in like manner be exchanged for one or more new Bonds of the same series of other authorized denominations but of the same aggregate principal amount; all subject to the terms and conditions set forth in the Amended Indenture.

As provided in Section 7.04 of the Authority Bond Indenture, from and after the Release Date (as defined in the Authority Bond Indenture), the obligations of the Company with respect to this Bond shall be deemed to be satisfied and discharged, this Bond shall cease to secure in any manner the Company's obligations under the Agreement with respect to the payment of any Authority Bonds outstanding under the Authority Bond Indenture, and, pursuant to Section 7.04 of the Authority Bond Indenture, the Authority Bond Trustee shall forthwith deliver this Bond to the Company for cancellation.

No recourse shall be had for the payment of the principal of, or the interest on, this Bond, or for any claim based hereon or on the Amended Indenture or any indenture supplemental thereto, against any incorporator, or against any stockholder, director or officer, past, present or future, of the Company, or of any predecessor or successor corporation, either directly or through the Company or any such predecessor or successor corporation, whether for amounts unpaid on stock subscriptions or by virtue of any constitution, statute or rule of law, or by the enforcement of any assessment or penalty or otherwise, all such liability, whether at common law, in equity,

by any constitution, statute or otherwise, of incorporators, stockholders, directors or officers being released by every owner hereof by the acceptance of this Bond and as part of the consideration for the issue hereof, and being likewise released by the terms of the Amended Indenture.

[END OF FORM OF REVERSE OF NEW BOND]

ARTICLE II

ISSUE OF THE NEW BONDS

Section 2.1. The principal amount of the New Bonds which may be authenticated and delivered hereunder is limited to an amount equal to the principal amount of Sixty Million Dollars ($60,000,000) consisting of Bonds maturing on September 1, 2033.

Section 2.2. The New Bonds in the aggregate principal amount set forth above, may forthwith be executed by the Company and delivered to the Trustee and shall be authenticated by the Trustee and delivered (either before or after the filing or recording hereof) to or upon the order of the Company, upon compliance by the Company with the applicable provisions of Article III and Article XVIII of the Original Indenture.

Section 2.3. As provided in Section 7.04 of the Authority Bond Indenture, from and after the Release Date (as defined in the Authority Bond Indenture), the obligations of the Company with respect to the New Bonds shall be deemed to be satisfied and discharged, the New Bonds shall cease to secure in any manner the Company's obligations under the Agreement with respect to the payment of any Authority Bonds outstanding under the Authority Bond Indenture, and, pursuant to
Section 7.04 of the Authority Bond Indenture, the Authority Bond Trustee shall forthwith deliver the New Bonds to the Company for cancellation.

ARTICLE III

REDEMPTION OF THE NEW BONDS

Section 3.1. The New Bonds are, subject to the provisions of the Original Indenture, subject to redemption in the amounts, at the times, at the prices and under the circumstances under which the Authority Bonds are subject to redemption, under the same terms and conditions set forth in the Authority Bond Indenture for the redemption of the Authority Bonds. In the event that less than all the New Bonds are to be redeemed, the New Bonds to be redeemed shall be determined by lot in such manner as the Trustee in its discretion shall deem proper, as in the Original Indenture provided.

The New Bonds are also subject to mandatory redemption as set forth in the form of New Bonds in Section 1.3 of Article I of this Supplemental Indenture.

Section 3.2. Subject to the provisions of Article V of the Original Indenture, notice of redemption shall be delivered by the Company at least 60 days prior to the date of redemption, to the registered owner of such Bonds at its address as the same shall appear on the transfer register of the Company.

Section 3.3. As provided in the Authority Bond Indenture, any amounts of money held in the Bond Fund provided in said Indenture and available for such purpose, which are at the request of the Company applied to the payments of the principal of, premium, if any, and interest on the Authority Bonds on any payment or redemption date, shall be applied as a credit on amounts otherwise due under the New Bonds; provided that the amount of such credit shall be established by an officers' certificate (as defined in the Amended Indenture), concurred in by the Authority Bond Trustee which shall be filed with the Trustee prior to the application of any such credit.

Upon cancellation in full or in part of any of the Authority Bonds (or provision for payment thereof having been made in accordance with the provisions of the Authority Bond Indenture) and payment of all fees and charges of the trustee thereunder, such trustee shall deliver to the Trustee, for cancellation a corresponding amount of New Bonds remaining in its possession or shall request such Trustee to issue a New Bond reflecting any such cancellation

ARTICLE IV

COVENANTS

The Company hereby covenants, warrants and agrees;

Section 4.1. That the Company is lawfully seized and possessed of all of the mortgaged property described in the granting clauses of this Supplemental Indenture; that it has good right and lawful authority to mortgage the same as provided in this Supplemental Indenture; and that such mortgaged property is, at the actual date of the issue of the New Bonds, free and clear of any deed of trust, mortgage, lien, charge or encumbrance thereon or affecting the title thereto prior to the Original Indenture, except as set forth in the granting clauses of the Original Indenture or this Supplemental Indenture.

Section 4.2. That, so long as any of the New Bonds are outstanding, whenever any officers' certificate is required to be filed or deposited with the Trustee pursuant to Section 3(b) of Article III of the Original Indenture upon an application for the authentication of additional Bonds pursuant to Article III of the Original Indenture, such officers' certificate shall include, in addition to the matters required to be stated therein by said Section 3(b), the statement with respect to the net earnings of the Company available for interest after property retirement appropriations required by Section 2 of Article V of the Supplemental Indenture of July 1, 1956.

Section 4.3. That, so long as any of the New Bonds are outstanding, the Company will not apply for the authentication and delivery of additional Bonds pursuant to Section 4 of Article III of the Original Indenture or the withdrawal of cash from the trust estate or the reduction of the amount of cash required to be paid into the trust estate or to satisfy the

maintenance and improvement funds under any provision of the Original Indenture or the Supplemental Indentures creating prior series of Bonds, on the basis of the amount of $15,000,000 excluded from net bondable value of property additions not subject to an unfunded prior lien pursuant to Section 3 of Article V of the Supplemental Indenture of October 1, 1945, or on the basis of the amount of $7,500,000 excluded from net bondable value of property additions not subject to an unfunded prior lien pursuant to Section 3 of Article V of the Supplemental Indenture of July 1, 1956.

Section 4.4. That, so long as any of the New Bonds are outstanding, the Company will not issue or permit to be issued any prior lien bonds secured by an unfunded prior lien in addition to the prior lien bonds secured by such unfunded prior lien at the time of first acquisition by the Company of property subject thereto (other than in lieu of lost, stolen or mutilated bonds or on the exchange for bonds already outstanding of an equal principal amount of other bonds of the same issue and the same series, if any, and of the same maturity), except upon compliance with the provisions of Section 16 of Article IV of the Original Indenture, nor unless the net earnings of the Company available for interest after property retirement appropriations (determined as provided in
Section 2 of Article V of the Supplemental Indenture of July 1, 1956), for any 12 consecutive calendar months during the period of 15 calendar months immediately preceding the first day of the month in which the additional prior lien bonds are to be issued, have been, in the aggregate, equal to not less than twice the annual interest charges on the indebtedness specified in subparagraphs
(i) and (ii) of paragraph (1) of Section 2(a) of said Article V; provided that, if the application for the issue of such additional prior lien bonds is upon the basis of payment at maturity of prior lien bonds theretofore sold or otherwise disposed of or the redemption or purchase thereof after a date two years prior to the date of maturity, the additional requirement imposed by this Section 4 with respect to net earnings of the Company available for interest after property retirement appropriations shall not apply. Any officers' certificate with respect to net earnings of the Company, required to be filed with the Trustee as a condition precedent to the issue of such additional prior lien bonds, shall include, in addition to the matters otherwise required to be stated therein, the matters required to be stated in an officers' certificate pursuant to paragraphs (1) and (2) of Section 2(a) of said Article V.

Section 4.5. That, so long as any of the New Bonds are outstanding, the Company will not acquire, by purchase, merger or otherwise, any property subject to a lien or liens which will on acquisition be an unfunded prior lien or prior liens, except upon compliance with the provisions of Section 14 of Article IV of the Original Indenture, nor unless the net earnings of such property available for interest after property retirement appropriations (determined in the manner provided in Section 2 of Article V of the Supplemental Indenture of July 1, 1956), for any 12 consecutive calendar months during the period of 15 calendar months immediately preceding the first day of the month in which the first acquisition of property subject to such lien or liens occurs, have been, in the aggregate, equal to not less than twice the amount of annual interest charges, on all outstanding indebtedness secured by such lien or liens. Any officers' certificate with respect to net earnings of such property, required to be filed with the Trustee as a condition precedent to the acquisition of such property, shall include, in addition to the matters otherwise required to be stated therein, the matters required to be stated in an officers' certificate pursuant to Section 2 of said Article V applicable, however, only to the net earnings of such property and to the indebtedness secured by such liens to which such property is subject.

ARTICLE V

THE TRUSTEE

The Trustee hereby accepts the trusts hereby declared and provided, and agrees to perform the same upon the terms and conditions in the Original Indenture and in this Supplemental Indenture set forth, and upon the following terms and conditions:

The Trustee shall not be responsible in any manner whatsoever for or in respect of the validity or sufficiency of this Supplemental Indenture or the due execution hereof by the Company or for or in respect of the recitals contained herein, all of which recitals are made by the Company solely.

ARTICLE VI

MISCELLANEOUS PROVISIONS

Section 6.1. Except as otherwise defined herein, all terms contained in this Supplemental Indenture shall, for all purposes thereof, have the meanings given to such terms in Article I of the Original Indenture.

Section 6.2. This Supplemental Indenture may be simultaneously executed in any number of counterparts, each of which when so executed shall be deemed to be an original; but such counterparts shall together constitute but one and the same instrument.

IN WITNESS WHEREOF, said Union Electric Company has caused this Supplemental Indenture to be executed on its behalf by its Chairman of the Board or President or one of its Vice Presidents and its corporate seal to be hereto affixed and said seal and this Supplemental Indenture to be attested by its Secretary or one of its Assistant Secretaries; and said The Bank of New York, in evidence of its acceptance of the trust hereby created, has caused this Supplemental Indenture to be executed on its behalf by its President or one of its Vice Presidents, and its corporate seal to be hereto affixed and said seal and this Supplemental Indenture to be attested by its Secretary, or one of its Assistant Secretaries; all as of the 1st day of February, Two thousand and four.

Attested:                               UNION ELECTRIC COMPANY,
                                          1901 Chouteau Avenue
                                          St. Louis, Missouri  63103


/s/ G. L. Waters                        By: /s/ Jerre E. Birdsong
----------------------------------         -------------------------------------
          G. L. Waters                  Name:   Jerre E. Birdsong
      Assistant Secretary               Title:  Vice President and Treasurer


Signed, sealed and delivered by
       UNION ELECTRIC COMPANY
       in the presence of:


/s/ Daphyne Bradley
----------------------------------
            Daphyne Bradley


/s/ Wayne K. Forbes
----------------------------------
            Wayne K. Forbes

As Witnesses

Attested:                               THE BANK OF NEW YORK,
                                          911 Washington Avenue
                                          St. Louis, Missouri  63101


/s/ Thomas Maple                        By: /s/ Robert J. Dunn
--------------------------------           -------------------------------------
                                        Name:   Robert J. Dunn
                                        Title:    As Agent


Signed, sealed and delivered by
       THE BANK OF NEW YORK
       in the presence of:


/s/ Daniel G. Dwyer
--------------------------------


/s/ Richard F. Novosak
--------------------------------

STATE OF MISSOURI          )
                           )  SS:
CITY OF ST. LOUIS          )

On this 17th day of February, 2004, before me appeared JERRE E. BIRDSONG, to me personally known, who, being by me duly sworn, did say that he is Vice President and Treasurer of UNION ELECTRIC COMPANY, a corporation, and that the seal affixed to the foregoing instrument is the corporate seal of said corporation, and that said instrument was signed and sealed in behalf of said corporation by authority of its Board of Directors, and said JERRE E. BIRDSONG acknowledged said instrument to be the free act and deed of said corporation.

IN TESTIMONY WHEREOF, I have hereto set my hand and affixed my official seal at my office, in the City and State aforesaid, the day and year last above written.

/s/ S. A. Kitchens
--------------------------------------

STATE OF MISSOURI          )
                           )  SS:
CITY OF ST. LOUIS          )

On this 17th day of February, 2004, before me appeared Rober J. Dunn, to me personally known, who, being by me duly sworn, did say that he is an Agent of THE BANK OF NEW YORK, a corporation, and that the seal affixed to the foregoing instrument is the corporate seal of said corporation, and that said instrument was signed and sealed in behalf of said corporation, as the trustee thereunder by authority of its Board of Directors, and said Vice President, acknowledged said instrument to be the free act and deed of said corporation as the trustee under said instrument.

IN TESTIMONY WHEREOF, I have hereto set my hand and affixed my official seal at my office, in the City and State aforesaid, the day and year last above written.

/s/ Sally Lardge
--------------------------------------

Exhibit 4.2

WHEN RECORDED
MAIL TO:

Executed in 35 Counterparts, No. 35

SUPPLEMENTAL INDENTURE

DATED FEBRUARY 1, 2004

UNION ELECTRIC COMPANY

TO

THE BANK OF NEW YORK,
AS TRUSTEE

(SUPPLEMENTAL TO THE INDENTURE OF MORTGAGE AND DEED OF
TRUST DATED JUNE 15, 1937, AS AMENDED, EXECUTED BY

UNION ELECTRIC COMPANY
TO THE BANK OF NEW YORK, AS TRUSTEE)

First Mortgage Bonds, Environmental Improvement Series 2004B (1998B Bonds)

This instrument was prepared by Steven R. Sullivan, Senior Vice President Governmental/Regulatory Policy, General Counsel and Secretary of Union Electric Company, 1901 Chouteau Avenue, St. Louis, Missouri 63103, (314) 554-2098.

SUPPLEMENTAL INDENTURE, dated the 1st day of February, Two thousand and four (2004) made by and between UNION ELECTRIC COMPANY, a corporation organized and existing under the laws of the State of Missouri (hereinafter called the "Company"), party of the first part, and The Bank of New York (successor trustee to Bank of America, National Association, formerly Boatmen's Trust Company), a bank existing under the laws of the State of New York (hereinafter called the "Trustee"), as Trustee under the Indenture of Mortgage and Deed of Trust dated June 15, 1937, hereinafter mentioned, party of the second part:

WHEREAS, the Company has heretofore executed and delivered to the Trustee its Indenture of Mortgage and Deed of Trust, dated June 15, 1937, as amended May 1, 1941, April 1, 1971, February 1, 1974, July 7, 1980, February 1, 2000 and August 15, 2002 (said Indenture of Mortgage and Deed of Trust as so amended, being hereinafter referred to as the "Original Indenture"), to secure the payment of the principal of and the interest (and premium, if any) on all bonds at any time issued and outstanding thereunder, and indentures supplemental thereto dated June 15, 1937, May 1, 1941, March 17, 1942, April 13, 1945, April 27, 1945, October 1, 1945, April 11, 1947, April 13, 1949, September 13, 1950, December 1, 1950, September 20, 1951, May 1, 1952, March 1, 1954, May 1, 1955, August 31, 1955, April 1, 1956, July 1, 1956, August 1, 1957, February 1, 1958, March 1, 1958, November 5, 1958, March 16, 1959, June 24, 1959, December 11, 1959, August 17, 1960, September 1, 1960, October 24, 1960, June 30, 1961, July 1, 1961, August 9, 1962, September 30, 1963, November 1, 1963, March 12, 1965, April 1, 1965, April 14, 1966, May 1, 1966, February 17, 1967, March 1, 1967, February 19, 1968, March 15, 1968, August 21, 1968, April 7, 1969, May 1, 1969, September 12, 1969, October 1, 1969, March 26, 1970, April 1, 1970, June 12, 1970, January 1, 1971, April 1, 1971, September 15, 1971, December 3, 1973, February 1, 1974, April 25, 1974, February 3, 1975, March 1, 1975, June 11, 1975, May 12, 1976, August 16, 1976, April 26, 1977, October 15, 1977, November 7, 1977, December 1, 1977, August 1, 1978, October 12, 1979, November 1, 1979, July 7, 1980, August 1, 1980, August 20, 1980, February 1, 1981, October 8, 1981, August 27, 1982, September 1, 1982, December 15, 1982, March 1, 1983, June 21, 1984, December 12, 1984, June 11, 1985, March 1, 1986, May 1, 1986, May 1, 1990, December 1, 1991, December 4, 1991, January 1, 1992, September 30, 1992, October 1, 1992, December 1, 1992, February 1, 1993, February 18, 1993, May 1, 1993, August 1, 1993, October 1, 1993, January 1, 1994, February 1, 2000, August 15, 2002, March 5, 2003, April 1, 2003, July 15, 2003 and October 1, 2003, respectively, have heretofore been entered into between the Company and the Trustee; and

WHEREAS, Bonds have heretofore been issued by the Company under the Original Indenture as follows:

(1) $80,000,000 principal amount of First Mortgage and Collateral Trust Bonds, 3-3/4% Series due 1962, all of which have been redeemed prior to the date of the execution hereof;

(2) $90,000,000 principal amount of First Mortgage and Collateral Trust Bonds, 3-3/8% Series due 1971, which are described in the Supplemental Indenture dated

May 1, 1941 (hereinafter called the "Supplemental Indenture of May 1, 1941"), all of which have been paid at maturity prior to the date of the execution hereof;

(3) $13,000,000 principal amount of First Mortgage and Collateral Trust Bonds, 2-3/4% Series due 1975 (herein called the "Bonds of 1975 Series"), which are described in the Supplemental Indenture dated October 1, 1945 (hereinafter called the "Supplemental Indenture of October 1, 1945"), all of which have been paid at maturity prior to the date of the execution hereof;

(4) $25,000,000 principal amount of First Mortgage and Collateral Trust Bonds, 2-7/8% Series due 1980 (herein called the "Bonds of 1980 Series"), which are described in the Supplemental Indenture dated December 1, 1950 (hereinafter called the "Supplemental Indenture of December 1, 1950"), all of which have been paid at maturity prior to the date of the execution hereof;

(5) $30,000,000 principal amount of First Mortgage and Collateral Trust Bonds, 3-1/4% Series due 1982 (herein called the "Bonds of 1982 Series"), which are described in the Supplemental Indenture dated May 1, 1952 (hereinafter called the "Supplemental Indenture of May 1, 1952"), all of which have been paid at maturity prior to the date of the execution hereof;

(6) $40,000,000 principal amount of First Mortgage Bonds, 3-3/4% Series due 1986 (herein called the "Bonds of 1986 Series"), which are described in the Supplemental Indenture dated July 1, 1956 (hereinafter called the "Supplemental Indenture of July 1, 1956"), all of which have been paid at maturity prior to the date of the execution hereof;

(7) $35,000,000 principal amount of First Mortgage Bonds, 4-3/8% Series due 1988 (herein called the "Bonds of 1988 Series"), which are described in the Supplemental Indenture dated March 1, 1958 (hereinafter called the "Supplemental Indenture of March 1, 1958"), all of which have been paid at maturity prior to the date of the execution hereof;

(8) $50,000,000 principal amount of First Mortgage Bonds, 4-3/4% Series due 1990 (herein called the "Bonds of 1990 Series"), which are described in the Supplemental Indenture dated September 1, 1960 (hereinafter called the "Supplemental Indenture of September 1, 1960"), all of which have been paid at maturity prior to the date of the execution hereof;

(9) $30,000,000 principal amount of First Mortgage Bonds, 4-3/4% Series due 1991 (herein called the "Bonds of 1991 Series"), which are described in the Supplemental Indenture dated July 1, 1961 (hereinafter called the "Supplemental Indenture of July 1, 1961"), all of which have been paid at maturity prior to the date of the execution hereof;

(10) $30,000,000 principal amount of First Mortgage Bonds, 4-1/2% Series due 1993 (herein called the "Bonds of 1993 Series"), which are described in the

Supplemental Indenture dated November 1, 1963 (hereinafter called the "Supplemental Indenture of November 1, 1963"), all of which have been redeemed prior to the date of the execution hereof;

(11) $35,000,000 principal amount of First Mortgage Bonds, 4-1/2% Series due 1995 (herein called the "Bonds of 1995 Series"), which are described in the Supplemental Indenture dated April 1, 1965 (hereinafter called the "Supplemental Indenture of April 1, 1965"), all of which have been paid at maturity prior to the date of the execution hereof;

(12) $30,000,000 principal amount of First Mortgage Bonds, 5-1/2% Series due 1996 (herein called the "Bonds of 1996 Series"), which are described in the Supplemental Indenture dated May 1, 1966 (hereinafter called the "Supplemental Indenture of May 1, 1966"), all of which have been paid at maturity prior to the date of the execution hereof;

(13) $40,000,000 principal amount of First Mortgage Bonds, 5-1/2% Series due 1997 (herein called the "Bonds of 1997 Series"), which are described in the Supplemental Indenture dated March 1, 1967 (hereinafter called the "Supplemental Indenture of March 1, 1967"), all of which have been paid at maturity prior to the date of the execution hereof;

(14) $50,000,000 principal amount of First Mortgage Bonds, 7% Series due 1998 (herein called the "Bonds of 1998 Series"), which are described in the Supplemental Indenture dated March 15, 1968 (hereinafter called the "Supplemental Indenture of March 15, 1968"), all of which have been redeemed prior to the date of the execution hereof;

(15) $35,000,000 principal amount of First Mortgage Bonds, 7-3/8% Series due 1999 (herein called the "Bonds of May 1999 Series"), which are described in the Supplemental Indenture dated May 1, 1969 (hereinafter called the "Supplemental Indenture of May 1, 1969"), all of which have been redeemed prior to the date of the execution hereof;

(16) $40,000,000 principal amount of First Mortgage Bonds, 8-1/4% Series due 1999 (herein called the "Bonds of October 1999 Series"), which are described in the Supplemental Indenture dated October 1, 1969 (hereinafter called the "Supplemental Indenture of October 1, 1969"), all of which have been redeemed prior to the date of the execution hereof;

(17) $100,000,000 principal amount of First Mortgage Bonds, 9.95% Series due 1999 (herein called the "Bonds of November 1999 Series"), which are described in the Supplemental Indenture dated November 1, 1979 (hereinafter called the "Supplemental Indenture of November 1, 1979"), all of which have been redeemed prior to the date of the execution hereof;

(18) $60,000,000 principal amount of First Mortgage Bonds, 9% Series due 2000 (herein called the "Bonds of 2000 Series"), which are described in the Supplemental Indenture dated April 1, 1970 (hereinafter called the "Supplemental Indenture of April 1, 1970"), all of which have been redeemed prior to the date of the execution hereof;

(19) $50,000,000 principal amount of First Mortgage Bonds, 7-7/8% Series due 2001 (herein called the "Bonds of January 2001 Series"), which are described in the Supplemental Indenture dated January 1, 1971 (hereinafter called the "Supplemental Indenture of January 1, 1971"), all of which have been redeemed prior to the date of the execution hereof;

(20) $50,000,000 principal amount of First Mortgage Bonds, 7 5/8% Series due 2001 (herein called the "Bonds of April 2001 Series"), which are described in the Supplemental Indenture dated April 1, 1971 (hereinafter called the "Supplemental Indenture of April 1, 1971"), all of which have been redeemed prior to the date of the execution hereof;

(21) $60,000,000 principal amount of First Mortgage Bonds, 8 1/8% Series due 2001 (herein called the "Bonds of October 2001 Series"), which are described in the Supplemental Indenture dated September 15, 1971 (hereinafter called the "Supplemental Indenture of September 15, 1971"), all of which have been redeemed prior to the date of the execution hereof;

(22) $70,000,000 principal amount of First Mortgage Bonds, 8-3/8% Series due 2004 (herein called the "Bonds of 2004 Series"), which are described in the Supplemental Indenture dated February 1, 1974 (hereinafter called the "Supplemental Indenture of February 1, 1974"), all of which have been redeemed prior to the date of the execution hereof;

(23) $70,000,000 principal amount of First Mortgage Bonds, 10-1/2% Series due 2005 (herein called the "Bonds of 2005 Series"), which are described in the Supplemental Indenture dated March 1, 1975 (hereinafter called the "Supplemental Indenture of March 1, 1975"), all of which have been redeemed prior to the date of the execution hereof;

(24) $70,000,000 principal amount of First Mortgage Bonds, 8-7/8% Series due 2006 (herein called the "Bonds of 2006 Series"), which are described in the Supplemental Indenture dated August 16, 1976 (hereinafter called the "Supplemental Indenture of August 16, 1976"), all of which have been redeemed prior to the date of the execution hereof;

(25) $27,085,000 principal amount of First Mortgage Bonds, 5.80% Environmental Improvement Series 1977, which are described in the Supplemental Indenture dated October 15, 1977 (hereinafter called the "Supplemental Indenture of October 15, 1977"), all of which have been redeemed prior to the date of the execution hereof;

(26) $60,000,000 principal amount of First Mortgage Bonds, 8 5/8% Series due 2007 (herein called the "Bonds of 2007 Series"), which are described in the Supplemental Indenture dated December 1, 1977 (hereinafter called the "Supplemental Indenture of December 1, 1977"), all of which have been redeemed prior to the date of the execution hereof;

(27) $55,000,000 principal amount of First Mortgage Bonds, 9.35% Series due 2008 (herein called the "Bonds of 2008 Series"), which are described in the Supplemental Indenture dated August 1, 1978 (hereinafter called the "Supplemental Indenture of August 1, 1978"), all of which have been redeemed prior to the date of the execution hereof;

(28) $60,000,000 principal amount of First Mortgage Bonds, Environmental Improvement Series 1980, which are described in the Supplemental Indenture dated August 1, 1980 (hereinafter called the "Supplemental Indenture of August 1, 1980"), all of which have been redeemed prior to the date of the execution hereof;

(29) $150,000,000 principal amount of First Mortgage Bonds, 15-3/8% Series due 1991 (herein called the "Bonds of February 1991 Series"), which are described in the Supplemental Indenture dated February 1, 1981 (hereinafter called the "Supplemental Indenture of February 1, 1981"), all of which have been redeemed prior to the date of the execution hereof;

(30) $125,000,000 principal amount of First Mortgage Bonds, 15% Series due 1992 (herein called the "Bonds of 1992 Series"), which are described in the Supplemental Indenture dated September 1, 1982 (hereinafter called the "Supplemental Indenture of September 1, 1982"), all of which have been redeemed prior to the date of the execution hereof;

(31) $100,000,000 principal amount of First Mortgage Bonds, 13% Series due 2013 (herein called the "Bonds of 2013 Series"), which are described in the Supplemental Indenture dated March 1, 1983 (hereinafter called the "Supplemental Indenture of March 1, 1983"), all of which have been redeemed prior to the date of the execution hereof;

(32) $100,000,000 principal amount of First Mortgage Bonds, 9-3/8% Series due 2016 (herein called the "Bonds of 2016 Series"), which are described in the Supplemental Indenture dated March 1, 1986 (hereinafter called the "Supplemental Indenture of March 1, 1986"), all of which have been redeemed prior to the date of the execution hereof;

(33) $100,000,000 principal amount of First Mortgage Bonds, 8-7/8% Series due 1996 (herein called the "Bonds of 1996 Series"), which are described in the Supplemental Indenture dated May 1, 1986 (hereinafter called the "Supplemental Indenture of May 1, 1986"), all of which have been redeemed prior to the date of the execution hereof;

(34) $60,000,000 principal amount of First Mortgage Bonds, Environmental Improvement Series 1990A, which are described in the Supplemental Indenture dated May 1, 1990 (hereinafter called the "Supplemental Indenture of May 1, 1990"), all of which have been redeemed prior to the date of the execution hereof;

(35) $125,000,000 principal amount of First Mortgage Bonds, 8-3/4% Series due 2021 (herein called the "Bonds of 2021 Series"), which are described in the Supplemental Indenture dated December 1, 1991 (hereinafter called the "Supplemental Indenture of December 1, 1991"), all of which have been redeemed prior to the date of the execution hereof;

(36) $75,000,000 principal amount of First Mortgage Bonds, 8.33% Series due 2002 (herein called the "Bonds of 2002 Series"), which are described in the Supplemental Indenture dated December 4, 1991 (hereinafter called the "Supplemental Indenture of December 4, 1991"), all of which have been paid at maturity prior to the date of the execution hereof;

(37) $100,000,000 principal amount of First Mortgage Bonds, 7.65% Series due 2003 (herein called the "Bonds of 2003 Series"), which are described in the Supplemental Indenture dated January 1, 1992 (hereinafter called the "Supplemental Indenture of January 1, 1992"), all of which have been paid at maturity prior to the date of the execution hereof;

(38) $204,000,000 aggregate principal amount of First Mortgage Bonds, consisting of $100,000,000 principal amount of 6-3/4% Series due 1999 and $104,000,000 principal amount of 8-1/4% Series due 2022 (herein called the "Bonds of 1999 Series" and "Bonds of 2022 Series", respectively), which are described in the Supplemental Indenture dated October 1, 1992 (hereinafter called the "Supplemental Indenture of October 1, 1992"), of which the Bonds of 1999 Series have been paid at maturity prior to the date of execution hereof and the Bonds of 2022 Series have been redeemed prior to the date of the execution hereof;

(39) $170,000,000 aggregate principal amount of First Mortgage Bonds, consisting of $85,000,000 principal amount of 7-3/8% Series due 2004 and $85,000,000 principal amount of 8% Series due 2022 (herein called the "Bonds of December 2004 Series" and "Bonds of December 2022 Series", respectively, which are described in the Supplemental Indenture dated December 1, 1992, (hereinafter called the "Supplemental Indenture of December 1, 1992"), of which the Bonds of December 2022 Series have been redeemed prior to the date of the execution hereof and the Bonds of December 2004 Series are outstanding at the date of the execution hereof;

(40) $188,000,000 principal amount of First Mortgage Bonds, 6-7/8% Series due 2004 (herein called the "Bonds of August 2004 Series"), which are described in the Supplemental Indenture dated February 1, 1993 (hereinafter called the "Supplemental Indenture of February 1, 1993"), all of which are outstanding at the date of the execution hereof;

(41) $148,000,000 principal amount of First Mortgage Bonds, 6-3/4% Series due 2008 (herein called the "Bonds of May 2008 Series"), which are described in the Supplemental Indenture dated May 1, 1993 (hereinafter called the "Supplemental Indenture of May 1, 1993"), all of which are outstanding at the date of the execution hereof;

(42) $75,000,000 principal amount of First Mortgage Bonds, 7.15% Series due 2023 (herein called the "Bonds of 2023 Series"), which are described in the Supplemental Indenture dated August 1, 1993 (hereinafter called the "Supplemental Indenture of August 1, 1993"), all of which have been redeemed prior to the date of the execution hereof;

(43) $44,000,000 principal amount of First Mortgage Bonds, Environmental Improvement Series 1993 (herein called the "Bonds of 2028 Series"), which are described in the Supplemental Indenture dated October 1, 1993 (hereinafter called the "Supplemental Indenture of October 1, 1993"), all of which are outstanding at the date of the execution hereof;

(44) $100,000,000 principal amount of First Mortgage Bonds, 7% Series due 2024 (herein called the "Bonds of 2024 Series"), which are described in the Supplemental Indenture dated January 1, 1994 (hereinafter called the "Supplemental Indenture of January 1, 1994"), all of which are outstanding at the date of the execution hereof;

(45) $173,000,000 principal amount of First Mortgage Bonds, Senior Notes Series AA (herein called the "Bonds of 2012 Series"), which are described in the Supplemental Indenture dated August 15, 2002 (hereinafter called the "Supplemental Indenture of August 15, 2002"), all of which are outstanding at the date of the execution hereof;

(46) $184,000,000 principal amount of First Mortgage Bonds, Senior Notes Series BB (herein called the "Bonds of 2034 Series"), which are described in the Supplemental Indenture dated March 5, 2003 (hereinafter called the "Supplemental Indenture of March 5, 2003"), all of which are outstanding at the date of the execution hereof;

(47) $114,000,000 principal amount of First Mortgage Bonds, Senior Notes Series CC (herein called the "Bonds of 2015 Series"), which are described in the Supplemental Indenture dated April 1, 2003 (hereinafter called the "Supplemental Indenture of April 1, 2003"), all of which are outstanding at the date of the execution hereof;

(48) $200,000,000 principal amount of First Mortgage Bonds, Senior Notes Series DD (herein called the "Bonds of 2018 Series"), which are described in the Supplemental Indenture dated July 15, 2003 (hereinafter called the "Supplemental Indenture of July 15, 2003"), all of which are outstanding at the date of the execution hereof; and

(49) $200,000,000 principal amount of First Mortgage Bonds, Senior Notes Series EE (herein called the "Bonds of 2013 Series"), which are described in the Supplemental Indenture dated October 1, 2003 (hereinafter called the "Supplemental Indenture of October 1, 2003"), all of which are outstanding at the date of the execution hereof; and

WHEREAS, the following Bonds will be issued by the Company pursuant to this Supplemental Indenture or pursuant to a separate Supplemental Indenture each dated February 1, 2004 and each series of such Bonds will be outstanding upon the authentication by the Trustee of such Bonds:

(A) $50,000,000 principal amount of First Mortgage Bonds, Environmental Improvement Series 2004B (1998B Bonds) (herein called the "New Bonds"), which are described in the Supplemental Indenture dated February 1, 2004 (hereinafter called "this Supplemental Indenture" or the "Supplemental Indenture of February 1, 2004 (2004B)"), all of which will be outstanding upon the authentication by the Trustee of the New Bonds; and

(B) $60,000,000 principal amount of First Mortgage Bonds, Environmental Improvement Series 2004A (1998A Bonds) (herein called the "Bonds of 2033 (Series 1998A)"), which are described in the Supplemental Indenture dated February 1, 2004 (hereinafter called the "Supplemental Indenture of February 1, 2004 (2004A)"), all of which will be outstanding upon the authentication by the Trustee of the Bonds of 2033 (Series 1998A);

(C) $50,000,000 principal amount of First Mortgage Bonds, Environmental Improvement Series 2004C (1998C Bonds) (herein called the "Bonds of 2033 (Series 1998C)"), which are described in the Supplemental Indenture dated February 1, 2004 (hereinafter called the "Supplemental Indenture of February 1, 2004 (2004C)"), all of which will be outstanding upon the authentication by the Trustee of the Bonds of 2033 (Series 1998C);

and

WHEREAS, the Company on August 31, 1955 acquired all of the properties of Union Electric Power Company, the Subsidiary as defined in Article I of the Original Indenture, upon the dissolution of the Subsidiary; the Company, by Supplemental Indenture dated August 31, 1955, conveyed all of the properties so acquired (other than property of the character defined as excepted property in the granting clauses of the Original Indenture) to the Trustee upon the terms and trusts in the Original Indenture and the indentures supplemental thereto set forth for the equal and proportionate benefit and security of all present and future holders of the Bonds and coupons issued and to be issued thereunder, all the shares of stock of the Subsidiary were released from the lien of the Original Indenture; and the Company became entitled to change the general designation of the Bonds so as to omit the words "and Collateral Trust"; and

WHEREAS, the Articles of Incorporation of the Company were duly amended on April 23, 1956, to change its corporate name from "Union Electric Company of Missouri" to "Union Electric Company"; and

WHEREAS, the Articles of Agreement of the Trustee were duly amended effective on January 4, 1982 to change its corporate name from "St. Louis Union Trust Company" to "Centerre Trust Company of St. Louis", and further amended on December 9, 1988, to change its corporate name from "Centerre Trust Company of St. Louis" to "Boatmen's Trust Company"; and

WHEREAS, that on March 13, 1998, Boatmen's Trust Company merged into NationsBank, National Association and effective July 5, 1999, changed its name to Bank of America, National Association; and

WHEREAS, that on February 1, 2000, The Bank of New York, as transferee of the corporate trust business of Bank of America, National Association (formerly known as Boatmen's Trust Company), Trustee under the Original Indenture, became successor Trustee under the Original Indenture; and

WHEREAS, the Company is entitled at this time to have authenticated and delivered additional Bonds on the basis of property additions upon compliance with and pursuant to the provisions of Article III, Section 4 of the Original Indenture; and

WHEREAS, the Company has entered into a Loan Agreement dated as of September 1, 1998 (the "Original Loan Agreement") with the State Environmental Improvement and Energy Resources Authority of the State of Missouri (the "Authority") pursuant to which the Authority agreed to issue $50,000,000 aggregate principal amount of its Environmental Improvement Revenue Refunding Bonds (Union Electric Company Project) Series 1998B (the "Authority Bonds"), all of which are presently outstanding and loan the proceeds thereof to the Company; and

WHEREAS, the Authority Bonds were issued pursuant to an Indenture of Trust dated as of September 1, 1998 (the "Original Authority Bond Indenture") between the Authority and UMB Bank & Trust, N.A., as successor to State Street Bank and Trust Company of Missouri, N.A., as trustee (the "Authority Bond Trustee"); and

WHEREAS, the Company has determined it to be necessary and desirable to further secure rights of the owners of the Authority Bonds to the payment of principal and interest on the Authority Bonds by obtaining a Financial Guaranty Insurance Policy with respect to the Authority Bonds (the "Authority Bond Insurance Policy") from MBIA Insurance Corporation and in furtherance thereof
(i) the Authority and the Authority Bond Trustee will enter into an Amended and Restated Indenture of Trust dated as of February 1, 2004 (the "Authority Bond Indenture") which amends and restates the Original Authority Bond Indenture, and
(ii) the Authority and the Company will enter into the First Amendment to Loan Agreement dated as of February 1, 2004 (the "First Amendment to Loan Agreement"), which amends the Original Loan

Agreement (the Original Loan Agreement as so amended is referred to herein as the "Agreement"); and

WHEREAS, in connection with obtaining the Authority Bond Insurance Policy, the Company desires by this Supplemental Indenture to provide for the issuance to the Authority Bond Trustee of a new series of Bonds under the Original Indenture as security for the Company's obligations under the Agreement with respect to the payment of the Authority Bonds, to have the designation provided in Article I, Section 1 hereof (herein called the "New Bonds"), and the Original Indenture provides that certain terms and provisions, as determined by the Board of Directors of the Company, of the Bonds of any particular series may be expressed in and provided by the execution of an appropriate supplemental indenture; and

WHEREAS, the Original Indenture provides that the Company and the Trustee may enter into indentures supplemental to the Original Indenture specifically to convey, transfer and assign to the Trustee and to subject to the lien of the Original Indenture additional properties acquired by the Company; and

WHEREAS, the Company, in the exercise of the powers and authority conferred upon and reserved to it under the provisions of the Original Indenture and pursuant to appropriate resolutions of the Board of Directors, has duly resolved and determined to make, execute and deliver to the Trustee a Supplemental Indenture in the form hereof for the purposes herein provided; and

WHEREAS, all conditions and requirements necessary to make this Supplemental Indenture a valid, binding and legal instrument have been done, performed and fulfilled and the execution and delivery hereof have been in all respects duly authorized;

NOW, THEREFORE, THIS INDENTURE WITNESSETH:

That, in consideration of the premises and of the mutual covenants herein contained and of the acceptance of this trust by the Trustee and of the sum of One Dollar duly paid by the Trustee to the Company at or before the time of the execution of this Supplemental Indenture, and of other valuable considerations, the receipt whereof is hereby acknowledged, and in order further to secure the payment of the principal of and interest (and premium, if any) on all Bonds at any time issued and outstanding under the Original Indenture, according to their tenor and effect, and to secure the Company's obligations under the Agreement with respect to the payment of the Authority Bonds, the Company has executed and delivered this Supplemental Indenture and has granted, bargained, sold, warranted, aliened, remised, released, conveyed, assigned, transferred, mortgaged, pledged, set over and confirmed and by these presents does grant, bargain, sell, warrant, alien, remise, release, convey, assign, transfer, mortgage, pledge, set over and confirm unto The Bank of New York, as Trustee, and to its successors in trust under the Original Indenture forever, all and singular the following described properties (in addition to all other properties heretofore subjected to the lien of the Original Indenture and not heretofore released from the lien thereof) - that is to say:

FIRST

ALL power houses, plants, buildings and other structures, dams, dam sites, substations, heating plants, gas works, holders and tanks, together with all and singular the electric, heating, gas and mechanical appliances appurtenant thereto of every nature whatsoever, now owned by the Company, including all and singular the machinery, engines, boilers, furnaces, generators, dynamos, turbines and motors, and all and every character of mechanical appliance for generating or producing electricity, steam, gas and other agencies for light, heat, cold, or power or other purposes, and all transmission and distribution systems used for the transmission and distribution of electricity, steam, gas and other agencies for light, heat, cold or power or any other purpose whatsoever, whether underground or overhead, surface or otherwise, now owned by the Company, including all poles, towers, posts, wires, cables, conduits, manholes, mains, pipes, tubes, drains, furnaces, switchboards, transformers, conductors, insulators, supports, meters, lamps, fuses, junction boxes, regulator stations, and other electric, steam and gas fixtures and apparatus; all of the aforementioned property being located in the City of St. Louis, the counties of Adair, Audrain, Benton, Bollinger, Boone, Butler, Caldwell, Callaway, Camden, Cape Girardeau, Clark, Clay, Clinton, Cole, Cooper, Crawford, Daviess, Dunklin, Franklin, Gasconade, Howard, Iron, Jefferson, Knox, Lewis, Lincoln, Livingston, Macon, Madison, Maries, Marion, Miller, Mississippi, Moniteau, Montgomery, Morgan, New Madrid, Osage, Pemiscot, Perry, Pettis, Phelps, Pike, Pulaski, Ralls, Randolph, Ray, Reynolds, Ripley, St. Charles, St. Francois, Ste. Genevieve, St. Louis, Saline, Schuyler, Scott, Stoddard, Warren, Washington, and Wayne, Missouri, the counties of Adams, Alexander, Calhoun, Franklin, Hancock, Henderson, Jackson, Jersey, Macoupin, Madison, Massac, Monroe, Perry, Pike, Pulaski, St. Clair, Union, and Washington, Illinois, and the counties of Des Moines, Henry, Johnson, Lee, and Washington, Iowa, upon real estate owned by the Company, or occupied by it under rights to so occupy, which real estate is described in the Indenture of Mortgage and Deed of Trust dated June 15, 1937, in the Supplemental Indentures dated May 1, 1941, March 17, 1942, April 13, 1945, April 27, 1945, October 1, 1945, April 11, 1947, April 13, 1949, September 13, 1950, December 1, 1950, September 20, 1951, May 1, 1952, March 1, 1954, May 1, 1955, August 31, 1955, April 1, 1956, July 1, 1956, August 1, 1957, February 1, 1958, March 1, 1958, November 5, 1958, March 16, 1959, June 24, 1959, December 11, 1959, August 17, 1960, September 1, 1960, October 24, 1960, June 30, 1961, July 1, 1961, August 9, 1962, September 30, 1963, November 1, 1963, March 12, 1965, April 1, 1965, April 14, 1966, May 1, 1966, February 17, 1967, March 1, 1967, February 19, 1968, March 15, 1968, August 21, 1968, April 7, 1969, May 1, 1969, September 12, 1969, October 1, 1969, March 26, 1970, April 1, 1970, June 12, 1970, January 1, 1971, April 1, 1971, September 15, 1971, December 3, 1973, February 1, 1974, April 25, 1974, February 3, 1975, March 1, 1975, June 11, 1975, May 12, 1976, August 16, 1976, April 26, 1977, October 15, 1977, November 7, 1977, December 1, 1977, August 1, 1978, October 12, 1979, November 1, 1979, July 7, 1980, August 1, 1980, August 20, 1980, February 1, 1981, October 8, 1981, August 27, 1982, September 1, 1982, December 15, 1982, March 1, 1983, June 21, 1984, December 12, 1984, June 11, 1985, March 1, 1986, May 1, 1986, May 1, 1990, December 1, 1991, December 4, 1991, January 1, 1992, September 30, 1992, October 1, 1992, December 1, 1992, February 1, 1993, February 18, 1993, May 1, 1993, August 1, 1993, October 1, 1993, January 1, 1994, February 1, 2000, August 15, 2002, March 5, 2003, April 1, 2003, July 15, 2003, October 1, 2003 and in this Supplemental Indenture and the seven other Supplemental Indentures each dated

February 1, 2004, or attached to or connected with such real estate or transmission or distribution systems of the Company leading from or into such real estate.

SECOND

ALSO, (except as in the Original Indenture expressly excepted) all franchises and all permits, ordinances, easements, privileges, immunities and licenses, all rights to construct, maintain and operate overhead, surface and underground systems for the distribution and transmission of electricity, steam, gas or other agencies for the supply to itself or others of light, heat, cold or power, all rights-of-way, all waters, water rights and flowage rights and all grants and consents, now owned or, subject to the provisions of Article XII of the Original Indenture, which it may hereafter acquire.

ALSO, (except as in the Original Indenture expressly excepted) all inventions, patent rights and licenses of every kind now owned by the Company or, subject to the provisions of Article XII of the Original Indenture, which it may hereafter acquire.

THIRD

ALSO, subject to the provisions of Article XII of the Original Indenture, all other property, real, personal and mixed (except as therein or herein expressly excepted) of every nature and kind and wheresoever situated now or hereafter possessed by or belonging to the Company, or to which it is now, or may at any time hereafter be, in any manner entitled at law or in equity.

TO HAVE AND TO HOLD all said properties, real, personal and mixed, mortgaged, pledged and conveyed by the Company as aforesaid, or intended so to be, unto the Trustee and its successors and assigns forever;

SUBJECT, HOWEVER, to the exceptions and reservations and matters hereinabove recited, to existing leases, to existing liens upon rights of way for transmission or distribution line purposes, as defined in Article I of the Original Indenture, and any extensions thereof, and subject to existing easements for streets, alleys, highways, rights-of-way and railroad purposes over, upon and across certain of the property hereinbefore described, and subject also to all the terms, conditions, agreements, covenants, exceptions and reservations expressed or provided in the deeds or other instruments respectively under and by virtue of which the Company acquired the properties hereinabove described, and to undetermined liens and charges, if any, incidental to construction or other existing permitted liens as defined in Article I of the Original Indenture;

IN TRUST, NEVERTHELESS, upon the terms and trusts in the Original Indenture and the indentures supplemental thereto, including this Supplemental Indenture, set forth, for the equal and proportionate benefit and security of all present and future holders of the Bonds and coupons issued and to be issued thereunder, or any of them, without preference of any of said Bonds and coupons of any particular series over the Bonds and coupons of any other series, by reason of priority in the time of the issue, sale or negotiation thereof, or by reason of the purpose of issue

or otherwise howsoever, except as otherwise provided in Section 2 of Article IV of the Original Indenture.

AND IT IS HEREBY COVENANTED, DECLARED AND AGREED, by and between the parties hereto, for the benefit of those who shall hold the Bonds and coupons, or any of them to be issued under the Original Indenture, as follows:

ARTICLE I

DESCRIPTION OF THE NEW BONDS

Section 1.1. There is hereby created a new series of Bonds to be executed, authenticated and delivered under and secured by the Original Indenture which shall, subject to the provisions of Section 1 of Article II of the Original Indenture, be designated as "First Mortgage Bonds, Environmental Improvement Series 2004B (1998B Bonds)" (the "New Bonds") of the Company. The New Bonds shall be executed, authenticated and delivered in accordance with the provisions of, and shall in all respects be subject to all of the terms, conditions and covenants of, the Original Indenture and shall be issued to, and registered in the name of, the Authority Bond Trustee under the Authority Bond Indenture to secure any and all obligations of the Company under the Agreement with respect to the payment of the Authority Bonds.

The New Bonds shall mature, subject to prior redemption, on September 1, 2033, and shall bear interest at the same rate or rates of interest as the Authority Bonds which, in turn, shall be determined by the methods set forth in the Authority Bond Indenture, which provides for an Auction Rate, a Daily Rate, a Weekly Rate, a Commercial Paper Rate or a Long-Term Interest Rate (each as defined in the Authority Bonds Indenture). Reference is made to the provisions of the Authority Bond Indenture concerning the methods by which such interest rates are determined, and the means by which the method of determining such interest rates may be changed, and such provisions are included in this Supplemental Indenture as if fully set forth herein. Interest on the New Bonds is payable on the same dates as interest on the Authority Bonds is paid, until the principal sum of the New Bonds is paid in full. The New Bonds shall be payable as to principal and interest in any coin or currency of the United States of America which at the time of payment is legal tender for public and private debts, and shall be payable, in immediately available funds, at the office of the Authority Bond Trustee.

Section 1.2. The New Bonds shall not be assignable or transferable except as permitted or required by Section 12.13 of the Authority Bond Indenture. Any such transfer shall be effected at the principal office or place of business of the Trustee under the Original Indenture. The New Bonds are exchangeable for the New Bonds of other denominations, as in the Original Indenture provided, except that payment of a service charge therefor will not be required by the Company.

Notwithstanding the provisions of Section 6 of Article II of the Original Indenture, the New Bonds shall be dated their date of authentication and shall bear interest from the interest payment date to which interest on the New Bonds has been paid next preceding the date thereof,

unless such date is an interest payment date to which interest has been paid, in which case they shall bear interest from the date thereof.

Upon any payment of the principal of and interest on, all or any portion of the Authority Bonds, whether at maturity or otherwise or upon provision for the payment thereof having been made in accordance with Section 7.01 of the Authority Bond Indenture, the New Bonds in a principal amount equal to the principal amount of such Authority Bonds shall, to the extent of such payment of principal and interest, be deemed paid and the obligation of the Company thereunder to make such payment shall be discharged to such extent and, in the case of the payment of principal, such New Bonds shall be surrendered to the Company for cancellation as provided in and subject to the terms of Section 7.04 of the Authority Bond Indenture. The Trustee may at any time and all times conclusively assume that the obligation of the Company under the Agreement to make payments with respect to the principal of and interest on the Authority Bonds, so far as such payments at the time have become due, has been fully satisfied and discharged pursuant to the foregoing sentence unless and until the Trustee shall have received a written notice from the Authority Bond Trustee signed by one of its officers stating (i) the timely payment of principal or interest on, the Authority Bonds has not been made, (ii) that the Company is in arrears as to the payments required to be made by it to the Authority Bond Trustee pursuant to the Agreement, and (iii) the amount of the arrearage.

                           [Form of Face of New Bond]

No. ____                                                         $________

                               Ill. C. C. No. 6315

NOTWITHSTANDING ANY PROVISIONS HEREOF OR IN THE ORIGINAL INDENTURE THIS BOND IS

NOT ASSIGNABLE OR TRANSFERABLE EXCEPT AS PERMITTED OR REQUIRED BY
SECTION 12.13 OF THE AMENDED AND RESTATED INDENTURE OF TRUST DATED AS OF FEBRUARY 1, 2004, BETWEEN THE STATE ENVIRONMENTAL IMPROVEMENT AND ENERGY RESOURCES AUTHORITY OF THE STATE OF MISSOURI AND UMB BANK & TRUST, N.A., AS SUCCESSOR TO STATE STREET BANK AND TRUST COMPANY OF MISSOURI, N.A., AS TRUSTEE

UNION ELECTRIC COMPANY
(Incorporated under the laws of the State of Missouri)

First Mortgage Bonds, Environmental Improvement Series 2004B (1998B Bonds)

Illinois Commerce Commission Identification No. 6315

UNION ELECTRIC COMPANY, a corporation organized and existing under the laws of the State of Missouri (hereinafter called the "Company," which term shall include any successor corporation as defined in the Amended Indenture referred to on the reverse hereof), for value received, hereby promises to pay to UMB Bank & Trust, N.A., as successor to State Street Bank and Trust Company of Missouri, N.A., as trustee under the Authority Bond Indenture hereinafter referred to, or registered assigns, the sum of _________________________ Dollars, on the 1st day of September, 2033, subject to prior redemption, in any coin or currency of the United States of America which at the time of payment is legal tender for public and private debts, and to pay interest thereon, in like coin or currency, at the same rate or rates of interest as the Authority Bonds (as determined in accordance with the Authority Bond Indenture referred to below), but in no event shall the interest rate on this Bond exceed twelve percent (12%) per annum. Interest on overdue principal premium, if any, and, to the extent permitted by law, on overdue interest, shall be payable at the interest rate payable on the Authority Bonds. Interest on this Bond is payable on the same dates as interest on the Authority Bonds, or, if this Bond shall be duly called for redemption, until the redemption date, or if the Company shall default in the payment of the principal hereof, until the Company's obligation to pay principal shall be discharged as provided in the Amended Indenture is paid, until the principal sum is paid in full. The principal of, and interest on, this Bond are payable, in immediately available funds, at the office of the Authority Bond Trustee hereinafter referred to.

Under an Indenture of Trust dated as of September 1, 1998, as amended and restated by the Amended and Restated Indenture of Trust dated as of February 1, 2004 (as so amended and restated, the "Authority Bond Indenture") between the State Environmental Improvement and Energy Resources Authority of the State of Missouri (the "Authority") and UMB Bank & Trust, N.A., as successor to State Street Bank and Trust Company of Missouri, N.A., as trustee (the "Authority Bond Trustee"), the Authority has issued its Environmental Improvement Revenue

Refunding Bonds (Union Electric Company Project) Series 1998B in the aggregate principal amount of $50,000,000 (the "Authority Bonds"). The Company has agreed to pay the principal of and interest on the Authority Bonds pursuant to a Loan Agreement dated as of September 1, 1998, as supplemented and amended by the First Amendment to Loan Agreement dated as of February 1, 2004 (as so amended, the "Agreement") between the Company and the Authority. Pursuant to the Granting Clause of the Authority Bond Indenture, this Bond is issued to the Authority Bond Trustee to secure any and all obligations of the Company under the Agreement with respect to payment of the Authority Bonds. Payment of principal of, or interest on, the Authority Bonds shall constitute payments on this Bond as further provided herein and in the Supplemental Indenture dated February 1, 2004 pursuant to which this Bond has been issued (the "Supplemental Indenture").

Upon any payment of the principal of, and interest on, all or any portion of the Authority Bonds, whether at maturity or otherwise or upon provision for the payment thereof having been made in accordance with Section 7.01 of the Authority Bond Indenture, a principal amount of this Bond equal to the principal amount of such Authority Bonds shall, to the extent of such payment of principal and interest, be deemed paid and the obligation of the Company thereunder to make such payment shall be discharged to such extent and, in the case of the payment of principal, such Bonds shall be surrendered to the Company for cancellation as provided in Section 7.04 of the Authority Bond Indenture. The Trustee (as hereinafter defined) may at any time and all times conclusively assume that the obligation of the Company to make payments under the Agreement with respect to the principal of, and interest on, the Authority Bonds, so far as such payments at the time have become due, has been fully satisfied and discharged pursuant to the foregoing sentence unless and until the Trustee shall have received a written notice from the Authority Bond Trustee signed by one of its officers stating (i) that timely payment of principal of, or interest on, the Authority Bonds has not been made, (ii) that the Company is in arrears as to the payments required to be made by it to the Authority Bond Trustee pursuant to the Agreement, and (iii) the amount of the arrearage.

This Bond shall not be entitled to any benefit under the Amended Indenture or any indenture supplemental thereto, or become valid or obligatory for any purpose, until The Bank of New York, the Trustee under the Amended Indenture, or a successor trustee thereto under the Amended Indenture, or an agent therefor, shall have signed the form of certificate endorsed hereon.

The provisions of this Bond are continued on the reverse hereof and such continued provisions shall for all purposes have the same effect as though fully set forth at this place.

IN WITNESS WHEREOF, Union Electric Company has caused this Bond to be signed in its name by its Chairman of the Board or President or a Vice President by manual signature or a facsimile thereof, and its corporate seal (or a facsimile thereof) to be hereto affixed and attested by its Secretary or an Assistant Secretary by manual signature or a facsimile thereof.

Dated,
UNION ELECTRIC COMPANY,

[CORPORATE SEAL]

Attest:

[FORM OF TRUSTEE'S CERTIFICATE]

This Bond is one of the Bonds, of the series designated therein, described in the within-mentioned Amended Indenture and Supplemental Indenture of February 1, 2004.

THE BANK OF NEW YORK, as Trustee

[FORM OF REVERSE OF NEW BOND]

This Bond is one of a duly authorized issue of Bonds of the Company (herein called the "Bonds"), limited to an aggregate principal amount of $50,000,000, of the series hereinafter specified, all issued under and equally secured by the Indenture of Mortgage and Deed of Trust, dated June 15, 1937, executed by the Company to The Bank of New York (successor trustee to Bank of America, National Association, formerly Boatmen's Trust Company), as trustee (herein called the "Trustee"), as amended by indentures supplemental thereto dated May 1, 1941, April 1, 1971, February 1, 1974, July 7, 1980, February 1, 2000 and August 15, 2002, between the Company and the Trustee (said mortgage and deed of trust, as so amended, being herein called the "Amended Indenture"), to which Amended Indenture and all indentures supplemental thereto reference is hereby made for a description of the properties mortgaged and pledged, the nature and extent of the security, the rights of the bearers or registered owners of the Bonds and of the Trustee in respect thereto, and the terms and conditions upon which the Bonds are, and are to be, secured. To the extent permitted by, and as provided in, the Amended Indenture, modifications or alterations of the Amended Indenture, or of any indenture supplemental thereto, and of the rights and obligations of the Company and of the holders of the Bonds may be made with the consent of the Company by an affirmative vote of not less than 60% in amount of the Bonds entitled to vote then outstanding, at a meeting of Bondholders called and held as provided in the Amended Indenture, and by an affirmative vote of not less than 60% in amount of the

Bonds of any series entitled to vote then outstanding and affected by such modification or alteration, in case one or more but less than all of the series of Bonds then outstanding under the Amended Indenture are so affected. Additionally, the Company may amend the Amended Indenture, as supplemented, by an appropriate written consent of not less than 60% in aggregate principal amount of the Bonds outstanding (and, if the rights of one or more, but less than all, series of Bonds then outstanding are to be affected by action taken pursuant to such consent, then also by consent of the holders of at least 60% in principal amount of each series of Bonds so to be affected and outstanding hereunder) without a meeting of such Bondholders. No such modification or alteration shall be made which will affect the terms of payment of the principal of, or interest on, this Bond, which are unconditional. The Bonds may be issued in series, for various principal sums, may mature at different times, may bear interest at different rates and may otherwise vary as in the Amended Indenture provided. This Bond is one of a series designated as the "First Mortgage Bonds, Environmental Improvement Series 2004B (1998B Bonds)" (herein called the "Bonds of this Series") of the Company, issued under and secured by the Amended Indenture and described in the indenture (hereinafter called the "Supplemental Indenture") dated February 1, 2004, between the Company and the Trustee, supplemental to the Amended Indenture.

The Bonds of this Series are not entitled to the benefit of any improvement, maintenance or analogous fund.

This Bond is, subject to the provisions of the Amended Indenture, subject to redemption in the amounts, at the times, at the prices and under the circumstances under which the Authority Bonds are subject to redemption under the same terms and circumstances set forth in the Authority Bond Indenture for the redemption of the Authority Bonds.

This Bond is also subject to mandatory redemption at the principal amount hereof plus accrued interest to the date fixed for redemption if the Trustee or the Company is notified that an "Event of Default" under the Authority Bond Indenture has occurred and is continuing and the Authority Bond Trustee has declared the principal amount of all Authority Bonds then outstanding due and payable in accordance with the Authority Bond Indenture.

The Company may, by notice to the Trustee at least 60 days prior to any date on which any principal amount is due on this Bond, elect to receive a credit in respect of such principal payment (a) for any Bonds of this Series then due which have been redeemed prior to such principal payment date or otherwise acquired and delivered to the Trustee for cancellation by said Trustee prior to the giving of such notice, or (b) for any Authority Bonds which have been purchased, delivered for cancellation or previously redeemed, which in each case have not theretofore been applied as a credit against such principal payment. Each Bond with respect to which the Company elects to receive a credit will be credited by the Trustee at 100% of the principal amount thereof against such principal payment, provided further that in the case of a credit with respect to any Authority Bonds, the principal amount thereof shall be established by an officers' certificate (as defined in the Amended Indenture) concurred in by the Authority Bond Trustee, included with the above-mentioned notice to the Trustee. The principal amount of Bonds to be paid on the due date of such principal payment will be reduced by the amount of any such credit or credits in respect of Bonds previously redeemed or delivered as provided above.

Upon cancellation in full or in part of any of the Authority Bonds (or provision for payment thereof having been made in accordance with the provisions of the Authority Bond Indenture) and payment of all fees and charges of the trustee thereunder, such trustee shall deliver to the Trustee, for cancellation a corresponding amount of Bonds remaining in its possession.

Such redemption in every case shall be effected upon notice delivered by the Company at least 60 days prior to the date of redemption, to the registered owner of the Bonds at its address as the same shall appear on the transfer register of the Company, all subject to the conditions of, and as more fully set forth in, the Amended Indenture and Supplemental Indenture.

In case an event of default, as defined in the Amended Indenture, shall occur, the principal of all the bonds at any such time outstanding under the Amended Indenture may be declared or may become due and payable, upon the conditions and in the manner and with the effect provided in the Amended Indenture. The Amended Indenture provides that such declaration may in certain events be waived by the holders of a majority in principal amount of the bonds outstanding.

This Bond shall not be assignable or transferable except as permitted or required by Section 12.13 of the Authority Bond Indenture. This Bond is exchangeable by the registered owner hereof, in person or by duly authorized attorney, on the books of the Company to be kept for that purpose at the office of the Company in the City of St. Louis, Missouri, upon surrender and cancellation of this Bond and on presentation of a duly executed written instrument of transfer, and thereupon a new Bond or Bonds of the same series, of the same aggregate principal amount and in authorized denominations will be issued to the transferee or transferees in exchange herefor, without payment of any charge other than stamp taxes and other governmental charges incident thereto; and this Bond with or without others of like series, may in like manner be exchanged for one or more new Bonds of the same series of other authorized denominations but of the same aggregate principal amount; all subject to the terms and conditions set forth in the Amended Indenture.

As provided in Section 7.04 of the Authority Bond Indenture, from and after the Release Date (as defined in the Authority Bond Indenture), the obligations of the Company with respect to this Bond shall be deemed to be satisfied and discharged, this Bond shall cease to secure in any manner the Company's obligations under the Agreement with respect to the payment of any Authority Bonds outstanding under the Authority Bond Indenture, and, pursuant to Section 7.04 of the Authority Bond Indenture, the Authority Bond Trustee shall forthwith deliver this Bond to the Company for cancellation.

No recourse shall be had for the payment of the principal of, or the interest on, this Bond, or for any claim based hereon or on the Amended Indenture or any indenture supplemental thereto, against any incorporator, or against any stockholder, director or officer, past, present or future, of the Company, or of any predecessor or successor corporation, either directly or through the Company or any such predecessor or successor corporation, whether for amounts unpaid on stock subscriptions or by virtue of any constitution, statute or rule of law, or by the enforcement of any assessment or penalty or otherwise, all such liability, whether at common law, in equity,

by any constitution, statute or otherwise, of incorporators, stockholders, directors or officers being released by every owner hereof by the acceptance of this Bond and as part of the consideration for the issue hereof, and being likewise released by the terms of the Amended Indenture.

[END OF FORM OF REVERSE OF NEW BOND]

ARTICLE II

ISSUE OF THE NEW BONDS

Section 2.1. The principal amount of the New Bonds which may be authenticated and delivered hereunder is limited to an amount equal to the principal amount of Fifty Million Dollars ($50,000,000) consisting of Bonds maturing on September 1, 2033.

Section 2.2. The New Bonds in the aggregate principal amount set forth above, may forthwith be executed by the Company and delivered to the Trustee and shall be authenticated by the Trustee and delivered (either before or after the filing or recording hereof) to or upon the order of the Company, upon compliance by the Company with the applicable provisions of Article III and Article XVIII of the Original Indenture.

Section 2.3. As provided in Section 7.04 of the Authority Bond Indenture, from and after the Release Date (as defined in the Authority Bond Indenture), the obligations of the Company with respect to the New Bonds shall be deemed to be satisfied and discharged, the New Bonds shall cease to secure in any manner the Company's obligations under the Agreement with respect to the payment of any Authority Bonds outstanding under the Authority Bond Indenture, and, pursuant to
Section 7.04 of the Authority Bond Indenture, the Authority Bond Trustee shall forthwith deliver the New Bonds to the Company for cancellation.

ARTICLE III

REDEMPTION OF THE NEW BONDS

Section 3.1. The New Bonds are, subject to the provisions of the Original Indenture, subject to redemption in the amounts, at the times, at the prices and under the circumstances under which the Authority Bonds are subject to redemption, under the same terms and conditions set forth in the Authority Bond Indenture for the redemption of the Authority Bonds. In the event that less than all the New Bonds are to be redeemed, the New Bonds to be redeemed shall be determined by lot in such manner as the Trustee in its discretion shall deem proper, as in the Original Indenture provided.

The New Bonds are also subject to mandatory redemption as set forth in the form of New Bonds in Section 1.3 of Article I of this Supplemental Indenture.

Section 3.2. Subject to the provisions of Article V of the Original Indenture, notice of redemption shall be delivered by the Company at least 60 days prior to the date of redemption, to the registered owner of such Bonds at its address as the same shall appear on the transfer register of the Company.

Section 3.3. As provided in the Authority Bond Indenture, any amounts of money held in the Bond Fund provided in said Indenture and available for such purpose, which are at the request of the Company applied to the payments of the principal of, premium, if any, and interest on the Authority Bonds on any payment or redemption date, shall be applied as a credit on amounts otherwise due under the New Bonds; provided that the amount of such credit shall be established by an officers' certificate (as defined in the Amended Indenture), concurred in by the Authority Bond Trustee which shall be filed with the Trustee prior to the application of any such credit.

Upon cancellation in full or in part of any of the Authority Bonds (or provision for payment thereof having been made in accordance with the provisions of the Authority Bond Indenture) and payment of all fees and charges of the trustee thereunder, such trustee shall deliver to the Trustee, for cancellation a corresponding amount of New Bonds remaining in its possession or shall request such Trustee to issue a New Bond reflecting any such cancellation

ARTICLE IV

COVENANTS

The Company hereby covenants, warrants and agrees;

Section 4.1. That the Company is lawfully seized and possessed of all of the mortgaged property described in the granting clauses of this Supplemental Indenture; that it has good right and lawful authority to mortgage the same as provided in this Supplemental Indenture; and that such mortgaged property is, at the actual date of the issue of the New Bonds, free and clear of any deed of trust, mortgage, lien, charge or encumbrance thereon or affecting the title thereto prior to the Original Indenture, except as set forth in the granting clauses of the Original Indenture or this Supplemental Indenture.

Section 4.2. That, so long as any of the New Bonds are outstanding, whenever any officers' certificate is required to be filed or deposited with the Trustee pursuant to Section 3(b) of Article III of the Original Indenture upon an application for the authentication of additional Bonds pursuant to Article III of the Original Indenture, such officers' certificate shall include, in addition to the matters required to be stated therein by said Section 3(b), the statement with respect to the net earnings of the Company available for interest after property retirement appropriations required by Section 2 of Article V of the Supplemental Indenture of July 1, 1956.

Section 4.3. That, so long as any of the New Bonds are outstanding, the Company will not apply for the authentication and delivery of additional Bonds pursuant to Section 4 of Article III of the Original Indenture or the withdrawal of cash from the trust estate or the reduction of the amount of cash required to be paid into the trust estate or to satisfy the

maintenance and improvement funds under any provision of the Original Indenture or the Supplemental Indentures creating prior series of Bonds, on the basis of the amount of $15,000,000 excluded from net bondable value of property additions not subject to an unfunded prior lien pursuant to Section 3 of Article V of the Supplemental Indenture of October 1, 1945, or on the basis of the amount of $7,500,000 excluded from net bondable value of property additions not subject to an unfunded prior lien pursuant to Section 3 of Article V of the Supplemental Indenture of July 1, 1956.

Section 4.4. That, so long as any of the New Bonds are outstanding, the Company will not issue or permit to be issued any prior lien bonds secured by an unfunded prior lien in addition to the prior lien bonds secured by such unfunded prior lien at the time of first acquisition by the Company of property subject thereto (other than in lieu of lost, stolen or mutilated bonds or on the exchange for bonds already outstanding of an equal principal amount of other bonds of the same issue and the same series, if any, and of the same maturity), except upon compliance with the provisions of Section 16 of Article IV of the Original Indenture, nor unless the net earnings of the Company available for interest after property retirement appropriations (determined as provided in
Section 2 of Article V of the Supplemental Indenture of July 1, 1956), for any 12 consecutive calendar months during the period of 15 calendar months immediately preceding the first day of the month in which the additional prior lien bonds are to be issued, have been, in the aggregate, equal to not less than twice the annual interest charges on the indebtedness specified in subparagraphs
(i) and (ii) of paragraph (1) of Section 2(a) of said Article V; provided that, if the application for the issue of such additional prior lien bonds is upon the basis of payment at maturity of prior lien bonds theretofore sold or otherwise disposed of or the redemption or purchase thereof after a date two years prior to the date of maturity, the additional requirement imposed by this Section 4 with respect to net earnings of the Company available for interest after property retirement appropriations shall not apply. Any officers' certificate with respect to net earnings of the Company, required to be filed with the Trustee as a condition precedent to the issue of such additional prior lien bonds, shall include, in addition to the matters otherwise required to be stated therein, the matters required to be stated in an officers' certificate pursuant to paragraphs (1) and (2) of Section 2(a) of said Article V.

Section 4.5. That, so long as any of the New Bonds are outstanding, the Company will not acquire, by purchase, merger or otherwise, any property subject to a lien or liens which will on acquisition be an unfunded prior lien or prior liens, except upon compliance with the provisions of Section 14 of Article IV of the Original Indenture, nor unless the net earnings of such property available for interest after property retirement appropriations (determined in the manner provided in Section 2 of Article V of the Supplemental Indenture of July 1, 1956), for any 12 consecutive calendar months during the period of 15 calendar months immediately preceding the first day of the month in which the first acquisition of property subject to such lien or liens occurs, have been, in the aggregate, equal to not less than twice the amount of annual interest charges, on all outstanding indebtedness secured by such lien or liens. Any officers' certificate with respect to net earnings of such property, required to be filed with the Trustee as a condition precedent to the acquisition of such property, shall include, in addition to the matters otherwise required to be stated therein, the matters required to be stated in an officers' certificate pursuant to Section 2 of said Article V applicable, however, only to the net earnings of such property and to the indebtedness secured by such liens to which such property is subject.

ARTICLE V

THE TRUSTEE

The Trustee hereby accepts the trusts hereby declared and provided, and agrees to perform the same upon the terms and conditions in the Original Indenture and in this Supplemental Indenture set forth, and upon the following terms and conditions:

The Trustee shall not be responsible in any manner whatsoever for or in respect of the validity or sufficiency of this Supplemental Indenture or the due execution hereof by the Company or for or in respect of the recitals contained herein, all of which recitals are made by the Company solely.

ARTICLE VI

MISCELLANEOUS PROVISIONS

Section 6.1. Except as otherwise defined herein, all terms contained in this Supplemental Indenture shall, for all purposes thereof, have the meanings given to such terms in Article I of the Original Indenture.

Section 6.2. This Supplemental Indenture may be simultaneously executed in any number of counterparts, each of which when so executed shall be deemed to be an original; but such counterparts shall together constitute but one and the same instrument.

IN WITNESS WHEREOF, said Union Electric Company has caused this Supplemental Indenture to be executed on its behalf by its Chairman of the Board or President or one of its Vice Presidents and its corporate seal to be hereto affixed and said seal and this Supplemental Indenture to be attested by its Secretary or one of its Assistant Secretaries; and said The Bank of New York, in evidence of its acceptance of the trust hereby created, has caused this Supplemental Indenture to be executed on its behalf by its President or one of its Vice Presidents, and its corporate seal to be hereto affixed and said seal and this Supplemental Indenture to be attested by its Secretary, or one of its Assistant Secretaries; all as of the 1st day of February, Two thousand and four.

Attested:                                UNION ELECTRIC COMPANY,
                                           1901 Chouteau Avenue
                                           St. Louis, Missouri  63103


/s/ G. L. Waters                         By: /s/ Jerre E. Birdsong
------------------------------------        ------------------------------------
              G. L. Waters               Name:   Jerre E. Birdsong
          Assistant Secretary            Title: Vice President and Treasurer


Signed, sealed and delivered by
       UNION ELECTRIC COMPANY
       in the presence of:


/s/ Daphyne Bradley
------------------------------------
                Daphyne Bradley


/s/ Wayne K. Forbes
------------------------------------
                Wayne K. Forbes

As Witnesses

Attested:                                THE BANK OF NEW YORK,
                                           911 Washington Avenue
                                           St. Louis, Missouri  63101


/s/ Thomas Maple                         By: /s/ Robert J. Dunn
------------------------------------        ------------------------------------
                                         Name:   Robert J. Dunn
                                         Title:  As Agent


Signed, sealed and delivered by
       THE BANK OF NEW YORK
       in the presence of:


/s/ Daniel G. Dwyer
------------------------------------


/s/ Richard F. Novosak
------------------------------------

STATE OF MISSOURI          )
                           )  SS:
CITY OF ST. LOUIS          )

On this 17th day of February, 2004, before me appeared JERRE E. BIRDSONG, to me personally known, who, being by me duly sworn, did say that he is Vice President and Treasurer of UNION ELECTRIC COMPANY, a corporation, and that the seal affixed to the foregoing instrument is the corporate seal of said corporation, and that said instrument was signed and sealed in behalf of said corporation by authority of its Board of Directors, and said JERRE E. BIRDSONG acknowledged said instrument to be the free act and deed of said corporation.

IN TESTIMONY WHEREOF, I have hereto set my hand and affixed my official seal at my office, in the City and State aforesaid, the day and year last above written.

/s/ S. A. Kitchens
---------------------------------------

STATE OF MISSOURI          )
                           )  SS:
CITY OF ST. LOUIS          )

On this 17th day of February, 2004, before me appeared Rober J. Dunn, to me personally known, who, being by me duly sworn, did say that he is an Agent of THE BANK OF NEW YORK, a corporation, and that the seal affixed to the foregoing instrument is the corporate seal of said corporation, and that said instrument was signed and sealed in behalf of said corporation, as the trustee thereunder by authority of its Board of Directors, and said Vice President, acknowledged said instrument to be the free act and deed of said corporation as the trustee under said instrument.

IN TESTIMONY WHEREOF, I have hereto set my hand and affixed my official seal at my office, in the City and State aforesaid, the day and year last above written.

/s/ Sally Lardge
---------------------------------------

Exhibit 4.3

WHEN RECORDED
MAIL TO:

Executed in 35 Counterparts, No. 35

SUPPLEMENTAL INDENTURE

DATED FEBRUARY 1, 2004

UNION ELECTRIC COMPANY

TO

THE BANK OF NEW YORK,
AS TRUSTEE

(SUPPLEMENTAL TO THE INDENTURE OF MORTGAGE AND DEED OF
TRUST DATED JUNE 15, 1937, AS AMENDED, EXECUTED BY

UNION ELECTRIC COMPANY
TO THE BANK OF NEW YORK, AS TRUSTEE)

First Mortgage Bonds, Environmental Improvement Series 2004C (1998C Bonds)

This instrument was prepared by Steven R. Sullivan, Senior Vice President Governmental/Regulatory Policy, General Counsel and Secretary of Union Electric Company, 1901 Chouteau Avenue, St. Louis, Missouri 63103, (314) 554-2098.

SUPPLEMENTAL INDENTURE, dated the 1st day of February, Two thousand and four (2004) made by and between UNION ELECTRIC COMPANY, a corporation organized and existing under the laws of the State of Missouri (hereinafter called the "Company"), party of the first part, and The Bank of New York (successor trustee to Bank of America, National Association, formerly Boatmen's Trust Company), a bank existing under the laws of the State of New York (hereinafter called the "Trustee"), as Trustee under the Indenture of Mortgage and Deed of Trust dated June 15, 1937, hereinafter mentioned, party of the second part:

WHEREAS, the Company has heretofore executed and delivered to the Trustee its Indenture of Mortgage and Deed of Trust, dated June 15, 1937, as amended May 1, 1941, April 1, 1971, February 1, 1974, July 7, 1980, February 1, 2000 and August 15, 2002 (said Indenture of Mortgage and Deed of Trust as so amended, being hereinafter referred to as the "Original Indenture"), to secure the payment of the principal of and the interest (and premium, if any) on all bonds at any time issued and outstanding thereunder, and indentures supplemental thereto dated June 15, 1937, May 1, 1941, March 17, 1942, April 13, 1945, April 27, 1945, October 1, 1945, April 11, 1947, April 13, 1949, September 13, 1950, December 1, 1950, September 20, 1951, May 1, 1952, March 1, 1954, May 1, 1955, August 31, 1955, April 1, 1956, July 1, 1956, August 1, 1957, February 1, 1958, March 1, 1958, November 5, 1958, March 16, 1959, June 24, 1959, December 11, 1959, August 17, 1960, September 1, 1960, October 24, 1960, June 30, 1961, July 1, 1961, August 9, 1962, September 30, 1963, November 1, 1963, March 12, 1965, April 1, 1965, April 14, 1966, May 1, 1966, February 17, 1967, March 1, 1967, February 19, 1968, March 15, 1968, August 21, 1968, April 7, 1969, May 1, 1969, September 12, 1969, October 1, 1969, March 26, 1970, April 1, 1970, June 12, 1970, January 1, 1971, April 1, 1971, September 15, 1971, December 3, 1973, February 1, 1974, April 25, 1974, February 3, 1975, March 1, 1975, June 11, 1975, May 12, 1976, August 16, 1976, April 26, 1977, October 15, 1977, November 7, 1977, December 1, 1977, August 1, 1978, October 12, 1979, November 1, 1979, July 7, 1980, August 1, 1980, August 20, 1980, February 1, 1981, October 8, 1981, August 27, 1982, September 1, 1982, December 15, 1982, March 1, 1983, June 21, 1984, December 12, 1984, June 11, 1985, March 1, 1986, May 1, 1986, May 1, 1990, December 1, 1991, December 4, 1991, January 1, 1992, September 30, 1992, October 1, 1992, December 1, 1992, February 1, 1993, February 18, 1993, May 1, 1993, August 1, 1993, October 1, 1993, January 1, 1994, February 1, 2000, August 15, 2002, March 5, 2003, April 1, 2003, July 15, 2003 and October 1, 2003, respectively, have heretofore been entered into between the Company and the Trustee; and

WHEREAS, Bonds have heretofore been issued by the Company under the Original Indenture as follows:

(1) $80,000,000 principal amount of First Mortgage and Collateral Trust Bonds, 3-3/4% Series due 1962, all of which have been redeemed prior to the date of the execution hereof;

(2) $90,000,000 principal amount of First Mortgage and Collateral Trust Bonds, 3-3/8% Series due 1971, which are described in the Supplemental Indenture dated

May 1, 1941 (hereinafter called the "Supplemental Indenture of May 1, 1941"), all of which have been paid at maturity prior to the date of the execution hereof;

(3) $13,000,000 principal amount of First Mortgage and Collateral Trust Bonds, 2-3/4% Series due 1975 (herein called the "Bonds of 1975 Series"), which are described in the Supplemental Indenture dated October 1, 1945 (hereinafter called the "Supplemental Indenture of October 1, 1945"), all of which have been paid at maturity prior to the date of the execution hereof;

(4) $25,000,000 principal amount of First Mortgage and Collateral Trust Bonds, 2-7/8% Series due 1980 (herein called the "Bonds of 1980 Series"), which are described in the Supplemental Indenture dated December 1, 1950 (hereinafter called the "Supplemental Indenture of December 1, 1950"), all of which have been paid at maturity prior to the date of the execution hereof;

(5) $30,000,000 principal amount of First Mortgage and Collateral Trust Bonds, 3-1/4% Series due 1982 (herein called the "Bonds of 1982 Series"), which are described in the Supplemental Indenture dated May 1, 1952 (hereinafter called the "Supplemental Indenture of May 1, 1952"), all of which have been paid at maturity prior to the date of the execution hereof;

(6) $40,000,000 principal amount of First Mortgage Bonds, 3-3/4% Series due 1986 (herein called the "Bonds of 1986 Series"), which are described in the Supplemental Indenture dated July 1, 1956 (hereinafter called the "Supplemental Indenture of July 1, 1956"), all of which have been paid at maturity prior to the date of the execution hereof;

(7) $35,000,000 principal amount of First Mortgage Bonds, 4-3/8% Series due 1988 (herein called the "Bonds of 1988 Series"), which are described in the Supplemental Indenture dated March 1, 1958 (hereinafter called the "Supplemental Indenture of March 1, 1958"), all of which have been paid at maturity prior to the date of the execution hereof;

(8) $50,000,000 principal amount of First Mortgage Bonds, 4-3/4% Series due 1990 (herein called the "Bonds of 1990 Series"), which are described in the Supplemental Indenture dated September 1, 1960 (hereinafter called the "Supplemental Indenture of September 1, 1960"), all of which have been paid at maturity prior to the date of the execution hereof;

(9) $30,000,000 principal amount of First Mortgage Bonds, 4-3/4% Series due 1991 (herein called the "Bonds of 1991 Series"), which are described in the Supplemental Indenture dated July 1, 1961 (hereinafter called the "Supplemental Indenture of July 1, 1961"), all of which have been paid at maturity prior to the date of the execution hereof;

(10) $30,000,000 principal amount of First Mortgage Bonds, 4-1/2% Series due 1993 (herein called the "Bonds of 1993 Series"), which are described in the

Supplemental Indenture dated November 1, 1963 (hereinafter called the "Supplemental Indenture of November 1, 1963"), all of which have been redeemed prior to the date of the execution hereof;

(11) $35,000,000 principal amount of First Mortgage Bonds, 4-1/2% Series due 1995 (herein called the "Bonds of 1995 Series"), which are described in the Supplemental Indenture dated April 1, 1965 (hereinafter called the "Supplemental Indenture of April 1, 1965"), all of which have been paid at maturity prior to the date of the execution hereof;

(12) $30,000,000 principal amount of First Mortgage Bonds, 5-1/2% Series due 1996 (herein called the "Bonds of 1996 Series"), which are described in the Supplemental Indenture dated May 1, 1966 (hereinafter called the "Supplemental Indenture of May 1, 1966"), all of which have been paid at maturity prior to the date of the execution hereof;

(13) $40,000,000 principal amount of First Mortgage Bonds, 5-1/2% Series due 1997 (herein called the "Bonds of 1997 Series"), which are described in the Supplemental Indenture dated March 1, 1967 (hereinafter called the "Supplemental Indenture of March 1, 1967"), all of which have been paid at maturity prior to the date of the execution hereof;

(14) $50,000,000 principal amount of First Mortgage Bonds, 7% Series due 1998 (herein called the "Bonds of 1998 Series"), which are described in the Supplemental Indenture dated March 15, 1968 (hereinafter called the "Supplemental Indenture of March 15, 1968"), all of which have been redeemed prior to the date of the execution hereof;

(15) $35,000,000 principal amount of First Mortgage Bonds, 7-3/8% Series due 1999 (herein called the "Bonds of May 1999 Series"), which are described in the Supplemental Indenture dated May 1, 1969 (hereinafter called the "Supplemental Indenture of May 1, 1969"), all of which have been redeemed prior to the date of the execution hereof;

(16) $40,000,000 principal amount of First Mortgage Bonds, 8-1/4% Series due 1999 (herein called the "Bonds of October 1999 Series"), which are described in the Supplemental Indenture dated October 1, 1969 (hereinafter called the "Supplemental Indenture of October 1, 1969"), all of which have been redeemed prior to the date of the execution hereof;

(17) $100,000,000 principal amount of First Mortgage Bonds, 9.95% Series due 1999 (herein called the "Bonds of November 1999 Series"), which are described in the Supplemental Indenture dated November 1, 1979 (hereinafter called the "Supplemental Indenture of November 1, 1979"), all of which have been redeemed prior to the date of the execution hereof;

(18) $60,000,000 principal amount of First Mortgage Bonds, 9% Series due 2000 (herein called the "Bonds of 2000 Series"), which are described in the Supplemental Indenture dated April 1, 1970 (hereinafter called the "Supplemental Indenture of April 1, 1970"), all of which have been redeemed prior to the date of the execution hereof;

(19) $50,000,000 principal amount of First Mortgage Bonds, 7-7/8% Series due 2001 (herein called the "Bonds of January 2001 Series"), which are described in the Supplemental Indenture dated January 1, 1971 (hereinafter called the "Supplemental Indenture of January 1, 1971"), all of which have been redeemed prior to the date of the execution hereof;

(20) $50,000,000 principal amount of First Mortgage Bonds, 7 5/8% Series due 2001 (herein called the "Bonds of April 2001 Series"), which are described in the Supplemental Indenture dated April 1, 1971 (hereinafter called the "Supplemental Indenture of April 1, 1971"), all of which have been redeemed prior to the date of the execution hereof;

(21) $60,000,000 principal amount of First Mortgage Bonds, 8 1/8% Series due 2001 (herein called the "Bonds of October 2001 Series"), which are described in the Supplemental Indenture dated September 15, 1971 (hereinafter called the "Supplemental Indenture of September 15, 1971"), all of which have been redeemed prior to the date of the execution hereof;

(22) $70,000,000 principal amount of First Mortgage Bonds, 8-3/8% Series due 2004 (herein called the "Bonds of 2004 Series"), which are described in the Supplemental Indenture dated February 1, 1974 (hereinafter called the "Supplemental Indenture of February 1, 1974"), all of which have been redeemed prior to the date of the execution hereof;

(23) $70,000,000 principal amount of First Mortgage Bonds, 10-1/2% Series due 2005 (herein called the "Bonds of 2005 Series"), which are described in the Supplemental Indenture dated March 1, 1975 (hereinafter called the "Supplemental Indenture of March 1, 1975"), all of which have been redeemed prior to the date of the execution hereof;

(24) $70,000,000 principal amount of First Mortgage Bonds, 8-7/8% Series due 2006 (herein called the "Bonds of 2006 Series"), which are described in the Supplemental Indenture dated August 16, 1976 (hereinafter called the "Supplemental Indenture of August 16, 1976"), all of which have been redeemed prior to the date of the execution hereof;

(25) $27,085,000 principal amount of First Mortgage Bonds, 5.80% Environmental Improvement Series 1977, which are described in the Supplemental Indenture dated October 15, 1977 (hereinafter called the "Supplemental Indenture of October 15, 1977"), all of which have been redeemed prior to the date of the execution hereof;

(26) $60,000,000 principal amount of First Mortgage Bonds, 8 5/8% Series due 2007 (herein called the "Bonds of 2007 Series"), which are described in the Supplemental Indenture dated December 1, 1977 (hereinafter called the "Supplemental Indenture of December 1, 1977"), all of which have been redeemed prior to the date of the execution hereof;

(27) $55,000,000 principal amount of First Mortgage Bonds, 9.35% Series due 2008 (herein called the "Bonds of 2008 Series"), which are described in the Supplemental Indenture dated August 1, 1978 (hereinafter called the "Supplemental Indenture of August 1, 1978"), all of which have been redeemed prior to the date of the execution hereof;

(28) $60,000,000 principal amount of First Mortgage Bonds, Environmental Improvement Series 1980, which are described in the Supplemental Indenture dated August 1, 1980 (hereinafter called the "Supplemental Indenture of August 1, 1980"), all of which have been redeemed prior to the date of the execution hereof;

(29) $150,000,000 principal amount of First Mortgage Bonds, 15-3/8% Series due 1991 (herein called the "Bonds of February 1991 Series"), which are described in the Supplemental Indenture dated February 1, 1981 (hereinafter called the "Supplemental Indenture of February 1, 1981"), all of which have been redeemed prior to the date of the execution hereof;

(30) $125,000,000 principal amount of First Mortgage Bonds, 15% Series due 1992 (herein called the "Bonds of 1992 Series"), which are described in the Supplemental Indenture dated September 1, 1982 (hereinafter called the "Supplemental Indenture of September 1, 1982"), all of which have been redeemed prior to the date of the execution hereof;

(31) $100,000,000 principal amount of First Mortgage Bonds, 13% Series due 2013 (herein called the "Bonds of 2013 Series"), which are described in the Supplemental Indenture dated March 1, 1983 (hereinafter called the "Supplemental Indenture of March 1, 1983"), all of which have been redeemed prior to the date of the execution hereof;

(32) $100,000,000 principal amount of First Mortgage Bonds, 9-3/8% Series due 2016 (herein called the "Bonds of 2016 Series"), which are described in the Supplemental Indenture dated March 1, 1986 (hereinafter called the "Supplemental Indenture of March 1, 1986"), all of which have been redeemed prior to the date of the execution hereof;

(33) $100,000,000 principal amount of First Mortgage Bonds, 8-7/8% Series due 1996 (herein called the "Bonds of 1996 Series"), which are described in the Supplemental Indenture dated May 1, 1986 (hereinafter called the "Supplemental Indenture of May 1, 1986"), all of which have been redeemed prior to the date of the execution hereof;

(34) $60,000,000 principal amount of First Mortgage Bonds, Environmental Improvement Series 1990A, which are described in the Supplemental Indenture dated May 1, 1990 (hereinafter called the "Supplemental Indenture of May 1, 1990"), all of which have been redeemed prior to the date of the execution hereof;

(35) $125,000,000 principal amount of First Mortgage Bonds, 8-3/4% Series due 2021 (herein called the "Bonds of 2021 Series"), which are described in the Supplemental Indenture dated December 1, 1991 (hereinafter called the "Supplemental Indenture of December 1, 1991"), all of which have been redeemed prior to the date of the execution hereof;

(36) $75,000,000 principal amount of First Mortgage Bonds, 8.33% Series due 2002 (herein called the "Bonds of 2002 Series"), which are described in the Supplemental Indenture dated December 4, 1991 (hereinafter called the "Supplemental Indenture of December 4, 1991"), all of which have been paid at maturity prior to the date of the execution hereof;

(37) $100,000,000 principal amount of First Mortgage Bonds, 7.65% Series due 2003 (herein called the "Bonds of 2003 Series"), which are described in the Supplemental Indenture dated January 1, 1992 (hereinafter called the "Supplemental Indenture of January 1, 1992"), all of which have been paid at maturity prior to the date of the execution hereof;

(38) $204,000,000 aggregate principal amount of First Mortgage Bonds, consisting of $100,000,000 principal amount of 6-3/4% Series due 1999 and $104,000,000 principal amount of 8-1/4% Series due 2022 (herein called the "Bonds of 1999 Series" and "Bonds of 2022 Series", respectively), which are described in the Supplemental Indenture dated October 1, 1992 (hereinafter called the "Supplemental Indenture of October 1, 1992"), of which the Bonds of 1999 Series have been paid at maturity prior to the date of execution hereof and the Bonds of 2022 Series have been redeemed prior to the date of the execution hereof;

(39) $170,000,000 aggregate principal amount of First Mortgage Bonds, consisting of $85,000,000 principal amount of 7-3/8% Series due 2004 and $85,000,000 principal amount of 8% Series due 2022 (herein called the "Bonds of December 2004 Series" and "Bonds of December 2022 Series", respectively, which are described in the Supplemental Indenture dated December 1, 1992, (hereinafter called the "Supplemental Indenture of December 1, 1992"), of which the Bonds of December 2022 Series have been redeemed prior to the date of the execution hereof and the Bonds of December 2004 Series are outstanding at the date of the execution hereof;

(40) $188,000,000 principal amount of First Mortgage Bonds, 6-7/8% Series due 2004 (herein called the "Bonds of August 2004 Series"), which are described in the Supplemental Indenture dated February 1, 1993 (hereinafter called the "Supplemental Indenture of February 1, 1993"), all of which are outstanding at the date of the execution hereof;

(41) $148,000,000 principal amount of First Mortgage Bonds, 6-3/4% Series due 2008 (herein called the "Bonds of May 2008 Series"), which are described in the Supplemental Indenture dated May 1, 1993 (hereinafter called the "Supplemental Indenture of May 1, 1993"), all of which are outstanding at the date of the execution hereof;

(42) $75,000,000 principal amount of First Mortgage Bonds, 7.15% Series due 2023 (herein called the "Bonds of 2023 Series"), which are described in the Supplemental Indenture dated August 1, 1993 (hereinafter called the "Supplemental Indenture of August 1, 1993"), all of which have been redeemed prior to the date of the execution hereof;

(43) $44,000,000 principal amount of First Mortgage Bonds, Environmental Improvement Series 1993 (herein called the "Bonds of 2028 Series"), which are described in the Supplemental Indenture dated October 1, 1993 (hereinafter called the "Supplemental Indenture of October 1, 1993"), all of which are outstanding at the date of the execution hereof;

(44) $100,000,000 principal amount of First Mortgage Bonds, 7% Series due 2024 (herein called the "Bonds of 2024 Series"), which are described in the Supplemental Indenture dated January 1, 1994 (hereinafter called the "Supplemental Indenture of January 1, 1994"), all of which are outstanding at the date of the execution hereof;

(45) $173,000,000 principal amount of First Mortgage Bonds, Senior Notes Series AA (herein called the "Bonds of 2012 Series"), which are described in the Supplemental Indenture dated August 15, 2002 (hereinafter called the "Supplemental Indenture of August 15, 2002"), all of which are outstanding at the date of the execution hereof;

(46) $184,000,000 principal amount of First Mortgage Bonds, Senior Notes Series BB (herein called the "Bonds of 2034 Series"), which are described in the Supplemental Indenture dated March 5, 2003 (hereinafter called the "Supplemental Indenture of March 5, 2003"), all of which are outstanding at the date of the execution hereof;

(47) $114,000,000 principal amount of First Mortgage Bonds, Senior Notes Series CC (herein called the "Bonds of 2015 Series"), which are described in the Supplemental Indenture dated April 1, 2003 (hereinafter called the "Supplemental Indenture of April 1, 2003"), all of which are outstanding at the date of the execution hereof;

(48) $200,000,000 principal amount of First Mortgage Bonds, Senior Notes Series DD (herein called the "Bonds of 2018 Series"), which are described in the Supplemental Indenture dated July 15, 2003 (hereinafter called the "Supplemental Indenture of July 15, 2003"), all of which are outstanding at the date of the execution hereof; and

(49) $200,000,000 principal amount of First Mortgage Bonds, Senior Notes Series EE (herein called the "Bonds of 2013 Series"), which are described in the Supplemental Indenture dated October 1, 2003 (hereinafter called the "Supplemental Indenture of October 1, 2003"), all of which are outstanding at the date of the execution hereof; and

WHEREAS, the following Bonds will be issued by the Company pursuant to this Supplemental Indenture or pursuant to a separate Supplemental Indenture each dated February 1, 2004 and each series of such Bonds will be outstanding upon the authentication by the Trustee of such Bonds:

(A) $50,000,000 principal amount of First Mortgage Bonds, Environmental Improvement Series 2004C (1998C Bonds) (herein called the "New Bonds"), which are described in the Supplemental Indenture dated February 1, 2004 (hereinafter called "this Supplemental Indenture" or the "Supplemental Indenture of February 1, 2004 (2004C)"), all of which will be outstanding upon the authentication by the Trustee of the New Bonds; and

(B) $60,000,000 principal amount of First Mortgage Bonds, Environmental Improvement Series 2004A (1998A Bonds) (herein called the "Bonds of 2033 (Series 1998A)"), which are described in the Supplemental Indenture dated February 1, 2004 (hereinafter called the "Supplemental Indenture of February 1, 2004 (2004A)"), all of which will be outstanding upon the authentication by the Trustee of the Bonds of 2033 (Series 1998A);

(C) $50,000,000 principal amount of First Mortgage Bonds, Environmental Improvement Series 2004B (1998B Bonds) (herein called the "Bonds of 2033 (Series 1998B)"), which are described in the Supplemental Indenture dated February 1, 2004 (hereinafter called the "Supplemental Indenture of February 1, 2004 (2004B)"), all of which will be outstanding upon the authentication by the Trustee of the Bonds of 2033 (Series 1998B);

and

WHEREAS, the Company on August 31, 1955 acquired all of the properties of Union Electric Power Company, the Subsidiary as defined in Article I of the Original Indenture, upon the dissolution of the Subsidiary; the Company, by Supplemental Indenture dated August 31, 1955, conveyed all of the properties so acquired (other than property of the character defined as excepted property in the granting clauses of the Original Indenture) to the Trustee upon the terms and trusts in the Original Indenture and the indentures supplemental thereto set forth for the equal and proportionate benefit and security of all present and future holders of the Bonds and coupons issued and to be issued thereunder, all the shares of stock of the Subsidiary were released from the lien of the Original Indenture; and the Company became entitled to change the general designation of the Bonds so as to omit the words "and Collateral Trust"; and

WHEREAS, the Articles of Incorporation of the Company were duly amended on April 23, 1956, to change its corporate name from "Union Electric Company of Missouri" to "Union Electric Company"; and

WHEREAS, the Articles of Agreement of the Trustee were duly amended effective on January 4, 1982 to change its corporate name from "St. Louis Union Trust Company" to "Centerre Trust Company of St. Louis", and further amended on December 9, 1988, to change its corporate name from "Centerre Trust Company of St. Louis" to "Boatmen's Trust Company"; and

WHEREAS, that on March 13, 1998, Boatmen's Trust Company merged into NationsBank, National Association and effective July 5, 1999, changed its name to Bank of America, National Association; and

WHEREAS, that on February 1, 2000, The Bank of New York, as transferee of the corporate trust business of Bank of America, National Association (formerly known as Boatmen's Trust Company), Trustee under the Original Indenture, became successor Trustee under the Original Indenture; and

WHEREAS, the Company is entitled at this time to have authenticated and delivered additional Bonds on the basis of property additions upon compliance with and pursuant to the provisions of Article III, Section 4 of the Original Indenture; and

WHEREAS, the Company has entered into a Loan Agreement dated as of September 1, 1998 (the "Original Loan Agreement") with the State Environmental Improvement and Energy Resources Authority of the State of Missouri (the "Authority") pursuant to which the Authority agreed to issue $50,000,000 aggregate principal amount of its Environmental Improvement Revenue Refunding Bonds (Union Electric Company Project) Series 1998C (the "Authority Bonds"), all of which are presently outstanding and loan the proceeds thereof to the Company; and

WHEREAS, the Authority Bonds were issued pursuant to an Indenture of Trust dated as of September 1, 1998 (the "Original Authority Bond Indenture") between the Authority and UMB Bank & Trust, N.A., as successor to State Street Bank and Trust Company of Missouri, N.A., as trustee (the "Authority Bond Trustee"); and

WHEREAS, the Company has determined it to be necessary and desirable to further secure rights of the owners of the Authority Bonds to the payment of principal and interest on the Authority Bonds by obtaining a Financial Guaranty Insurance Policy with respect to the Authority Bonds (the "Authority Bond Insurance Policy") from MBIA Insurance Corporation and in furtherance thereof
(i) the Authority and the Authority Bond Trustee will enter into an Amended and Restated Indenture of Trust dated as of February 1, 2004 (the "Authority Bond Indenture") which amends and restates the Original Authority Bond Indenture, and
(ii) the Authority and the Company will enter into the First Amendment to Loan Agreement dated as of February 1, 2004 (the "First Amendment to Loan Agreement"), which amends the Original Loan

Agreement (the Original Loan Agreement as so amended is referred to herein as the "Agreement"); and

WHEREAS, in connection with obtaining the Authority Bond Insurance Policy, the Company desires by this Supplemental Indenture to provide for the issuance to the Authority Bond Trustee of a new series of Bonds under the Original Indenture as security for the Company's obligations under the Agreement with respect to the payment of the Authority Bonds, to have the designation provided in Article I, Section 1 hereof (herein called the "New Bonds"), and the Original Indenture provides that certain terms and provisions, as determined by the Board of Directors of the Company, of the Bonds of any particular series may be expressed in and provided by the execution of an appropriate supplemental indenture; and

WHEREAS, the Original Indenture provides that the Company and the Trustee may enter into indentures supplemental to the Original Indenture specifically to convey, transfer and assign to the Trustee and to subject to the lien of the Original Indenture additional properties acquired by the Company; and

WHEREAS, the Company, in the exercise of the powers and authority conferred upon and reserved to it under the provisions of the Original Indenture and pursuant to appropriate resolutions of the Board of Directors, has duly resolved and determined to make, execute and deliver to the Trustee a Supplemental Indenture in the form hereof for the purposes herein provided; and

WHEREAS, all conditions and requirements necessary to make this Supplemental Indenture a valid, binding and legal instrument have been done, performed and fulfilled and the execution and delivery hereof have been in all respects duly authorized;

NOW, THEREFORE, THIS INDENTURE WITNESSETH:

That, in consideration of the premises and of the mutual covenants herein contained and of the acceptance of this trust by the Trustee and of the sum of One Dollar duly paid by the Trustee to the Company at or before the time of the execution of this Supplemental Indenture, and of other valuable considerations, the receipt whereof is hereby acknowledged, and in order further to secure the payment of the principal of and interest (and premium, if any) on all Bonds at any time issued and outstanding under the Original Indenture, according to their tenor and effect, and to secure the Company's obligations under the Agreement with respect to the payment of the Authority Bonds, the Company has executed and delivered this Supplemental Indenture and has granted, bargained, sold, warranted, aliened, remised, released, conveyed, assigned, transferred, mortgaged, pledged, set over and confirmed and by these presents does grant, bargain, sell, warrant, alien, remise, release, convey, assign, transfer, mortgage, pledge, set over and confirm unto The Bank of New York, as Trustee, and to its successors in trust under the Original Indenture forever, all and singular the following described properties (in addition to all other properties heretofore subjected to the lien of the Original Indenture and not heretofore released from the lien thereof) - that is to say:

FIRST

ALL power houses, plants, buildings and other structures, dams, dam sites, substations, heating plants, gas works, holders and tanks, together with all and singular the electric, heating, gas and mechanical appliances appurtenant thereto of every nature whatsoever, now owned by the Company, including all and singular the machinery, engines, boilers, furnaces, generators, dynamos, turbines and motors, and all and every character of mechanical appliance for generating or producing electricity, steam, gas and other agencies for light, heat, cold, or power or other purposes, and all transmission and distribution systems used for the transmission and distribution of electricity, steam, gas and other agencies for light, heat, cold or power or any other purpose whatsoever, whether underground or overhead, surface or otherwise, now owned by the Company, including all poles, towers, posts, wires, cables, conduits, manholes, mains, pipes, tubes, drains, furnaces, switchboards, transformers, conductors, insulators, supports, meters, lamps, fuses, junction boxes, regulator stations, and other electric, steam and gas fixtures and apparatus; all of the aforementioned property being located in the City of St. Louis, the counties of Adair, Audrain, Benton, Bollinger, Boone, Butler, Caldwell, Callaway, Camden, Cape Girardeau, Clark, Clay, Clinton, Cole, Cooper, Crawford, Daviess, Dunklin, Franklin, Gasconade, Howard, Iron, Jefferson, Knox, Lewis, Lincoln, Livingston, Macon, Madison, Maries, Marion, Miller, Mississippi, Moniteau, Montgomery, Morgan, New Madrid, Osage, Pemiscot, Perry, Pettis, Phelps, Pike, Pulaski, Ralls, Randolph, Ray, Reynolds, Ripley, St. Charles, St. Francois, Ste. Genevieve, St. Louis, Saline, Schuyler, Scott, Stoddard, Warren, Washington, and Wayne, Missouri, the counties of Adams, Alexander, Calhoun, Franklin, Hancock, Henderson, Jackson, Jersey, Macoupin, Madison, Massac, Monroe, Perry, Pike, Pulaski, St. Clair, Union, and Washington, Illinois, and the counties of Des Moines, Henry, Johnson, Lee, and Washington, Iowa, upon real estate owned by the Company, or occupied by it under rights to so occupy, which real estate is described in the Indenture of Mortgage and Deed of Trust dated June 15, 1937, in the Supplemental Indentures dated May 1, 1941, March 17, 1942, April 13, 1945, April 27, 1945, October 1, 1945, April 11, 1947, April 13, 1949, September 13, 1950, December 1, 1950, September 20, 1951, May 1, 1952, March 1, 1954, May 1, 1955, August 31, 1955, April 1, 1956, July 1, 1956, August 1, 1957, February 1, 1958, March 1, 1958, November 5, 1958, March 16, 1959, June 24, 1959, December 11, 1959, August 17, 1960, September 1, 1960, October 24, 1960, June 30, 1961, July 1, 1961, August 9, 1962, September 30, 1963, November 1, 1963, March 12, 1965, April 1, 1965, April 14, 1966, May 1, 1966, February 17, 1967, March 1, 1967, February 19, 1968, March 15, 1968, August 21, 1968, April 7, 1969, May 1, 1969, September 12, 1969, October 1, 1969, March 26, 1970, April 1, 1970, June 12, 1970, January 1, 1971, April 1, 1971, September 15, 1971, December 3, 1973, February 1, 1974, April 25, 1974, February 3, 1975, March 1, 1975, June 11, 1975, May 12, 1976, August 16, 1976, April 26, 1977, October 15, 1977, November 7, 1977, December 1, 1977, August 1, 1978, October 12, 1979, November 1, 1979, July 7, 1980, August 1, 1980, August 20, 1980, February 1, 1981, October 8, 1981, August 27, 1982, September 1, 1982, December 15, 1982, March 1, 1983, June 21, 1984, December 12, 1984, June 11, 1985, March 1, 1986, May 1, 1986, May 1, 1990, December 1, 1991, December 4, 1991, January 1, 1992, September 30, 1992, October 1, 1992, December 1, 1992, February 1, 1993, February 18, 1993, May 1, 1993, August 1, 1993, October 1, 1993, January 1, 1994, February 1, 2000, August 15, 2002, March 5, 2003, April 1, 2003, July 15, 2003, October 1, 2003 and in this Supplemental Indenture and the seven other Supplemental Indentures each dated

February 1, 2004, or attached to or connected with such real estate or transmission or distribution systems of the Company leading from or into such real estate.

SECOND

ALSO, (except as in the Original Indenture expressly excepted) all franchises and all permits, ordinances, easements, privileges, immunities and licenses, all rights to construct, maintain and operate overhead, surface and underground systems for the distribution and transmission of electricity, steam, gas or other agencies for the supply to itself or others of light, heat, cold or power, all rights-of-way, all waters, water rights and flowage rights and all grants and consents, now owned or, subject to the provisions of Article XII of the Original Indenture, which it may hereafter acquire.

ALSO, (except as in the Original Indenture expressly excepted) all inventions, patent rights and licenses of every kind now owned by the Company or, subject to the provisions of Article XII of the Original Indenture, which it may hereafter acquire.

THIRD

ALSO, subject to the provisions of Article XII of the Original Indenture, all other property, real, personal and mixed (except as therein or herein expressly excepted) of every nature and kind and wheresoever situated now or hereafter possessed by or belonging to the Company, or to which it is now, or may at any time hereafter be, in any manner entitled at law or in equity.

TO HAVE AND TO HOLD all said properties, real, personal and mixed, mortgaged, pledged and conveyed by the Company as aforesaid, or intended so to be, unto the Trustee and its successors and assigns forever;

SUBJECT, HOWEVER, to the exceptions and reservations and matters hereinabove recited, to existing leases, to existing liens upon rights of way for transmission or distribution line purposes, as defined in Article I of the Original Indenture, and any extensions thereof, and subject to existing easements for streets, alleys, highways, rights-of-way and railroad purposes over, upon and across certain of the property hereinbefore described, and subject also to all the terms, conditions, agreements, covenants, exceptions and reservations expressed or provided in the deeds or other instruments respectively under and by virtue of which the Company acquired the properties hereinabove described, and to undetermined liens and charges, if any, incidental to construction or other existing permitted liens as defined in Article I of the Original Indenture;

IN TRUST, NEVERTHELESS, upon the terms and trusts in the Original Indenture and the indentures supplemental thereto, including this Supplemental Indenture, set forth, for the equal and proportionate benefit and security of all present and future holders of the Bonds and coupons issued and to be issued thereunder, or any of them, without preference of any of said Bonds and coupons of any particular series over the Bonds and coupons of any other series, by reason of priority in the time of the issue, sale or negotiation thereof, or by reason of the purpose of issue

or otherwise howsoever, except as otherwise provided in Section 2 of Article IV of the Original Indenture.

AND IT IS HEREBY COVENANTED, DECLARED AND AGREED, by and between the parties hereto, for the benefit of those who shall hold the Bonds and coupons, or any of them to be issued under the Original Indenture, as follows:

ARTICLE I

DESCRIPTION OF THE NEW BONDS

Section 1.1. There is hereby created a new series of Bonds to be executed, authenticated and delivered under and secured by the Original Indenture which shall, subject to the provisions of Section 1 of Article II of the Original Indenture, be designated as "First Mortgage Bonds, Environmental Improvement Series 2004C (1998C Bonds)" (the "New Bonds") of the Company. The New Bonds shall be executed, authenticated and delivered in accordance with the provisions of, and shall in all respects be subject to all of the terms, conditions and covenants of, the Original Indenture and shall be issued to, and registered in the name of, the Authority Bond Trustee under the Authority Bond Indenture to secure any and all obligations of the Company under the Agreement with respect to the payment of the Authority Bonds.

The New Bonds shall mature, subject to prior redemption, on September 1, 2033, and shall bear interest at the same rate or rates of interest as the Authority Bonds which, in turn, shall be determined by the methods set forth in the Authority Bond Indenture, which provides for an Auction Rate, a Daily Rate, a Weekly Rate, a Commercial Paper Rate or a Long-Term Interest Rate (each as defined in the Authority Bonds Indenture). Reference is made to the provisions of the Authority Bond Indenture concerning the methods by which such interest rates are determined, and the means by which the method of determining such interest rates may be changed, and such provisions are included in this Supplemental Indenture as if fully set forth herein. Interest on the New Bonds is payable on the same dates as interest on the Authority Bonds is paid, until the principal sum of the New Bonds is paid in full. The New Bonds shall be payable as to principal and interest in any coin or currency of the United States of America which at the time of payment is legal tender for public and private debts, and shall be payable, in immediately available funds, at the office of the Authority Bond Trustee.

Section 1.2. The New Bonds shall not be assignable or transferable except as permitted or required by Section 12.13 of the Authority Bond Indenture. Any such transfer shall be effected at the principal office or place of business of the Trustee under the Original Indenture. The New Bonds are exchangeable for the New Bonds of other denominations, as in the Original Indenture provided, except that payment of a service charge therefor will not be required by the Company.

Notwithstanding the provisions of Section 6 of Article II of the Original Indenture, the New Bonds shall be dated their date of authentication and shall bear interest from the interest payment date to which interest on the New Bonds has been paid next preceding the date thereof,

unless such date is an interest payment date to which interest has been paid, in which case they shall bear interest from the date thereof.

Upon any payment of the principal of and interest on, all or any portion of the Authority Bonds, whether at maturity or otherwise or upon provision for the payment thereof having been made in accordance with Section 7.01 of the Authority Bond Indenture, the New Bonds in a principal amount equal to the principal amount of such Authority Bonds shall, to the extent of such payment of principal and interest, be deemed paid and the obligation of the Company thereunder to make such payment shall be discharged to such extent and, in the case of the payment of principal, such New Bonds shall be surrendered to the Company for cancellation as provided in and subject to the terms of Section 7.04 of the Authority Bond Indenture. The Trustee may at any time and all times conclusively assume that the obligation of the Company under the Agreement to make payments with respect to the principal of and interest on the Authority Bonds, so far as such payments at the time have become due, has been fully satisfied and discharged pursuant to the foregoing sentence unless and until the Trustee shall have received a written notice from the Authority Bond Trustee signed by one of its officers stating (i) the timely payment of principal or interest on, the Authority Bonds has not been made, (ii) that the Company is in arrears as to the payments required to be made by it to the Authority Bond Trustee pursuant to the Agreement, and (iii) the amount of the arrearage.

                           [Form of Face of New Bond]

No. ____                                                      $________

                              Ill. C. C. No. 6316

NOTWITHSTANDING ANY PROVISIONS HEREOF OR IN THE ORIGINAL INDENTURE THIS BOND IS

NOT ASSIGNABLE OR TRANSFERABLE EXCEPT AS PERMITTED OR REQUIRED BY
SECTION 12.13 OF THE AMENDED AND RESTATED INDENTURE OF TRUST DATED AS OF FEBRUARY 1, 2004, BETWEEN THE STATE ENVIRONMENTAL IMPROVEMENT AND ENERGY RESOURCES AUTHORITY OF THE STATE OF MISSOURI AND UMB BANK & TRUST, N.A. AS SUCCESSOR TO STATE STREET BANK AND TRUST COMPANY OF MISSOURI, N.A., AS TRUSTEE

UNION ELECTRIC COMPANY
(Incorporated under the laws of the State of Missouri)

First Mortgage Bonds, Environmental Improvement Series 2004C (1998C Bonds)

Illinois Commerce Commission Identification No. 6316

UNION ELECTRIC COMPANY, a corporation organized and existing under the laws of the State of Missouri (hereinafter called the "Company," which term shall include any successor corporation as defined in the Amended Indenture referred to on the reverse hereof), for value received, hereby promises to pay to UMB Bank & Trust, N.A., as successor to State Street Bank and Trust Company of Missouri, N.A., as trustee under the Authority Bond Indenture hereinafter referred to, or registered assigns, the sum of _________________________ Dollars, on the 1st day of September, 2033, subject to prior redemption, in any coin or currency of the United States of America which at the time of payment is legal tender for public and private debts, and to pay interest thereon, in like coin or currency, at the same rate or rates of interest as the Authority Bonds (as determined in accordance with the Authority Bond Indenture referred to below), but in no event shall the interest rate on this Bond exceed twelve percent (12%) per annum. Interest on overdue principal premium, if any, and, to the extent permitted by law, on overdue interest, shall be payable at the interest rate payable on the Authority Bonds. Interest on this Bond is payable on the same dates as interest on the Authority Bonds, or, if this Bond shall be duly called for redemption, until the redemption date, or if the Company shall default in the payment of the principal hereof, until the Company's obligation to pay principal shall be discharged as provided in the Amended Indenture is paid, until the principal sum is paid in full. The principal of, and interest on, this Bond are payable, in immediately available funds, at the office of the Authority Bond Trustee hereinafter referred to.

Under an Indenture of Trust dated as of September 1, 1998, as amended and restated by the Amended and Restated Indenture of Trust dated as of February 1, 2004 (as so amended and restated, the "Authority Bond Indenture") between the State Environmental Improvement and Energy Resources Authority of the State of Missouri (the "Authority") and UMB Bank & Trust, N.A., as successor to State Street Bank and Trust Company of Missouri, N.A., as trustee (the "Authority Bond Trustee"), the Authority has issued its Environmental Improvement Revenue

Refunding Bonds (Union Electric Company Project) Series 1998C in the aggregate principal amount of $50,000,000 (the "Authority Bonds"). The Company has agreed to pay the principal of and interest on the Authority Bonds pursuant to a Loan Agreement dated as of September 1, 1998, as supplemented and amended by the First Amendment to Loan Agreement dated as of February 1, 2004 (as so amended, the "Agreement") between the Company and the Authority. Pursuant to the Granting Clause of the Authority Bond Indenture, this Bond is issued to the Authority Bond Trustee to secure any and all obligations of the Company under the Agreement with respect to payment of the Authority Bonds. Payment of principal of, or interest on, the Authority Bonds shall constitute payments on this Bond as further provided herein and in the Supplemental Indenture dated February 1, 2004 pursuant to which this Bond has been issued (the "Supplemental Indenture").

Upon any payment of the principal of, and interest on, all or any portion of the Authority Bonds, whether at maturity or otherwise or upon provision for the payment thereof having been made in accordance with Section 7.01 of the Authority Bond Indenture, a principal amount of this Bond equal to the principal amount of such Authority Bonds shall, to the extent of such payment of principal and interest, be deemed paid and the obligation of the Company thereunder to make such payment shall be discharged to such extent and, in the case of the payment of principal, such Bonds shall be surrendered to the Company for cancellation as provided in Section 7.04 of the Authority Bond Indenture. The Trustee (as hereinafter defined) may at any time and all times conclusively assume that the obligation of the Company to make payments under the Agreement with respect to the principal of, and interest on, the Authority Bonds, so far as such payments at the time have become due, has been fully satisfied and discharged pursuant to the foregoing sentence unless and until the Trustee shall have received a written notice from the Authority Bond Trustee signed by one of its officers stating (i) that timely payment of principal of, or interest on, the Authority Bonds has not been made, (ii) that the Company is in arrears as to the payments required to be made by it to the Authority Bond Trustee pursuant to the Agreement, and (iii) the amount of the arrearage.

This Bond shall not be entitled to any benefit under the Amended Indenture or any indenture supplemental thereto, or become valid or obligatory for any purpose, until The Bank of New York, the Trustee under the Amended Indenture, or a successor trustee thereto under the Amended Indenture, or an agent therefor, shall have signed the form of certificate endorsed hereon.

The provisions of this Bond are continued on the reverse hereof and such continued provisions shall for all purposes have the same effect as though fully set forth at this place.

IN WITNESS WHEREOF, Union Electric Company has caused this Bond to be signed in its name by its Chairman of the Board or President or a Vice President by manual signature or a facsimile thereof, and its corporate seal (or a facsimile thereof) to be hereto affixed and attested by its Secretary or an Assistant Secretary by manual signature or a facsimile thereof.

Dated,
UNION ELECTRIC COMPANY,

[CORPORATE SEAL]

Attest:

[FORM OF TRUSTEE'S CERTIFICATE]

This Bond is one of the Bonds, of the series designated therein, described in the within-mentioned Amended Indenture and Supplemental Indenture of February 1, 2004.

THE BANK OF NEW YORK, as Trustee

[FORM OF REVERSE OF NEW BOND]

This Bond is one of a duly authorized issue of Bonds of the Company (herein called the "Bonds"), limited to an aggregate principal amount of $50,000,000, of the series hereinafter specified, all issued under and equally secured by the Indenture of Mortgage and Deed of Trust, dated June 15, 1937, executed by the Company to The Bank of New York (successor trustee to Bank of America, National Association, formerly Boatmen's Trust Company), as trustee (herein called the "Trustee"), as amended by indentures supplemental thereto dated May 1, 1941, April 1, 1971, February 1, 1974, July 7, 1980, February 1, 2000 and August 15, 2002, between the Company and the Trustee (said mortgage and deed of trust, as so amended, being herein called the "Amended Indenture"), to which Amended Indenture and all indentures supplemental thereto reference is hereby made for a description of the properties mortgaged and pledged, the nature and extent of the security, the rights of the bearers or registered owners of the Bonds and of the Trustee in respect thereto, and the terms and conditions upon which the Bonds are, and are to be, secured. To the extent permitted by, and as provided in, the Amended Indenture, modifications or alterations of the Amended Indenture, or of any indenture supplemental thereto, and of the rights and obligations of the Company and of the holders of the Bonds may be made with the consent of the Company by an affirmative vote of not less than 60% in amount of the Bonds entitled to vote then outstanding, at a meeting of Bondholders called and held as provided in the Amended Indenture, and by an affirmative vote of not less than 60% in amount of the

Bonds of any series entitled to vote then outstanding and affected by such modification or alteration, in case one or more but less than all of the series of Bonds then outstanding under the Amended Indenture are so affected. Additionally, the Company may amend the Amended Indenture, as supplemented, by an appropriate written consent of not less than 60% in aggregate principal amount of the Bonds outstanding (and, if the rights of one or more, but less than all, series of Bonds then outstanding are to be affected by action taken pursuant to such consent, then also by consent of the holders of at least 60% in principal amount of each series of Bonds so to be affected and outstanding hereunder) without a meeting of such Bondholders. No such modification or alteration shall be made which will affect the terms of payment of the principal of, or interest on, this Bond, which are unconditional. The Bonds may be issued in series, for various principal sums, may mature at different times, may bear interest at different rates and may otherwise vary as in the Amended Indenture provided. This Bond is one of a series designated as the "First Mortgage Bonds, Environmental Improvement Series 2004C (1998C Bonds)" (herein called the "Bonds of this Series") of the Company, issued under and secured by the Amended Indenture and described in the indenture (hereinafter called the "Supplemental Indenture") dated February 1, 2004, between the Company and the Trustee, supplemental to the Amended Indenture.

The Bonds of this Series are not entitled to the benefit of any improvement, maintenance or analogous fund.

This Bond is, subject to the provisions of the Amended Indenture, subject to redemption in the amounts, at the times, at the prices and under the circumstances under which the Authority Bonds are subject to redemption under the same terms and circumstances set forth in the Authority Bond Indenture for the redemption of the Authority Bonds.

This Bond is also subject to mandatory redemption at the principal amount hereof plus accrued interest to the date fixed for redemption if the Trustee or the Company is notified that an "Event of Default" under the Authority Bond Indenture has occurred and is continuing and the Authority Bond Trustee has declared the principal amount of all Authority Bonds then outstanding due and payable in accordance with the Authority Bond Indenture.

The Company may, by notice to the Trustee at least 60 days prior to any date on which any principal amount is due on this Bond, elect to receive a credit in respect of such principal payment (a) for any Bonds of this Series then due which have been redeemed prior to such principal payment date or otherwise acquired and delivered to the Trustee for cancellation by said Trustee prior to the giving of such notice, or (b) for any Authority Bonds which have been purchased, delivered for cancellation or previously redeemed, which in each case have not theretofore been applied as a credit against such principal payment. Each Bond with respect to which the Company elects to receive a credit will be credited by the Trustee at 100% of the principal amount thereof against such principal payment, provided further that in the case of a credit with respect to any Authority Bonds, the principal amount thereof shall be established by an officers' certificate (as defined in the Amended Indenture) concurred in by the Authority Bond Trustee, included with the above-mentioned notice to the Trustee. The principal amount of Bonds to be paid on the due date of such principal payment will be reduced by the amount of any such credit or credits in respect of Bonds previously redeemed or delivered as provided above.

Upon cancellation in full or in part of any of the Authority Bonds (or provision for payment thereof having been made in accordance with the provisions of the Authority Bond Indenture) and payment of all fees and charges of the trustee thereunder, such trustee shall deliver to the Trustee, for cancellation a corresponding amount of Bonds remaining in its possession.

Such redemption in every case shall be effected upon notice delivered by the Company at least 60 days prior to the date of redemption, to the registered owner of the Bonds at its address as the same shall appear on the transfer register of the Company, all subject to the conditions of, and as more fully set forth in, the Amended Indenture and Supplemental Indenture.

In case an event of default, as defined in the Amended Indenture, shall occur, the principal of all the bonds at any such time outstanding under the Amended Indenture may be declared or may become due and payable, upon the conditions and in the manner and with the effect provided in the Amended Indenture. The Amended Indenture provides that such declaration may in certain events be waived by the holders of a majority in principal amount of the bonds outstanding.

This Bond shall not be assignable or transferable except as permitted or required by Section 12.13 of the Authority Bond Indenture. This Bond is exchangeable by the registered owner hereof, in person or by duly authorized attorney, on the books of the Company to be kept for that purpose at the office of the Company in the City of St. Louis, Missouri, upon surrender and cancellation of this Bond and on presentation of a duly executed written instrument of transfer, and thereupon a new Bond or Bonds of the same series, of the same aggregate principal amount and in authorized denominations will be issued to the transferee or transferees in exchange herefor, without payment of any charge other than stamp taxes and other governmental charges incident thereto; and this Bond with or without others of like series, may in like manner be exchanged for one or more new Bonds of the same series of other authorized denominations but of the same aggregate principal amount; all subject to the terms and conditions set forth in the Amended Indenture.

As provided in Section 7.04 of the Authority Bond Indenture, from and after the Release Date (as defined in the Authority Bond Indenture), the obligations of the Company with respect to this Bond shall be deemed to be satisfied and discharged, this Bond shall cease to secure in any manner the Company's obligations under the Agreement with respect to the payment of any Authority Bonds outstanding under the Authority Bond Indenture, and, pursuant to Section 7.04 of the Authority Bond Indenture, the Authority Bond Trustee shall forthwith deliver this Bond to the Company for cancellation.

No recourse shall be had for the payment of the principal of, or the interest on, this Bond, or for any claim based hereon or on the Amended Indenture or any indenture supplemental thereto, against any incorporator, or against any stockholder, director or officer, past, present or future, of the Company, or of any predecessor or successor corporation, either directly or through the Company or any such predecessor or successor corporation, whether for amounts unpaid on stock subscriptions or by virtue of any constitution, statute or rule of law, or by the enforcement of any assessment or penalty or otherwise, all such liability, whether at common law, in equity,

by any constitution, statute or otherwise, of incorporators, stockholders, directors or officers being released by every owner hereof by the acceptance of this Bond and as part of the consideration for the issue hereof, and being likewise released by the terms of the Amended Indenture.

[END OF FORM OF REVERSE OF NEW BOND]

ARTICLE II

ISSUE OF THE NEW BONDS

Section 2.1. The principal amount of the New Bonds which may be authenticated and delivered hereunder is limited to an amount equal to the principal amount of Fifty Million Dollars ($50,000,000) consisting of Bonds maturing on September 1, 2033.

Section 2.2. The New Bonds in the aggregate principal amount set forth above, may forthwith be executed by the Company and delivered to the Trustee and shall be authenticated by the Trustee and delivered (either before or after the filing or recording hereof) to or upon the order of the Company, upon compliance by the Company with the applicable provisions of Article III and Article XVIII of the Original Indenture.

Section 2.3. As provided in Section 7.04 of the Authority Bond Indenture, from and after the Release Date (as defined in the Authority Bond Indenture), the obligations of the Company with respect to the New Bonds shall be deemed to be satisfied and discharged, the New Bonds shall cease to secure in any manner the Company's obligations under the Agreement with respect to the payment of any Authority Bonds outstanding under the Authority Bond Indenture, and, pursuant to
Section 7.04 of the Authority Bond Indenture, the Authority Bond Trustee shall forthwith deliver the New Bonds to the Company for cancellation.

ARTICLE III

REDEMPTION OF THE NEW BONDS

Section 3.1. The New Bonds are, subject to the provisions of the Original Indenture, subject to redemption in the amounts, at the times, at the prices and under the circumstances under which the Authority Bonds are subject to redemption, under the same terms and conditions set forth in the Authority Bond Indenture for the redemption of the Authority Bonds. In the event that less than all the New Bonds are to be redeemed, the New Bonds to be redeemed shall be determined by lot in such manner as the Trustee in its discretion shall deem proper, as in the Original Indenture provided.

The New Bonds are also subject to mandatory redemption as set forth in the form of New Bonds in Section 1.3 of Article I of this Supplemental Indenture.

Section 3.2. Subject to the provisions of Article V of the Original Indenture, notice of redemption shall be delivered by the Company at least 60 days prior to the date of redemption, to the registered owner of such Bonds at its address as the same shall appear on the transfer register of the Company.

Section 3.3. As provided in the Authority Bond Indenture, any amounts of money held in the Bond Fund provided in said Indenture and available for such purpose, which are at the request of the Company applied to the payments of the principal of, premium, if any, and interest on the Authority Bonds on any payment or redemption date, shall be applied as a credit on amounts otherwise due under the New Bonds; provided that the amount of such credit shall be established by an officers' certificate (as defined in the Amended Indenture), concurred in by the Authority Bond Trustee which shall be filed with the Trustee prior to the application of any such credit.

Upon cancellation in full or in part of any of the Authority Bonds (or provision for payment thereof having been made in accordance with the provisions of the Authority Bond Indenture) and payment of all fees and charges of the trustee thereunder, such trustee shall deliver to the Trustee, for cancellation a corresponding amount of New Bonds remaining in its possession or shall request such Trustee to issue a New Bond reflecting any such cancellation

ARTICLE IV

COVENANTS

The Company hereby covenants, warrants and agrees;

Section 4.1. That the Company is lawfully seized and possessed of all of the mortgaged property described in the granting clauses of this Supplemental Indenture; that it has good right and lawful authority to mortgage the same as provided in this Supplemental Indenture; and that such mortgaged property is, at the actual date of the issue of the New Bonds, free and clear of any deed of trust, mortgage, lien, charge or encumbrance thereon or affecting the title thereto prior to the Original Indenture, except as set forth in the granting clauses of the Original Indenture or this Supplemental Indenture.

Section 4.2. That, so long as any of the New Bonds are outstanding, whenever any officers' certificate is required to be filed or deposited with the Trustee pursuant to Section 3(b) of Article III of the Original Indenture upon an application for the authentication of additional Bonds pursuant to Article III of the Original Indenture, such officers' certificate shall include, in addition to the matters required to be stated therein by said Section 3(b), the statement with respect to the net earnings of the Company available for interest after property retirement appropriations required by Section 2 of Article V of the Supplemental Indenture of July 1, 1956.

Section 4.3. That, so long as any of the New Bonds are outstanding, the Company will not apply for the authentication and delivery of additional Bonds pursuant to Section 4 of Article III of the Original Indenture or the withdrawal of cash from the trust estate or the reduction of the amount of cash required to be paid into the trust estate or to satisfy the

maintenance and improvement funds under any provision of the Original Indenture or the Supplemental Indentures creating prior series of Bonds, on the basis of the amount of $15,000,000 excluded from net bondable value of property additions not subject to an unfunded prior lien pursuant to Section 3 of Article V of the Supplemental Indenture of October 1, 1945, or on the basis of the amount of $7,500,000 excluded from net bondable value of property additions not subject to an unfunded prior lien pursuant to Section 3 of Article V of the Supplemental Indenture of July 1, 1956.

Section 4.4. That, so long as any of the New Bonds are outstanding, the Company will not issue or permit to be issued any prior lien bonds secured by an unfunded prior lien in addition to the prior lien bonds secured by such unfunded prior lien at the time of first acquisition by the Company of property subject thereto (other than in lieu of lost, stolen or mutilated bonds or on the exchange for bonds already outstanding of an equal principal amount of other bonds of the same issue and the same series, if any, and of the same maturity), except upon compliance with the provisions of Section 16 of Article IV of the Original Indenture, nor unless the net earnings of the Company available for interest after property retirement appropriations (determined as provided in
Section 2 of Article V of the Supplemental Indenture of July 1, 1956), for any 12 consecutive calendar months during the period of 15 calendar months immediately preceding the first day of the month in which the additional prior lien bonds are to be issued, have been, in the aggregate, equal to not less than twice the annual interest charges on the indebtedness specified in subparagraphs
(i) and (ii) of paragraph (1) of Section 2(a) of said Article V; provided that, if the application for the issue of such additional prior lien bonds is upon the basis of payment at maturity of prior lien bonds theretofore sold or otherwise disposed of or the redemption or purchase thereof after a date two years prior to the date of maturity, the additional requirement imposed by this Section 4 with respect to net earnings of the Company available for interest after property retirement appropriations shall not apply. Any officers' certificate with respect to net earnings of the Company, required to be filed with the Trustee as a condition precedent to the issue of such additional prior lien bonds, shall include, in addition to the matters otherwise required to be stated therein, the matters required to be stated in an officers' certificate pursuant to paragraphs (1) and (2) of Section 2(a) of said Article V.

Section 4.5. That, so long as any of the New Bonds are outstanding, the Company will not acquire, by purchase, merger or otherwise, any property subject to a lien or liens which will on acquisition be an unfunded prior lien or prior liens, except upon compliance with the provisions of Section 14 of Article IV of the Original Indenture, nor unless the net earnings of such property available for interest after property retirement appropriations (determined in the manner provided in Section 2 of Article V of the Supplemental Indenture of July 1, 1956), for any 12 consecutive calendar months during the period of 15 calendar months immediately preceding the first day of the month in which the first acquisition of property subject to such lien or liens occurs, have been, in the aggregate, equal to not less than twice the amount of annual interest charges, on all outstanding indebtedness secured by such lien or liens. Any officers' certificate with respect to net earnings of such property, required to be filed with the Trustee as a condition precedent to the acquisition of such property, shall include, in addition to the matters otherwise required to be stated therein, the matters required to be stated in an officers' certificate pursuant to Section 2 of said Article V applicable, however, only to the net earnings of such property and to the indebtedness secured by such liens to which such property is subject.

ARTICLE V

THE TRUSTEE

The Trustee hereby accepts the trusts hereby declared and provided, and agrees to perform the same upon the terms and conditions in the Original Indenture and in this Supplemental Indenture set forth, and upon the following terms and conditions:

The Trustee shall not be responsible in any manner whatsoever for or in respect of the validity or sufficiency of this Supplemental Indenture or the due execution hereof by the Company or for or in respect of the recitals contained herein, all of which recitals are made by the Company solely.

ARTICLE VI

MISCELLANEOUS PROVISIONS

Section 6.1. Except as otherwise defined herein, all terms contained in this Supplemental Indenture shall, for all purposes thereof, have the meanings given to such terms in Article I of the Original Indenture.

Section 6.2. This Supplemental Indenture may be simultaneously executed in any number of counterparts, each of which when so executed shall be deemed to be an original; but such counterparts shall together constitute but one and the same instrument.

IN WITNESS WHEREOF, said Union Electric Company has caused this Supplemental Indenture to be executed on its behalf by its Chairman of the Board or President or one of its Vice Presidents and its corporate seal to be hereto affixed and said seal and this Supplemental Indenture to be attested by its Secretary or one of its Assistant Secretaries; and said The Bank of New York, in evidence of its acceptance of the trust hereby created, has caused this Supplemental Indenture to be executed on its behalf by its President or one of its Vice Presidents, and its corporate seal to be hereto affixed and said seal and this Supplemental Indenture to be attested by its Secretary, or one of its Assistant Secretaries; all as of the 1st day of February, Two thousand and four.

Attested:                               UNION ELECTRIC COMPANY,
                                          1901 Chouteau Avenue
                                          St. Louis, Missouri  63103


/s/ G. L. Waters                        By: /s/ Jerre E. Birdsong
------------------------------             -------------------------------------
             G. L. Waters               Name:   Jerre E. Birdsong
          Assistant Secretary           Title:  Vice President and Treasurer


Signed, sealed and delivered by
       UNION ELECTRIC COMPANY
       in the presence of:


/s/ Daphyne Bradley
------------------------------
             Daphyne Bradley


/s/ Wayne K. Forbes
------------------------------
             Wayne K. Forbes

             As Witnesses

Attested:                               THE BANK OF NEW YORK,
                                          911 Washington Avenue
                                          St. Louis, Missouri  63101


/s/ Thomas Maple                        By: /s/ Robert J. Dunn
----------------------------------         --------------------
                                        Name:   Robert J. Dunn
                                        Title:  As Agent


Signed, sealed and delivered by
        THE BANK OF NEW YORK
        in the presence of:


/s/ Daniel G. Dwyer
----------------------------------


/s/ Richard F. Novosak
----------------------------------

                As Witnesses

STATE OF MISSOURI          )
                           )  SS:
CITY OF ST. LOUIS          )

On this 17th day of February, 2004, before me appeared JERRE E. BIRDSONG, to me personally known, who, being by me duly sworn, did say that he is Vice President and Treasurer of UNION ELECTRIC COMPANY, a corporation, and that the seal affixed to the foregoing instrument is the corporate seal of said corporation, and that said instrument was signed and sealed in behalf of said corporation by authority of its Board of Directors, and said JERRE E. BIRDSONG acknowledged said instrument to be the free act and deed of said corporation.

IN TESTIMONY WHEREOF, I have hereto set my hand and affixed my official seal at my office, in the City and State aforesaid, the day and year last above written.

/s/ S. A. Kitchens
-------------------------------------------

STATE OF MISSOURI          )
                           )  SS:
CITY OF ST. LOUIS          )

On this 17th day of February, 2004, before me appeared Rober J. Dunn, to me personally known, who, being by me duly sworn, did say that he is an Agent of THE BANK OF NEW YORK, a corporation, and that the seal affixed to the foregoing instrument is the corporate seal of said corporation, and that said instrument was signed and sealed in behalf of said corporation, as the trustee thereunder by authority of its Board of Directors, and said Vice President, acknowledged said instrument to be the free act and deed of said corporation as the trustee under said instrument.

IN TESTIMONY WHEREOF, I have hereto set my hand and affixed my official seal at my office, in the City and State aforesaid, the day and year last above written.

/s/ Sally Lardge
-------------------------------------------

Exhibit 4.4

WHEN RECORDED
MAIL TO:

Executed in 35 Counterparts, No. 35

SUPPLEMENTAL INDENTURE

DATED FEBRUARY 1, 2004

UNION ELECTRIC COMPANY

TO

THE BANK OF NEW YORK,
AS TRUSTEE

(SUPPLEMENTAL TO THE INDENTURE OF MORTGAGE AND DEED OF
TRUST DATED JUNE 15, 1937, AS AMENDED, EXECUTED BY

UNION ELECTRIC COMPANY
TO THE BANK OF NEW YORK, AS TRUSTEE)

First Mortgage Bonds, Environmental Improvement Series 2004D (2000B Bonds)

This instrument was prepared by Steven R. Sullivan, Senior Vice President Governmental/Regulatory Policy, General Counsel and Secretary of Union Electric Company, 1901 Chouteau Avenue, St. Louis, Missouri 63103, (314) 554-2098.

SUPPLEMENTAL INDENTURE, dated the 1st day of February, Two thousand and four (2004) made by and between UNION ELECTRIC COMPANY, a corporation organized and existing under the laws of the State of Missouri (hereinafter called the "Company"), party of the first part, and The Bank of New York (successor trustee to Bank of America, National Association, formerly Boatmen's Trust Company), a bank existing under the laws of the State of New York (hereinafter called the "Trustee"), as Trustee under the Indenture of Mortgage and Deed of Trust dated June 15, 1937, hereinafter mentioned, party of the second part:

WHEREAS, the Company has heretofore executed and delivered to the Trustee its Indenture of Mortgage and Deed of Trust, dated June 15, 1937, as amended May 1, 1941, April 1, 1971, February 1, 1974, July 7, 1980, February 1, 2000 and August 15, 2002 (said Indenture of Mortgage and Deed of Trust as so amended, being hereinafter referred to as the "Original Indenture"), to secure the payment of the principal of and the interest (and premium, if any) on all bonds at any time issued and outstanding thereunder, and indentures supplemental thereto dated June 15, 1937, May 1, 1941, March 17, 1942, April 13, 1945, April 27, 1945, October 1, 1945, April 11, 1947, April 13, 1949, September 13, 1950, December 1, 1950, September 20, 1951, May 1, 1952, March 1, 1954, May 1, 1955, August 31, 1955, April 1, 1956, July 1, 1956, August 1, 1957, February 1, 1958, March 1, 1958, November 5, 1958, March 16, 1959, June 24, 1959, December 11, 1959, August 17, 1960, September 1, 1960, October 24, 1960, June 30, 1961, July 1, 1961, August 9, 1962, September 30, 1963, November 1, 1963, March 12, 1965, April 1, 1965, April 14, 1966, May 1, 1966, February 17, 1967, March 1, 1967, February 19, 1968, March 15, 1968, August 21, 1968, April 7, 1969, May 1, 1969, September 12, 1969, October 1, 1969, March 26, 1970, April 1, 1970, June 12, 1970, January 1, 1971, April 1, 1971, September 15, 1971, December 3, 1973, February 1, 1974, April 25, 1974, February 3, 1975, March 1, 1975, June 11, 1975, May 12, 1976, August 16, 1976, April 26, 1977, October 15, 1977, November 7, 1977, December 1, 1977, August 1, 1978, October 12, 1979, November 1, 1979, July 7, 1980, August 1, 1980, August 20, 1980, February 1, 1981, October 8, 1981, August 27, 1982, September 1, 1982, December 15, 1982, March 1, 1983, June 21, 1984, December 12, 1984, June 11, 1985, March 1, 1986, May 1, 1986, May 1, 1990, December 1, 1991, December 4, 1991, January 1, 1992, September 30, 1992, October 1, 1992, December 1, 1992, February 1, 1993, February 18, 1993, May 1, 1993, August 1, 1993, October 1, 1993, January 1, 1994, February 1, 2000, August 15, 2002, March 5, 2003, April 1, 2003, July 15, 2003, October 1, 2003 and three indentures supplemental each dated as of February 1, 2004, respectively, have heretofore been entered into between the Company and the Trustee; and

WHEREAS, Bonds have heretofore been issued by the Company under the Original Indenture as follows:

(1) $80,000,000 principal amount of First Mortgage and Collateral Trust Bonds, 3-3/4% Series due 1962, all of which have been redeemed prior to the date of the execution hereof;

(2) $90,000,000 principal amount of First Mortgage and Collateral Trust Bonds, 3-3/8% Series due 1971, which are described in the Supplemental Indenture dated

May 1, 1941 (hereinafter called the "Supplemental Indenture of May 1, 1941"), all of which have been paid at maturity prior to the date of the execution hereof;

(3) $13,000,000 principal amount of First Mortgage and Collateral Trust Bonds, 2-3/4% Series due 1975 (herein called the "Bonds of 1975 Series"), which are described in the Supplemental Indenture dated October 1, 1945 (hereinafter called the "Supplemental Indenture of October 1, 1945"), all of which have been paid at maturity prior to the date of the execution hereof;

(4) $25,000,000 principal amount of First Mortgage and Collateral Trust Bonds, 2-7/8% Series due 1980 (herein called the "Bonds of 1980 Series"), which are described in the Supplemental Indenture dated December 1, 1950 (hereinafter called the "Supplemental Indenture of December 1, 1950"), all of which have been paid at maturity prior to the date of the execution hereof;

(5) $30,000,000 principal amount of First Mortgage and Collateral Trust Bonds, 3-1/4% Series due 1982 (herein called the "Bonds of 1982 Series"), which are described in the Supplemental Indenture dated May 1, 1952 (hereinafter called the "Supplemental Indenture of May 1, 1952"), all of which have been paid at maturity prior to the date of the execution hereof;

(6) $40,000,000 principal amount of First Mortgage Bonds, 3-3/4% Series due 1986 (herein called the "Bonds of 1986 Series"), which are described in the Supplemental Indenture dated July 1, 1956 (hereinafter called the "Supplemental Indenture of July 1, 1956"), all of which have been paid at maturity prior to the date of the execution hereof;

(7) $35,000,000 principal amount of First Mortgage Bonds, 4-3/8% Series due 1988 (herein called the "Bonds of 1988 Series"), which are described in the Supplemental Indenture dated March 1, 1958 (hereinafter called the "Supplemental Indenture of March 1, 1958"), all of which have been paid at maturity prior to the date of the execution hereof;

(8) $50,000,000 principal amount of First Mortgage Bonds, 4-3/4% Series due 1990 (herein called the "Bonds of 1990 Series"), which are described in the Supplemental Indenture dated September 1, 1960 (hereinafter called the "Supplemental Indenture of September 1, 1960"), all of which have been paid at maturity prior to the date of the execution hereof;

(9) $30,000,000 principal amount of First Mortgage Bonds, 4-3/4% Series due 1991 (herein called the "Bonds of 1991 Series"), which are described in the Supplemental Indenture dated July 1, 1961 (hereinafter called the "Supplemental Indenture of July 1, 1961"), all of which have been paid at maturity prior to the date of the execution hereof;

(10) $30,000,000 principal amount of First Mortgage Bonds, 4-1/2% Series due 1993 (herein called the "Bonds of 1993 Series"), which are described in the

Supplemental Indenture dated November 1, 1963 (hereinafter called the "Supplemental Indenture of November 1, 1963"), all of which have been redeemed prior to the date of the execution hereof;

(11) $35,000,000 principal amount of First Mortgage Bonds, 4-1/2% Series due 1995 (herein called the "Bonds of 1995 Series"), which are described in the Supplemental Indenture dated April 1, 1965 (hereinafter called the "Supplemental Indenture of April 1, 1965"), all of which have been paid at maturity prior to the date of the execution hereof;

(12) $30,000,000 principal amount of First Mortgage Bonds, 5-1/2% Series due 1996 (herein called the "Bonds of 1996 Series"), which are described in the Supplemental Indenture dated May 1, 1966 (hereinafter called the "Supplemental Indenture of May 1, 1966"), all of which have been paid at maturity prior to the date of the execution hereof;

(13) $40,000,000 principal amount of First Mortgage Bonds, 5-1/2% Series due 1997 (herein called the "Bonds of 1997 Series"), which are described in the Supplemental Indenture dated March 1, 1967 (hereinafter called the "Supplemental Indenture of March 1, 1967"), all of which have been paid at maturity prior to the date of the execution hereof;

(14) $50,000,000 principal amount of First Mortgage Bonds, 7% Series due 1998 (herein called the "Bonds of 1998 Series"), which are described in the Supplemental Indenture dated March 15, 1968 (hereinafter called the "Supplemental Indenture of March 15, 1968"), all of which have been redeemed prior to the date of the execution hereof;

(15) $35,000,000 principal amount of First Mortgage Bonds, 7-3/8% Series due 1999 (herein called the "Bonds of May 1999 Series"), which are described in the Supplemental Indenture dated May 1, 1969 (hereinafter called the "Supplemental Indenture of May 1, 1969"), all of which have been redeemed prior to the date of the execution hereof;

(16) $40,000,000 principal amount of First Mortgage Bonds, 8-1/4% Series due 1999 (herein called the "Bonds of October 1999 Series"), which are described in the Supplemental Indenture dated October 1, 1969 (hereinafter called the "Supplemental Indenture of October 1, 1969"), all of which have been redeemed prior to the date of the execution hereof;

(17) $100,000,000 principal amount of First Mortgage Bonds, 9.95% Series due 1999 (herein called the "Bonds of November 1999 Series"), which are described in the Supplemental Indenture dated November 1, 1979 (hereinafter called the "Supplemental Indenture of November 1, 1979"), all of which have been redeemed prior to the date of the execution hereof;

(18) $60,000,000 principal amount of First Mortgage Bonds, 9% Series due 2000 (herein called the "Bonds of 2000 Series"), which are described in the Supplemental Indenture dated April 1, 1970 (hereinafter called the "Supplemental Indenture of April 1, 1970"), all of which have been redeemed prior to the date of the execution hereof;

(19) $50,000,000 principal amount of First Mortgage Bonds, 7-7/8% Series due 2001 (herein called the "Bonds of January 2001 Series"), which are described in the Supplemental Indenture dated January 1, 1971 (hereinafter called the "Supplemental Indenture of January 1, 1971"), all of which have been redeemed prior to the date of the execution hereof;

(20) $50,000,000 principal amount of First Mortgage Bonds, 7 5/8% Series due 2001 (herein called the "Bonds of April 2001 Series"), which are described in the Supplemental Indenture dated April 1, 1971 (hereinafter called the "Supplemental Indenture of April 1, 1971"), all of which have been redeemed prior to the date of the execution hereof;

(21) $60,000,000 principal amount of First Mortgage Bonds, 8 1/8% Series due 2001 (herein called the "Bonds of October 2001 Series"), which are described in the Supplemental Indenture dated September 15, 1971 (hereinafter called the "Supplemental Indenture of September 15, 1971"), all of which have been redeemed prior to the date of the execution hereof;

(22) $70,000,000 principal amount of First Mortgage Bonds, 8-3/8% Series due 2004 (herein called the "Bonds of 2004 Series"), which are described in the Supplemental Indenture dated February 1, 1974 (hereinafter called the "Supplemental Indenture of February 1, 1974"), all of which have been redeemed prior to the date of the execution hereof;

(23) $70,000,000 principal amount of First Mortgage Bonds, 10-1/2% Series due 2005 (herein called the "Bonds of 2005 Series"), which are described in the Supplemental Indenture dated March 1, 1975 (hereinafter called the "Supplemental Indenture of March 1, 1975"), all of which have been redeemed prior to the date of the execution hereof;

(24) $70,000,000 principal amount of First Mortgage Bonds, 8-7/8% Series due 2006 (herein called the "Bonds of 2006 Series"), which are described in the Supplemental Indenture dated August 16, 1976 (hereinafter called the "Supplemental Indenture of August 16, 1976"), all of which have been redeemed prior to the date of the execution hereof;

(25) $27,085,000 principal amount of First Mortgage Bonds, 5.80% Environmental Improvement Series 1977, which are described in the Supplemental Indenture dated October 15, 1977 (hereinafter called the "Supplemental Indenture of October 15, 1977"), all of which have been redeemed prior to the date of the execution hereof;

(26) $60,000,000 principal amount of First Mortgage Bonds, 8 5/8% Series due 2007 (herein called the "Bonds of 2007 Series"), which are described in the Supplemental Indenture dated December 1, 1977 (hereinafter called the "Supplemental Indenture of December 1, 1977"), all of which have been redeemed prior to the date of the execution hereof;

(27) $55,000,000 principal amount of First Mortgage Bonds, 9.35% Series due 2008 (herein called the "Bonds of 2008 Series"), which are described in the Supplemental Indenture dated August 1, 1978 (hereinafter called the "Supplemental Indenture of August 1, 1978"), all of which have been redeemed prior to the date of the execution hereof;

(28) $60,000,000 principal amount of First Mortgage Bonds, Environmental Improvement Series 1980, which are described in the Supplemental Indenture dated August 1, 1980 (hereinafter called the "Supplemental Indenture of August 1, 1980"), all of which have been redeemed prior to the date of the execution hereof;

(29) $150,000,000 principal amount of First Mortgage Bonds, 15-3/8% Series due 1991 (herein called the "Bonds of February 1991 Series"), which are described in the Supplemental Indenture dated February 1, 1981 (hereinafter called the "Supplemental Indenture of February 1, 1981"), all of which have been redeemed prior to the date of the execution hereof;

(30) $125,000,000 principal amount of First Mortgage Bonds, 15% Series due 1992 (herein called the "Bonds of 1992 Series"), which are described in the Supplemental Indenture dated September 1, 1982 (hereinafter called the "Supplemental Indenture of September 1, 1982"), all of which have been redeemed prior to the date of the execution hereof;

(31) $100,000,000 principal amount of First Mortgage Bonds, 13% Series due 2013 (herein called the "Bonds of 2013 Series"), which are described in the Supplemental Indenture dated March 1, 1983 (hereinafter called the "Supplemental Indenture of March 1, 1983"), all of which have been redeemed prior to the date of the execution hereof;

(32) $100,000,000 principal amount of First Mortgage Bonds, 9-3/8% Series due 2016 (herein called the "Bonds of 2016 Series"), which are described in the Supplemental Indenture dated March 1, 1986 (hereinafter called the "Supplemental Indenture of March 1, 1986"), all of which have been redeemed prior to the date of the execution hereof;

(33) $100,000,000 principal amount of First Mortgage Bonds, 8-7/8% Series due 1996 (herein called the "Bonds of 1996 Series"), which are described in the Supplemental Indenture dated May 1, 1986 (hereinafter called the "Supplemental Indenture of May 1, 1986"), all of which have been redeemed prior to the date of the execution hereof;

(34) $60,000,000 principal amount of First Mortgage Bonds, Environmental Improvement Series 1990A, which are described in the Supplemental Indenture dated May 1, 1990 (hereinafter called the "Supplemental Indenture of May 1, 1990"), all of which have been redeemed prior to the date of the execution hereof;

(35) $125,000,000 principal amount of First Mortgage Bonds, 8-3/4% Series due 2021 (herein called the "Bonds of 2021 Series"), which are described in the Supplemental Indenture dated December 1, 1991 (hereinafter called the "Supplemental Indenture of December 1, 1991"), all of which have been redeemed prior to the date of the execution hereof;

(36) $75,000,000 principal amount of First Mortgage Bonds, 8.33% Series due 2002 (herein called the "Bonds of 2002 Series"), which are described in the Supplemental Indenture dated December 4, 1991 (hereinafter called the "Supplemental Indenture of December 4, 1991"), all of which have been paid at maturity prior to the date of the execution hereof;

(37) $100,000,000 principal amount of First Mortgage Bonds, 7.65% Series due 2003 (herein called the "Bonds of 2003 Series"), which are described in the Supplemental Indenture dated January 1, 1992 (hereinafter called the "Supplemental Indenture of January 1, 1992"), all of which have been paid at maturity prior to the date of the execution hereof;

(38) $204,000,000 aggregate principal amount of First Mortgage Bonds, consisting of $100,000,000 principal amount of 6-3/4% Series due 1999 and $104,000,000 principal amount of 8-1/4% Series due 2022 (herein called the "Bonds of 1999 Series" and "Bonds of 2022 Series", respectively), which are described in the Supplemental Indenture dated October 1, 1992 (hereinafter called the "Supplemental Indenture of October 1, 1992"), of which the Bonds of 1999 Series have been paid at maturity prior to the date of execution hereof and the Bonds of 2022 Series have been redeemed prior to the date of the execution hereof;

(39) $170,000,000 aggregate principal amount of First Mortgage Bonds, consisting of $85,000,000 principal amount of 7-3/8% Series due 2004 and $85,000,000 principal amount of 8% Series due 2022 (herein called the "Bonds of December 2004 Series" and "Bonds of December 2022 Series", respectively, which are described in the Supplemental Indenture dated December 1, 1992, (hereinafter called the "Supplemental Indenture of December 1, 1992"), of which the Bonds of December 2022 Series have been redeemed prior to the date of the execution hereof and the Bonds of December 2004 Series are outstanding at the date of the execution hereof;

(40) $188,000,000 principal amount of First Mortgage Bonds, 6-7/8% Series due 2004 (herein called the "Bonds of August 2004 Series"), which are described in the Supplemental Indenture dated February 1, 1993 (hereinafter called the "Supplemental Indenture of February 1, 1993"), all of which are outstanding at the date of the execution hereof;

(41) $148,000,000 principal amount of First Mortgage Bonds, 6-3/4% Series due 2008 (herein called the "Bonds of May 2008 Series"), which are described in the Supplemental Indenture dated May 1, 1993 (hereinafter called the "Supplemental Indenture of May 1, 1993"), all of which are outstanding at the date of the execution hereof;

(42) $75,000,000 principal amount of First Mortgage Bonds, 7.15% Series due 2023 (herein called the "Bonds of 2023 Series"), which are described in the Supplemental Indenture dated August 1, 1993 (hereinafter called the "Supplemental Indenture of August 1, 1993"), all of which have been redeemed prior to the date of the execution hereof;

(43) $44,000,000 principal amount of First Mortgage Bonds, Environmental Improvement Series 1993 (herein called the "Bonds of 2028 Series"), which are described in the Supplemental Indenture dated October 1, 1993 (hereinafter called the "Supplemental Indenture of October 1, 1993"), all of which are outstanding at the date of the execution hereof;

(44) $100,000,000 principal amount of First Mortgage Bonds, 7% Series due 2024 (herein called the "Bonds of 2024 Series"), which are described in the Supplemental Indenture dated January 1, 1994 (hereinafter called the "Supplemental Indenture of January 1, 1994"), all of which are outstanding at the date of the execution hereof;

(45) $173,000,000 principal amount of First Mortgage Bonds, Senior Notes Series AA (herein called the "Bonds of 2012 Series"), which are described in the Supplemental Indenture dated August 15, 2002 (hereinafter called the "Supplemental Indenture of August 15, 2002"), all of which are outstanding at the date of the execution hereof;

(46) $184,000,000 principal amount of First Mortgage Bonds, Senior Notes Series BB (herein called the "Bonds of 2034 Series"), which are described in the Supplemental Indenture dated March 5, 2003 (hereinafter called the "Supplemental Indenture of March 5, 2003"), all of which are outstanding at the date of the execution hereof;

(47) $114,000,000 principal amount of First Mortgage Bonds, Senior Notes Series CC (herein called the "Bonds of 2015 Series"), which are described in the Supplemental Indenture dated April 1, 2003 (hereinafter called the "Supplemental Indenture of April 1, 2003"), all of which are outstanding at the date of the execution hereof;

(48) $200,000,000 principal amount of First Mortgage Bonds, Senior Notes Series DD (herein called the "Bonds of 2018 Series"), which are described in the Supplemental Indenture dated July 15, 2003 (hereinafter called the "Supplemental Indenture of July 15, 2003"), all of which are outstanding at the date of the execution hereof;

(49) $200,000,000 principal amount of First Mortgage Bonds, Senior Notes Series EE (herein called the "Bonds of 2013 Series"), which are described in the Supplemental Indenture dated October 1, 2003 (hereinafter called the "Supplemental Indenture of October 1, 2003"), all of which are outstanding at the date of the execution hereof;

(50) $60,000,000 principal amount of First Mortgage Bonds, Environmental Improvement Series 2004A (1998A Bonds) (herein called the "Bonds of 2033 (Series 1998A)"), which are described in the Supplemental Indenture dated February 1, 2004 (hereinafter called the "Supplemental Indenture of February 1, 2004 (2004A)"), all of which are outstanding at the date of the execution hereof;

(51) $50,000,000 principal amount of First Mortgage Bonds, Environmental Improvement Series 2004B (1998B Bonds) (herein called the "Bonds of 2033 (Series 1998B)"), which are described in the Supplemental Indenture dated February 1, 2004 (hereinafter called the "Supplemental Indenture of February 1, 2004 (2004B)"), all of which are outstanding at the date of the execution hereof; and

(52) $50,000,000 principal amount of First Mortgage Bonds, Environmental Improvement Series 2004C (1998C Bonds) (herein called the "Bonds of 2033 (Series 1998C)"), which are described in the Supplemental Indenture dated February 1, 2004 (hereinafter called the "Supplemental Indenture of February 1, 2004 (2004C)"), all of which are outstanding at the date of the execution hereof; and

WHEREAS, the Company on August 31, 1955 acquired all of the properties of Union Electric Power Company, the Subsidiary as defined in Article I of the Original Indenture, upon the dissolution of the Subsidiary; the Company, by Supplemental Indenture dated August 31, 1955, conveyed all of the properties so acquired (other than property of the character defined as excepted property in the granting clauses of the Original Indenture) to the Trustee upon the terms and trusts in the Original Indenture and the indentures supplemental thereto set forth for the equal and proportionate benefit and security of all present and future holders of the Bonds and coupons issued and to be issued thereunder, all the shares of stock of the Subsidiary were released from the lien of the Original Indenture; and the Company became entitled to change the general designation of the Bonds so as to omit the words "and Collateral Trust"; and

WHEREAS, the Articles of Incorporation of the Company were duly amended on April 23, 1956, to change its corporate name from "Union Electric Company of Missouri" to "Union Electric Company"; and

WHEREAS, the Articles of Agreement of the Trustee were duly amended effective on January 4, 1982 to change its corporate name from "St. Louis Union Trust Company" to "Centerre Trust Company of St. Louis", and further amended on December 9, 1988, to change its corporate name from "Centerre Trust Company of St. Louis" to "Boatmen's Trust Company"; and

WHEREAS, that on March 13, 1998, Boatmen's Trust Company merged into NationsBank, National Association and effective July 5, 1999, changed its name to Bank of America, National Association; and

WHEREAS, that on February 1, 2000, The Bank of New York, as transferee of the corporate trust business of Bank of America, National Association (formerly known as Boatmen's Trust Company), Trustee under the Original Indenture, became successor Trustee under the Original Indenture; and

WHEREAS, the Company is entitled at this time to have authenticated and delivered additional Bonds on the basis of property additions upon compliance with and pursuant to the provisions of Article III, Section 4 of the Original Indenture; and

WHEREAS, the Company has entered into a Loan Agreement dated as of March 1, 2000 (the "Original Loan Agreement") with the State Environmental Improvement and Energy Resources Authority of the State of Missouri (the "Authority") pursuant to which the Authority agreed to issue $63,000,000 aggregate principal amount of its Environmental Improvement Revenue Refunding Bonds (AmerenUE Project) Series 2000B (the "Authority Bonds"), all of which are presently outstanding and loan the proceeds thereof to the Company; and

WHEREAS, the Authority Bonds were issued pursuant to a Trust Indenture dated as of March 1, 2000 (the "Original Authority Bond Indenture") between the Authority and UMB Bank & Trust, N.A., as successor to State Street Bank and Trust Company of Missouri, N.A., as trustee (the "Authority Bond Trustee"); and

WHEREAS, the Company has determined it to be necessary and desirable to further secure rights of the owners of the Authority Bonds to the payment of principal and interest on the Authority Bonds by obtaining a Financial Guaranty Insurance Policy with respect to the Authority Bonds (the "Authority Bond Insurance Policy") from XL Capital Assurance Inc. and in furtherance thereof (i) the Authority and the Authority Bond Trustee will enter into an Amended and Restated Trust Indenture dated as of February 1, 2004 (the "Authority Bond Indenture") which amends and restates the Original Authority Bond Indenture, and
(ii) the Authority and the Company will enter into the First Amendment to Loan Agreement dated as of February 1, 2004 (the "First Amendment to Loan Agreement"), which amends the Original Loan Agreement (the Original Loan Agreement as so amended is referred to herein as the "Agreement"); and

WHEREAS, in connection with obtaining the Authority Bond Insurance Policy, the Company desires by this Supplemental Indenture to provide for the issuance to the Authority Bond Trustee of a new series of Bonds under the Original Indenture as security for the Company's obligations under the Agreement with respect to the payment of the Authority Bonds, to have the designation provided in Article I, Section 1 hereof (herein called the "New Bonds"), and the Original Indenture provides that certain terms and provisions, as determined by the Board of Directors of the Company, of the Bonds of any particular series may be expressed in and provided by the execution of an appropriate supplemental indenture; and

WHEREAS, the Original Indenture provides that the Company and the Trustee may enter into indentures supplemental to the Original Indenture specifically to convey, transfer and assign to the Trustee and to subject to the lien of the Original Indenture additional properties acquired by the Company; and

WHEREAS, the Company, in the exercise of the powers and authority conferred upon and reserved to it under the provisions of the Original Indenture and pursuant to appropriate resolutions of the Board of Directors, has duly resolved and determined to make, execute and deliver to the Trustee a Supplemental Indenture in the form hereof for the purposes herein provided; and

WHEREAS, all conditions and requirements necessary to make this Supplemental Indenture a valid, binding and legal instrument have been done, performed and fulfilled and the execution and delivery hereof have been in all respects duly authorized;

NOW, THEREFORE, THIS INDENTURE WITNESSETH:

That, in consideration of the premises and of the mutual covenants herein contained and of the acceptance of this trust by the Trustee and of the sum of One Dollar duly paid by the Trustee to the Company at or before the time of the execution of this Supplemental Indenture, and of other valuable considerations, the receipt whereof is hereby acknowledged, and in order further to secure the payment of the principal of and interest (and premium, if any) on all Bonds at any time issued and outstanding under the Original Indenture, according to their tenor and effect, and to secure the Company's obligations under the Agreement with respect to the payment of the Authority Bonds, the Company has executed and delivered this Supplemental Indenture and has granted, bargained, sold, warranted, aliened, remised, released, conveyed, assigned, transferred, mortgaged, pledged, set over and confirmed and by these presents does grant, bargain, sell, warrant, alien, remise, release, convey, assign, transfer, mortgage, pledge, set over and confirm unto The Bank of New York, as Trustee, and to its successors in trust under the Original Indenture forever, all and singular the following described properties (in addition to all other properties heretofore subjected to the lien of the Original Indenture and not heretofore released from the lien thereof) - that is to say:

FIRST

ALL power houses, plants, buildings and other structures, dams, dam sites, substations, heating plants, gas works, holders and tanks, together with all and singular the electric, heating, gas and mechanical appliances appurtenant thereto of every nature whatsoever, now owned by the Company, including all and singular the machinery, engines, boilers, furnaces, generators, dynamos, turbines and motors, and all and every character of mechanical appliance for generating or producing electricity, steam, gas and other agencies for light, heat, cold, or power or other purposes, and all transmission and distribution systems used for the transmission and distribution of electricity, steam, gas and other agencies for light, heat, cold or power or any other purpose whatsoever, whether underground or overhead, surface or otherwise, now owned by the Company, including all poles, towers, posts, wires, cables, conduits, manholes, mains, pipes, tubes, drains, furnaces, switchboards, transformers, conductors, insulators, supports,

meters, lamps, fuses, junction boxes, regulator stations, and other electric, steam and gas fixtures and apparatus; all of the aforementioned property being located in the City of St. Louis, the counties of Adair, Audrain, Benton, Bollinger, Boone, Butler, Caldwell, Callaway, Camden, Cape Girardeau, Clark, Clay, Clinton, Cole, Cooper, Crawford, Daviess, Dunklin, Franklin, Gasconade, Howard, Iron, Jefferson, Knox, Lewis, Lincoln, Livingston, Macon, Madison, Maries, Marion, Miller, Mississippi, Moniteau, Montgomery, Morgan, New Madrid, Osage, Pemiscot, Perry, Pettis, Phelps, Pike, Pulaski, Ralls, Randolph, Ray, Reynolds, Ripley, St. Charles, St. Francois, Ste. Genevieve, St. Louis, Saline, Schuyler, Scott, Stoddard, Warren, Washington, and Wayne, Missouri, the counties of Adams, Alexander, Calhoun, Franklin, Hancock, Henderson, Jackson, Jersey, Macoupin, Madison, Massac, Monroe, Perry, Pike, Pulaski, St. Clair, Union, and Washington, Illinois, and the counties of Des Moines, Henry, Johnson, Lee, and Washington, Iowa, upon real estate owned by the Company, or occupied by it under rights to so occupy, which real estate is described in the Indenture of Mortgage and Deed of Trust dated June 15, 1937, in the Supplemental Indentures dated May 1, 1941, March 17, 1942, April 13, 1945, April 27, 1945, October 1, 1945, April 11, 1947, April 13, 1949, September 13, 1950, December 1, 1950, September 20, 1951, May 1, 1952, March 1, 1954, May 1, 1955, August 31, 1955, April 1, 1956, July 1, 1956, August 1, 1957, February 1, 1958, March 1, 1958, November 5, 1958, March 16, 1959, June 24, 1959, December 11, 1959, August 17, 1960, September 1, 1960, October 24, 1960, June 30, 1961, July 1, 1961, August 9, 1962, September 30, 1963, November 1, 1963, March 12, 1965, April 1, 1965, April 14, 1966, May 1, 1966, February 17, 1967, March 1, 1967, February 19, 1968, March 15, 1968, August 21, 1968, April 7, 1969, May 1, 1969, September 12, 1969, October 1, 1969, March 26, 1970, April 1, 1970, June 12, 1970, January 1, 1971, April 1, 1971, September 15, 1971, December 3, 1973, February 1, 1974, April 25, 1974, February 3, 1975, March 1, 1975, June 11, 1975, May 12, 1976, August 16, 1976, April 26, 1977, October 15, 1977, November 7, 1977, December 1, 1977, August 1, 1978, October 12, 1979, November 1, 1979, July 7, 1980, August 1, 1980, August 20, 1980, February 1, 1981, October 8, 1981, August 27, 1982, September 1, 1982, December 15, 1982, March 1, 1983, June 21, 1984, December 12, 1984, June 11, 1985, March 1, 1986, May 1, 1986, May 1, 1990, December 1, 1991, December 4, 1991, January 1, 1992, September 30, 1992, October 1, 1992, December 1, 1992, February 1, 1993, February 18, 1993, May 1, 1993, August 1, 1993, October 1, 1993, January 1, 1994, February 1, 2000, August 15, 2002, March 5, 2003, April 1, 2003, July 15, 2003, October 1, 2003 and in this Supplemental Indenture and the seven other Supplemental Indentures each dated February 1, 2004, or attached to or connected with such real estate or transmission or distribution systems of the Company leading from or into such real estate.

SECOND

ALSO, (except as in the Original Indenture expressly excepted) all franchises and all permits, ordinances, easements, privileges, immunities and licenses, all rights to construct, maintain and operate overhead, surface and underground systems for the distribution and transmission of electricity, steam, gas or other agencies for the supply to itself or others of light, heat, cold or power, all rights-of-way, all waters, water rights and flowage rights and all grants and consents, now owned or, subject to the provisions of Article XII of the Original Indenture, which it may hereafter acquire.

ALSO, (except as in the Original Indenture expressly excepted) all inventions, patent rights and licenses of every kind now owned by the Company or, subject to the provisions of Article XII of the Original Indenture, which it may hereafter acquire.

THIRD

ALSO, subject to the provisions of Article XII of the Original Indenture, all other property, real, personal and mixed (except as therein or herein expressly excepted) of every nature and kind and wheresoever situated now or hereafter possessed by or belonging to the Company, or to which it is now, or may at any time hereafter be, in any manner entitled at law or in equity.

TO HAVE AND TO HOLD all said properties, real, personal and mixed, mortgaged, pledged and conveyed by the Company as aforesaid, or intended so to be, unto the Trustee and its successors and assigns forever;

SUBJECT, HOWEVER, to the exceptions and reservations and matters hereinabove recited, to existing leases, to existing liens upon rights of way for transmission or distribution line purposes, as defined in Article I of the Original Indenture, and any extensions thereof, and subject to existing easements for streets, alleys, highways, rights-of-way and railroad purposes over, upon and across certain of the property hereinbefore described, and subject also to all the terms, conditions, agreements, covenants, exceptions and reservations expressed or provided in the deeds or other instruments respectively under and by virtue of which the Company acquired the properties hereinabove described, and to undetermined liens and charges, if any, incidental to construction or other existing permitted liens as defined in Article I of the Original Indenture;

IN TRUST, NEVERTHELESS, upon the terms and trusts in the Original Indenture and the indentures supplemental thereto, including this Supplemental Indenture, set forth, for the equal and proportionate benefit and security of all present and future holders of the Bonds and coupons issued and to be issued thereunder, or any of them, without preference of any of said Bonds and coupons of any particular series over the Bonds and coupons of any other series, by reason of priority in the time of the issue, sale or negotiation thereof, or by reason of the purpose of issue or otherwise howsoever, except as otherwise provided in
Section 2 of Article IV of the Original Indenture.

AND IT IS HEREBY COVENANTED, DECLARED AND AGREED, by and between the parties hereto, for the benefit of those who shall hold the Bonds and coupons, or any of them to be issued under the Original Indenture, as follows:

ARTICLE I

DESCRIPTION OF THE NEW BONDS

Section 1.1. There is hereby created a new series of Bonds to be executed, authenticated and delivered under and secured by the Original Indenture which shall, subject to the provisions

of Section 1 of Article II of the Original Indenture, be designated as "First Mortgage Bonds, Environmental Improvement Series 2004D (2000B Bonds)" (the "New Bonds") of the Company. The New Bonds shall be executed, authenticated and delivered in accordance with the provisions of, and shall in all respects be subject to all of the terms, conditions and covenants of, the Original Indenture and shall be issued to, and registered in the name of, the Authority Bond Trustee under the Authority Bond Indenture to secure any and all obligations of the Company under the Agreement with respect to the payment of the Authority Bonds.

The New Bonds shall mature, subject to prior redemption, on March 1, 2035, and shall bear interest at the same rate or rates of interest as the Authority Bonds which, in turn, shall be determined by the methods set forth in the Authority Bond Indenture, which provides for a PARS Rate, a Daily Interest Rate, a Weekly Interest Rate, a Flexible Interest Rate or a Term Interest Rate (each as defined in the Authority Bonds Indenture). Reference is made to the provisions of the Authority Bond Indenture concerning the methods by which such interest rates are determined, and the means by which the method of determining such interest rates may be changed, and such provisions are included in this Supplemental Indenture as if fully set forth herein. Interest on the New Bonds is payable on the same dates as interest on the Authority Bonds is paid, until the principal sum of the New Bonds is paid in full. The New Bonds shall be payable as to principal and interest in any coin or currency of the United States of America which at the time of payment is legal tender for public and private debts, and shall be payable, in immediately available funds, at the office of the Authority Bond Trustee.

Section 1.2. The New Bonds shall not be assignable or transferable except as permitted or required by Section 13.15 of the Authority Bond Indenture. Any such transfer shall be effected at the principal office or place of business of the Trustee under the Original Indenture. The New Bonds are exchangeable for the New Bonds of other denominations, as in the Original Indenture provided, except that payment of a service charge therefor will not be required by the Company.

Notwithstanding the provisions of Section 6 of Article II of the Original Indenture, the New Bonds shall be dated their date of authentication and shall bear interest from the interest payment date to which interest on the New Bonds has been paid next preceding the date thereof, unless such date is an interest payment date to which interest has been paid, in which case they shall bear interest from the date thereof.

Upon any payment of the principal of and interest on, all or any portion of the Authority Bonds, whether at maturity or otherwise or upon provision for the payment thereof having been made in accordance with Section 8.01 of the Authority Bond Indenture, the New Bonds in a principal amount equal to the principal amount of such Authority Bonds shall, to the extent of such payment of principal and interest, be deemed paid and the obligation of the Company thereunder to make such payment shall be discharged to such extent and, in the case of the payment of principal, such New Bonds shall be surrendered to the Company for cancellation as provided in and subject to the terms of Section 8.02 of the Authority Bond Indenture. The Trustee may at any time and all times conclusively assume that the obligation of the Company under the Agreement to make payments with respect to the principal of and interest on the Authority Bonds, so far as such payments at the time have become due, has been fully satisfied

and discharged pursuant to the foregoing sentence unless and until the Trustee shall have received a written notice from the Authority Bond Trustee signed by one of its officers stating (i) the timely payment of principal or interest on, the Authority Bonds has not been made, (ii) that the Company is in arrears as to the payments required to be made by it to the Authority Bond Trustee pursuant to the Agreement, and (iii) the amount of the arrearage.

Section 1.3. The New Bonds and the Trustee's certificate on the New Bonds shall be substantially in the following forms respectively:

                           [Form of Face of New Bond]

No. ____                                                         $________

                               Ill. C. C. No. 6318

NOTWITHSTANDING ANY PROVISIONS HEREOF OR IN THE ORIGINAL INDENTURE THIS BOND IS
NOT ASSIGNABLE OR TRANSFERABLE EXCEPT AS PERMITTED OR REQUIRED BY

SECTION 13.15 OF THE AMENDED AND RESTATED TRUST INDENTURE DATED AS OF FEBRUARY 1, 2004, BETWEEN THE STATE ENVIRONMENTAL IMPROVEMENT AND ENERGY
RESOURCES AUTHORITY OF THE STATE OF MISSOURI AND UMB BANK & TRUST, N.A., AS SUCCESSOR TO STATE STREET BANK AND TRUST COMPANY OF MISSOURI, N.A., AS TRUSTEE

UNION ELECTRIC COMPANY
(Incorporated under the laws of the State of Missouri)

First Mortgage Bonds, Environmental Improvement Series 2004D (2000B Bonds)

Illinois Commerce Commission Identification No. 6318

UNION ELECTRIC COMPANY, a corporation organized and existing under the laws of the State of Missouri (hereinafter called the "Company," which term shall include any successor corporation as defined in the Amended Indenture referred to on the reverse hereof), for value received, hereby promises to pay to UMB Bank & Trust, N.A., as successor to State Street Bank and Trust Company of Missouri, N.A., as trustee under the Authority Bond Indenture hereinafter referred to, or registered assigns, the sum of _________________________ Dollars, on the 1st day of March, 2035, subject to prior redemption, in any coin or currency of the United States of America which at the time of payment is legal tender for public and private debts, and to pay interest thereon, in like coin or currency, at the same rate or rates of interest as the Authority Bonds (as determined in accordance with the Authority Bond Indenture referred to below), but in no event shall the interest rate on this Bond exceed eighteen percent (18%) per annum. Interest on overdue principal premium, if any, and, to the extent permitted by law, on overdue interest, shall be payable at the interest rate payable on the Authority Bonds. Interest on this Bond is payable on the same dates as interest on the Authority Bonds, or, if this Bond shall be duly called for redemption, until the redemption date, or if the Company shall default in the payment of the principal hereof, until the Company's obligation to pay principal shall be discharged as provided in the Amended Indenture is paid, until the principal sum is paid in full. The principal of, and interest on, this Bond are payable, in immediately available funds, at the office of the Authority Bond Trustee hereinafter referred to.

Under a Trust Indenture dated as of March 1, 2000, as amended and restated by the Amended and Restated Trust Indenture dated as of February 1, 2004 (as so amended and restated, the "Authority Bond Indenture") between the State Environmental Improvement and Energy Resources Authority of the State of Missouri (the "Authority") and UMB Bank & Trust, N.A., as successor to State Street Bank and Trust Company of Missouri, N.A., as trustee (the "Authority Bond Trustee"), the Authority has issued its Environmental Improvement Revenue

Refunding Bonds (AmerenUE Project) Series 2000B in the aggregate principal amount of $63,000,000 (the "Authority Bonds"). The Company has agreed to pay the principal of and interest on the Authority Bonds pursuant to a Loan Agreement dated as of March 1, 2000, as supplemented and amended by the First Amendment to Loan Agreement dated as of February 1, 2004 (as so amended, the "Agreement") between the Company and the Authority. Pursuant to the Granting Clauses of the Authority Bond Indenture, this Bond is issued to the Authority Bond Trustee to secure any and all obligations of the Company under the Agreement with respect to payment of the Authority Bonds. Payment of principal of, or interest on, the Authority Bonds shall constitute payments on this Bond as further provided herein and in the Supplemental Indenture dated February 1, 2004 pursuant to which this Bond has been issued (the "Supplemental Indenture").

Upon any payment of the principal of, and interest on, all or any portion of the Authority Bonds, whether at maturity or otherwise or upon provision for the payment thereof having been made in accordance with Section 8.01 of the Authority Bond Indenture, a principal amount of this Bond equal to the principal amount of such Authority Bonds shall, to the extent of such payment of principal and interest, be deemed paid and the obligation of the Company thereunder to make such payment shall be discharged to such extent and, in the case of the payment of principal, such Bonds shall be surrendered to the Company for cancellation as provided in Section 8.02 of the Authority Bond Indenture. The Trustee (as hereinafter defined) may at any time and all times conclusively assume that the obligation of the Company to make payments under the Agreement with respect to the principal of, and interest on, the Authority Bonds, so far as such payments at the time have become due, has been fully satisfied and discharged pursuant to the foregoing sentence unless and until the Trustee shall have received a written notice from the Authority Bond Trustee signed by one of its officers stating (i) that timely payment of principal of, or interest on, the Authority Bonds has not been made, (ii) that the Company is in arrears as to the payments required to be made by it to the Authority Bond Trustee pursuant to the Agreement, and (iii) the amount of the arrearage.

This Bond shall not be entitled to any benefit under the Amended Indenture or any indenture supplemental thereto, or become valid or obligatory for any purpose, until The Bank of New York, the Trustee under the Amended Indenture, or a successor trustee thereto under the Amended Indenture, or an agent therefor, shall have signed the form of certificate endorsed hereon.

The provisions of this Bond are continued on the reverse hereof and such continued provisions shall for all purposes have the same effect as though fully set forth at this place.

IN WITNESS WHEREOF, Union Electric Company has caused this Bond to be signed in its name by its Chairman of the Board or President or a Vice President by manual signature or a facsimile thereof, and its corporate seal (or a facsimile thereof) to be hereto affixed and attested by its Secretary or an Assistant Secretary by manual signature or a facsimile thereof.

Dated,
UNION ELECTRIC COMPANY,

[CORPORATE SEAL]

Attest:

[FORM OF TRUSTEE'S CERTIFICATE]

This Bond is one of the Bonds, of the series designated therein, described in the within-mentioned Amended Indenture and Supplemental Indenture of February 1, 2004.

THE BANK OF NEW YORK, as Trustee

[FORM OF REVERSE OF NEW BOND]

This Bond is one of a duly authorized issue of Bonds of the Company (herein called the "Bonds"), limited to an aggregate principal amount of $50,000,000, of the series hereinafter specified, all issued under and equally secured by the Indenture of Mortgage and Deed of Trust, dated June 15, 1937, executed by the Company to The Bank of New York (successor trustee to Bank of America, National Association, formerly Boatmen's Trust Company), as trustee (herein called the "Trustee"), as amended by indentures supplemental thereto dated May 1, 1941, April 1, 1971, February 1, 1974, July 7, 1980, February 1, 2000 and August 15, 2002, between the Company and the Trustee (said mortgage and deed of trust, as so amended, being herein called the "Amended Indenture"), to which Amended Indenture and all indentures supplemental thereto reference is hereby made for a description of the properties mortgaged and pledged, the nature and extent of the security, the rights of the bearers or registered owners of the Bonds and of the Trustee in respect thereto, and the terms and conditions upon which the Bonds are, and are to be, secured. To the extent permitted by, and as provided in, the Amended Indenture, modifications or alterations of the Amended Indenture, or of any indenture supplemental thereto, and of the rights and obligations of the Company and of the holders of the Bonds may be made with the consent of the Company by an affirmative vote of not less than 60% in amount of the

Bonds entitled to vote then outstanding, at a meeting of Bondholders called and held as provided in the Amended Indenture, and by an affirmative vote of not less than 60% in amount of the Bonds of any series entitled to vote then outstanding and affected by such modification or alteration, in case one or more but less than all of the series of Bonds then outstanding under the Amended Indenture are so affected. Additionally, the Company may amend the Amended Indenture, as supplemented, by an appropriate written consent of not less than 60% in aggregate principal amount of the Bonds outstanding (and, if the rights of one or more, but less than all, series of Bonds then outstanding are to be affected by action taken pursuant to such consent, then also by consent of the holders of at least 60% in principal amount of each series of Bonds so to be affected and outstanding hereunder) without a meeting of such Bondholders. No such modification or alteration shall be made which will affect the terms of payment of the principal of, or interest on, this Bond, which are unconditional. The Bonds may be issued in series, for various principal sums, may mature at different times, may bear interest at different rates and may otherwise vary as in the Amended Indenture provided. This Bond is one of a series designated as the "First Mortgage Bonds, Environmental Improvement Series 2004D (2000B Bonds)" (herein called the "Bonds of this Series") of the Company, issued under and secured by the Amended Indenture and described in the indenture (hereinafter called the "Supplemental Indenture") dated February 1, 2004, between the Company and the Trustee, supplemental to the Amended Indenture.

The Bonds of this Series are not entitled to the benefit of any improvement, maintenance or analogous fund.

This Bond is, subject to the provisions of the Amended Indenture, subject to redemption in the amounts, at the times, at the prices and under the circumstances under which the Authority Bonds are subject to redemption under the same terms and circumstances set forth in the Authority Bond Indenture for the redemption of the Authority Bonds.

This Bond is also subject to mandatory redemption at the principal amount hereof plus accrued interest to the date fixed for redemption if the Trustee or the Company is notified that an "Event of Default" under the Authority Bond Indenture has occurred and is continuing and the Authority Bond Trustee has declared the principal amount of all Authority Bonds then outstanding due and payable in accordance with the Authority Bond Indenture.

The Company may, by notice to the Trustee at least 60 days prior to any date on which any principal amount is due on this Bond, elect to receive a credit in respect of such principal payment (a) for any Bonds of this Series then due which have been redeemed prior to such principal payment date or otherwise acquired and delivered to the Trustee for cancellation by said Trustee prior to the giving of such notice, or (b) for any Authority Bonds which have been purchased, delivered for cancellation or previously redeemed, which in each case have not theretofore been applied as a credit against such principal payment. Each Bond with respect to which the Company elects to receive a credit will be credited by the Trustee at 100% of the principal amount thereof against such principal payment, provided further that in the case of a credit with respect to any Authority Bonds, the principal amount thereof shall be established by an officers' certificate (as defined in the Amended Indenture) concurred in by the Authority Bond Trustee, included with the above-mentioned notice to the Trustee. The principal amount of Bonds to be paid on the due date of such principal payment will be reduced by the amount of any such credit or credits in respect of Bonds previously redeemed or delivered as provided above.

Upon cancellation in full or in part of any of the Authority Bonds (or provision for payment thereof having been made in accordance with the provisions of the Authority Bond Indenture) and payment of all fees and charges of the trustee thereunder, such trustee shall deliver to the Trustee, for cancellation a corresponding amount of Bonds remaining in its possession.

Such redemption in every case shall be effected upon notice delivered by the Company at least 60 days prior to the date of redemption, to the registered owner of the Bonds at its address as the same shall appear on the transfer register of the Company, all subject to the conditions of, and as more fully set forth in, the Amended Indenture and Supplemental Indenture.

In case an event of default, as defined in the Amended Indenture, shall occur, the principal of all the bonds at any such time outstanding under the Amended Indenture may be declared or may become due and payable, upon the conditions and in the manner and with the effect provided in the Amended Indenture. The Amended Indenture provides that such declaration may in certain events be waived by the holders of a majority in principal amount of the bonds outstanding.

This Bond shall not be assignable or transferable except as permitted or required by Section 13.15 of the Authority Bond Indenture. This Bond is exchangeable by the registered owner hereof, in person or by duly authorized attorney, on the books of the Company to be kept for that purpose at the office of the Company in the City of St. Louis, Missouri, upon surrender and cancellation of this Bond and on presentation of a duly executed written instrument of transfer, and thereupon a new Bond or Bonds of the same series, of the same aggregate principal amount and in authorized denominations will be issued to the transferee or transferees in exchange herefor, without payment of any charge other than stamp taxes and other governmental charges incident thereto; and this Bond with or without others of like series, may in like manner be exchanged for one or more new Bonds of the same series of other authorized denominations but of the same aggregate principal amount; all subject to the terms and conditions set forth in the Amended Indenture.

As provided in Section 8.02 of the Authority Bond Indenture, from and after the Release Date (as defined in the Authority Bond Indenture), the obligations of the Company with respect to this Bond shall be deemed to be satisfied and discharged, this Bond shall cease to secure in any manner the Company's obligations under the Agreement with respect to the payment of any Authority Bonds outstanding under the Authority Bond Indenture, and, pursuant to Section 8.02 of the Authority Bond Indenture, the Authority Bond Trustee shall forthwith deliver this Bond to the Company for cancellation.

No recourse shall be had for the payment of the principal of, or the interest on, this Bond, or for any claim based hereon or on the Amended Indenture or any indenture supplemental thereto, against any incorporator, or against any stockholder, director or officer, past, present or future, of the Company, or of any predecessor or successor corporation, either directly or through the Company or any such predecessor or successor corporation, whether for amounts unpaid on stock subscriptions or by virtue of any constitution, statute or rule of law, or by the enforcement of any assessment or penalty or otherwise, all such liability, whether at common law, in equity,

by any constitution, statute or otherwise, of incorporators, stockholders, directors or officers being released by every owner hereof by the acceptance of this Bond and as part of the consideration for the issue hereof, and being likewise released by the terms of the Amended Indenture.

[END OF FORM OF REVERSE OF NEW BOND]

ARTICLE II

ISSUE OF THE NEW BONDS

Section 2.1. The principal amount of the New Bonds which may be authenticated and delivered hereunder is limited to an amount equal to the principal amount of Sixty Three Million Dollars ($63,000,000) consisting of Bonds maturing on March 1, 2035.

Section 2.2. The New Bonds in the aggregate principal amount set forth above, may forthwith be executed by the Company and delivered to the Trustee and shall be authenticated by the Trustee and delivered (either before or after the filing or recording hereof) to or upon the order of the Company, upon compliance by the Company with the applicable provisions of Article III and Article XVIII of the Original Indenture.

Section 2.3. As provided in Section 8.02 of the Authority Bond Indenture, from and after the Release Date (as defined in the Authority Bond Indenture), the obligations of the Company with respect to the New Bonds shall be deemed to be satisfied and discharged, the New Bonds shall cease to secure in any manner the Company's obligations under the Agreement with respect to the payment of any Authority Bonds outstanding under the Authority Bond Indenture, and, pursuant to
Section 8.02 of the Authority Bond Indenture, the Authority Bond Trustee shall forthwith deliver the New Bonds to the Company for cancellation.

ARTICLE III

REDEMPTION OF THE NEW BONDS

Section 3.1. The New Bonds are, subject to the provisions of the Original Indenture, subject to redemption in the amounts, at the times, at the prices and under the circumstances under which the Authority Bonds are subject to redemption, under the same terms and conditions set forth in the Authority Bond Indenture for the redemption of the Authority Bonds. In the event that less than all the New Bonds are to be redeemed, the New Bonds to be redeemed shall be determined by lot in such manner as the Trustee in its discretion shall deem proper, as in the Original Indenture provided.

The New Bonds are also subject to mandatory redemption as set forth in the form of New Bonds in Section 1.3 of Article I of this Supplemental Indenture.

Section 3.2. Subject to the provisions of Article V of the Original Indenture, notice of redemption shall be delivered by the Company at least 60 days prior to the date of redemption, to the registered owner of such Bonds at its address as the same shall appear on the transfer register of the Company.

Section 3.3. As provided in the Authority Bond Indenture, any amounts of money held in the Bond Fund provided in said Indenture and available for such purpose, which are at the request of the Company applied to the payments of the principal of, premium, if any, and interest on the Authority Bonds on any payment or redemption date, shall be applied as a credit on amounts otherwise due under the New Bonds; provided that the amount of such credit shall be established by an officers' certificate (as defined in the Amended Indenture), concurred in by the Authority Bond Trustee which shall be filed with the Trustee prior to the application of any such credit.

Upon cancellation in full or in part of any of the Authority Bonds (or provision for payment thereof having been made in accordance with the provisions of the Authority Bond Indenture) and payment of all fees and charges of the trustee thereunder, such trustee shall deliver to the Trustee, for cancellation a corresponding amount of New Bonds remaining in its possession or shall request such Trustee to issue a New Bond reflecting any such cancellation

ARTICLE IV

COVENANTS

The Company hereby covenants, warrants and agrees;

Section 4.1. That the Company is lawfully seized and possessed of all of the mortgaged property described in the granting clauses of this Supplemental Indenture; that it has good right and lawful authority to mortgage the same as provided in this Supplemental Indenture; and that such mortgaged property is, at the actual date of the issue of the New Bonds, free and clear of any deed of trust, mortgage, lien, charge or encumbrance thereon or affecting the title thereto prior to the Original Indenture, except as set forth in the granting clauses of the Original Indenture or this Supplemental Indenture.

Section 4.2. That, so long as any of the New Bonds are outstanding, whenever any officers' certificate is required to be filed or deposited with the Trustee pursuant to Section 3(b) of Article III of the Original Indenture upon an application for the authentication of additional Bonds pursuant to Article III of the Original Indenture, such officers' certificate shall include, in addition to the matters required to be stated therein by said Section 3(b), the statement with respect to the net earnings of the Company available for interest after property retirement appropriations required by Section 2 of Article V of the Supplemental Indenture of July 1, 1956.

Section 4.3. That, so long as any of the New Bonds are outstanding, the Company will not apply for the authentication and delivery of additional Bonds pursuant to Section 4 of Article III of the Original Indenture or the withdrawal of cash from the trust estate or the reduction of the amount of cash required to be paid into the trust estate or to satisfy the

maintenance and improvement funds under any provision of the Original Indenture or the Supplemental Indentures creating prior series of Bonds, on the basis of the amount of $15,000,000 excluded from net bondable value of property additions not subject to an unfunded prior lien pursuant to Section 3 of Article V of the Supplemental Indenture of October 1, 1945, or on the basis of the amount of $7,500,000 excluded from net bondable value of property additions not subject to an unfunded prior lien pursuant to Section 3 of Article V of the Supplemental Indenture of July 1, 1956.

Section 4.4. That, so long as any of the New Bonds are outstanding, the Company will not issue or permit to be issued any prior lien bonds secured by an unfunded prior lien in addition to the prior lien bonds secured by such unfunded prior lien at the time of first acquisition by the Company of property subject thereto (other than in lieu of lost, stolen or mutilated bonds or on the exchange for bonds already outstanding of an equal principal amount of other bonds of the same issue and the same series, if any, and of the same maturity), except upon compliance with the provisions of Section 16 of Article IV of the Original Indenture, nor unless the net earnings of the Company available for interest after property retirement appropriations (determined as provided in
Section 2 of Article V of the Supplemental Indenture of July 1, 1956), for any 12 consecutive calendar months during the period of 15 calendar months immediately preceding the first day of the month in which the additional prior lien bonds are to be issued, have been, in the aggregate, equal to not less than twice the annual interest charges on the indebtedness specified in subparagraphs
(i) and (ii) of paragraph (1) of Section 2(a) of said Article V; provided that, if the application for the issue of such additional prior lien bonds is upon the basis of payment at maturity of prior lien bonds theretofore sold or otherwise disposed of or the redemption or purchase thereof after a date two years prior to the date of maturity, the additional requirement imposed by this Section 4 with respect to net earnings of the Company available for interest after property retirement appropriations shall not apply. Any officers' certificate with respect to net earnings of the Company, required to be filed with the Trustee as a condition precedent to the issue of such additional prior lien bonds, shall include, in addition to the matters otherwise required to be stated therein, the matters required to be stated in an officers' certificate pursuant to paragraphs (1) and (2) of Section 2(a) of said Article V.

Section 4.5. That, so long as any of the New Bonds are outstanding, the Company will not acquire, by purchase, merger or otherwise, any property subject to a lien or liens which will on acquisition be an unfunded prior lien or prior liens, except upon compliance with the provisions of Section 14 of Article IV of the Original Indenture, nor unless the net earnings of such property available for interest after property retirement appropriations (determined in the manner provided in Section 2 of Article V of the Supplemental Indenture of July 1, 1956), for any 12 consecutive calendar months during the period of 15 calendar months immediately preceding the first day of the month in which the first acquisition of property subject to such lien or liens occurs, have been, in the aggregate, equal to not less than twice the amount of annual interest charges, on all outstanding indebtedness secured by such lien or liens. Any officers' certificate with respect to net earnings of such property, required to be filed with the Trustee as a condition precedent to the acquisition of such property, shall include, in addition to the matters otherwise required to be stated therein, the matters required to be stated in an officers' certificate pursuant to Section 2 of said Article V applicable, however, only to the net earnings of such property and to the indebtedness secured by such liens to which such property is subject.

ARTICLE V

THE TRUSTEE

The Trustee hereby accepts the trusts hereby declared and provided, and agrees to perform the same upon the terms and conditions in the Original Indenture and in this Supplemental Indenture set forth, and upon the following terms and conditions:

The Trustee shall not be responsible in any manner whatsoever for or in respect of the validity or sufficiency of this Supplemental Indenture or the due execution hereof by the Company or for or in respect of the recitals contained herein, all of which recitals are made by the Company solely.

ARTICLE VI

MISCELLANEOUS PROVISIONS

Section 6.1. Except as otherwise defined herein, all terms contained in this Supplemental Indenture shall, for all purposes thereof, have the meanings given to such terms in Article I of the Original Indenture.

Section 6.2. This Supplemental Indenture may be simultaneously executed in any number of counterparts, each of which when so executed shall be deemed to be an original; but such counterparts shall together constitute but one and the same instrument.

IN WITNESS WHEREOF, said Union Electric Company has caused this Supplemental Indenture to be executed on its behalf by its Chairman of the Board or President or one of its Vice Presidents and its corporate seal to be hereto affixed and said seal and this Supplemental Indenture to be attested by its Secretary or one of its Assistant Secretaries; and said The Bank of New York, in evidence of its acceptance of the trust hereby created, has caused this Supplemental Indenture to be executed on its behalf by its President or one of its Vice Presidents, and its corporate seal to be hereto affixed and said seal and this Supplemental Indenture to be attested by its Secretary, or one of its Assistant Secretaries; all as of the 1st day of February, Two thousand and four.

Attested:                              UNION ELECTRIC COMPANY,
                                         1901 Chouteau Avenue
                                         St. Louis, Missouri  63103


/s/ G. L. Waters                       By:  /s/ Jerre E. Birdsong
-----------------------------             --------------------------------------
          G. L. Waters                 Name:    Jerre E. Birdsong
      Assistant Secretary              Title: Vice President and Treasurer


Signed, sealed and delivered by
       UNION ELECTRIC COMPANY
       in the presence of:


/s/ D. Bradley
-----------------------------
          Daphyne Bradley


/s/ Wayne K. Forbes
-----------------------------
          Wayne K. Forbes

As Witnesses

Attested:                              THE BANK OF NEW YORK,
                                         911 Washington Avenue
                                         St. Louis, Missouri  63101


/s/ Belinda Brown                      By:  /s/ Robert J. Dunn
----------------------------------        --------------------------------------
Belinda Brown                          Name:    Robert J. Dunn
As Agent                               Title:   As Agent

Signed, sealed and delivered by
THE BANK OF NEW YORK
in the presence of:

/s/ Daniel G. Dwyer
----------------------------------
Daniel G. Dwyer


/s/ Richard F. Novosak
----------------------------------
Richard F. Novosak

STATE OF MISSOURI          )
                           )  SS:
CITY OF ST. LOUIS          )

On this 9th day of March 2004, before me appeared JERRE E. BIRDSONG, to me personally known, who, being by me duly sworn, did say that he is Vice President and Treasurer of UNION ELECTRIC COMPANY, a corporation, and that the seal affixed to the foregoing instrument is the corporate seal of said corporation, and that said instrument was signed and sealed in behalf of said corporation by authority of its Board of Directors, and said JERRE E. BIRDSONG acknowledged said instrument to be the free act and deed of said corporation.

IN TESTIMONY WHEREOF, I have hereto set my hand and affixed my official seal at my office, in the City and State aforesaid, the day and year last above written.

/s/ S.A. Kitchens
---------------------------------------

STATE OF MISSOURI          )
                           )  SS:
CITY OF ST. LOUIS          )

On this 9th day of March 2004, before me appeared Robert J. Dunn, to me personally known, who, being by me duly sworn, did say that he is an Agent of THE BANK OF NEW YORK, a corporation, and that the seal affixed to the foregoing instrument is the corporate seal of said corporation, and that said instrument was signed and sealed in behalf of said corporation, as the trustee thereunder by authority of its Board of Directors, and said Vice President, acknowledged said instrument to be the free act and deed of said corporation as the trustee under said instrument.

IN TESTIMONY WHEREOF, I have hereto set my hand and affixed my official seal at my office, in the City and State aforesaid, the day and year last above written.

/s/ Renee Beard
---------------------------------------

Exhibit 4.5

WHEN RECORDED
MAIL TO:

Executed in 35 Counterparts, No. 35

SUPPLEMENTAL INDENTURE

DATED FEBRUARY 1, 2004

UNION ELECTRIC COMPANY

TO

THE BANK OF NEW YORK,
AS TRUSTEE

(SUPPLEMENTAL TO THE INDENTURE OF MORTGAGE AND DEED OF
TRUST DATED JUNE 15, 1937, AS AMENDED, EXECUTED BY

UNION ELECTRIC COMPANY
TO THE BANK OF NEW YORK, AS TRUSTEE)

First Mortgage Bonds, Environmental Improvement Series 2004E (2000A Bonds)

This instrument was prepared by Steven R. Sullivan, Senior Vice President Governmental/Regulatory Policy, General Counsel and Secretary of Union Electric Company, 1901 Chouteau Avenue, St. Louis, Missouri 63103, (314) 554-2098.

SUPPLEMENTAL INDENTURE, dated the 1st day of February, Two thousand and four (2004) made by and between UNION ELECTRIC COMPANY, a corporation organized and existing under the laws of the State of Missouri (hereinafter called the "Company"), party of the first part, and The Bank of New York (successor trustee to Bank of America, National Association, formerly Boatmen's Trust Company), a bank existing under the laws of the State of New York (hereinafter called the "Trustee"), as Trustee under the Indenture of Mortgage and Deed of Trust dated June 15, 1937, hereinafter mentioned, party of the second part:

WHEREAS, the Company has heretofore executed and delivered to the Trustee its Indenture of Mortgage and Deed of Trust, dated June 15, 1937, as amended May 1, 1941, April 1, 1971, February 1, 1974, July 7, 1980, February 1, 2000 and August 15, 2002 (said Indenture of Mortgage and Deed of Trust as so amended, being hereinafter referred to as the "Original Indenture"), to secure the payment of the principal of and the interest (and premium, if any) on all bonds at any time issued and outstanding thereunder, and indentures supplemental thereto dated June 15, 1937, May 1, 1941, March 17, 1942, April 13, 1945, April 27, 1945, October 1, 1945, April 11, 1947, April 13, 1949, September 13, 1950, December 1, 1950, September 20, 1951, May 1, 1952, March 1, 1954, May 1, 1955, August 31, 1955, April 1, 1956, July 1, 1956, August 1, 1957, February 1, 1958, March 1, 1958, November 5, 1958, March 16, 1959, June 24, 1959, December 11, 1959, August 17, 1960, September 1, 1960, October 24, 1960, June 30, 1961, July 1, 1961, August 9, 1962, September 30, 1963, November 1, 1963, March 12, 1965, April 1, 1965, April 14, 1966, May 1, 1966, February 17, 1967, March 1, 1967, February 19, 1968, March 15, 1968, August 21, 1968, April 7, 1969, May 1, 1969, September 12, 1969, October 1, 1969, March 26, 1970, April 1, 1970, June 12, 1970, January 1, 1971, April 1, 1971, September 15, 1971, December 3, 1973, February 1, 1974, April 25, 1974, February 3, 1975, March 1, 1975, June 11, 1975, May 12, 1976, August 16, 1976, April 26, 1977, October 15, 1977, November 7, 1977, December 1, 1977, August 1, 1978, October 12, 1979, November 1, 1979, July 7, 1980, August 1, 1980, August 20, 1980, February 1, 1981, October 8, 1981, August 27, 1982, September 1, 1982, December 15, 1982, March 1, 1983, June 21, 1984, December 12, 1984, June 11, 1985, March 1, 1986, May 1, 1986, May 1, 1990, December 1, 1991, December 4, 1991, January 1, 1992, September 30, 1992, October 1, 1992, December 1, 1992, February 1, 1993, February 18, 1993, May 1, 1993, August 1, 1993, October 1, 1993, January 1, 1994, February 1, 2000, August 15, 2002, March 5, 2003, April 1, 2003, July 15, 2003, October 1, 2003 and the four indentures supplemental each dated as of February 1, 2004, respectively, have heretofore been entered into between the Company and the Trustee; and

WHEREAS, Bonds have heretofore been issued by the Company under the Original Indenture as follows:

(1) $80,000,000 principal amount of First Mortgage and Collateral Trust Bonds, 3-3/4% Series due 1962, all of which have been redeemed prior to the date of the execution hereof;

(2) $90,000,000 principal amount of First Mortgage and Collateral Trust Bonds, 3-3/8% Series due 1971, which are described in the Supplemental Indenture dated

May 1, 1941 (hereinafter called the "Supplemental Indenture of May 1, 1941"), all of which have been paid at maturity prior to the date of the execution hereof;

(3) $13,000,000 principal amount of First Mortgage and Collateral Trust Bonds, 2-3/4% Series due 1975 (herein called the "Bonds of 1975 Series"), which are described in the Supplemental Indenture dated October 1, 1945 (hereinafter called the "Supplemental Indenture of October 1, 1945"), all of which have been paid at maturity prior to the date of the execution hereof;

(4) $25,000,000 principal amount of First Mortgage and Collateral Trust Bonds, 2-7/8% Series due 1980 (herein called the "Bonds of 1980 Series"), which are described in the Supplemental Indenture dated December 1, 1950 (hereinafter called the "Supplemental Indenture of December 1, 1950"), all of which have been paid at maturity prior to the date of the execution hereof;

(5) $30,000,000 principal amount of First Mortgage and Collateral Trust Bonds, 3-1/4% Series due 1982 (herein called the "Bonds of 1982 Series"), which are described in the Supplemental Indenture dated May 1, 1952 (hereinafter called the "Supplemental Indenture of May 1, 1952"), all of which have been paid at maturity prior to the date of the execution hereof;

(6) $40,000,000 principal amount of First Mortgage Bonds, 3-3/4% Series due 1986 (herein called the "Bonds of 1986 Series"), which are described in the Supplemental Indenture dated July 1, 1956 (hereinafter called the "Supplemental Indenture of July 1, 1956"), all of which have been paid at maturity prior to the date of the execution hereof;

(7) $35,000,000 principal amount of First Mortgage Bonds, 4-3/8% Series due 1988 (herein called the "Bonds of 1988 Series"), which are described in the Supplemental Indenture dated March 1, 1958 (hereinafter called the "Supplemental Indenture of March 1, 1958"), all of which have been paid at maturity prior to the date of the execution hereof;

(8) $50,000,000 principal amount of First Mortgage Bonds, 4-3/4% Series due 1990 (herein called the "Bonds of 1990 Series"), which are described in the Supplemental Indenture dated September 1, 1960 (hereinafter called the "Supplemental Indenture of September 1, 1960"), all of which have been paid at maturity prior to the date of the execution hereof;

(9) $30,000,000 principal amount of First Mortgage Bonds, 4-3/4% Series due 1991 (herein called the "Bonds of 1991 Series"), which are described in the Supplemental Indenture dated July 1, 1961 (hereinafter called the "Supplemental Indenture of July 1, 1961"), all of which have been paid at maturity prior to the date of the execution hereof;

(10) $30,000,000 principal amount of First Mortgage Bonds, 4-1/2% Series due 1993 (herein called the "Bonds of 1993 Series"), which are described in the

Supplemental Indenture dated November 1, 1963 (hereinafter called the "Supplemental Indenture of November 1, 1963"), all of which have been redeemed prior to the date of the execution hereof;

(11) $35,000,000 principal amount of First Mortgage Bonds, 4-1/2% Series due 1995 (herein called the "Bonds of 1995 Series"), which are described in the Supplemental Indenture dated April 1, 1965 (hereinafter called the "Supplemental Indenture of April 1, 1965"), all of which have been paid at maturity prior to the date of the execution hereof;

(12) $30,000,000 principal amount of First Mortgage Bonds, 5-1/2% Series due 1996 (herein called the "Bonds of 1996 Series"), which are described in the Supplemental Indenture dated May 1, 1966 (hereinafter called the "Supplemental Indenture of May 1, 1966"), all of which have been paid at maturity prior to the date of the execution hereof;

(13) $40,000,000 principal amount of First Mortgage Bonds, 5-1/2% Series due 1997 (herein called the "Bonds of 1997 Series"), which are described in the Supplemental Indenture dated March 1, 1967 (hereinafter called the "Supplemental Indenture of March 1, 1967"), all of which have been paid at maturity prior to the date of the execution hereof;

(14) $50,000,000 principal amount of First Mortgage Bonds, 7% Series due 1998 (herein called the "Bonds of 1998 Series"), which are described in the Supplemental Indenture dated March 15, 1968 (hereinafter called the "Supplemental Indenture of March 15, 1968"), all of which have been redeemed prior to the date of the execution hereof;

(15) $35,000,000 principal amount of First Mortgage Bonds, 7-3/8% Series due 1999 (herein called the "Bonds of May 1999 Series"), which are described in the Supplemental Indenture dated May 1, 1969 (hereinafter called the "Supplemental Indenture of May 1, 1969"), all of which have been redeemed prior to the date of the execution hereof;

(16) $40,000,000 principal amount of First Mortgage Bonds, 8-1/4% Series due 1999 (herein called the "Bonds of October 1999 Series"), which are described in the Supplemental Indenture dated October 1, 1969 (hereinafter called the "Supplemental Indenture of October 1, 1969"), all of which have been redeemed prior to the date of the execution hereof;

(17) $100,000,000 principal amount of First Mortgage Bonds, 9.95% Series due 1999 (herein called the "Bonds of November 1999 Series"), which are described in the Supplemental Indenture dated November 1, 1979 (hereinafter called the "Supplemental Indenture of November 1, 1979"), all of which have been redeemed prior to the date of the execution hereof;

(18) $60,000,000 principal amount of First Mortgage Bonds, 9% Series due 2000 (herein called the "Bonds of 2000 Series"), which are described in the Supplemental Indenture dated April 1, 1970 (hereinafter called the "Supplemental Indenture of April 1, 1970"), all of which have been redeemed prior to the date of the execution hereof;

(19) $50,000,000 principal amount of First Mortgage Bonds, 7-7/8% Series due 2001 (herein called the "Bonds of January 2001 Series"), which are described in the Supplemental Indenture dated January 1, 1971 (hereinafter called the "Supplemental Indenture of January 1, 1971"), all of which have been redeemed prior to the date of the execution hereof;

(20) $50,000,000 principal amount of First Mortgage Bonds, 7 5/8% Series due 2001 (herein called the "Bonds of April 2001 Series"), which are described in the Supplemental Indenture dated April 1, 1971 (hereinafter called the "Supplemental Indenture of April 1, 1971"), all of which have been redeemed prior to the date of the execution hereof;

(21) $60,000,000 principal amount of First Mortgage Bonds, 8 1/8% Series due 2001 (herein called the "Bonds of October 2001 Series"), which are described in the Supplemental Indenture dated September 15, 1971 (hereinafter called the "Supplemental Indenture of September 15, 1971"), all of which have been redeemed prior to the date of the execution hereof;

(22) $70,000,000 principal amount of First Mortgage Bonds, 8-3/8% Series due 2004 (herein called the "Bonds of 2004 Series"), which are described in the Supplemental Indenture dated February 1, 1974 (hereinafter called the "Supplemental Indenture of February 1, 1974"), all of which have been redeemed prior to the date of the execution hereof;

(23) $70,000,000 principal amount of First Mortgage Bonds, 10-1/2% Series due 2005 (herein called the "Bonds of 2005 Series"), which are described in the Supplemental Indenture dated March 1, 1975 (hereinafter called the "Supplemental Indenture of March 1, 1975"), all of which have been redeemed prior to the date of the execution hereof;

(24) $70,000,000 principal amount of First Mortgage Bonds, 8-7/8% Series due 2006 (herein called the "Bonds of 2006 Series"), which are described in the Supplemental Indenture dated August 16, 1976 (hereinafter called the "Supplemental Indenture of August 16, 1976"), all of which have been redeemed prior to the date of the execution hereof;

(25) $27,085,000 principal amount of First Mortgage Bonds, 5.80% Environmental Improvement Series 1977, which are described in the Supplemental Indenture dated October 15, 1977 (hereinafter called the "Supplemental Indenture of October 15, 1977"), all of which have been redeemed prior to the date of the execution hereof;

(26) $60,000,000 principal amount of First Mortgage Bonds, 8 5/8% Series due 2007 (herein called the "Bonds of 2007 Series"), which are described in the Supplemental Indenture dated December 1, 1977 (hereinafter called the "Supplemental Indenture of December 1, 1977"), all of which have been redeemed prior to the date of the execution hereof;

(27) $55,000,000 principal amount of First Mortgage Bonds, 9.35% Series due 2008 (herein called the "Bonds of 2008 Series"), which are described in the Supplemental Indenture dated August 1, 1978 (hereinafter called the "Supplemental Indenture of August 1, 1978"), all of which have been redeemed prior to the date of the execution hereof;

(28) $60,000,000 principal amount of First Mortgage Bonds, Environmental Improvement Series 1980, which are described in the Supplemental Indenture dated August 1, 1980 (hereinafter called the "Supplemental Indenture of August 1, 1980"), all of which have been redeemed prior to the date of the execution hereof;

(29) $150,000,000 principal amount of First Mortgage Bonds, 15-3/8% Series due 1991 (herein called the "Bonds of February 1991 Series"), which are described in the Supplemental Indenture dated February 1, 1981 (hereinafter called the "Supplemental Indenture of February 1, 1981"), all of which have been redeemed prior to the date of the execution hereof;

(30) $125,000,000 principal amount of First Mortgage Bonds, 15% Series due 1992 (herein called the "Bonds of 1992 Series"), which are described in the Supplemental Indenture dated September 1, 1982 (hereinafter called the "Supplemental Indenture of September 1, 1982"), all of which have been redeemed prior to the date of the execution hereof;

(31) $100,000,000 principal amount of First Mortgage Bonds, 13% Series due 2013 (herein called the "Bonds of 2013 Series"), which are described in the Supplemental Indenture dated March 1, 1983 (hereinafter called the "Supplemental Indenture of March 1, 1983"), all of which have been redeemed prior to the date of the execution hereof;

(32) $100,000,000 principal amount of First Mortgage Bonds, 9-3/8% Series due 2016 (herein called the "Bonds of 2016 Series"), which are described in the Supplemental Indenture dated March 1, 1986 (hereinafter called the "Supplemental Indenture of March 1, 1986"), all of which have been redeemed prior to the date of the execution hereof;

(33) $100,000,000 principal amount of First Mortgage Bonds, 8-7/8% Series due 1996 (herein called the "Bonds of 1996 Series"), which are described in the Supplemental Indenture dated May 1, 1986 (hereinafter called the "Supplemental Indenture of May 1, 1986"), all of which have been redeemed prior to the date of the execution hereof;

(34) $60,000,000 principal amount of First Mortgage Bonds, Environmental Improvement Series 1990A, which are described in the Supplemental Indenture dated May 1, 1990 (hereinafter called the "Supplemental Indenture of May 1, 1990"), all of which have been redeemed prior to the date of the execution hereof;

(35) $125,000,000 principal amount of First Mortgage Bonds, 8-3/4% Series due 2021 (herein called the "Bonds of 2021 Series"), which are described in the Supplemental Indenture dated December 1, 1991 (hereinafter called the "Supplemental Indenture of December 1, 1991"), all of which have been redeemed prior to the date of the execution hereof;

(36) $75,000,000 principal amount of First Mortgage Bonds, 8.33% Series due 2002 (herein called the "Bonds of 2002 Series"), which are described in the Supplemental Indenture dated December 4, 1991 (hereinafter called the "Supplemental Indenture of December 4, 1991"), all of which have been paid at maturity prior to the date of the execution hereof;

(37) $100,000,000 principal amount of First Mortgage Bonds, 7.65% Series due 2003 (herein called the "Bonds of 2003 Series"), which are described in the Supplemental Indenture dated January 1, 1992 (hereinafter called the "Supplemental Indenture of January 1, 1992"), all of which have been paid at maturity prior to the date of the execution hereof;

(38) $204,000,000 aggregate principal amount of First Mortgage Bonds, consisting of $100,000,000 principal amount of 6-3/4% Series due 1999 and $104,000,000 principal amount of 8-1/4% Series due 2022 (herein called the "Bonds of 1999 Series" and "Bonds of 2022 Series", respectively), which are described in the Supplemental Indenture dated October 1, 1992 (hereinafter called the "Supplemental Indenture of October 1, 1992"), of which the Bonds of 1999 Series have been paid at maturity prior to the date of execution hereof and the Bonds of 2022 Series have been redeemed prior to the date of the execution hereof;

(39) $170,000,000 aggregate principal amount of First Mortgage Bonds, consisting of $85,000,000 principal amount of 7-3/8% Series due 2004 and $85,000,000 principal amount of 8% Series due 2022 (herein called the "Bonds of December 2004 Series" and "Bonds of December 2022 Series", respectively, which are described in the Supplemental Indenture dated December 1, 1992, (hereinafter called the "Supplemental Indenture of December 1, 1992"), of which the Bonds of December 2022 Series have been redeemed prior to the date of the execution hereof and the Bonds of December 2004 Series are outstanding at the date of the execution hereof;

(40) $188,000,000 principal amount of First Mortgage Bonds, 6-7/8% Series due 2004 (herein called the "Bonds of August 2004 Series"), which are described in the Supplemental Indenture dated February 1, 1993 (hereinafter called the "Supplemental Indenture of February 1, 1993"), all of which are outstanding at the date of the execution hereof;

(41) $148,000,000 principal amount of First Mortgage Bonds, 6-3/4% Series due 2008 (herein called the "Bonds of May 2008 Series"), which are described in the Supplemental Indenture dated May 1, 1993 (hereinafter called the "Supplemental Indenture of May 1, 1993"), all of which are outstanding at the date of the execution hereof;

(42) $75,000,000 principal amount of First Mortgage Bonds, 7.15% Series due 2023 (herein called the "Bonds of 2023 Series"), which are described in the Supplemental Indenture dated August 1, 1993 (hereinafter called the "Supplemental Indenture of August 1, 1993"), all of which have been redeemed prior to the date of the execution hereof;

(43) $44,000,000 principal amount of First Mortgage Bonds, Environmental Improvement Series 1993 (herein called the "Bonds of 2028 Series"), which are described in the Supplemental Indenture dated October 1, 1993 (hereinafter called the "Supplemental Indenture of October 1, 1993"), all of which are outstanding at the date of the execution hereof;

(44) $100,000,000 principal amount of First Mortgage Bonds, 7% Series due 2024 (herein called the "Bonds of 2024 Series"), which are described in the Supplemental Indenture dated January 1, 1994 (hereinafter called the "Supplemental Indenture of January 1, 1994"), all of which are outstanding at the date of the execution hereof;

(45) $173,000,000 principal amount of First Mortgage Bonds, Senior Notes Series AA (herein called the "Bonds of 2012 Series"), which are described in the Supplemental Indenture dated August 15, 2002 (hereinafter called the "Supplemental Indenture of August 15, 2002"), all of which are outstanding at the date of the execution hereof;

(46) $184,000,000 principal amount of First Mortgage Bonds, Senior Notes Series BB (herein called the "Bonds of 2034 Series"), which are described in the Supplemental Indenture dated March 5, 2003 (hereinafter called the "Supplemental Indenture of March 5, 2003"), all of which are outstanding at the date of the execution hereof;

(47) $114,000,000 principal amount of First Mortgage Bonds, Senior Notes Series CC (herein called the "Bonds of 2015 Series"), which are described in the Supplemental Indenture dated April 1, 2003 (hereinafter called the "Supplemental Indenture of April 1, 2003"), all of which are outstanding at the date of the execution hereof;

(48) $200,000,000 principal amount of First Mortgage Bonds, Senior Notes Series DD (herein called the "Bonds of 2018 Series"), which are described in the Supplemental Indenture dated July 15, 2003 (hereinafter called the "Supplemental Indenture of July 15, 2003"), all of which are outstanding at the date of the execution hereof;

(49) $200,000,000 principal amount of First Mortgage Bonds, Senior Notes Series EE (herein called the "Bonds of 2013 Series"), which are described in the Supplemental Indenture dated October 1, 2003 (hereinafter called the "Supplemental Indenture of October 1, 2003"), all of which are outstanding at the date of the execution hereof;

(50) $60,000,000 principal amount of First Mortgage Bonds, Environmental Improvement Series 2004A (1998A Bonds) (herein called the "Bonds of 2033 (Series 1998A)"), which are described in the Supplemental Indenture dated February 1, 2004 (hereinafter called the "Supplemental Indenture of February 1, 2004 (2004A)"), all of which are outstanding at the date of the execution hereof;

(51) $50,000,000 principal amount of First Mortgage Bonds, Environmental Improvement Series 2004B) (1998B Bonds) (herein called the "Bonds of 2033 (Series 1998B)"), which are described in the Supplemental Indenture dated February 1, 2004 (hereinafter called the "Supplemental Indenture of February 1, 2004 (2004B)"), all of which are outstanding at the date of the execution hereof;

(52) $50,000,000 principal amount of First Mortgage Bonds, Environmental Improvement Series 2004C (1998C Bonds) (herein called the "Bonds of 2033 (Series 1998C)"), which are described in the Supplemental Indenture dated February 1, 2004 (hereinafter called the "Supplemental Indenture of February 1, 2004 (2004C)"), all of which are outstanding at the date of the execution hereof; and

(53) $63,000,000 principal amount of First Mortgage Bonds, Environmental Improvement Series 2004D (2000B Bonds) (herein called the "Bonds of 2035 (Series 2000B)"), which are described in the Supplemental Indenture dated February 1, 2004 (hereinafter called the "Supplemental Indenture of February 1, 2004 (2004D)"), all of which are outstanding at the date of the execution hereof; and

WHEREAS, the Company on August 31, 1955 acquired all of the properties of Union Electric Power Company, the Subsidiary as defined in Article I of the Original Indenture, upon the dissolution of the Subsidiary; the Company, by Supplemental Indenture dated August 31, 1955, conveyed all of the properties so acquired (other than property of the character defined as excepted property in the granting clauses of the Original Indenture) to the Trustee upon the terms and trusts in the Original Indenture and the indentures supplemental thereto set forth for the equal and proportionate benefit and security of all present and future holders of the Bonds and coupons issued and to be issued thereunder, all the shares of stock of the Subsidiary were released from the lien of the Original Indenture; and the Company became entitled to change the general designation of the Bonds so as to omit the words "and Collateral Trust"; and

WHEREAS, the Articles of Incorporation of the Company were duly amended on April 23, 1956, to change its corporate name from "Union Electric Company of Missouri" to "Union Electric Company"; and

WHEREAS, the Articles of Agreement of the Trustee were duly amended effective on January 4, 1982 to change its corporate name from "St. Louis Union Trust Company" to "Centerre Trust Company of St. Louis", and further amended on December 9, 1988, to change its corporate name from "Centerre Trust Company of St. Louis" to "Boatmen's Trust Company"; and

WHEREAS, that on March 13, 1998, Boatmen's Trust Company merged into NationsBank, National Association and effective July 5, 1999, changed its name to Bank of America, National Association; and

WHEREAS, that on February 1, 2000, The Bank of New York, as transferee of the corporate trust business of Bank of America, National Association (formerly known as Boatmen's Trust Company), Trustee under the Original Indenture, became successor Trustee under the Original Indenture; and

WHEREAS, the Company is entitled at this time to have authenticated and delivered additional Bonds on the basis of property additions upon compliance with and pursuant to the provisions of Article III, Section 4 of the Original Indenture; and

WHEREAS, the Company has entered into a Loan Agreement dated as of March 1, 2000 (the "Original Loan Agreement") with the State Environmental Improvement and Energy Resources Authority of the State of Missouri (the "Authority") pursuant to which the Authority agreed to issue $63,500,000 aggregate principal amount of its Environmental Improvement Revenue Refunding Bonds (AmerenUE Project) Series 2000A (the "Authority Bonds"), all of which are presently outstanding and loan the proceeds thereof to the Company; and

WHEREAS, the Authority Bonds were issued pursuant to a Trust Indenture dated as of March 1, 2000 (the "Original Authority Bond Indenture") between the Authority and UMB Bank & Trust, N.A., as successor to State Street Bank and Trust Company of Missouri, N.A., as trustee (the "Authority Bond Trustee"); and

WHEREAS, the Company has determined it to be necessary and desirable to further secure rights of the owners of the Authority Bonds to the payment of principal and interest on the Authority Bonds by obtaining a Financial Guaranty Insurance Policy with respect to the Authority Bonds (the "Authority Bond Insurance Policy") from XL Capital Assurance Inc. and in furtherance thereof (i) the Authority and the Authority Bond Trustee will enter into an Amended and Restated Trust Indenture dated as of February 1, 2004 (the "Authority Bond Indenture") which amends and restates the Original Authority Bond Indenture, and
(ii) the Authority and the Company will enter into the First Amendment to Loan Agreement dated as of February 1, 2004 (the "First Amendment to Loan Agreement"), which amends the Original Loan Agreement (the Original Loan Agreement as so amended is referred to herein as the "Agreement"); and

WHEREAS, in connection with obtaining the Authority Bond Insurance Policy, the Company desires by this Supplemental Indenture to provide for the issuance to the Authority Bond Trustee of a new series of Bonds under the Original Indenture as security for the

Company's obligations under the Agreement with respect to the payment of the Authority Bonds, to have the designation provided in Article I, Section 1 hereof (herein called the "New Bonds"), and the Original Indenture provides that certain terms and provisions, as determined by the Board of Directors of the Company, of the Bonds of any particular series may be expressed in and provided by the execution of an appropriate supplemental indenture; and

WHEREAS, the Original Indenture provides that the Company and the Trustee may enter into indentures supplemental to the Original Indenture specifically to convey, transfer and assign to the Trustee and to subject to the lien of the Original Indenture additional properties acquired by the Company; and

WHEREAS, the Company, in the exercise of the powers and authority conferred upon and reserved to it under the provisions of the Original Indenture and pursuant to appropriate resolutions of the Board of Directors, has duly resolved and determined to make, execute and deliver to the Trustee a Supplemental Indenture in the form hereof for the purposes herein provided; and

WHEREAS, all conditions and requirements necessary to make this Supplemental Indenture a valid, binding and legal instrument have been done, performed and fulfilled and the execution and delivery hereof have been in all respects duly authorized;

NOW, THEREFORE, THIS INDENTURE WITNESSETH:

That, in consideration of the premises and of the mutual covenants herein contained and of the acceptance of this trust by the Trustee and of the sum of One Dollar duly paid by the Trustee to the Company at or before the time of the execution of this Supplemental Indenture, and of other valuable considerations, the receipt whereof is hereby acknowledged, and in order further to secure the payment of the principal of and interest (and premium, if any) on all Bonds at any time issued and outstanding under the Original Indenture, according to their tenor and effect, and to secure the Company's obligations under the Agreement with respect to the payment of the Authority Bonds, the Company has executed and delivered this Supplemental Indenture and has granted, bargained, sold, warranted, aliened, remised, released, conveyed, assigned, transferred, mortgaged, pledged, set over and confirmed and by these presents does grant, bargain, sell, warrant, alien, remise, release, convey, assign, transfer, mortgage, pledge, set over and confirm unto The Bank of New York, as Trustee, and to its successors in trust under the Original Indenture forever, all and singular the following described properties (in addition to all other properties heretofore subjected to the lien of the Original Indenture and not heretofore released from the lien thereof) - that is to say:

FIRST

ALL power houses, plants, buildings and other structures, dams, dam sites, substations, heating plants, gas works, holders and tanks, together with all and singular the electric, heating, gas and mechanical appliances appurtenant thereto of every nature whatsoever, now owned by the Company, including all and singular the machinery, engines, boilers, furnaces, generators, dynamos, turbines and motors, and all and every character of mechanical appliance for

generating or producing electricity, steam, gas and other agencies for light, heat, cold, or power or other purposes, and all transmission and distribution systems used for the transmission and distribution of electricity, steam, gas and other agencies for light, heat, cold or power or any other purpose whatsoever, whether underground or overhead, surface or otherwise, now owned by the Company, including all poles, towers, posts, wires, cables, conduits, manholes, mains, pipes, tubes, drains, furnaces, switchboards, transformers, conductors, insulators, supports, meters, lamps, fuses, junction boxes, regulator stations, and other electric, steam and gas fixtures and apparatus; all of the aforementioned property being located in the City of St. Louis, the counties of Adair, Audrain, Benton, Bollinger, Boone, Butler, Caldwell, Callaway, Camden, Cape Girardeau, Clark, Clay, Clinton, Cole, Cooper, Crawford, Daviess, Dunklin, Franklin, Gasconade, Howard, Iron, Jefferson, Knox, Lewis, Lincoln, Livingston, Macon, Madison, Maries, Marion, Miller, Mississippi, Moniteau, Montgomery, Morgan, New Madrid, Osage, Pemiscot, Perry, Pettis, Phelps, Pike, Pulaski, Ralls, Randolph, Ray, Reynolds, Ripley, St. Charles, St. Francois, Ste. Genevieve, St. Louis, Saline, Schuyler, Scott, Stoddard, Warren, Washington, and Wayne, Missouri, the counties of Adams, Alexander, Calhoun, Franklin, Hancock, Henderson, Jackson, Jersey, Macoupin, Madison, Massac, Monroe, Perry, Pike, Pulaski, St. Clair, Union, and Washington, Illinois, and the counties of Des Moines, Henry, Johnson, Lee, and Washington, Iowa, upon real estate owned by the Company, or occupied by it under rights to so occupy, which real estate is described in the Indenture of Mortgage and Deed of Trust dated June 15, 1937, in the Supplemental Indentures dated May 1, 1941, March 17, 1942, April 13, 1945, April 27, 1945, October 1, 1945, April 11, 1947, April 13, 1949, September 13, 1950, December 1, 1950, September 20, 1951, May 1, 1952, March 1, 1954, May 1, 1955, August 31, 1955, April 1, 1956, July 1, 1956, August 1, 1957, February 1, 1958, March 1, 1958, November 5, 1958, March 16, 1959, June 24, 1959, December 11, 1959, August 17, 1960, September 1, 1960, October 24, 1960, June 30, 1961, July 1, 1961, August 9, 1962, September 30, 1963, November 1, 1963, March 12, 1965, April 1, 1965, April 14, 1966, May 1, 1966, February 17, 1967, March 1, 1967, February 19, 1968, March 15, 1968, August 21, 1968, April 7, 1969, May 1, 1969, September 12, 1969, October 1, 1969, March 26, 1970, April 1, 1970, June 12, 1970, January 1, 1971, April 1, 1971, September 15, 1971, December 3, 1973, February 1, 1974, April 25, 1974, February 3, 1975, March 1, 1975, June 11, 1975, May 12, 1976, August 16, 1976, April 26, 1977, October 15, 1977, November 7, 1977, December 1, 1977, August 1, 1978, October 12, 1979, November 1, 1979, July 7, 1980, August 1, 1980, August 20, 1980, February 1, 1981, October 8, 1981, August 27, 1982, September 1, 1982, December 15, 1982, March 1, 1983, June 21, 1984, December 12, 1984, June 11, 1985, March 1, 1986, May 1, 1986, May 1, 1990, December 1, 1991, December 4, 1991, January 1, 1992, September 30, 1992, October 1, 1992, December 1, 1992, February 1, 1993, February 18, 1993, May 1, 1993, August 1, 1993, October 1, 1993, January 1, 1994, February 1, 2000, August 15, 2002, March 5, 2003, April 1, 2003, July 15, 2003, October 1, 2003 and in this Supplemental Indenture and the seven other Supplemental Indentures each dated February 1, 2004, or attached to or connected with such real estate or transmission or distribution systems of the Company leading from or into such real estate.

SECOND

ALSO, (except as in the Original Indenture expressly excepted) all franchises and all permits, ordinances, easements, privileges, immunities and licenses, all rights to construct,

maintain and operate overhead, surface and underground systems for the distribution and transmission of electricity, steam, gas or other agencies for the supply to itself or others of light, heat, cold or power, all rights-of-way, all waters, water rights and flowage rights and all grants and consents, now owned or, subject to the provisions of Article XII of the Original Indenture, which it may hereafter acquire.

ALSO, (except as in the Original Indenture expressly excepted) all inventions, patent rights and licenses of every kind now owned by the Company or, subject to the provisions of Article XII of the Original Indenture, which it may hereafter acquire.

THIRD

ALSO, subject to the provisions of Article XII of the Original Indenture, all other property, real, personal and mixed (except as therein or herein expressly excepted) of every nature and kind and wheresoever situated now or hereafter possessed by or belonging to the Company, or to which it is now, or may at any time hereafter be, in any manner entitled at law or in equity.

TO HAVE AND TO HOLD all said properties, real, personal and mixed, mortgaged, pledged and conveyed by the Company as aforesaid, or intended so to be, unto the Trustee and its successors and assigns forever;

SUBJECT, HOWEVER, to the exceptions and reservations and matters hereinabove recited, to existing leases, to existing liens upon rights of way for transmission or distribution line purposes, as defined in Article I of the Original Indenture, and any extensions thereof, and subject to existing easements for streets, alleys, highways, rights-of-way and railroad purposes over, upon and across certain of the property hereinbefore described, and subject also to all the terms, conditions, agreements, covenants, exceptions and reservations expressed or provided in the deeds or other instruments respectively under and by virtue of which the Company acquired the properties hereinabove described, and to undetermined liens and charges, if any, incidental to construction or other existing permitted liens as defined in Article I of the Original Indenture;

IN TRUST, NEVERTHELESS, upon the terms and trusts in the Original Indenture and the indentures supplemental thereto, including this Supplemental Indenture, set forth, for the equal and proportionate benefit and security of all present and future holders of the Bonds and coupons issued and to be issued thereunder, or any of them, without preference of any of said Bonds and coupons of any particular series over the Bonds and coupons of any other series, by reason of priority in the time of the issue, sale or negotiation thereof, or by reason of the purpose of issue or otherwise howsoever, except as otherwise provided in
Section 2 of Article IV of the Original Indenture.

AND IT IS HEREBY COVENANTED, DECLARED AND AGREED, by and between the parties hereto, for the benefit of those who shall hold the Bonds and coupons, or any of them to be issued under the Original Indenture, as follows:

ARTICLE I

DESCRIPTION OF THE NEW BONDS

Section 1.1. There is hereby created a new series of Bonds to be executed, authenticated and delivered under and secured by the Original Indenture which shall, subject to the provisions of Section 1 of Article II of the Original Indenture, be designated as "First Mortgage Bonds, Environmental Improvement Series 2004E (2000A Bonds)" (the "New Bonds") of the Company. The New Bonds shall be executed, authenticated and delivered in accordance with the provisions of, and shall in all respects be subject to all of the terms, conditions and covenants of, the Original Indenture and shall be issued to, and registered in the name of, the Authority Bond Trustee under the Authority Bond Indenture to secure any and all obligations of the Company under the Agreement with respect to the payment of the Authority Bonds.

The New Bonds shall mature, subject to prior redemption, on March 1, 2035, and shall bear interest at the same rate or rates of interest as the Authority Bonds which, in turn, shall be determined by the methods set forth in the Authority Bond Indenture, which provides for a PARS Rate, a Daily Interest Rate, a Weekly Interest Rate, a Flexible Interest Rate or a Term Interest Rate (each as defined in the Authority Bonds Indenture). Reference is made to the provisions of the Authority Bond Indenture concerning the methods by which such interest rates are determined, and the means by which the method of determining such interest rates may be changed, and such provisions are included in this Supplemental Indenture as if fully set forth herein. Interest on the New Bonds is payable on the same dates as interest on the Authority Bonds is paid, until the principal sum of the New Bonds is paid in full. The New Bonds shall be payable as to principal and interest in any coin or currency of the United States of America which at the time of payment is legal tender for public and private debts, and shall be payable, in immediately available funds, at the office of the Authority Bond Trustee.

Section 1.2. The New Bonds shall not be assignable or transferable except as permitted or required by Section 13.15 of the Authority Bond Indenture. Any such transfer shall be effected at the principal office or place of business of the Trustee under the Original Indenture. The New Bonds are exchangeable for the New Bonds of other denominations, as in the Original Indenture provided, except that payment of a service charge therefor will not be required by the Company.

Notwithstanding the provisions of Section 6 of Article II of the Original Indenture, the New Bonds shall be dated their date of authentication and shall bear interest from the interest payment date to which interest on the New Bonds has been paid next preceding the date thereof, unless such date is an interest payment date to which interest has been paid, in which case they shall bear interest from the date thereof.

Upon any payment of the principal of and interest on, all or any portion of the Authority Bonds, whether at maturity or otherwise or upon provision for the payment thereof having been made in accordance with Section 8.01 of the Authority Bond Indenture, the New Bonds in a principal amount equal to the principal amount of such Authority Bonds shall, to the extent of such payment of principal and interest, be deemed paid and the obligation of the Company

thereunder to make such payment shall be discharged to such extent and, in the case of the payment of principal, such New Bonds shall be surrendered to the Company for cancellation as provided in and subject to the terms of Section 8.02 of the Authority Bond Indenture. The Trustee may at any time and all times conclusively assume that the obligation of the Company under the Agreement to make payments with respect to the principal of and interest on the Authority Bonds, so far as such payments at the time have become due, has been fully satisfied and discharged pursuant to the foregoing sentence unless and until the Trustee shall have received a written notice from the Authority Bond Trustee signed by one of its officers stating (i) the timely payment of principal or interest on, the Authority Bonds has not been made, (ii) that the Company is in arrears as to the payments required to be made by it to the Authority Bond Trustee pursuant to the Agreement, and (iii) the amount of the arrearage.

                           [Form of Face of New Bond]

No. ____                                                          $________

                               Ill. C. C. No. 6317

NOTWITHSTANDING ANY PROVISIONS HEREOF OR IN THE ORIGINAL INDENTURE THIS BOND IS NOT ASSIGNABLE OR TRANSFERABLE EXCEPT AS PERMITTED OR REQUIRED BY
SECTION 13.15 OF THE AMENDED AND RESTATED TRUST INDENTURE DATED AS OF FEBRUARY 1, 2004, BETWEEN THE STATE ENVIRONMENTAL IMPROVEMENT AND ENERGY
RESOURCES AUTHORITY OF THE STATE OF MISSOURI AND UMB BANK & TRUST, N.A., AS SUCCESSOR TO STATE STREET BANK AND TRUST COMPANY OF MISSOURI, N.A., AS TRUSTEE

UNION ELECTRIC COMPANY
(Incorporated under the laws of the State of Missouri)

First Mortgage Bonds, Environmental Improvement Series 2004E (2000A Bonds)

Illinois Commerce Commission Identification No. 6317

UNION ELECTRIC COMPANY, a corporation organized and existing under the laws of the State of Missouri (hereinafter called the "Company," which term shall include any successor corporation as defined in the Amended Indenture referred to on the reverse hereof), for value received, hereby promises to pay to UMB Bank & Trust, N.A., as successor to State Street Bank and Trust Company of Missouri, N.A., as trustee under the Authority Bond Indenture hereinafter referred to, or registered assigns, the sum of _________________________ Dollars, on the 1st day of March, 2035, subject to prior redemption, in any coin or currency of the United States of America which at the time of payment is legal tender for public and private debts, and to pay interest thereon, in like coin or currency, at the same rate or rates of interest as the Authority Bonds (as determined in accordance with the Authority Bond Indenture referred to below), but in no event shall the interest rate on this Bond exceed eighteen percent (18%) per annum. Interest on overdue principal premium, if any, and, to the extent permitted by law, on overdue interest, shall be payable at the interest rate payable on the Authority Bonds. Interest on this Bond is payable on the same dates as interest on the Authority Bonds, or, if this Bond shall be duly called for redemption, until the redemption date, or if the Company shall default in the payment of the principal hereof, until the Company's obligation to pay principal shall be discharged as provided in the Amended Indenture is paid, until the principal sum is paid in full. The principal of, and interest on, this Bond are payable, in immediately available funds, at the office of the Authority Bond Trustee hereinafter referred to.

Under a Trust Indenture dated as of March 1, 2000, as amended and restated by the Amended and Restated Trust Indenture dated as of February 1, 2004 (as so amended and restated, the "Authority Bond Indenture") between the State Environmental Improvement and Energy Resources Authority of the State of Missouri (the "Authority") and UMB Bank & Trust, N.A., as successor to State Street Bank and Trust Company of Missouri, N.A., as trustee (the "Authority Bond Trustee"), the Authority has issued its Environmental Improvement Revenue

Refunding Bonds (AmerenUE Project) Series 2000A in the aggregate principal amount of $63,500,000 (the "Authority Bonds"). The Company has agreed to pay the principal of and interest on the Authority Bonds pursuant to a Loan Agreement dated as of March 1, 2000, as supplemented and amended by the First Amendment to Loan Agreement dated as of February 1, 2004 (as so amended, the "Agreement") between the Company and the Authority. Pursuant to the Granting Clauses of the Authority Bond Indenture, this Bond is issued to the Authority Bond Trustee to secure any and all obligations of the Company under the Agreement with respect to payment of the Authority Bonds. Payment of principal of, or interest on, the Authority Bonds shall constitute payments on this Bond as further provided herein and in the Supplemental Indenture dated February 1, 2004 pursuant to which this Bond has been issued (the "Supplemental Indenture").

Upon any payment of the principal of, and interest on, all or any portion of the Authority Bonds, whether at maturity or otherwise or upon provision for the payment thereof having been made in accordance with Section 8.01 of the Authority Bond Indenture, a principal amount of this Bond equal to the principal amount of such Authority Bonds shall, to the extent of such payment of principal and interest, be deemed paid and the obligation of the Company thereunder to make such payment shall be discharged to such extent and, in the case of the payment of principal, such Bonds shall be surrendered to the Company for cancellation as provided in Section 8.02 of the Authority Bond Indenture. The Trustee (as hereinafter defined) may at any time and all times conclusively assume that the obligation of the Company to make payments under the Agreement with respect to the principal of, and interest on, the Authority Bonds, so far as such payments at the time have become due, has been fully satisfied and discharged pursuant to the foregoing sentence unless and until the Trustee shall have received a written notice from the Authority Bond Trustee signed by one of its officers stating (i) that timely payment of principal of, or interest on, the Authority Bonds has not been made, (ii) that the Company is in arrears as to the payments required to be made by it to the Authority Bond Trustee pursuant to the Agreement, and (iii) the amount of the arrearage.

This Bond shall not be entitled to any benefit under the Amended Indenture or any indenture supplemental thereto, or become valid or obligatory for any purpose, until The Bank of New York, the Trustee under the Amended Indenture, or a successor trustee thereto under the Amended Indenture, or an agent therefor, shall have signed the form of certificate endorsed hereon.

The provisions of this Bond are continued on the reverse hereof and such continued provisions shall for all purposes have the same effect as though fully set forth at this place.

IN WITNESS WHEREOF, Union Electric Company has caused this Bond to be signed in its name by its Chairman of the Board or President or a Vice President by manual signature or a facsimile thereof, and its corporate seal (or a facsimile thereof) to be hereto affixed and attested by its Secretary or an Assistant Secretary by manual signature or a facsimile thereof.

Dated,
UNION ELECTRIC COMPANY,

[CORPORATE SEAL]

Attest:

[FORM OF TRUSTEE'S CERTIFICATE]

This Bond is one of the Bonds, of the series designated therein, described in the within-mentioned Amended Indenture and Supplemental Indenture of February 1, 2004.

THE BANK OF NEW YORK, as Trustee

[FORM OF REVERSE OF NEW BOND]

This Bond is one of a duly authorized issue of Bonds of the Company (herein called the "Bonds"), limited to an aggregate principal amount of $60,000,000, of the series hereinafter specified, all issued under and equally secured by the Indenture of Mortgage and Deed of Trust, dated June 15, 1937, executed by the Company to The Bank of New York (successor trustee to Bank of America, National Association, formerly Boatmen's Trust Company), as trustee (herein called the "Trustee"), as amended by indentures supplemental thereto dated May 1, 1941, April 1, 1971, February 1, 1974, July 7, 1980, February 1, 2000 and August 15, 2002, between the Company and the Trustee (said mortgage and deed of trust, as so amended, being herein called the "Amended Indenture"), to which Amended Indenture and all indentures supplemental thereto reference is hereby made for a description of the properties mortgaged and pledged, the nature and extent of the security, the rights of the bearers or registered owners of the Bonds and of the Trustee in respect thereto, and the terms and conditions upon which the Bonds are, and are to be, secured. To the extent permitted by, and as provided in, the Amended Indenture, modifications or alterations of the Amended Indenture, or of any indenture supplemental thereto, and of the rights and obligations of the Company and of the holders of the Bonds may be made with the consent of the Company by an affirmative vote of not less than 60% in amount of the

Bonds entitled to vote then outstanding, at a meeting of Bondholders called and held as provided in the Amended Indenture, and by an affirmative vote of not less than 60% in amount of the Bonds of any series entitled to vote then outstanding and affected by such modification or alteration, in case one or more but less than all of the series of Bonds then outstanding under the Amended Indenture are so affected. Additionally, the Company may amend the Amended Indenture, as supplemented, by an appropriate written consent of not less than 60% in aggregate principal amount of the Bonds outstanding (and, if the rights of one or more, but less than all, series of Bonds then outstanding are to be affected by action taken pursuant to such consent, then also by consent of the holders of at least 60% in principal amount of each series of Bonds so to be affected and outstanding hereunder) without a meeting of such Bondholders. No such modification or alteration shall be made which will affect the terms of payment of the principal of, or interest on, this Bond, which are unconditional. The Bonds may be issued in series, for various principal sums, may mature at different times, may bear interest at different rates and may otherwise vary as in the Amended Indenture provided. This Bond is one of a series designated as the "First Mortgage Bonds, Environmental Improvement Series 2004E (2000A Bonds)" (herein called the "Bonds of this Series") of the Company, issued under and secured by the Amended Indenture and described in the indenture (hereinafter called the "Supplemental Indenture") dated February 1, 2004, between the Company and the Trustee, supplemental to the Amended Indenture.

The Bonds of this Series are not entitled to the benefit of any improvement, maintenance or analogous fund.

This Bond is, subject to the provisions of the Amended Indenture, subject to redemption in the amounts, at the times, at the prices and under the circumstances under which the Authority Bonds are subject to redemption under the same terms and circumstances set forth in the Authority Bond Indenture for the redemption of the Authority Bonds.

This Bond is also subject to mandatory redemption at the principal amount hereof plus accrued interest to the date fixed for redemption if the Trustee or the Company is notified that an "Event of Default" under the Authority Bond Indenture has occurred and is continuing and the Authority Bond Trustee has declared the principal amount of all Authority Bonds then outstanding due and payable in accordance with the Authority Bond Indenture.

The Company may, by notice to the Trustee at least 60 days prior to any date on which any principal amount is due on this Bond, elect to receive a credit in respect of such principal payment (a) for any Bonds of this Series then due which have been redeemed prior to such principal payment date or otherwise acquired and delivered to the Trustee for cancellation by said Trustee prior to the giving of such notice, or (b) for any Authority Bonds which have been purchased, delivered for cancellation or previously redeemed, which in each case have not theretofore been applied as a credit against such principal payment. Each Bond with respect to which the Company elects to receive a credit will be credited by the Trustee at 100% of the principal amount thereof against such principal payment, provided further that in the case of a credit with respect to any Authority Bonds, the principal amount thereof shall be established by an officers' certificate (as defined in the Amended Indenture) concurred in by the Authority Bond Trustee, included with the above-mentioned notice to the Trustee. The principal amount of Bonds to be paid on the due date of such principal payment will be reduced by the amount of any such credit or credits in respect of Bonds previously redeemed or delivered as provided above.

Upon cancellation in full or in part of any of the Authority Bonds (or provision for payment thereof having been made in accordance with the provisions of the Authority Bond Indenture) and payment of all fees and charges of the trustee thereunder, such trustee shall deliver to the Trustee, for cancellation a corresponding amount of Bonds remaining in its possession.

Such redemption in every case shall be effected upon notice delivered by the Company at least 60 days prior to the date of redemption, to the registered owner of the Bonds at its address as the same shall appear on the transfer register of the Company, all subject to the conditions of, and as more fully set forth in, the Amended Indenture and Supplemental Indenture.

In case an event of default, as defined in the Amended Indenture, shall occur, the principal of all the bonds at any such time outstanding under the Amended Indenture may be declared or may become due and payable, upon the conditions and in the manner and with the effect provided in the Amended Indenture. The Amended Indenture provides that such declaration may in certain events be waived by the holders of a majority in principal amount of the bonds outstanding.

This Bond shall not be assignable or transferable except as permitted or required by Section 13.15 of the Authority Bond Indenture. This Bond is exchangeable by the registered owner hereof, in person or by duly authorized attorney, on the books of the Company to be kept for that purpose at the office of the Company in the City of St. Louis, Missouri, upon surrender and cancellation of this Bond and on presentation of a duly executed written instrument of transfer, and thereupon a new Bond or Bonds of the same series, of the same aggregate principal amount and in authorized denominations will be issued to the transferee or transferees in exchange herefor, without payment of any charge other than stamp taxes and other governmental charges incident thereto; and this Bond with or without others of like series, may in like manner be exchanged for one or more new Bonds of the same series of other authorized denominations but of the same aggregate principal amount; all subject to the terms and conditions set forth in the Amended Indenture.

As provided in Section 8.02 of the Authority Bond Indenture, from and after the Release Date (as defined in the Authority Bond Indenture), the obligations of the Company with respect to this Bond shall be deemed to be satisfied and discharged, this Bond shall cease to secure in any manner the Company's obligations under the Agreement with respect to the payment of any Authority Bonds outstanding under the Authority Bond Indenture, and, pursuant to Section 8.02 of the Authority Bond Indenture, the Authority Bond Trustee shall forthwith deliver this Bond to the Company for cancellation.

No recourse shall be had for the payment of the principal of, or the interest on, this Bond, or for any claim based hereon or on the Amended Indenture or any indenture supplemental thereto, against any incorporator, or against any stockholder, director or officer, past, present or future, of the Company, or of any predecessor or successor corporation, either directly or through the Company or any such predecessor or successor corporation, whether for amounts unpaid on stock subscriptions or by virtue of any constitution, statute or rule of law, or by the enforcement of any assessment or penalty or otherwise, all such liability, whether at common law, in equity,

by any constitution, statute or otherwise, of incorporators, stockholders, directors or officers being released by every owner hereof by the acceptance of this Bond and as part of the consideration for the issue hereof, and being likewise released by the terms of the Amended Indenture.

[END OF FORM OF REVERSE OF NEW BOND]

ARTICLE II

ISSUE OF THE NEW BONDS

Section 2.1. The principal amount of the New Bonds which may be authenticated and delivered hereunder is limited to an amount equal to the principal amount of Sixty Three Million Five Hundred Thousand Dollars ($63,500,000) consisting of Bonds maturing on March 1, 2035.

Section 2.2. The New Bonds in the aggregate principal amount set forth above, may forthwith be executed by the Company and delivered to the Trustee and shall be authenticated by the Trustee and delivered (either before or after the filing or recording hereof) to or upon the order of the Company, upon compliance by the Company with the applicable provisions of Article III and Article XVIII of the Original Indenture.

Section 2.3. As provided in Section 8.02 of the Authority Bond Indenture, from and after the Release Date (as defined in the Authority Bond Indenture), the obligations of the Company with respect to the New Bonds shall be deemed to be satisfied and discharged, the New Bonds shall cease to secure in any manner the Company's obligations under the Agreement with respect to the payment of any Authority Bonds outstanding under the Authority Bond Indenture, and, pursuant to
Section 8.02 of the Authority Bond Indenture, the Authority Bond Trustee shall forthwith deliver the New Bonds to the Company for cancellation.

ARTICLE III

REDEMPTION OF THE NEW BONDS

Section 3.1. The New Bonds are, subject to the provisions of the Original Indenture, subject to redemption in the amounts, at the times, at the prices and under the circumstances under which the Authority Bonds are subject to redemption, under the same terms and conditions set forth in the Authority Bond Indenture for the redemption of the Authority Bonds. In the event that less than all the New Bonds are to be redeemed, the New Bonds to be redeemed shall be determined by lot in such manner as the Trustee in its discretion shall deem proper, as in the Original Indenture provided.

The New Bonds are also subject to mandatory redemption as set forth in the form of New Bonds in Section 1.3 of Article I of this Supplemental Indenture.

Section 3.2. Subject to the provisions of Article V of the Original Indenture, notice of redemption shall be delivered by the Company at least 60 days prior to the date of redemption, to the registered owner of such Bonds at its address as the same shall appear on the transfer register of the Company.

Section 3.3. As provided in the Authority Bond Indenture, any amounts of money held in the Bond Fund provided in said Indenture and available for such purpose, which are at the request of the Company applied to the payments of the principal of, premium, if any, and interest on the Authority Bonds on any payment or redemption date, shall be applied as a credit on amounts otherwise due under the New Bonds; provided that the amount of such credit shall be established by an officers' certificate (as defined in the Amended Indenture), concurred in by the Authority Bond Trustee which shall be filed with the Trustee prior to the application of any such credit.

Upon cancellation in full or in part of any of the Authority Bonds (or provision for payment thereof having been made in accordance with the provisions of the Authority Bond Indenture) and payment of all fees and charges of the trustee thereunder, such trustee shall deliver to the Trustee, for cancellation a corresponding amount of New Bonds remaining in its possession or shall request such Trustee to issue a New Bond reflecting any such cancellation

ARTICLE IV

COVENANTS

The Company hereby covenants, warrants and agrees;

Section 4.1. That the Company is lawfully seized and possessed of all of the mortgaged property described in the granting clauses of this Supplemental Indenture; that it has good right and lawful authority to mortgage the same as provided in this Supplemental Indenture; and that such mortgaged property is, at the actual date of the issue of the New Bonds, free and clear of any deed of trust, mortgage, lien, charge or encumbrance thereon or affecting the title thereto prior to the Original Indenture, except as set forth in the granting clauses of the Original Indenture or this Supplemental Indenture.

Section 4.2. That, so long as any of the New Bonds are outstanding, whenever any officers' certificate is required to be filed or deposited with the Trustee pursuant to Section 3(b) of Article III of the Original Indenture upon an application for the authentication of additional Bonds pursuant to Article III of the Original Indenture, such officers' certificate shall include, in addition to the matters required to be stated therein by said Section 3(b), the statement with respect to the net earnings of the Company available for interest after property retirement appropriations required by Section 2 of Article V of the Supplemental Indenture of July 1, 1956.

Section 4.3. That, so long as any of the New Bonds are outstanding, the Company will not apply for the authentication and delivery of additional Bonds pursuant to Section 4 of Article III of the Original Indenture or the withdrawal of cash from the trust estate or the reduction of the amount of cash required to be paid into the trust estate or to satisfy the

maintenance and improvement funds under any provision of the Original Indenture or the Supplemental Indentures creating prior series of Bonds, on the basis of the amount of $15,000,000 excluded from net bondable value of property additions not subject to an unfunded prior lien pursuant to Section 3 of Article V of the Supplemental Indenture of October 1, 1945, or on the basis of the amount of $7,500,000 excluded from net bondable value of property additions not subject to an unfunded prior lien pursuant to Section 3 of Article V of the Supplemental Indenture of July 1, 1956.

Section 4.4. That, so long as any of the New Bonds are outstanding, the Company will not issue or permit to be issued any prior lien bonds secured by an unfunded prior lien in addition to the prior lien bonds secured by such unfunded prior lien at the time of first acquisition by the Company of property subject thereto (other than in lieu of lost, stolen or mutilated bonds or on the exchange for bonds already outstanding of an equal principal amount of other bonds of the same issue and the same series, if any, and of the same maturity), except upon compliance with the provisions of Section 16 of Article IV of the Original Indenture, nor unless the net earnings of the Company available for interest after property retirement appropriations (determined as provided in
Section 2 of Article V of the Supplemental Indenture of July 1, 1956), for any 12 consecutive calendar months during the period of 15 calendar months immediately preceding the first day of the month in which the additional prior lien bonds are to be issued, have been, in the aggregate, equal to not less than twice the annual interest charges on the indebtedness specified in subparagraphs
(i) and (ii) of paragraph (1) of Section 2(a) of said Article V; provided that, if the application for the issue of such additional prior lien bonds is upon the basis of payment at maturity of prior lien bonds theretofore sold or otherwise disposed of or the redemption or purchase thereof after a date two years prior to the date of maturity, the additional requirement imposed by this Section 4 with respect to net earnings of the Company available for interest after property retirement appropriations shall not apply. Any officers' certificate with respect to net earnings of the Company, required to be filed with the Trustee as a condition precedent to the issue of such additional prior lien bonds, shall include, in addition to the matters otherwise required to be stated therein, the matters required to be stated in an officers' certificate pursuant to paragraphs (1) and (2) of Section 2(a) of said Article V.

Section 4.5. That, so long as any of the New Bonds are outstanding, the Company will not acquire, by purchase, merger or otherwise, any property subject to a lien or liens which will on acquisition be an unfunded prior lien or prior liens, except upon compliance with the provisions of Section 14 of Article IV of the Original Indenture, nor unless the net earnings of such property available for interest after property retirement appropriations (determined in the manner provided in Section 2 of Article V of the Supplemental Indenture of July 1, 1956), for any 12 consecutive calendar months during the period of 15 calendar months immediately preceding the first day of the month in which the first acquisition of property subject to such lien or liens occurs, have been, in the aggregate, equal to not less than twice the amount of annual interest charges, on all outstanding indebtedness secured by such lien or liens. Any officers' certificate with respect to net earnings of such property, required to be filed with the Trustee as a condition precedent to the acquisition of such property, shall include, in addition to the matters otherwise required to be stated therein, the matters required to be stated in an officers' certificate pursuant to Section 2 of said Article V applicable, however, only to the net earnings of such property and to the indebtedness secured by such liens to which such property is subject.

ARTICLE V

THE TRUSTEE

The Trustee hereby accepts the trusts hereby declared and provided, and agrees to perform the same upon the terms and conditions in the Original Indenture and in this Supplemental Indenture set forth, and upon the following terms and conditions:

The Trustee shall not be responsible in any manner whatsoever for or in respect of the validity or sufficiency of this Supplemental Indenture or the due execution hereof by the Company or for or in respect of the recitals contained herein, all of which recitals are made by the Company solely.

ARTICLE VI

MISCELLANEOUS PROVISIONS

Section 6.1. Except as otherwise defined herein, all terms contained in this Supplemental Indenture shall, for all purposes thereof, have the meanings given to such terms in Article I of the Original Indenture.

Section 6.2. This Supplemental Indenture may be simultaneously executed in any number of counterparts, each of which when so executed shall be deemed to be an original; but such counterparts shall together constitute but one and the same instrument.

IN WITNESS WHEREOF, said Union Electric Company has caused this Supplemental Indenture to be executed on its behalf by its Chairman of the Board or President or one of its Vice Presidents and its corporate seal to be hereto affixed and said seal and this Supplemental Indenture to be attested by its Secretary or one of its Assistant Secretaries; and said The Bank of New York, in evidence of its acceptance of the trust hereby created, has caused this Supplemental Indenture to be executed on its behalf by its President or one of its Vice Presidents, and its corporate seal to be hereto affixed and said seal and this Supplemental Indenture to be attested by its Secretary, or one of its Assistant Secretaries; all as of the 1st day of February, Two thousand and four.

Attested:                                    UNION ELECTRIC COMPANY,
                                               1901 Chouteau Avenue
                                               St. Louis, Missouri  63103


/s/ G. L. Waters                             By:  /s/ Jerre E. Birdsong
--------------------------------                --------------------------------
          G. L. Waters                       Name:    Jerre E. Birdsong
      Assistant Secretary                    Title: Vice President and Treasurer


Signed, sealed and delivered by
      UNION ELECTRIC COMPANY
      in the presence of:


/s/ D. Bradley
--------------------------------
                Daphyne Bradley


/s/ Wayne K. Forbes
--------------------------------
                Wayne K. Forbes

As Witnesses

Attested:                                    THE BANK OF NEW YORK,
                                               911 Washington Avenue
                                               St. Louis, Missouri  63101


/s/ Belinda Brown                            By:  /s/ Robert J. Dunn
----------------------------------              --------------------------------
Belinda Brown                                Name:    Robert J. Dunn
As Agent                                     Title:   As Agent

Signed, sealed and delivered by
THE BANK OF NEW YORK
in the presence of:

/s/ Daniel G. Dwyer
----------------------------------
Daniel G. Dwyer


/s/ Richard F. Novosak
----------------------------------
Richard F. Novosak

STATE OF MISSOURI          )
                           )  SS:
CITY OF ST. LOUIS          )

On this 9th day of March 2004, before me appeared JERRE E. BIRDSONG, to me personally known, who, being by me duly sworn, did say that he is Vice President and Treasurer of UNION ELECTRIC COMPANY, a corporation, and that the seal affixed to the foregoing instrument is the corporate seal of said corporation, and that said instrument was signed and sealed in behalf of said corporation by authority of its Board of Directors, and said JERRE E. BIRDSONG acknowledged said instrument to be the free act and deed of said corporation.

IN TESTIMONY WHEREOF, I have hereto set my hand and affixed my official seal at my office, in the City and State aforesaid, the day and year last above written.

/s/ S.A. Kitchens
--------------------------------------

STATE OF MISSOURI          )
                           )  SS:
CITY OF ST. LOUIS          )

On this 9th day of March 2004, before me appeared Robert J. Dunn, to me personally known, who, being by me duly sworn, did say that he is an Agent of THE BANK OF NEW YORK, a corporation, and that the seal affixed to the foregoing instrument is the corporate seal of said corporation, and that said instrument was signed and sealed in behalf of said corporation, as the trustee thereunder by authority of its Board of Directors, and said Vice President, acknowledged said instrument to be the free act and deed of said corporation as the trustee under said instrument.

IN TESTIMONY WHEREOF, I have hereto set my hand and affixed my official seal at my office, in the City and State aforesaid, the day and year last above written.

/s/ Renee Beard
--------------------------------------

Exhibit 4.6

WHEN RECORDED
MAIL TO:

Executed in 35 Counterparts, No. 35

SUPPLEMENTAL INDENTURE

DATED FEBRUARY 1, 2004

UNION ELECTRIC COMPANY

TO

THE BANK OF NEW YORK,
AS TRUSTEE

(SUPPLEMENTAL TO THE INDENTURE OF MORTGAGE AND DEED OF
TRUST DATED JUNE 15, 1937, AS AMENDED, EXECUTED BY

UNION ELECTRIC COMPANY
TO THE BANK OF NEW YORK, AS TRUSTEE)

First Mortgage Bonds, Environmental Improvement Series 2004F (2000C Bonds)

This instrument was prepared by Steven R. Sullivan, Senior Vice President Governmental/Regulatory Policy, General Counsel and Secretary of Union Electric Company, 1901 Chouteau Avenue, St. Louis, Missouri 63103, (314) 554-2098.

SUPPLEMENTAL INDENTURE, dated the 1st day of February, Two thousand and four (2004) made by and between UNION ELECTRIC COMPANY, a corporation organized and existing under the laws of the State of Missouri (hereinafter called the "Company"), party of the first part, and The Bank of New York (successor trustee to Bank of America, National Association, formerly Boatmen's Trust Company), a bank existing under the laws of the State of New York (hereinafter called the "Trustee"), as Trustee under the Indenture of Mortgage and Deed of Trust dated June 15, 1937, hereinafter mentioned, party of the second part:

WHEREAS, the Company has heretofore executed and delivered to the Trustee its Indenture of Mortgage and Deed of Trust, dated June 15, 1937, as amended May 1, 1941, April 1, 1971, February 1, 1974, July 7, 1980, February 1, 2000 and August 15, 2002 (said Indenture of Mortgage and Deed of Trust as so amended, being hereinafter referred to as the "Original Indenture"), to secure the payment of the principal of and the interest (and premium, if any) on all bonds at any time issued and outstanding thereunder, and indentures supplemental thereto dated June 15, 1937, May 1, 1941, March 17, 1942, April 13, 1945, April 27, 1945, October 1, 1945, April 11, 1947, April 13, 1949, September 13, 1950, December 1, 1950, September 20, 1951, May 1, 1952, March 1, 1954, May 1, 1955, August 31, 1955, April 1, 1956, July 1, 1956, August 1, 1957, February 1, 1958, March 1, 1958, November 5, 1958, March 16, 1959, June 24, 1959, December 11, 1959, August 17, 1960, September 1, 1960, October 24, 1960, June 30, 1961, July 1, 1961, August 9, 1962, September 30, 1963, November 1, 1963, March 12, 1965, April 1, 1965, April 14, 1966, May 1, 1966, February 17, 1967, March 1, 1967, February 19, 1968, March 15, 1968, August 21, 1968, April 7, 1969, May 1, 1969, September 12, 1969, October 1, 1969, March 26, 1970, April 1, 1970, June 12, 1970, January 1, 1971, April 1, 1971, September 15, 1971, December 3, 1973, February 1, 1974, April 25, 1974, February 3, 1975, March 1, 1975, June 11, 1975, May 12, 1976, August 16, 1976, April 26, 1977, October 15, 1977, November 7, 1977, December 1, 1977, August 1, 1978, October 12, 1979, November 1, 1979, July 7, 1980, August 1, 1980, August 20, 1980, February 1, 1981, October 8, 1981, August 27, 1982, September 1, 1982, December 15, 1982, March 1, 1983, June 21, 1984, December 12, 1984, June 11, 1985, March 1, 1986, May 1, 1986, May 1, 1990, December 1, 1991, December 4, 1991, January 1, 1992, September 30, 1992, October 1, 1992, December 1, 1992, February 1, 1993, February 18, 1993, May 1, 1993, August 1, 1993, October 1, 1993, January 1, 1994, February 1, 2000, August 15, 2002, March 5, 2003, April 1, 2003, July 15, 2003, October 1, 2003 and the five indentures supplemental each dated as of February 1, 2004, respectively, have heretofore been entered into between the Company and the Trustee; and

WHEREAS, Bonds have heretofore been issued by the Company under the Original Indenture as follows:

(1) $80,000,000 principal amount of First Mortgage and Collateral Trust Bonds, 3-3/4% Series due 1962, all of which have been redeemed prior to the date of the execution hereof;

(2) $90,000,000 principal amount of First Mortgage and Collateral Trust Bonds, 3-3/8% Series due 1971, which are described in the Supplemental Indenture dated

May 1, 1941 (hereinafter called the "Supplemental Indenture of May 1, 1941"), all of which have been paid at maturity prior to the date of the execution hereof;

(3) $13,000,000 principal amount of First Mortgage and Collateral Trust Bonds, 2-3/4% Series due 1975 (herein called the "Bonds of 1975 Series"), which are described in the Supplemental Indenture dated October 1, 1945 (hereinafter called the "Supplemental Indenture of October 1, 1945"), all of which have been paid at maturity prior to the date of the execution hereof;

(4) $25,000,000 principal amount of First Mortgage and Collateral Trust Bonds, 2-7/8% Series due 1980 (herein called the "Bonds of 1980 Series"), which are described in the Supplemental Indenture dated December 1, 1950 (hereinafter called the "Supplemental Indenture of December 1, 1950"), all of which have been paid at maturity prior to the date of the execution hereof;

(5) $30,000,000 principal amount of First Mortgage and Collateral Trust Bonds, 3-1/4% Series due 1982 (herein called the "Bonds of 1982 Series"), which are described in the Supplemental Indenture dated May 1, 1952 (hereinafter called the "Supplemental Indenture of May 1, 1952"), all of which have been paid at maturity prior to the date of the execution hereof;

(6) $40,000,000 principal amount of First Mortgage Bonds, 3-3/4% Series due 1986 (herein called the "Bonds of 1986 Series"), which are described in the Supplemental Indenture dated July 1, 1956 (hereinafter called the "Supplemental Indenture of July 1, 1956"), all of which have been paid at maturity prior to the date of the execution hereof;

(7) $35,000,000 principal amount of First Mortgage Bonds, 4-3/8% Series due 1988 (herein called the "Bonds of 1988 Series"), which are described in the Supplemental Indenture dated March 1, 1958 (hereinafter called the "Supplemental Indenture of March 1, 1958"), all of which have been paid at maturity prior to the date of the execution hereof;

(8) $50,000,000 principal amount of First Mortgage Bonds, 4-3/4% Series due 1990 (herein called the "Bonds of 1990 Series"), which are described in the Supplemental Indenture dated September 1, 1960 (hereinafter called the "Supplemental Indenture of September 1, 1960"), all of which have been paid at maturity prior to the date of the execution hereof;

(9) $30,000,000 principal amount of First Mortgage Bonds, 4-3/4% Series due 1991 (herein called the "Bonds of 1991 Series"), which are described in the Supplemental Indenture dated July 1, 1961 (hereinafter called the "Supplemental Indenture of July 1, 1961"), all of which have been paid at maturity prior to the date of the execution hereof;

(10) $30,000,000 principal amount of First Mortgage Bonds, 4-1/2% Series due 1993 (herein called the "Bonds of 1993 Series"), which are described in the

Supplemental Indenture dated November 1, 1963 (hereinafter called the "Supplemental Indenture of November 1, 1963"), all of which have been redeemed prior to the date of the execution hereof;

(11) $35,000,000 principal amount of First Mortgage Bonds, 4-1/2% Series due 1995 (herein called the "Bonds of 1995 Series"), which are described in the Supplemental Indenture dated April 1, 1965 (hereinafter called the "Supplemental Indenture of April 1, 1965"), all of which have been paid at maturity prior to the date of the execution hereof;

(12) $30,000,000 principal amount of First Mortgage Bonds, 5-1/2% Series due 1996 (herein called the "Bonds of 1996 Series"), which are described in the Supplemental Indenture dated May 1, 1966 (hereinafter called the "Supplemental Indenture of May 1, 1966"), all of which have been paid at maturity prior to the date of the execution hereof;

(13) $40,000,000 principal amount of First Mortgage Bonds, 5-1/2% Series due 1997 (herein called the "Bonds of 1997 Series"), which are described in the Supplemental Indenture dated March 1, 1967 (hereinafter called the "Supplemental Indenture of March 1, 1967"), all of which have been paid at maturity prior to the date of the execution hereof;

(14) $50,000,000 principal amount of First Mortgage Bonds, 7% Series due 1998 (herein called the "Bonds of 1998 Series"), which are described in the Supplemental Indenture dated March 15, 1968 (hereinafter called the "Supplemental Indenture of March 15, 1968"), all of which have been redeemed prior to the date of the execution hereof;

(15) $35,000,000 principal amount of First Mortgage Bonds, 7-3/8% Series due 1999 (herein called the "Bonds of May 1999 Series"), which are described in the Supplemental Indenture dated May 1, 1969 (hereinafter called the "Supplemental Indenture of May 1, 1969"), all of which have been redeemed prior to the date of the execution hereof;

(16) $40,000,000 principal amount of First Mortgage Bonds, 8-1/4% Series due 1999 (herein called the "Bonds of October 1999 Series"), which are described in the Supplemental Indenture dated October 1, 1969 (hereinafter called the "Supplemental Indenture of October 1, 1969"), all of which have been redeemed prior to the date of the execution hereof;

(17) $100,000,000 principal amount of First Mortgage Bonds, 9.95% Series due 1999 (herein called the "Bonds of November 1999 Series"), which are described in the Supplemental Indenture dated November 1, 1979 (hereinafter called the "Supplemental Indenture of November 1, 1979"), all of which have been redeemed prior to the date of the execution hereof;

(18) $60,000,000 principal amount of First Mortgage Bonds, 9% Series due 2000 (herein called the "Bonds of 2000 Series"), which are described in the Supplemental Indenture dated April 1, 1970 (hereinafter called the "Supplemental Indenture of April 1, 1970"), all of which have been redeemed prior to the date of the execution hereof;

(19) $50,000,000 principal amount of First Mortgage Bonds, 7-7/8% Series due 2001 (herein called the "Bonds of January 2001 Series"), which are described in the Supplemental Indenture dated January 1, 1971 (hereinafter called the "Supplemental Indenture of January 1, 1971"), all of which have been redeemed prior to the date of the execution hereof;

(20) $50,000,000 principal amount of First Mortgage Bonds, 7 5/8% Series due 2001 (herein called the "Bonds of April 2001 Series"), which are described in the Supplemental Indenture dated April 1, 1971 (hereinafter called the "Supplemental Indenture of April 1, 1971"), all of which have been redeemed prior to the date of the execution hereof;

(21) $60,000,000 principal amount of First Mortgage Bonds, 8 1/8% Series due 2001 (herein called the "Bonds of October 2001 Series"), which are described in the Supplemental Indenture dated September 15, 1971 (hereinafter called the "Supplemental Indenture of September 15, 1971"), all of which have been redeemed prior to the date of the execution hereof;

(22) $70,000,000 principal amount of First Mortgage Bonds, 8-3/8% Series due 2004 (herein called the "Bonds of 2004 Series"), which are described in the Supplemental Indenture dated February 1, 1974 (hereinafter called the "Supplemental Indenture of February 1, 1974"), all of which have been redeemed prior to the date of the execution hereof;

(23) $70,000,000 principal amount of First Mortgage Bonds, 10-1/2% Series due 2005 (herein called the "Bonds of 2005 Series"), which are described in the Supplemental Indenture dated March 1, 1975 (hereinafter called the "Supplemental Indenture of March 1, 1975"), all of which have been redeemed prior to the date of the execution hereof;

(24) $70,000,000 principal amount of First Mortgage Bonds, 8-7/8% Series due 2006 (herein called the "Bonds of 2006 Series"), which are described in the Supplemental Indenture dated August 16, 1976 (hereinafter called the "Supplemental Indenture of August 16, 1976"), all of which have been redeemed prior to the date of the execution hereof;

(25) $27,085,000 principal amount of First Mortgage Bonds, 5.80% Environmental Improvement Series 1977, which are described in the Supplemental Indenture dated October 15, 1977 (hereinafter called the "Supplemental Indenture of October 15, 1977"), all of which have been redeemed prior to the date of the execution hereof;

(26) $60,000,000 principal amount of First Mortgage Bonds, 8 5/8% Series due 2007 (herein called the "Bonds of 2007 Series"), which are described in the Supplemental Indenture dated December 1, 1977 (hereinafter called the "Supplemental Indenture of December 1, 1977"), all of which have been redeemed prior to the date of the execution hereof;

(27) $55,000,000 principal amount of First Mortgage Bonds, 9.35% Series due 2008 (herein called the "Bonds of 2008 Series"), which are described in the Supplemental Indenture dated August 1, 1978 (hereinafter called the "Supplemental Indenture of August 1, 1978"), all of which have been redeemed prior to the date of the execution hereof;

(28) $60,000,000 principal amount of First Mortgage Bonds, Environmental Improvement Series 1980, which are described in the Supplemental Indenture dated August 1, 1980 (hereinafter called the "Supplemental Indenture of August 1, 1980"), all of which have been redeemed prior to the date of the execution hereof;

(29) $150,000,000 principal amount of First Mortgage Bonds, 15-3/8% Series due 1991 (herein called the "Bonds of February 1991 Series"), which are described in the Supplemental Indenture dated February 1, 1981 (hereinafter called the "Supplemental Indenture of February 1, 1981"), all of which have been redeemed prior to the date of the execution hereof;

(30) $125,000,000 principal amount of First Mortgage Bonds, 15% Series due 1992 (herein called the "Bonds of 1992 Series"), which are described in the Supplemental Indenture dated September 1, 1982 (hereinafter called the "Supplemental Indenture of September 1, 1982"), all of which have been redeemed prior to the date of the execution hereof;

(31) $100,000,000 principal amount of First Mortgage Bonds, 13% Series due 2013 (herein called the "Bonds of 2013 Series"), which are described in the Supplemental Indenture dated March 1, 1983 (hereinafter called the "Supplemental Indenture of March 1, 1983"), all of which have been redeemed prior to the date of the execution hereof;

(32) $100,000,000 principal amount of First Mortgage Bonds, 9-3/8% Series due 2016 (herein called the "Bonds of 2016 Series"), which are described in the Supplemental Indenture dated March 1, 1986 (hereinafter called the "Supplemental Indenture of March 1, 1986"), all of which have been redeemed prior to the date of the execution hereof;

(33) $100,000,000 principal amount of First Mortgage Bonds, 8-7/8% Series due 1996 (herein called the "Bonds of 1996 Series"), which are described in the Supplemental Indenture dated May 1, 1986 (hereinafter called the "Supplemental Indenture of May 1, 1986"), all of which have been redeemed prior to the date of the execution hereof;

(34) $60,000,000 principal amount of First Mortgage Bonds, Environmental Improvement Series 1990A, which are described in the Supplemental Indenture dated May 1, 1990 (hereinafter called the "Supplemental Indenture of May 1, 1990"), all of which have been redeemed prior to the date of the execution hereof;

(35) $125,000,000 principal amount of First Mortgage Bonds, 8-3/4% Series due 2021 (herein called the "Bonds of 2021 Series"), which are described in the Supplemental Indenture dated December 1, 1991 (hereinafter called the "Supplemental Indenture of December 1, 1991"), all of which have been redeemed prior to the date of the execution hereof;

(36) $75,000,000 principal amount of First Mortgage Bonds, 8.33% Series due 2002 (herein called the "Bonds of 2002 Series"), which are described in the Supplemental Indenture dated December 4, 1991 (hereinafter called the "Supplemental Indenture of December 4, 1991"), all of which have been paid at maturity prior to the date of the execution hereof;

(37) $100,000,000 principal amount of First Mortgage Bonds, 7.65% Series due 2003 (herein called the "Bonds of 2003 Series"), which are described in the Supplemental Indenture dated January 1, 1992 (hereinafter called the "Supplemental Indenture of January 1, 1992"), all of which have been paid at maturity prior to the date of the execution hereof;

(38) $204,000,000 aggregate principal amount of First Mortgage Bonds, consisting of $100,000,000 principal amount of 6-3/4% Series due 1999 and $104,000,000 principal amount of 8-1/4% Series due 2022 (herein called the "Bonds of 1999 Series" and "Bonds of 2022 Series", respectively), which are described in the Supplemental Indenture dated October 1, 1992 (hereinafter called the "Supplemental Indenture of October 1, 1992"), of which the Bonds of 1999 Series have been paid at maturity prior to the date of execution hereof and the Bonds of 2022 Series have been redeemed prior to the date of the execution hereof;

(39) $170,000,000 aggregate principal amount of First Mortgage Bonds, consisting of $85,000,000 principal amount of 7-3/8% Series due 2004 and $85,000,000 principal amount of 8% Series due 2022 (herein called the "Bonds of December 2004 Series" and "Bonds of December 2022 Series", respectively, which are described in the Supplemental Indenture dated December 1, 1992, (hereinafter called the "Supplemental Indenture of December 1, 1992"), of which the Bonds of December 2022 Series have been redeemed prior to the date of the execution hereof and the Bonds of December 2004 Series are outstanding at the date of the execution hereof;

(40) $188,000,000 principal amount of First Mortgage Bonds, 6-7/8% Series due 2004 (herein called the "Bonds of August 2004 Series"), which are described in the Supplemental Indenture dated February 1, 1993 (hereinafter called the "Supplemental Indenture of February 1, 1993"), all of which are outstanding at the date of the execution hereof;

(41) $148,000,000 principal amount of First Mortgage Bonds, 6-3/4% Series due 2008 (herein called the "Bonds of May 2008 Series"), which are described in the Supplemental Indenture dated May 1, 1993 (hereinafter called the "Supplemental Indenture of May 1, 1993"), all of which are outstanding at the date of the execution hereof;

(42) $75,000,000 principal amount of First Mortgage Bonds, 7.15% Series due 2023 (herein called the "Bonds of 2023 Series"), which are described in the Supplemental Indenture dated August 1, 1993 (hereinafter called the "Supplemental Indenture of August 1, 1993"), all of which have been redeemed prior to the date of the execution hereof;

(43) $44,000,000 principal amount of First Mortgage Bonds, Environmental Improvement Series 1993 (herein called the "Bonds of 2028 Series"), which are described in the Supplemental Indenture dated October 1, 1993 (hereinafter called the "Supplemental Indenture of October 1, 1993"), all of which are outstanding at the date of the execution hereof;

(44) $100,000,000 principal amount of First Mortgage Bonds, 7% Series due 2024 (herein called the "Bonds of 2024 Series"), which are described in the Supplemental Indenture dated January 1, 1994 (hereinafter called the "Supplemental Indenture of January 1, 1994"), all of which are outstanding at the date of the execution hereof;

(45) $173,000,000 principal amount of First Mortgage Bonds, Senior Notes Series AA (herein called the "Bonds of 2012 Series"), which are described in the Supplemental Indenture dated August 15, 2002 (hereinafter called the "Supplemental Indenture of August 15, 2002"), all of which are outstanding at the date of the execution hereof;

(46) $184,000,000 principal amount of First Mortgage Bonds, Senior Notes Series BB (herein called the "Bonds of 2034 Series"), which are described in the Supplemental Indenture dated March 5, 2003 (hereinafter called the "Supplemental Indenture of March 5, 2003"), all of which are outstanding at the date of the execution hereof;

(47) $114,000,000 principal amount of First Mortgage Bonds, Senior Notes Series CC (herein called the "Bonds of 2015 Series"), which are described in the Supplemental Indenture dated April 1, 2003 (hereinafter called the "Supplemental Indenture of April 1, 2003"), all of which are outstanding at the date of the execution hereof;

(48) $200,000,000 principal amount of First Mortgage Bonds, Senior Notes Series DD (herein called the "Bonds of 2018 Series"), which are described in the Supplemental Indenture dated July 15, 2003 (hereinafter called the "Supplemental Indenture of July 15, 2003"), all of which are outstanding at the date of the execution hereof;

(49) $200,000,000 principal amount of First Mortgage Bonds, Senior Notes Series EE (herein called the "Bonds of 2013 Series"), which are described in the Supplemental Indenture dated October 1, 2003 (hereinafter called the "Supplemental Indenture of October 1, 2003"), all of which are outstanding at the date of the execution hereof;

(50) $60,000,000 principal amount of First Mortgage Bonds, Environmental Improvement Series 2004A (1998A Bonds) (herein called the "Bonds of 2033 (Series 1998A)"), which are described in the Supplemental Indenture dated February 1, 2004 (hereinafter called the "Supplemental Indenture of February 1, 2004 (2004A)"), all of which are outstanding at the date of the execution hereof;

(51) $50,000,000 principal amount of First Mortgage Bonds, Environmental Improvement Series 2004B (1998B Bonds) (herein called the "Bonds of 2033 (Series 1998B)"), which are described in the Supplemental Indenture dated February 1, 2004 (hereinafter called the "Supplemental Indenture of February 1, 2004 (2004B)"), all of which are outstanding at the date of the execution hereof;

(52) $50,000,000 principal amount of First Mortgage Bonds, Environmental Improvement Series 2004C (1998C Bonds) (herein called the "Bonds of 2033 (Series 1998C)"), which are described in the Supplemental Indenture dated February 1, 2004 (hereinafter called the "Supplemental Indenture of February 1, 2004 (2004C)"), all of which are outstanding at the date of the execution hereof;

(53) $63,000,000 principal amount of First Mortgage Bonds, Environmental Improvement Series 2004D (2000B Bonds) (herein called the "Bonds of 2035 (Series 2000B)"), which are described in the Supplemental Indenture dated February 1, 2004 (hereinafter called the "Supplemental Indenture of February 1, 2004 (2004D)"), all of which are outstanding at the date of the execution hereof; and

(54) $63,500,000 principal amount of First Mortgage Bonds, Environmental Improvement Series 2004E (2000A Bonds) (herein called the "Bonds of 2035 (Series 2000A)"), which are described in the Supplemental Indenture dated February 1, 2004 (hereinafter called the "Supplemental Indenture of February 1, 2004 (2004E)"), all of which are outstanding at the date of the execution hereof; and

WHEREAS, the Company on August 31, 1955 acquired all of the properties of Union Electric Power Company, the Subsidiary as defined in Article I of the Original Indenture, upon the dissolution of the Subsidiary; the Company, by Supplemental Indenture dated August 31, 1955, conveyed all of the properties so acquired (other than property of the character defined as excepted property in the granting clauses of the Original Indenture) to the Trustee upon the terms and trusts in the Original Indenture and the indentures supplemental thereto set forth for the equal and proportionate benefit and security of all present and future holders of the Bonds and coupons issued and to be issued thereunder, all the shares of stock of the Subsidiary were released from the lien of the Original Indenture; and the Company became entitled to change the general designation of the Bonds so as to omit the words "and Collateral Trust"; and

WHEREAS, the Articles of Incorporation of the Company were duly amended on April 23, 1956, to change its corporate name from "Union Electric Company of Missouri" to "Union Electric Company"; and

WHEREAS, the Articles of Agreement of the Trustee were duly amended effective on January 4, 1982 to change its corporate name from "St. Louis Union Trust Company" to "Centerre Trust Company of St. Louis", and further amended on December 9, 1988, to change its corporate name from "Centerre Trust Company of St. Louis" to "Boatmen's Trust Company"; and

WHEREAS, that on March 13, 1998, Boatmen's Trust Company merged into NationsBank, National Association and effective July 5, 1999, changed its name to Bank of America, National Association; and

WHEREAS, that on February 1, 2000, The Bank of New York, as transferee of the corporate trust business of Bank of America, National Association (formerly known as Boatmen's Trust Company), Trustee under the Original Indenture, became successor Trustee under the Original Indenture; and

WHEREAS, the Company is entitled at this time to have authenticated and delivered additional Bonds on the basis of property additions upon compliance with and pursuant to the provisions of Article III, Section 4 of the Original Indenture; and

WHEREAS, the Company has entered into a Loan Agreement dated as of March 1, 2000 (the "Original Loan Agreement") with the State Environmental Improvement and Energy Resources Authority of the State of Missouri (the "Authority") pursuant to which the Authority agreed to issue $60,000,000 aggregate principal amount of its Environmental Improvement Revenue Refunding Bonds (AmerenUE Project) Series 2000C (the "Authority Bonds"), all of which are presently outstanding and loan the proceeds thereof to the Company; and

WHEREAS, the Authority Bonds were issued pursuant to a Trust Indenture dated as of March 1, 2000 (the "Original Authority Bond Indenture") between the Authority and UMB Bank & Trust, N.A., as successor to State Street Bank and Trust Company of Missouri, N.A., as trustee (the "Authority Bond Trustee"); and

WHEREAS, the Company has determined it to be necessary and desirable to further secure rights of the owners of the Authority Bonds to the payment of principal and interest on the Authority Bonds by obtaining a Financial Guaranty Insurance Policy with respect to the Authority Bonds (the "Authority Bond Insurance Policy") from XL Capital Assurance Inc. and in furtherance thereof (i) the Authority and the Authority Bond Trustee will enter into an Amended and Restated Trust Indenture dated as of February 1, 2004 (the "Authority Bond Indenture") which amends and restates the Original Authority Bond Indenture, and
(ii) the Authority and the Company will enter into the First Amendment to Loan Agreement dated as of February 1, 2004 (the "First Amendment to Loan Agreement"), which amends the Original Loan Agreement (the Original Loan Agreement as so amended is referred to herein as the "Agreement"); and

WHEREAS, in connection with obtaining the Authority Bond Insurance Policy, the Company desires by this Supplemental Indenture to provide for the issuance to the Authority Bond Trustee of a new series of Bonds under the Original Indenture as security for the Company's obligations under the Agreement with respect to the payment of the Authority Bonds, to have the designation provided in Article I, Section 1 hereof (herein called the "New Bonds"), and the Original Indenture provides that certain terms and provisions, as determined by the Board of Directors of the Company, of the Bonds of any particular series may be expressed in and provided by the execution of an appropriate supplemental indenture; and

WHEREAS, the Original Indenture provides that the Company and the Trustee may enter into indentures supplemental to the Original Indenture specifically to convey, transfer and assign to the Trustee and to subject to the lien of the Original Indenture additional properties acquired by the Company; and

WHEREAS, the Company, in the exercise of the powers and authority conferred upon and reserved to it under the provisions of the Original Indenture and pursuant to appropriate resolutions of the Board of Directors, has duly resolved and determined to make, execute and deliver to the Trustee a Supplemental Indenture in the form hereof for the purposes herein provided; and

WHEREAS, all conditions and requirements necessary to make this Supplemental Indenture a valid, binding and legal instrument have been done, performed and fulfilled and the execution and delivery hereof have been in all respects duly authorized;

NOW, THEREFORE, THIS INDENTURE WITNESSETH:

That, in consideration of the premises and of the mutual covenants herein contained and of the acceptance of this trust by the Trustee and of the sum of One Dollar duly paid by the Trustee to the Company at or before the time of the execution of this Supplemental Indenture, and of other valuable considerations, the receipt whereof is hereby acknowledged, and in order further to secure the payment of the principal of and interest (and premium, if any) on all Bonds at any time issued and outstanding under the Original Indenture, according to their tenor and effect, and to secure the Company's obligations under the Agreement with respect to the payment of the Authority Bonds, the Company has executed and delivered this Supplemental Indenture and has granted, bargained, sold, warranted, aliened, remised, released, conveyed, assigned, transferred, mortgaged, pledged, set over and confirmed and by these presents does grant, bargain, sell, warrant, alien, remise, release, convey, assign, transfer, mortgage, pledge, set over and confirm unto The Bank of New York, as Trustee, and to its successors in trust under the Original Indenture forever, all and singular the following described properties (in addition to all other properties heretofore subjected to the lien of the Original Indenture and not heretofore released from the lien thereof) - that is to say:

FIRST

ALL power houses, plants, buildings and other structures, dams, dam sites, substations, heating plants, gas works, holders and tanks, together with all and singular the electric, heating,

gas and mechanical appliances appurtenant thereto of every nature whatsoever, now owned by the Company, including all and singular the machinery, engines, boilers, furnaces, generators, dynamos, turbines and motors, and all and every character of mechanical appliance for generating or producing electricity, steam, gas and other agencies for light, heat, cold, or power or other purposes, and all transmission and distribution systems used for the transmission and distribution of electricity, steam, gas and other agencies for light, heat, cold or power or any other purpose whatsoever, whether underground or overhead, surface or otherwise, now owned by the Company, including all poles, towers, posts, wires, cables, conduits, manholes, mains, pipes, tubes, drains, furnaces, switchboards, transformers, conductors, insulators, supports, meters, lamps, fuses, junction boxes, regulator stations, and other electric, steam and gas fixtures and apparatus; all of the aforementioned property being located in the City of St. Louis, the counties of Adair, Audrain, Benton, Bollinger, Boone, Butler, Caldwell, Callaway, Camden, Cape Girardeau, Clark, Clay, Clinton, Cole, Cooper, Crawford, Daviess, Dunklin, Franklin, Gasconade, Howard, Iron, Jefferson, Knox, Lewis, Lincoln, Livingston, Macon, Madison, Maries, Marion, Miller, Mississippi, Moniteau, Montgomery, Morgan, New Madrid, Osage, Pemiscot, Perry, Pettis, Phelps, Pike, Pulaski, Ralls, Randolph, Ray, Reynolds, Ripley, St. Charles, St. Francois, Ste. Genevieve, St. Louis, Saline, Schuyler, Scott, Stoddard, Warren, Washington, and Wayne, Missouri, the counties of Adams, Alexander, Calhoun, Franklin, Hancock, Henderson, Jackson, Jersey, Macoupin, Madison, Massac, Monroe, Perry, Pike, Pulaski, St. Clair, Union, and Washington, Illinois, and the counties of Des Moines, Henry, Johnson, Lee, and Washington, Iowa, upon real estate owned by the Company, or occupied by it under rights to so occupy, which real estate is described in the Indenture of Mortgage and Deed of Trust dated June 15, 1937, in the Supplemental Indentures dated May 1, 1941, March 17, 1942, April 13, 1945, April 27, 1945, October 1, 1945, April 11, 1947, April 13, 1949, September 13, 1950, December 1, 1950, September 20, 1951, May 1, 1952, March 1, 1954, May 1, 1955, August 31, 1955, April 1, 1956, July 1, 1956, August 1, 1957, February 1, 1958, March 1, 1958, November 5, 1958, March 16, 1959, June 24, 1959, December 11, 1959, August 17, 1960, September 1, 1960, October 24, 1960, June 30, 1961, July 1, 1961, August 9, 1962, September 30, 1963, November 1, 1963, March 12, 1965, April 1, 1965, April 14, 1966, May 1, 1966, February 17, 1967, March 1, 1967, February 19, 1968, March 15, 1968, August 21, 1968, April 7, 1969, May 1, 1969, September 12, 1969, October 1, 1969, March 26, 1970, April 1, 1970, June 12, 1970, January 1, 1971, April 1, 1971, September 15, 1971, December 3, 1973, February 1, 1974, April 25, 1974, February 3, 1975, March 1, 1975, June 11, 1975, May 12, 1976, August 16, 1976, April 26, 1977, October 15, 1977, November 7, 1977, December 1, 1977, August 1, 1978, October 12, 1979, November 1, 1979, July 7, 1980, August 1, 1980, August 20, 1980, February 1, 1981, October 8, 1981, August 27, 1982, September 1, 1982, December 15, 1982, March 1, 1983, June 21, 1984, December 12, 1984, June 11, 1985, March 1, 1986, May 1, 1986, May 1, 1990, December 1, 1991, December 4, 1991, January 1, 1992, September 30, 1992, October 1, 1992, December 1, 1992, February 1, 1993, February 18, 1993, May 1, 1993, August 1, 1993, October 1, 1993, January 1, 1994, February 1, 2000, August 15, 2002, March 5, 2003, April 1, 2003, July 15, 2003, October 1, 2003 and in this Supplemental Indenture and the seven other Supplemental Indentures each dated February 1, 2004, or attached to or connected with such real estate or transmission or distribution systems of the Company leading from or into such real estate.

SECOND

ALSO, (except as in the Original Indenture expressly excepted) all franchises and all permits, ordinances, easements, privileges, immunities and licenses, all rights to construct, maintain and operate overhead, surface and underground systems for the distribution and transmission of electricity, steam, gas or other agencies for the supply to itself or others of light, heat, cold or power, all rights-of-way, all waters, water rights and flowage rights and all grants and consents, now owned or, subject to the provisions of Article XII of the Original Indenture, which it may hereafter acquire.

ALSO, (except as in the Original Indenture expressly excepted) all inventions, patent rights and licenses of every kind now owned by the Company or, subject to the provisions of Article XII of the Original Indenture, which it may hereafter acquire.

THIRD

ALSO, subject to the provisions of Article XII of the Original Indenture, all other property, real, personal and mixed (except as therein or herein expressly excepted) of every nature and kind and wheresoever situated now or hereafter possessed by or belonging to the Company, or to which it is now, or may at any time hereafter be, in any manner entitled at law or in equity.

TO HAVE AND TO HOLD all said properties, real, personal and mixed, mortgaged, pledged and conveyed by the Company as aforesaid, or intended so to be, unto the Trustee and its successors and assigns forever;

SUBJECT, HOWEVER, to the exceptions and reservations and matters hereinabove recited, to existing leases, to existing liens upon rights of way for transmission or distribution line purposes, as defined in Article I of the Original Indenture, and any extensions thereof, and subject to existing easements for streets, alleys, highways, rights-of-way and railroad purposes over, upon and across certain of the property hereinbefore described, and subject also to all the terms, conditions, agreements, covenants, exceptions and reservations expressed or provided in the deeds or other instruments respectively under and by virtue of which the Company acquired the properties hereinabove described, and to undetermined liens and charges, if any, incidental to construction or other existing permitted liens as defined in Article I of the Original Indenture;

IN TRUST, NEVERTHELESS, upon the terms and trusts in the Original Indenture and the indentures supplemental thereto, including this Supplemental Indenture, set forth, for the equal and proportionate benefit and security of all present and future holders of the Bonds and coupons issued and to be issued thereunder, or any of them, without preference of any of said Bonds and coupons of any particular series over the Bonds and coupons of any other series, by reason of priority in the time of the issue, sale or negotiation thereof, or by reason of the purpose of issue or otherwise howsoever, except as otherwise provided in
Section 2 of Article IV of the Original Indenture.

AND IT IS HEREBY COVENANTED, DECLARED AND AGREED, by and between the parties hereto, for the benefit of those who shall hold the Bonds and coupons, or any of them to be issued under the Original Indenture, as follows:

ARTICLE I

DESCRIPTION OF THE NEW BONDS

Section 1.1. There is hereby created a new series of Bonds to be executed, authenticated and delivered under and secured by the Original Indenture which shall, subject to the provisions of Section 1 of Article II of the Original Indenture, be designated as "First Mortgage Bonds, Environmental Improvement Series 2004F (2000C Bonds)" (the "New Bonds") of the Company. The New Bonds shall be executed, authenticated and delivered in accordance with the provisions of, and shall in all respects be subject to all of the terms, conditions and covenants of, the Original Indenture and shall be issued to, and registered in the name of, the Authority Bond Trustee under the Authority Bond Indenture to secure any and all obligations of the Company under the Agreement with respect to the payment of the Authority Bonds.

The New Bonds shall mature, subject to prior redemption, on March 1, 2035, and shall bear interest at the same rate or rates of interest as the Authority Bonds which, in turn, shall be determined by the methods set forth in the Authority Bond Indenture, which provides for a PARS Rate, a Daily Interest Rate, a Weekly Interest Rate, a Flexible Interest Rate or a Term Interest Rate (each as defined in the Authority Bonds Indenture). Reference is made to the provisions of the Authority Bond Indenture concerning the methods by which such interest rates are determined, and the means by which the method of determining such interest rates may be changed, and such provisions are included in this Supplemental Indenture as if fully set forth herein. Interest on the New Bonds is payable on the same dates as interest on the Authority Bonds is paid, until the principal sum of the New Bonds is paid in full. The New Bonds shall be payable as to principal and interest in any coin or currency of the United States of America which at the time of payment is legal tender for public and private debts, and shall be payable, in immediately available funds, at the office of the Authority Bond Trustee.

Section 1.2. The New Bonds shall not be assignable or transferable except as permitted or required by Section 13.15 of the Authority Bond Indenture. Any such transfer shall be effected at the principal office or place of business of the Trustee under the Original Indenture. The New Bonds are exchangeable for the New Bonds of other denominations, as in the Original Indenture provided, except that payment of a service charge therefor will not be required by the Company.

Notwithstanding the provisions of Section 6 of Article II of the Original Indenture, the New Bonds shall be dated their date of authentication and shall bear interest from the interest payment date to which interest on the New Bonds has been paid next preceding the date thereof, unless such date is an interest payment date to which interest has been paid, in which case they shall bear interest from the date thereof.

Upon any payment of the principal of and interest on, all or any portion of the Authority Bonds, whether at maturity or otherwise or upon provision for the payment thereof having been made in accordance with Section 8.01 of the Authority Bond Indenture, the New Bonds in a principal amount equal to the principal amount of such Authority Bonds shall, to the extent of such payment of principal and interest, be deemed paid and the obligation of the Company thereunder to make such payment shall be discharged to such extent and, in the case of the payment of principal, such New Bonds shall be surrendered to the Company for cancellation as provided in and subject to the terms of Section 8.02 of the Authority Bond Indenture. The Trustee may at any time and all times conclusively assume that the obligation of the Company under the Agreement to make payments with respect to the principal of and interest on the Authority Bonds, so far as such payments at the time have become due, has been fully satisfied and discharged pursuant to the foregoing sentence unless and until the Trustee shall have received a written notice from the Authority Bond Trustee signed by one of its officers stating (i) the timely payment of principal or interest on, the Authority Bonds has not been made, (ii) that the Company is in arrears as to the payments required to be made by it to the Authority Bond Trustee pursuant to the Agreement, and (iii) the amount of the arrearage.

                           [Form of Face of New Bond]

No. ____                                                       $________

                               Ill. C. C. No. 6319

NOTWITHSTANDING ANY PROVISIONS HEREOF OR IN THE ORIGINAL INDENTURE THIS BOND IS
NOT ASSIGNABLE OR TRANSFERABLE EXCEPT AS PERMITTED OR REQUIRED BY

SECTION 13.15 OF THE AMENDED AND RESTATED TRUST INDENTURE DATED AS OF FEBRUARY 1, 2004, BETWEEN THE STATE ENVIRONMENTAL IMPROVEMENT AND ENERGY
RESOURCES AUTHORITY OF THE STATE OF MISSOURI AND UMB BANK & TRUST, N.A., AS SUCCESSOR TO STATE STREET BANK AND TRUST COMPANY OF MISSOURI, N.A., AS TRUSTEE

UNION ELECTRIC COMPANY
(Incorporated under the laws of the State of Missouri)

First Mortgage Bonds, Environmental Improvement Series 2004F (2000C Bonds)

Illinois Commerce Commission Identification No. 6319

UNION ELECTRIC COMPANY, a corporation organized and existing under the laws of the State of Missouri (hereinafter called the "Company," which term shall include any successor corporation as defined in the Amended Indenture referred to on the reverse hereof), for value received, hereby promises to pay to UMB Bank & Trust, N.A., as successor to State Street Bank and Trust Company of Missouri, N.A., as trustee under the Authority Bond Indenture hereinafter referred to, or registered assigns, the sum of _________________________ Dollars, on the 1st day of March, 2035, subject to prior redemption, in any coin or currency of the United States of America which at the time of payment is legal tender for public and private debts, and to pay interest thereon, in like coin or currency, at the same rate or rates of interest as the Authority Bonds (as determined in accordance with the Authority Bond Indenture referred to below), but in no event shall the interest rate on this Bond exceed eighteen percent (18%) per annum. Interest on overdue principal premium, if any, and, to the extent permitted by law, on overdue interest, shall be payable at the interest rate payable on the Authority Bonds. Interest on this Bond is payable on the same dates as interest on the Authority Bonds, or, if this Bond shall be duly called for redemption, until the redemption date, or if the Company shall default in the payment of the principal hereof, until the Company's obligation to pay principal shall be discharged as provided in the Amended Indenture is paid, until the principal sum is paid in full. The principal of, and interest on, this Bond are payable, in immediately available funds, at the office of the Authority Bond Trustee hereinafter referred to.

Under a Trust Indenture dated as of March 1, 2000, as amended and restated by the Amended and Restated Trust Indenture dated as of February 1, 2004 (as so amended and restated, the "Authority Bond Indenture") between the State Environmental Improvement and Energy Resources Authority of the State of Missouri (the "Authority") and UMB Bank & Trust, N.A., as successor to State Street Bank and Trust Company of Missouri, N.A., as trustee (the "Authority Bond Trustee"), the Authority has issued its Environmental Improvement Revenue

Refunding Bonds (AmerenUE Project) Series 2000C in the aggregate principal amount of $60,000,000 (the "Authority Bonds"). The Company has agreed to pay the principal of and interest on the Authority Bonds pursuant to a Loan Agreement dated as of March 1, 2000, as supplemented and amended by the First Amendment to Loan Agreement dated as of February 1, 2004 (as so amended, the "Agreement") between the Company and the Authority. Pursuant to the Granting Clauses of the Authority Bond Indenture, this Bond is issued to the Authority Bond Trustee to secure any and all obligations of the Company under the Agreement with respect to payment of the Authority Bonds. Payment of principal of, or interest on, the Authority Bonds shall constitute payments on this Bond as further provided herein and in the Supplemental Indenture dated February 1, 2004 pursuant to which this Bond has been issued (the "Supplemental Indenture").

Upon any payment of the principal of, and interest on, all or any portion of the Authority Bonds, whether at maturity or otherwise or upon provision for the payment thereof having been made in accordance with Section 8.01 of the Authority Bond Indenture, a principal amount of this Bond equal to the principal amount of such Authority Bonds shall, to the extent of such payment of principal and interest, be deemed paid and the obligation of the Company thereunder to make such payment shall be discharged to such extent and, in the case of the payment of principal, such Bonds shall be surrendered to the Company for cancellation as provided in Section 8.02 of the Authority Bond Indenture. The Trustee (as hereinafter defined) may at any time and all times conclusively assume that the obligation of the Company to make payments under the Agreement with respect to the principal of, and interest on, the Authority Bonds, so far as such payments at the time have become due, has been fully satisfied and discharged pursuant to the foregoing sentence unless and until the Trustee shall have received a written notice from the Authority Bond Trustee signed by one of its officers stating (i) that timely payment of principal of, or interest on, the Authority Bonds has not been made, (ii) that the Company is in arrears as to the payments required to be made by it to the Authority Bond Trustee pursuant to the Agreement, and (iii) the amount of the arrearage.

This Bond shall not be entitled to any benefit under the Amended Indenture or any indenture supplemental thereto, or become valid or obligatory for any purpose, until The Bank of New York, the Trustee under the Amended Indenture, or a successor trustee thereto under the Amended Indenture, or an agent therefor, shall have signed the form of certificate endorsed hereon.

The provisions of this Bond are continued on the reverse hereof and such continued provisions shall for all purposes have the same effect as though fully set forth at this place.

IN WITNESS WHEREOF, Union Electric Company has caused this Bond to be signed in its name by its Chairman of the Board or President or a Vice President by manual signature or a facsimile thereof, and its corporate seal (or a facsimile thereof) to be hereto affixed and attested by its Secretary or an Assistant Secretary by manual signature or a facsimile thereof.

Dated,
UNION ELECTRIC COMPANY,

[CORPORATE SEAL]

Attest:

[FORM OF TRUSTEE'S CERTIFICATE]

This Bond is one of the Bonds, of the series designated therein, described in the within-mentioned Amended Indenture and Supplemental Indenture of February 1, 2004.

THE BANK OF NEW YORK, as Trustee

[FORM OF REVERSE OF NEW BOND]

This Bond is one of a duly authorized issue of Bonds of the Company (herein called the "Bonds"), limited to an aggregate principal amount of $50,000,000, of the series hereinafter specified, all issued under and equally secured by the Indenture of Mortgage and Deed of Trust, dated June 15, 1937, executed by the Company to The Bank of New York (successor trustee to Bank of America, National Association, formerly Boatmen's Trust Company), as trustee (herein called the "Trustee"), as amended by indentures supplemental thereto dated May 1, 1941, April 1, 1971, February 1, 1974, July 7, 1980, February 1, 2000 and August 15, 2002, between the Company and the Trustee (said mortgage and deed of trust, as so amended, being herein called the "Amended Indenture"), to which Amended Indenture and all indentures supplemental thereto reference is hereby made for a description of the properties mortgaged and pledged, the nature and extent of the security, the rights of the bearers or registered owners of the Bonds and of the Trustee in respect thereto, and the terms and conditions upon which the Bonds are, and are to be, secured. To the extent permitted by, and as provided in, the Amended Indenture, modifications or alterations of the Amended Indenture, or of any indenture supplemental thereto, and of the rights and obligations of the Company and of the holders of the Bonds may be made with the consent of the Company by an affirmative vote of not less than 60% in amount of the Bonds entitled to vote then outstanding, at a meeting of Bondholders called and held as provided in the Amended Indenture, and by an affirmative vote of not less than 60% in amount of the

Bonds of any series entitled to vote then outstanding and affected by such modification or alteration, in case one or more but less than all of the series of Bonds then outstanding under the Amended Indenture are so affected. Additionally, the Company may amend the Amended Indenture, as supplemented, by an appropriate written consent of not less than 60% in aggregate principal amount of the Bonds outstanding (and, if the rights of one or more, but less than all, series of Bonds then outstanding are to be affected by action taken pursuant to such consent, then also by consent of the holders of at least 60% in principal amount of each series of Bonds so to be affected and outstanding hereunder) without a meeting of such Bondholders. No such modification or alteration shall be made which will affect the terms of payment of the principal of, or interest on, this Bond, which are unconditional. The Bonds may be issued in series, for various principal sums, may mature at different times, may bear interest at different rates and may otherwise vary as in the Amended Indenture provided. This Bond is one of a series designated as the "First Mortgage Bonds, Environmental Improvement Series 2004F (2000C Bonds)" (herein called the "Bonds of this Series") of the Company, issued under and secured by the Amended Indenture and described in the indenture (hereinafter called the "Supplemental Indenture") dated February 1, 2004, between the Company and the Trustee, supplemental to the Amended Indenture.

The Bonds of this Series are not entitled to the benefit of any improvement, maintenance or analogous fund.

This Bond is, subject to the provisions of the Amended Indenture, subject to redemption in the amounts, at the times, at the prices and under the circumstances under which the Authority Bonds are subject to redemption under the same terms and circumstances set forth in the Authority Bond Indenture for the redemption of the Authority Bonds.

This Bond is also subject to mandatory redemption at the principal amount hereof plus accrued interest to the date fixed for redemption if the Trustee or the Company is notified that an "Event of Default" under the Authority Bond Indenture has occurred and is continuing and the Authority Bond Trustee has declared the principal amount of all Authority Bonds then outstanding due and payable in accordance with the Authority Bond Indenture.

The Company may, by notice to the Trustee at least 60 days prior to any date on which any principal amount is due on this Bond, elect to receive a credit in respect of such principal payment (a) for any Bonds of this Series then due which have been redeemed prior to such principal payment date or otherwise acquired and delivered to the Trustee for cancellation by said Trustee prior to the giving of such notice, or (b) for any Authority Bonds which have been purchased, delivered for cancellation or previously redeemed, which in each case have not theretofore been applied as a credit against such principal payment. Each Bond with respect to which the Company elects to receive a credit will be credited by the Trustee at 100% of the principal amount thereof against such principal payment, provided further that in the case of a credit with respect to any Authority Bonds, the principal amount thereof shall be established by an officers' certificate (as defined in the Amended Indenture) concurred in by the Authority Bond Trustee, included with the above-mentioned notice to the Trustee. The principal amount of Bonds to be paid on the due date of such principal payment will be reduced by the amount of any such credit or credits in respect of Bonds previously redeemed or delivered as provided above.

Upon cancellation in full or in part of any of the Authority Bonds (or provision for payment thereof having been made in accordance with the provisions of the Authority Bond Indenture) and payment of all fees and charges of the trustee thereunder, such trustee shall deliver to the Trustee, for cancellation a corresponding amount of Bonds remaining in its possession.

Such redemption in every case shall be effected upon notice delivered by the Company at least 60 days prior to the date of redemption, to the registered owner of the Bonds at its address as the same shall appear on the transfer register of the Company, all subject to the conditions of, and as more fully set forth in, the Amended Indenture and Supplemental Indenture.

In case an event of default, as defined in the Amended Indenture, shall occur, the principal of all the bonds at any such time outstanding under the Amended Indenture may be declared or may become due and payable, upon the conditions and in the manner and with the effect provided in the Amended Indenture. The Amended Indenture provides that such declaration may in certain events be waived by the holders of a majority in principal amount of the bonds outstanding.

This Bond shall not be assignable or transferable except as permitted or required by Section 13.15 of the Authority Bond Indenture. This Bond is exchangeable by the registered owner hereof, in person or by duly authorized attorney, on the books of the Company to be kept for that purpose at the office of the Company in the City of St. Louis, Missouri, upon surrender and cancellation of this Bond and on presentation of a duly executed written instrument of transfer, and thereupon a new Bond or Bonds of the same series, of the same aggregate principal amount and in authorized denominations will be issued to the transferee or transferees in exchange herefor, without payment of any charge other than stamp taxes and other governmental charges incident thereto; and this Bond with or without others of like series, may in like manner be exchanged for one or more new Bonds of the same series of other authorized denominations but of the same aggregate principal amount; all subject to the terms and conditions set forth in the Amended Indenture.

As provided in Section 8.02 of the Authority Bond Indenture, from and after the Release Date (as defined in the Authority Bond Indenture), the obligations of the Company with respect to this Bond shall be deemed to be satisfied and discharged, this Bond shall cease to secure in any manner the Company's obligations under the Agreement with respect to the payment of any Authority Bonds outstanding under the Authority Bond Indenture, and, pursuant to Section 8.02 of the Authority Bond Indenture, the Authority Bond Trustee shall forthwith deliver this Bond to the Company for cancellation.

No recourse shall be had for the payment of the principal of, or the interest on, this Bond, or for any claim based hereon or on the Amended Indenture or any indenture supplemental thereto, against any incorporator, or against any stockholder, director or officer, past, present or future, of the Company, or of any predecessor or successor corporation, either directly or through the Company or any such predecessor or successor corporation, whether for amounts unpaid on stock subscriptions or by virtue of any constitution, statute or rule of law, or by the enforcement of any assessment or penalty or otherwise, all such liability, whether at common law, in equity,

by any constitution, statute or otherwise, of incorporators, stockholders, directors or officers being released by every owner hereof by the acceptance of this Bond and as part of the consideration for the issue hereof, and being likewise released by the terms of the Amended Indenture.

[END OF FORM OF REVERSE OF NEW BOND]

ARTICLE II

ISSUE OF THE NEW BONDS

Section 2.1. The principal amount of the New Bonds which may be authenticated and delivered hereunder is limited to an amount equal to the principal amount of Sixty Million Dollars ($60,000,000) consisting of Bonds maturing on March 1, 2035.

Section 2.2. The New Bonds in the aggregate principal amount set forth above, may forthwith be executed by the Company and delivered to the Trustee and shall be authenticated by the Trustee and delivered (either before or after the filing or recording hereof) to or upon the order of the Company, upon compliance by the Company with the applicable provisions of Article III and Article XVIII of the Original Indenture.

Section 2.3. As provided in Section 8.02 of the Authority Bond Indenture, from and after the Release Date (as defined in the Authority Bond Indenture), the obligations of the Company with respect to the New Bonds shall be deemed to be satisfied and discharged, the New Bonds shall cease to secure in any manner the Company's obligations under the Agreement with respect to the payment of any Authority Bonds outstanding under the Authority Bond Indenture, and, pursuant to
Section 8.02 of the Authority Bond Indenture, the Authority Bond Trustee shall forthwith deliver the New Bonds to the Company for cancellation.

ARTICLE III

REDEMPTION OF THE NEW BONDS

Section 3.1. The New Bonds are, subject to the provisions of the Original Indenture, subject to redemption in the amounts, at the times, at the prices and under the circumstances under which the Authority Bonds are subject to redemption, under the same terms and conditions set forth in the Authority Bond Indenture for the redemption of the Authority Bonds. In the event that less than all the New Bonds are to be redeemed, the New Bonds to be redeemed shall be determined by lot in such manner as the Trustee in its discretion shall deem proper, as in the Original Indenture provided.

The New Bonds are also subject to mandatory redemption as set forth in the form of New Bonds in Section 1.3 of Article I of this Supplemental Indenture.

Section 3.2. Subject to the provisions of Article V of the Original Indenture, notice of redemption shall be delivered by the Company at least 60 days prior to the date of redemption, to the registered owner of such Bonds at its address as the same shall appear on the transfer register of the Company.

Section 3.3. As provided in the Authority Bond Indenture, any amounts of money held in the Bond Fund provided in said Indenture and available for such purpose, which are at the request of the Company applied to the payments of the principal of, premium, if any, and interest on the Authority Bonds on any payment or redemption date, shall be applied as a credit on amounts otherwise due under the New Bonds; provided that the amount of such credit shall be established by an officers' certificate (as defined in the Amended Indenture), concurred in by the Authority Bond Trustee which shall be filed with the Trustee prior to the application of any such credit.

Upon cancellation in full or in part of any of the Authority Bonds (or provision for payment thereof having been made in accordance with the provisions of the Authority Bond Indenture) and payment of all fees and charges of the trustee thereunder, such trustee shall deliver to the Trustee, for cancellation a corresponding amount of New Bonds remaining in its possession or shall request such Trustee to issue a New Bond reflecting any such cancellation.

Article IV

Covenants

The Company hereby covenants, warrants and agrees;

Section 4.1. That the Company is lawfully seized and possessed of all of the mortgaged property described in the granting clauses of this Supplemental Indenture; that it has good right and lawful authority to mortgage the same as provided in this Supplemental Indenture; and that such mortgaged property is, at the actual date of the issue of the New Bonds, free and clear of any deed of trust, mortgage, lien, charge or encumbrance thereon or affecting the title thereto prior to the Original Indenture, except as set forth in the granting clauses of the Original Indenture or this Supplemental Indenture.

Section 4.2. That, so long as any of the New Bonds are outstanding, whenever any officers' certificate is required to be filed or deposited with the Trustee pursuant to Section 3(b) of Article III of the Original Indenture upon an application for the authentication of additional Bonds pursuant to Article III of the Original Indenture, such officers' certificate shall include, in addition to the matters required to be stated therein by said Section 3(b), the statement with respect to the net earnings of the Company available for interest after property retirement appropriations required by Section 2 of Article V of the Supplemental Indenture of July 1, 1956.

Section 4.3. That, so long as any of the New Bonds are outstanding, the Company will not apply for the authentication and delivery of additional Bonds pursuant to Section 4 of Article III of the Original Indenture or the withdrawal of cash from the trust estate or the reduction of the amount of cash required to be paid into the trust estate or to satisfy the

maintenance and improvement funds under any provision of the Original Indenture or the Supplemental Indentures creating prior series of Bonds, on the basis of the amount of $15,000,000 excluded from net bondable value of property additions not subject to an unfunded prior lien pursuant to Section 3 of Article V of the Supplemental Indenture of October 1, 1945, or on the basis of the amount of $7,500,000 excluded from net bondable value of property additions not subject to an unfunded prior lien pursuant to Section 3 of Article V of the Supplemental Indenture of July 1, 1956.

Section 4.4. That, so long as any of the New Bonds are outstanding, the Company will not issue or permit to be issued any prior lien bonds secured by an unfunded prior lien in addition to the prior lien bonds secured by such unfunded prior lien at the time of first acquisition by the Company of property subject thereto (other than in lieu of lost, stolen or mutilated bonds or on the exchange for bonds already outstanding of an equal principal amount of other bonds of the same issue and the same series, if any, and of the same maturity), except upon compliance with the provisions of Section 16 of Article IV of the Original Indenture, nor unless the net earnings of the Company available for interest after property retirement appropriations (determined as provided in
Section 2 of Article V of the Supplemental Indenture of July 1, 1956), for any 12 consecutive calendar months during the period of 15 calendar months immediately preceding the first day of the month in which the additional prior lien bonds are to be issued, have been, in the aggregate, equal to not less than twice the annual interest charges on the indebtedness specified in subparagraphs
(i) and (ii) of paragraph (1) of Section 2(a) of said Article V; provided that, if the application for the issue of such additional prior lien bonds is upon the basis of payment at maturity of prior lien bonds theretofore sold or otherwise disposed of or the redemption or purchase thereof after a date two years prior to the date of maturity, the additional requirement imposed by this Section 4 with respect to net earnings of the Company available for interest after property retirement appropriations shall not apply. Any officers' certificate with respect to net earnings of the Company, required to be filed with the Trustee as a condition precedent to the issue of such additional prior lien bonds, shall include, in addition to the matters otherwise required to be stated therein, the matters required to be stated in an officers' certificate pursuant to paragraphs (1) and (2) of Section 2(a) of said Article V.

Section 4.5. That, so long as any of the New Bonds are outstanding, the Company will not acquire, by purchase, merger or otherwise, any property subject to a lien or liens which will on acquisition be an unfunded prior lien or prior liens, except upon compliance with the provisions of Section 14 of Article IV of the Original Indenture, nor unless the net earnings of such property available for interest after property retirement appropriations (determined in the manner provided in Section 2 of Article V of the Supplemental Indenture of July 1, 1956), for any 12 consecutive calendar months during the period of 15 calendar months immediately preceding the first day of the month in which the first acquisition of property subject to such lien or liens occurs, have been, in the aggregate, equal to not less than twice the amount of annual interest charges, on all outstanding indebtedness secured by such lien or liens. Any officers' certificate with respect to net earnings of such property, required to be filed with the Trustee as a condition precedent to the acquisition of such property, shall include, in addition to the matters otherwise required to be stated therein, the matters required to be stated in an officers' certificate pursuant to Section 2 of said Article V applicable, however, only to the net earnings of such property and to the indebtedness secured by such liens to which such property is subject.

ARTICLE V

THE TRUSTEE

The Trustee hereby accepts the trusts hereby declared and provided, and agrees to perform the same upon the terms and conditions in the Original Indenture and in this Supplemental Indenture set forth, and upon the following terms and conditions:

The Trustee shall not be responsible in any manner whatsoever for or in respect of the validity or sufficiency of this Supplemental Indenture or the due execution hereof by the Company or for or in respect of the recitals contained herein, all of which recitals are made by the Company solely.

ARTICLE VI

MISCELLANEOUS PROVISIONS

Section 6.1. Except as otherwise defined herein, all terms contained in this Supplemental Indenture shall, for all purposes thereof, have the meanings given to such terms in Article I of the Original Indenture.

Section 6.2. This Supplemental Indenture may be simultaneously executed in any number of counterparts, each of which when so executed shall be deemed to be an original; but such counterparts shall together constitute but one and the same instrument.

IN WITNESS WHEREOF, said Union Electric Company has caused this Supplemental Indenture to be executed on its behalf by its Chairman of the Board or President or one of its Vice Presidents and its corporate seal to be hereto affixed and said seal and this Supplemental Indenture to be attested by its Secretary or one of its Assistant Secretaries; and said The Bank of New York, in evidence of its acceptance of the trust hereby created, has caused this Supplemental Indenture to be executed on its behalf by its President or one of its Vice Presidents, and its corporate seal to be hereto affixed and said seal and this Supplemental Indenture to be attested by its Secretary, or one of its Assistant Secretaries; all as of the 1st day of February, Two thousand and four.

Attested:                               UNION ELECTRIC COMPANY,
                                          1901 Chouteau Avenue
                                          St. Louis, Missouri  63103


/s/ G. L. Waters                        By:  /s/ Jerre E. Birdsong
-------------------------------         ----------------------------------------
           G. L. Waters                 Name:    Jerre E. Birdsong
        Assistant Secretary             Title: Vice President and Treasurer


Signed, sealed and delivered by
       UNION ELECTRIC COMPANY
       in the presence of:


/s/ D. Bradley
-------------------------------
           Daphyne Bradley


/s/ Wayne K. Forbes
-------------------------------
           Wayne K. Forbes

           As Witnesses

Attested:                               THE BANK OF NEW YORK,
                                          911 Washington Avenue
                                          St. Louis, Missouri  63101


/s/ Belinda Brown                       By:  /s/ Robert J.
----------------------------------         -------------------------------------
Belinda Brown                           Name:    Robert J. Dunn
As Agent                                Title:   As Agent

Signed, sealed and delivered by
THE BANK OF NEW YORK
in the presence of:

/s/ Daniel G. Dwyer
-----------------------------------
Daniel G. Dwyer


/s/ Richard F. Novosak
-----------------------------------
Richard F. Novosak

STATE OF MISSOURI          )
                           )  SS:
CITY OF ST. LOUIS          )

On this 9th day of March 2004, before me appeared JERRE E. BIRDSONG, to me personally known, who, being by me duly sworn, did say that he is Vice President and Treasurer of UNION ELECTRIC COMPANY, a corporation, and that the seal affixed to the foregoing instrument is the corporate seal of said corporation, and that said instrument was signed and sealed in behalf of said corporation by authority of its Board of Directors, and said JERRE E. BIRDSONG acknowledged said instrument to be the free act and deed of said corporation.

IN TESTIMONY WHEREOF, I have hereto set my hand and affixed my official seal at my office, in the City and State aforesaid, the day and year last above written.

/s/ S.A. Kitchens
-----------------------------------

STATE OF MISSOURI          )
                           )  SS:
CITY OF ST. LOUIS          )

On this 9th day of March 2004, before me appeared Robert J. Dunn, to me personally known, who, being by me duly sworn, did say that he is an Agent of THE BANK OF NEW YORK, a corporation, and that the seal affixed to the foregoing instrument is the corporate seal of said corporation, and that said instrument was signed and sealed in behalf of said corporation, as the trustee thereunder by authority of its Board of Directors, and said Vice President, acknowledged said instrument to be the free act and deed of said corporation as the trustee under said instrument.

IN TESTIMONY WHEREOF, I have hereto set my hand and affixed my official seal at my office, in the City and State aforesaid, the day and year last above written.

/s/ Renee Beard
-----------------------------------

Exhibit 4.7

WHEN RECORDED
MAIL TO:

Gerald L. Waters
Union Electric Company
1901 Chouteau Avenue
St. Louis, MO 61303

Executed in 35 Counterparts, No. 35

SUPPLEMENTAL INDENTURE

DATED FEBRUARY 1, 2004

UNION ELECTRIC COMPANY

TO

THE BANK OF NEW YORK,
AS TRUSTEE

(SUPPLEMENTAL TO THE INDENTURE OF MORTGAGE AND DEED OF
TRUST DATED JUNE 15, 1937, AS AMENDED, EXECUTED BY

UNION ELECTRIC COMPANY
TO THE BANK OF NEW YORK, AS TRUSTEE)

First Mortgage Bonds, Environmental Improvement Series 2004G (1991 Bonds)

This instrument was prepared by Steven R. Sullivan, Senior Vice President Governmental/Regulatory Policy, General Counsel and Secretary of Union Electric Company, 1901 Chouteau Avenue, St.

Louis, Missouri 63103, (314) 554-2098.

SUPPLEMENTAL INDENTURE, dated the 1st day of February, Two thousand and four (2004) made by and between UNION ELECTRIC COMPANY, a corporation organized and existing under the laws of the State of Missouri (hereinafter called the "Company"), party of the first part, and The Bank of New York (successor trustee to Bank of America, National Association, formerly Boatmen's Trust Company), a bank existing under the laws of the State of New York (hereinafter called the "Trustee"), as Trustee under the Indenture of Mortgage and Deed of Trust dated June 15, 1937, hereinafter mentioned, party of the second part:

WHEREAS, the Company has heretofore executed and delivered to the Trustee its Indenture of Mortgage and Deed of Trust, dated June 15, 1937, as amended May 1, 1941, April 1, 1971, February 1, 1974, July 7, 1980, February 1, 2000 and August 15, 2002 (said Indenture of Mortgage and Deed of Trust as so amended, being hereinafter referred to as the "Original Indenture"), to secure the payment of the principal of and the interest (and premium, if any) on all bonds at any time issued and outstanding thereunder, and indentures supplemental thereto dated June 15, 1937, May 1, 1941, March 17, 1942, April 13, 1945, April 27, 1945, October 1, 1945, April 11, 1947, April 13, 1949, September 13, 1950, December 1, 1950, September 20, 1951, May 1, 1952, March 1, 1954, May 1, 1955, August 31, 1955, April 1, 1956, July 1, 1956, August 1, 1957, February 1, 1958, March 1, 1958, November 5, 1958, March 16, 1959, June 24, 1959, December 11, 1959, August 17, 1960, September 1, 1960, October 24, 1960, June 30, 1961, July 1, 1961, August 9, 1962, September 30, 1963, November 1, 1963, March 12, 1965, April 1, 1965, April 14, 1966, May 1, 1966, February 17, 1967, March 1, 1967, February 19, 1968, March 15, 1968, August 21, 1968, April 7, 1969, May 1, 1969, September 12, 1969, October 1, 1969, March 26, 1970, April 1, 1970, June 12, 1970, January 1, 1971, April 1, 1971, September 15, 1971, December 3, 1973, February 1, 1974, April 25, 1974, February 3, 1975, March 1, 1975, June 11, 1975, May 12, 1976, August 16, 1976, April 26, 1977, October 15, 1977, November 7, 1977, December 1, 1977, August 1, 1978, October 12, 1979, November 1, 1979, July 7, 1980, August 1, 1980, August 20, 1980, February 1, 1981, October 8, 1981, August 27, 1982, September 1, 1982, December 15, 1982, March 1, 1983, June 21, 1984, December 12, 1984, June 11, 1985, March 1, 1986, May 1, 1986, May 1, 1990, December 1, 1991, December 4, 1991, January 1, 1992, September 30, 1992, October 1, 1992, December 1, 1992, February 1, 1993, February 18, 1993, May 1, 1993, August 1, 1993, October 1, 1993, January 1, 1994, February 1, 2000, August 15, 2002, March 5, 2003, April 1, 2003, July 15, 2003, October 1, 2003 and the six indentures supplemental each dated as of February 1, 2004, respectively, have heretofore been entered into between the Company and the Trustee; and

WHEREAS, Bonds have heretofore been issued by the Company under the Original Indenture as follows:

(1) $80,000,000 principal amount of First Mortgage and Collateral Trust Bonds, 3-3/4% Series due 1962, all of which have been redeemed prior to the date of the execution hereof;

(2) $90,000,000 principal amount of First Mortgage and Collateral Trust Bonds, 3-3/8% Series due 1971, which are described in the Supplemental Indenture dated

May 1, 1941 (hereinafter called the "Supplemental Indenture of May 1, 1941"), all of which have been paid at maturity prior to the date of the execution hereof;

(3) $13,000,000 principal amount of First Mortgage and Collateral Trust Bonds, 2-3/4% Series due 1975 (herein called the "Bonds of 1975 Series"), which are described in the Supplemental Indenture dated October 1, 1945 (hereinafter called the "Supplemental Indenture of October 1, 1945"), all of which have been paid at maturity prior to the date of the execution hereof;

(4) $25,000,000 principal amount of First Mortgage and Collateral Trust Bonds, 2-7/8% Series due 1980 (herein called the "Bonds of 1980 Series"), which are described in the Supplemental Indenture dated December 1, 1950 (hereinafter called the "Supplemental Indenture of December 1, 1950"), all of which have been paid at maturity prior to the date of the execution hereof;

(5) $30,000,000 principal amount of First Mortgage and Collateral Trust Bonds, 3-1/4% Series due 1982 (herein called the "Bonds of 1982 Series"), which are described in the Supplemental Indenture dated May 1, 1952 (hereinafter called the "Supplemental Indenture of May 1, 1952"), all of which have been paid at maturity prior to the date of the execution hereof;

(6) $40,000,000 principal amount of First Mortgage Bonds, 3-3/4% Series due 1986 (herein called the "Bonds of 1986 Series"), which are described in the Supplemental Indenture dated July 1, 1956 (hereinafter called the "Supplemental Indenture of July 1, 1956"), all of which have been paid at maturity prior to the date of the execution hereof;

(7) $35,000,000 principal amount of First Mortgage Bonds, 4-3/8% Series due 1988 (herein called the "Bonds of 1988 Series"), which are described in the Supplemental Indenture dated March 1, 1958 (hereinafter called the "Supplemental Indenture of March 1, 1958"), all of which have been paid at maturity prior to the date of the execution hereof;

(8) $50,000,000 principal amount of First Mortgage Bonds, 4-3/4% Series due 1990 (herein called the "Bonds of 1990 Series"), which are described in the Supplemental Indenture dated September 1, 1960 (hereinafter called the "Supplemental Indenture of September 1, 1960"), all of which have been paid at maturity prior to the date of the execution hereof;

(9) $30,000,000 principal amount of First Mortgage Bonds, 4-3/4% Series due 1991 (herein called the "Bonds of 1991 Series"), which are described in the Supplemental Indenture dated July 1, 1961 (hereinafter called the "Supplemental Indenture of July 1, 1961"), all of which have been paid at maturity prior to the date of the execution hereof;

(10) $30,000,000 principal amount of First Mortgage Bonds, 4-1/2% Series due 1993 (herein called the "Bonds of 1993 Series"), which are described in the

Supplemental Indenture dated November 1, 1963 (hereinafter called the "Supplemental Indenture of November 1, 1963"), all of which have been redeemed prior to the date of the execution hereof;

(11) $35,000,000 principal amount of First Mortgage Bonds, 4-1/2% Series due 1995 (herein called the "Bonds of 1995 Series"), which are described in the Supplemental Indenture dated April 1, 1965 (hereinafter called the "Supplemental Indenture of April 1, 1965"), all of which have been paid at maturity prior to the date of the execution hereof;

(12) $30,000,000 principal amount of First Mortgage Bonds, 5-1/2% Series due 1996 (herein called the "Bonds of 1996 Series"), which are described in the Supplemental Indenture dated May 1, 1966 (hereinafter called the "Supplemental Indenture of May 1, 1966"), all of which have been paid at maturity prior to the date of the execution hereof;

(13) $40,000,000 principal amount of First Mortgage Bonds, 5-1/2% Series due 1997 (herein called the "Bonds of 1997 Series"), which are described in the Supplemental Indenture dated March 1, 1967 (hereinafter called the "Supplemental Indenture of March 1, 1967"), all of which have been paid at maturity prior to the date of the execution hereof;

(14) $50,000,000 principal amount of First Mortgage Bonds, 7% Series due 1998 (herein called the "Bonds of 1998 Series"), which are described in the Supplemental Indenture dated March 15, 1968 (hereinafter called the "Supplemental Indenture of March 15, 1968"), all of which have been redeemed prior to the date of the execution hereof;

(15) $35,000,000 principal amount of First Mortgage Bonds, 7-3/8% Series due 1999 (herein called the "Bonds of May 1999 Series"), which are described in the Supplemental Indenture dated May 1, 1969 (hereinafter called the "Supplemental Indenture of May 1, 1969"), all of which have been redeemed prior to the date of the execution hereof;

(16) $40,000,000 principal amount of First Mortgage Bonds, 8-1/4% Series due 1999 (herein called the "Bonds of October 1999 Series"), which are described in the Supplemental Indenture dated October 1, 1969 (hereinafter called the "Supplemental Indenture of October 1, 1969"), all of which have been redeemed prior to the date of the execution hereof;

(17) $100,000,000 principal amount of First Mortgage Bonds, 9.95% Series due 1999 (herein called the "Bonds of November 1999 Series"), which are described in the Supplemental Indenture dated November 1, 1979 (hereinafter called the "Supplemental Indenture of November 1, 1979"), all of which have been redeemed prior to the date of the execution hereof;

(18) $60,000,000 principal amount of First Mortgage Bonds, 9% Series due 2000 (herein called the "Bonds of 2000 Series"), which are described in the Supplemental Indenture dated April 1, 1970 (hereinafter called the "Supplemental Indenture of April 1, 1970"), all of which have been redeemed prior to the date of the execution hereof;

(19) $50,000,000 principal amount of First Mortgage Bonds, 7-7/8% Series due 2001 (herein called the "Bonds of January 2001 Series"), which are described in the Supplemental Indenture dated January 1, 1971 (hereinafter called the "Supplemental Indenture of January 1, 1971"), all of which have been redeemed prior to the date of the execution hereof;

(20) $50,000,000 principal amount of First Mortgage Bonds, 7 5/8% Series due 2001 (herein called the "Bonds of April 2001 Series"), which are described in the Supplemental Indenture dated April 1, 1971 (hereinafter called the "Supplemental Indenture of April 1, 1971"), all of which have been redeemed prior to the date of the execution hereof;

(21) $60,000,000 principal amount of First Mortgage Bonds, 8 1/8% Series due 2001 (herein called the "Bonds of October 2001 Series"), which are described in the Supplemental Indenture dated September 15, 1971 (hereinafter called the "Supplemental Indenture of September 15, 1971"), all of which have been redeemed prior to the date of the execution hereof;

(22) $70,000,000 principal amount of First Mortgage Bonds, 8-3/8% Series due 2004 (herein called the "Bonds of 2004 Series"), which are described in the Supplemental Indenture dated February 1, 1974 (hereinafter called the "Supplemental Indenture of February 1, 1974"), all of which have been redeemed prior to the date of the execution hereof;

(23) $70,000,000 principal amount of First Mortgage Bonds, 10-1/2% Series due 2005 (herein called the "Bonds of 2005 Series"), which are described in the Supplemental Indenture dated March 1, 1975 (hereinafter called the "Supplemental Indenture of March 1, 1975"), all of which have been redeemed prior to the date of the execution hereof;

(24) $70,000,000 principal amount of First Mortgage Bonds, 8-7/8% Series due 2006 (herein called the "Bonds of 2006 Series"), which are described in the Supplemental Indenture dated August 16, 1976 (hereinafter called the "Supplemental Indenture of August 16, 1976"), all of which have been redeemed prior to the date of the execution hereof;

(25) $27,085,000 principal amount of First Mortgage Bonds, 5.80% Environmental Improvement Series 1977, which are described in the Supplemental Indenture dated October 15, 1977 (hereinafter called the "Supplemental Indenture of October 15, 1977"), all of which have been redeemed prior to the date of the execution hereof;

(26) $60,000,000 principal amount of First Mortgage Bonds, 8 5/8% Series due 2007 (herein called the "Bonds of 2007 Series"), which are described in the Supplemental Indenture dated December 1, 1977 (hereinafter called the "Supplemental Indenture of December 1, 1977"), all of which have been redeemed prior to the date of the execution hereof;

(27) $55,000,000 principal amount of First Mortgage Bonds, 9.35% Series due 2008 (herein called the "Bonds of 2008 Series"), which are described in the Supplemental Indenture dated August 1, 1978 (hereinafter called the "Supplemental Indenture of August 1, 1978"), all of which have been redeemed prior to the date of the execution hereof;

(28) $60,000,000 principal amount of First Mortgage Bonds, Environmental Improvement Series 1980, which are described in the Supplemental Indenture dated August 1, 1980 (hereinafter called the "Supplemental Indenture of August 1, 1980"), all of which have been redeemed prior to the date of the execution hereof;

(29) $150,000,000 principal amount of First Mortgage Bonds, 15-3/8% Series due 1991 (herein called the "Bonds of February 1991 Series"), which are described in the Supplemental Indenture dated February 1, 1981 (hereinafter called the "Supplemental Indenture of February 1, 1981"), all of which have been redeemed prior to the date of the execution hereof;

(30) $125,000,000 principal amount of First Mortgage Bonds, 15% Series due 1992 (herein called the "Bonds of 1992 Series"), which are described in the Supplemental Indenture dated September 1, 1982 (hereinafter called the "Supplemental Indenture of September 1, 1982"), all of which have been redeemed prior to the date of the execution hereof;

(31) $100,000,000 principal amount of First Mortgage Bonds, 13% Series due 2013 (herein called the "Bonds of 2013 Series"), which are described in the Supplemental Indenture dated March 1, 1983 (hereinafter called the "Supplemental Indenture of March 1, 1983"), all of which have been redeemed prior to the date of the execution hereof;

(32) $100,000,000 principal amount of First Mortgage Bonds, 9-3/8% Series due 2016 (herein called the "Bonds of 2016 Series"), which are described in the Supplemental Indenture dated March 1, 1986 (hereinafter called the "Supplemental Indenture of March 1, 1986"), all of which have been redeemed prior to the date of the execution hereof;

(33) $100,000,000 principal amount of First Mortgage Bonds, 8-7/8% Series due 1996 (herein called the "Bonds of 1996 Series"), which are described in the Supplemental Indenture dated May 1, 1986 (hereinafter called the "Supplemental Indenture of May 1, 1986"), all of which have been redeemed prior to the date of the execution hereof;

(34) $60,000,000 principal amount of First Mortgage Bonds, Environmental Improvement Series 1990A, which are described in the Supplemental Indenture dated May 1, 1990 (hereinafter called the "Supplemental Indenture of May 1, 1990"), all of which have been redeemed prior to the date of the execution hereof;

(35) $125,000,000 principal amount of First Mortgage Bonds, 8-3/4% Series due 2021 (herein called the "Bonds of 2021 Series"), which are described in the Supplemental Indenture dated December 1, 1991 (hereinafter called the "Supplemental Indenture of December 1, 1991"), all of which have been redeemed prior to the date of the execution hereof;

(36) $75,000,000 principal amount of First Mortgage Bonds, 8.33% Series due 2002 (herein called the "Bonds of 2002 Series"), which are described in the Supplemental Indenture dated December 4, 1991 (hereinafter called the "Supplemental Indenture of December 4, 1991"), all of which have been paid at maturity prior to the date of the execution hereof;

(37) $100,000,000 principal amount of First Mortgage Bonds, 7.65% Series due 2003 (herein called the "Bonds of 2003 Series"), which are described in the Supplemental Indenture dated January 1, 1992 (hereinafter called the "Supplemental Indenture of January 1, 1992"), all of which have been paid at maturity prior to the date of the execution hereof;

(38) $204,000,000 aggregate principal amount of First Mortgage Bonds, consisting of $100,000,000 principal amount of 6-3/4% Series due 1999 and $104,000,000 principal amount of 8-1/4% Series due 2022 (herein called the "Bonds of 1999 Series" and "Bonds of 2022 Series", respectively), which are described in the Supplemental Indenture dated October 1, 1992 (hereinafter called the "Supplemental Indenture of October 1, 1992"), of which the Bonds of 1999 Series have been paid at maturity prior to the date of execution hereof and the Bonds of 2022 Series have been redeemed prior to the date of the execution hereof;

(39) $170,000,000 aggregate principal amount of First Mortgage Bonds, consisting of $85,000,000 principal amount of 7-3/8% Series due 2004 and $85,000,000 principal amount of 8% Series due 2022 (herein called the "Bonds of December 2004 Series" and "Bonds of December 2022 Series", respectively, which are described in the Supplemental Indenture dated December 1, 1992, (hereinafter called the "Supplemental Indenture of December 1, 1992"), of which the Bonds of December 2022 Series have been redeemed prior to the date of the execution hereof and the Bonds of December 2004 Series are outstanding at the date of the execution hereof;

(40) $188,000,000 principal amount of First Mortgage Bonds, 6-7/8% Series due 2004 (herein called the "Bonds of August 2004 Series"), which are described in the Supplemental Indenture dated February 1, 1993 (hereinafter called the "Supplemental Indenture of February 1, 1993"), all of which are outstanding at the date of the execution hereof;

(41) $148,000,000 principal amount of First Mortgage Bonds, 6-3/4% Series due 2008 (herein called the "Bonds of May 2008 Series"), which are described in the Supplemental Indenture dated May 1, 1993 (hereinafter called the "Supplemental Indenture of May 1, 1993"), all of which are outstanding at the date of the execution hereof;

(42) $75,000,000 principal amount of First Mortgage Bonds, 7.15% Series due 2023 (herein called the "Bonds of 2023 Series"), which are described in the Supplemental Indenture dated August 1, 1993 (hereinafter called the "Supplemental Indenture of August 1, 1993"), all of which have been redeemed prior to the date of the execution hereof;

(43) $44,000,000 principal amount of First Mortgage Bonds, Environmental Improvement Series 1993 (herein called the "Bonds of 2028 Series"), which are described in the Supplemental Indenture dated October 1, 1993 (hereinafter called the "Supplemental Indenture of October 1, 1993"), all of which are outstanding at the date of the execution hereof;

(44) $100,000,000 principal amount of First Mortgage Bonds, 7% Series due 2024 (herein called the "Bonds of 2024 Series"), which are described in the Supplemental Indenture dated January 1, 1994 (hereinafter called the "Supplemental Indenture of January 1, 1994"), all of which are outstanding at the date of the execution hereof;

(45) $173,000,000 principal amount of First Mortgage Bonds, Senior Notes Series AA (herein called the "Bonds of 2012 Series"), which are described in the Supplemental Indenture dated August 15, 2002 (hereinafter called the "Supplemental Indenture of August 15, 2002"), all of which are outstanding at the date of the execution hereof;

(46) $184,000,000 principal amount of First Mortgage Bonds, Senior Notes Series BB (herein called the "Bonds of 2034 Series"), which are described in the Supplemental Indenture dated March 5, 2003 (hereinafter called the "Supplemental Indenture of March 5, 2003"), all of which are outstanding at the date of the execution hereof;

(47) $114,000,000 principal amount of First Mortgage Bonds, Senior Notes Series CC (herein called the "Bonds of 2015 Series"), which are described in the Supplemental Indenture dated April 1, 2003 (hereinafter called the "Supplemental Indenture of April 1, 2003"), all of which are outstanding at the date of the execution hereof;

(48) $200,000,000 principal amount of First Mortgage Bonds, Senior Notes Series DD (herein called the "Bonds of 2018 Series"), which are described in the Supplemental Indenture dated July 15, 2003 (hereinafter called the "Supplemental Indenture of July 15, 2003"), all of which are outstanding at the date of the execution hereof;

(49) $200,000,000 principal amount of First Mortgage Bonds, Senior Notes Series EE (herein called the "Bonds of 2013 Series"), which are described in the Supplemental Indenture dated October 1, 2003 (hereinafter called the "Supplemental Indenture of October 1, 2003"), all of which are outstanding at the date of the execution hereof;

(50) $60,000,000 principal amount of First Mortgage Bonds, Environmental Improvement Series 2004A (1998A Bonds) (herein called the "Bonds of 2033 (Series 1998A)"), which are described in the Supplemental Indenture dated February 1, 2004 (hereinafter called the "Supplemental Indenture of February 1, 2004 (2004A)"), all of which are outstanding at the date of the execution hereof;

(51) $50,000,000 principal amount of First Mortgage Bonds, Environmental Improvement Series 2004B (1998B Bonds) (herein called the "Bonds of 2033 (Series 1998B)"), which are described in the Supplemental Indenture dated February 1, 2004 (hereinafter called the "Supplemental Indenture of February 1, 2004 (2004B)"), all of which are outstanding at the date of the execution hereof;

(52) $50,000,000 principal amount of First Mortgage Bonds, Environmental Improvement Series 2004C (1998C Bonds) (herein called the "Bonds of 2033 (Series 1998C)"), which are described in the Supplemental Indenture dated February 1, 2004 (hereinafter called the "Supplemental Indenture of February 1, 2004 (2004C)"), all of which are outstanding at the date of the execution hereof;

(53) $63,000,000 principal amount of First Mortgage Bonds, Environmental Improvement Series 2004D (2000B Bonds) (herein called the "Bonds of 2035 (Series 2000B)"), which are described in the Supplemental Indenture dated February 1, 2004 (hereinafter called the "Supplemental Indenture of February 1, 2004 (2004D)"), all of which are outstanding at the date of the execution hereof;

(54) $63,500,000 principal amount of First Mortgage Bonds, Environmental Improvement Series 2004E (2000A Bonds) (herein called the "Bonds of 2035 (Series 2000A)"), which are described in the Supplemental Indenture dated February 1, 2004 (hereinafter called the "Supplemental Indenture of February 1, 2004 (2004E)"), all of which are outstanding at the date of the execution hereof; and

(55) $60,000,000 principal amount of First Mortgage Bonds, Environmental Improvement Series 2004F (2000C Bonds) (herein called the "Bonds of 2035 (Series 2000C)"), which are described in the Supplemental Indenture dated February 1, 2004 (hereinafter called the "Supplemental Indenture of February 1, 2004 (2004F)"), all of which are outstanding at the date of the execution hereof; and

WHEREAS, the Company on August 31, 1955 acquired all of the properties of Union Electric Power Company, the Subsidiary as defined in Article I of the Original Indenture, upon the dissolution of the Subsidiary; the Company, by Supplemental Indenture dated August 31, 1955, conveyed all of the properties so acquired (other than property of the character defined as excepted property in the granting clauses of the Original Indenture) to the Trustee upon the terms

and trusts in the Original Indenture and the indentures supplemental thereto set forth for the equal and proportionate benefit and security of all present and future holders of the Bonds and coupons issued and to be issued thereunder, all the shares of stock of the Subsidiary were released from the lien of the Original Indenture; and the Company became entitled to change the general designation of the Bonds so as to omit the words "and Collateral Trust"; and

WHEREAS, the Articles of Incorporation of the Company were duly amended on April 23, 1956, to change its corporate name from "Union Electric Company of Missouri" to "Union Electric Company"; and

WHEREAS, the Articles of Agreement of the Trustee were duly amended effective on January 4, 1982 to change its corporate name from "St. Louis Union Trust Company" to "Centerre Trust Company of St. Louis", and further amended on December 9, 1988, to change its corporate name from "Centerre Trust Company of St. Louis" to "Boatmen's Trust Company"; and

WHEREAS, that on March 13, 1998, Boatmen's Trust Company merged into NationsBank, National Association and effective July 5, 1999, changed its name to Bank of America, National Association; and

WHEREAS, that on February 1, 2000, The Bank of New York, as transferee of the corporate trust business of Bank of America, National Association (formerly known as Boatmen's Trust Company), Trustee under the Original Indenture, became successor Trustee under the Original Indenture; and

WHEREAS, the Company is entitled at this time to have authenticated and delivered additional Bonds on the basis of property additions upon compliance with and pursuant to the provisions of Article III, Section 4 of the Original Indenture; and

WHEREAS, the Company has entered into a Loan Agreement dated as of December 1, 1991 (the "Original Loan Agreement") with the State Environmental Improvement and Energy Resources Authority of the State of Missouri (the "Authority") pursuant to which the Authority agreed to issue $42,585,000 aggregate principal amount of its Environmental Improvement Revenue Refunding Bonds (Union Electric Company Project) Series 1991 (the "Authority Bonds"), all of which are presently outstanding and loan the proceeds thereof to the Company; and

WHEREAS, the Authority Bonds were issued pursuant to an Indenture of Trust dated as of December 1, 1991, (the "Original Authority Bond Indenture") between the Authority and UMB Bank & Trust, N.A., as successor to Mercantile Bank of St. Louis National Association, as trustee (the "Authority Bond Trustee"); and

WHEREAS, the Company has determined it to be necessary and desirable to further secure rights of the owners of the Authority Bonds to the payment of principal and interest on the Authority Bonds by obtaining a Municipal Bond Insurance Policy with respect to the Authority Bonds (the "Authority Bond Insurance Policy") from XL Capital Assurance Inc. and in

furtherance thereof (i) the Authority and the Authority Bond Trustee will enter into an Amended and Restated Indenture of Trust dated as of February 1, 2004 (the "Authority Bond Indenture") which amends and restates the Original Authority Bond Indenture and (ii) the Authority and the Company will enter into the First Amendment to Loan Agreement dated as of February 1, 2004 (the "First Amendment to Loan Agreement"), which amends the Original Loan Agreement (the Original Loan Agreement as so amended is referred to herein as the "Agreement"); and

WHEREAS, in connection with obtaining the Authority Bond Insurance Policy, the Company desires by this Supplemental Indenture to provide for the issuance to the Authority Bond Trustee of a new series of Bonds under the Original Indenture as security for the Company's obligations under the Agreement with respect to the payment of the Authority Bonds, to have the designation provided in Article I, Section 1 hereof (herein called the "New Bonds"), and the Original Indenture provides that certain terms and provisions, as determined by the Board of Directors of the Company, of the Bonds of any particular series may be expressed in and provided by the execution of an appropriate supplemental indenture; and

WHEREAS, the Original Indenture provides that the Company and the Trustee may enter into indentures supplemental to the Original Indenture specifically to convey, transfer and assign to the Trustee and to subject to the lien of the Original Indenture additional properties acquired by the Company; and

WHEREAS, the Company, in the exercise of the powers and authority conferred upon and reserved to it under the provisions of the Original Indenture and pursuant to appropriate resolutions of the Board of Directors, has duly resolved and determined to make, execute and deliver to the Trustee a Supplemental Indenture in the form hereof for the purposes herein provided; and

WHEREAS, all conditions and requirements necessary to make this Supplemental Indenture a valid, binding and legal instrument have been done, performed and fulfilled and the execution and delivery hereof have been in all respects duly authorized;

NOW, THEREFORE, THIS INDENTURE WITNESSETH:

That, in consideration of the premises and of the mutual covenants herein contained and of the acceptance of this trust by the Trustee and of the sum of One Dollar duly paid by the Trustee to the Company at or before the time of the execution of this Supplemental Indenture, and of other valuable considerations, the receipt whereof is hereby acknowledged, and in order further to secure the payment of the principal of and interest (and premium, if any) on all Bonds at any time issued and outstanding under the Original Indenture, according to their tenor and effect, and to secure the Company's obligations under the Agreement with respect to the payment of the Authority Bonds, the Company has executed and delivered this Supplemental Indenture and has granted, bargained, sold, warranted, aliened, remised, released, conveyed, assigned, transferred, mortgaged, pledged, set over and confirmed and by these presents does grant, bargain, sell, warrant, alien, remise, release, convey, assign, transfer, mortgage, pledge, set over and confirm unto The Bank of New York, as Trustee, and to its successors in trust under the Original Indenture forever, all and singular the following described properties (in addition to all

other properties heretofore subjected to the lien of the Original Indenture and not heretofore released from the lien thereof) - that is to say:

FIRST

ALL power houses, plants, buildings and other structures, dams, dam sites, substations, heating plants, gas works, holders and tanks, together with all and singular the electric, heating, gas and mechanical appliances appurtenant thereto of every nature whatsoever, now owned by the Company, including all and singular the machinery, engines, boilers, furnaces, generators, dynamos, turbines and motors, and all and every character of mechanical appliance for generating or producing electricity, steam, gas and other agencies for light, heat, cold, or power or other purposes, and all transmission and distribution systems used for the transmission and distribution of electricity, steam, gas and other agencies for light, heat, cold or power or any other purpose whatsoever, whether underground or overhead, surface or otherwise, now owned by the Company, including all poles, towers, posts, wires, cables, conduits, manholes, mains, pipes, tubes, drains, furnaces, switchboards, transformers, conductors, insulators, supports, meters, lamps, fuses, junction boxes, regulator stations, and other electric, steam and gas fixtures and apparatus; all of the aforementioned property being located in the City of St. Louis, the counties of Adair, Audrain, Benton, Bollinger, Boone, Butler, Caldwell, Callaway, Camden, Cape Girardeau, Clark, Clay, Clinton, Cole, Cooper, Crawford, Daviess, Dunklin, Franklin, Gasconade, Howard, Iron, Jefferson, Knox, Lewis, Lincoln, Livingston, Macon, Madison, Maries, Marion, Miller, Mississippi, Moniteau, Montgomery, Morgan, New Madrid, Osage, Pemiscot, Perry, Pettis, Phelps, Pike, Pulaski, Ralls, Randolph, Ray, Reynolds, Ripley, St. Charles, St. Francois, Ste. Genevieve, St. Louis, Saline, Schuyler, Scott, Stoddard, Warren, Washington, and Wayne, Missouri, the counties of Adams, Alexander, Calhoun, Franklin, Hancock, Henderson, Jackson, Jersey, Macoupin, Madison, Massac, Monroe, Perry, Pike, Pulaski, St. Clair, Union, and Washington, Illinois, and the counties of Des Moines, Henry, Johnson, Lee, and Washington, Iowa, upon real estate owned by the Company, or occupied by it under rights to so occupy, which real estate is described in the Indenture of Mortgage and Deed of Trust dated June 15, 1937, in the Supplemental Indentures dated May 1, 1941, March 17, 1942, April 13, 1945, April 27, 1945, October 1, 1945, April 11, 1947, April 13, 1949, September 13, 1950, December 1, 1950, September 20, 1951, May 1, 1952, March 1, 1954, May 1, 1955, August 31, 1955, April 1, 1956, July 1, 1956, August 1, 1957, February 1, 1958, March 1, 1958, November 5, 1958, March 16, 1959, June 24, 1959, December 11, 1959, August 17, 1960, September 1, 1960, October 24, 1960, June 30, 1961, July 1, 1961, August 9, 1962, September 30, 1963, November 1, 1963, March 12, 1965, April 1, 1965, April 14, 1966, May 1, 1966, February 17, 1967, March 1, 1967, February 19, 1968, March 15, 1968, August 21, 1968, April 7, 1969, May 1, 1969, September 12, 1969, October 1, 1969, March 26, 1970, April 1, 1970, June 12, 1970, January 1, 1971, April 1, 1971, September 15, 1971, December 3, 1973, February 1, 1974, April 25, 1974, February 3, 1975, March 1, 1975, June 11, 1975, May 12, 1976, August 16, 1976, April 26, 1977, October 15, 1977, November 7, 1977, December 1, 1977, August 1, 1978, October 12, 1979, November 1, 1979, July 7, 1980, August 1, 1980, August 20, 1980, February 1, 1981, October 8, 1981, August 27, 1982, September 1, 1982, December 15, 1982, March 1, 1983, June 21, 1984, December 12, 1984, June 11, 1985, March 1, 1986, May 1, 1986, May 1, 1990, December 1, 1991, December 4, 1991, January 1, 1992, September 30, 1992, October 1, 1992, December 1, 1992, February 1,

1993, February 18, 1993, May 1, 1993, August 1, 1993, October 1, 1993, January 1, 1994, February 1, 2000, August 15, 2002, March 5, 2003, April 1, 2003, July 15, 2003, October 1, 2003 and in this Supplemental Indenture and the seven other Supplemental Indentures each dated February 1, 2004, or attached to or connected with such real estate or transmission or distribution systems of the Company leading from or into such real estate.

SECOND

ALSO, (except as in the Original Indenture expressly excepted) all franchises and all permits, ordinances, easements, privileges, immunities and licenses, all rights to construct, maintain and operate overhead, surface and underground systems for the distribution and transmission of electricity, steam, gas or other agencies for the supply to itself or others of light, heat, cold or power, all rights-of-way, all waters, water rights and flowage rights and all grants and consents, now owned or, subject to the provisions of Article XII of the Original Indenture, which it may hereafter acquire.

ALSO, (except as in the Original Indenture expressly excepted) all inventions, patent rights and licenses of every kind now owned by the Company or, subject to the provisions of Article XII of the Original Indenture, which it may hereafter acquire.

THIRD

ALSO, subject to the provisions of Article XII of the Original Indenture, all other property, real, personal and mixed (except as therein or herein expressly excepted) of every nature and kind and wheresoever situated now or hereafter possessed by or belonging to the Company, or to which it is now, or may at any time hereafter be, in any manner entitled at law or in equity.

TO HAVE AND TO HOLD all said properties, real, personal and mixed, mortgaged, pledged and conveyed by the Company as aforesaid, or intended so to be, unto the Trustee and its successors and assigns forever;

SUBJECT, HOWEVER, to the exceptions and reservations and matters hereinabove recited, to existing leases, to existing liens upon rights of way for transmission or distribution line purposes, as defined in Article I of the Original Indenture, and any extensions thereof, and subject to existing easements for streets, alleys, highways, rights-of-way and railroad purposes over, upon and across certain of the property hereinbefore described, and subject also to all the terms, conditions, agreements, covenants, exceptions and reservations expressed or provided in the deeds or other instruments respectively under and by virtue of which the Company acquired the properties hereinabove described, and to undetermined liens and charges, if any, incidental to construction or other existing permitted liens as defined in Article I of the Original Indenture;

IN TRUST, NEVERTHELESS, upon the terms and trusts in the Original Indenture and the indentures supplemental thereto, including this Supplemental Indenture, set forth, for the equal and proportionate benefit and security of all present and future holders of the Bonds and coupons

issued and to be issued thereunder, or any of them, without preference of any of said Bonds and coupons of any particular series over the Bonds and coupons of any other series, by reason of priority in the time of the issue, sale or negotiation thereof, or by reason of the purpose of issue or otherwise howsoever, except as otherwise provided in Section 2 of Article IV of the Original Indenture.

AND IT IS HEREBY COVENANTED, DECLARED AND AGREED, by and between the parties hereto, for the benefit of those who shall hold the Bonds and coupons, or any of them to be issued under the Original Indenture, as follows:

ARTICLE I

DESCRIPTION OF THE NEW BONDS

Section 1.1. There is hereby created a new series of Bonds to be executed, authenticated and delivered under and secured by the Original Indenture which shall, subject to the provisions of Section 1 of Article II of the Original Indenture, be designated as "First Mortgage Bonds, Environmental Improvement Series 2004G (1991 Bonds)" (the "New Bonds") of the Company. The New Bonds shall be executed, authenticated and delivered in accordance with the provisions of, and shall in all respects be subject to all of the terms, conditions and covenants of, the Original Indenture and shall be issued to, and registered in the name of, the Authority Bond Trustee under the Authority Bond Indenture to secure any and all obligations of the Company under the Agreement with respect to the payment of the Authority Bonds.

The New Bonds shall mature, subject to prior redemption, on December 1, 2020, and shall bear interest at the same rate or rates of interest as the Authority Bonds which, in turn, shall be determined by the methods set forth in the Authority Bond Indenture, which provides for a Short-Term Auction Rate, a Long-Term Auction Rate, a Bond Interest Term Rate, a Weekly Rate or a Long-Term Interest Rate (each as defined in the Authority Bonds Indenture). Reference is made to the provisions of the Authority Bond Indenture concerning the methods by which such interest rates are determined, and the means by which the method of determining such interest rates may be changed, and such provisions are included in this Supplemental Indenture as if fully set forth herein. Interest on the New Bonds is payable on the same dates as interest on the Authority Bonds is paid, until the principal sum of the New Bonds is paid in full. The New Bonds shall be payable as to principal and interest in any coin or currency of the United States of America which at the time of payment is legal tender for public and private debts, and shall be payable, in immediately available funds, at the office of the Authority Bond Trustee.

Section 1.2. The New Bonds shall not be assignable or transferable except as permitted or required by Section 12.13 of the Authority Bond Indenture. Any such transfer shall be effected at the principal office or place of business of the Trustee under the Original Indenture. The New Bonds are exchangeable for the New Bonds of other denominations, as in the Original Indenture provided, except that payment of a service charge therefor will not be required by the Company.

Notwithstanding the provisions of Section 6 of Article II of the Original Indenture, the New Bonds shall be dated their date of authentication and shall bear interest from the interest payment date to which interest on the New Bonds has been paid next preceding the date thereof, unless such date is an interest payment date to which interest has been paid, in which case they shall bear interest from the date thereof.

Upon any payment of the principal of and interest on, all or any portion of the Authority Bonds, whether at maturity or otherwise or upon provision for the payment thereof having been made in accordance with Section 7.01 of the Authority Bond Indenture, the New Bonds in a principal amount equal to the principal amount of such Authority Bonds shall, to the extent of such payment of principal and interest, be deemed paid and the obligation of the Company thereunder to make such payment shall be discharged to such extent and, in the case of the payment of principal, such New Bonds shall be surrendered to the Company for cancellation as provided in and subject to the terms of Section 7.04 of the Authority Bond Indenture. The Trustee may at any time and all times conclusively assume that the obligation of the Company under the Agreement to make payments with respect to the principal of and interest on the Authority Bonds, so far as such payments at the time have become due, has been fully satisfied and discharged pursuant to the foregoing sentence unless and until the Trustee shall have received a written notice from the Authority Bond Trustee signed by one of its officers stating (i) the timely payment of principal or interest on, the Authority Bonds has not been made, (ii) that the Company is in arrears as to the payments required to be made by it to the Authority Bond Trustee pursuant to the Agreement, and (iii) the amount of the arrearage.

                           [Form of Face of New Bond]

No. ____                                                            $________
                               Ill. C. C. No. 6312

NOTWITHSTANDING ANY PROVISIONS HEREOF OR IN THE ORIGINAL INDENTURE THIS BOND IS NOT ASSIGNABLE OR TRANSFERABLE EXCEPT AS PERMITTED OR REQUIRED BY SECTION 12.13 OF THE AMENDED AND RESTATED INDENTURE OF TRUST DATED AS OF FEBRUARY 1, 2004, BETWEEN THE STATE ENVIRONMENTAL IMPROVEMENT AND ENERGY RESOURCES AUTHORITY OF THE STATE OF MISSOURI AND UMB BANK & TRUST, N.A., AS SUCCESSOR TO MERCANTILE BANK OF ST. LOUIS NATIONAL ASSOCIATION, AS TRUSTEE

UNION ELECTRIC COMPANY
(Incorporated under the laws of the State of Missouri)

First Mortgage Bonds, Environmental Improvement Series 2004G (1991 Bonds)

Illinois Commerce Commission Identification No. 6312

UNION ELECTRIC COMPANY, a corporation organized and existing under the laws of the State of Missouri (hereinafter called the "Company," which term shall include any successor corporation as defined in the Amended Indenture referred to on the reverse hereof), for value received, hereby promises to pay to UMB Bank & Trust, N.A., as successor to Mercantile Bank of St. Louis National Association, as trustee under the Authority Bond Indenture hereinafter referred to, or registered assigns, the sum of _________________________ Dollars, on the 1st day of December 1, 2020, subject to prior redemption, in any coin or currency of the United States of America which at the time of payment is legal tender for public and private debts, and to pay interest thereon, in like coin or currency, at the same rate or rates of interest as the Authority Bonds (as determined in accordance with the Authority Bond Indenture referred to below), but in no event shall the interest rate on this Bond exceed eighteen percent (18%) per annum. Interest on overdue principal premium, if any, and, to the extent permitted by law, on overdue interest, shall be payable at the interest rate payable on the Authority Bonds. Interest on this Bond is payable on the same dates as interest on the Authority Bonds, or, if this Bond shall be duly called for redemption, until the redemption date, or if the Company shall default in the payment of the principal hereof, until the Company's obligation to pay principal shall be discharged as provided in the Amended Indenture is paid, until the principal sum is paid in full. The principal of, and interest on, this Bond are payable, in immediately available funds, at the office of the Authority Bond Trustee hereinafter referred to.

Under an Indenture of Trust dated as of December 1, 1991, as amended and restated by the Amended and Restated Indenture of Trust dated as of February 1, 2004 (as so amended and restated, the "Authority Bond Indenture") between the State Environmental Improvement and Energy Resources Authority of the State of Missouri (the "Authority") and UMB Bank & Trust, N.A., as successor to Mercantile Bank of St. Louis National Association, as trustee (the "Authority Bond Trustee"), the Authority has issued its Environmental Improvement Revenue

Refunding Bonds (Union Electric Company Project) Series 1991 in the aggregate principal amount of $42,585,000 (the "Authority Bonds"). The Company has agreed to pay the principal of and interest on the Authority Bonds pursuant to a Loan Agreement dated as of December 1, 1991, as supplemented and amended by the First Amendment to Loan Agreement dated as of February 1, 2004 (as so amended, the "Agreement") between the Company and the Authority. Pursuant to the Granting Clause of the Authority Bond Indenture, this Bond is issued to the Authority Bond Trustee to secure any and all obligations of the Company under the Agreement with respect to payment of the Authority Bonds. Payment of principal of, or interest on, the Authority Bonds shall constitute payments on this Bond as further provided herein and in the Supplemental Indenture dated February 1, 2004 pursuant to which this Bond has been issued (the "Supplemental Indenture").

Upon any payment of the principal of, and interest on, all or any portion of the Authority Bonds, whether at maturity or otherwise or upon provision for the payment thereof having been made in accordance with Section 7.01 of the Authority Bond Indenture, a principal amount of this Bond equal to the principal amount of such Authority Bonds shall, to the extent of such payment of principal and interest, be deemed paid and the obligation of the Company thereunder to make such payment shall be discharged to such extent and, in the case of the payment of principal, such Bonds shall be surrendered to the Company for cancellation as provided in Section 7.04 of the Authority Bond Indenture. The Trustee (as hereinafter defined) may at any time and all times conclusively assume that the obligation of the Company to make payments under the Agreement with respect to the principal of, and interest on, the Authority Bonds, so far as such payments at the time have become due, has been fully satisfied and discharged pursuant to the foregoing sentence unless and until the Trustee shall have received a written notice from the Authority Bond Trustee signed by one of its officers stating (i) that timely payment of principal of, or interest on, the Authority Bonds has not been made, (ii) that the Company is in arrears as to the payments required to be made by it to the Authority Bond Trustee pursuant to the Agreement, and (iii) the amount of the arrearage.

This Bond shall not be entitled to any benefit under the Amended Indenture or any indenture supplemental thereto, or become valid or obligatory for any purpose, until The Bank of New York, the Trustee under the Amended Indenture, or a successor trustee thereto under the Amended Indenture, or an agent therefor, shall have signed the form of certificate endorsed hereon.

The provisions of this Bond are continued on the reverse hereof and such continued provisions shall for all purposes have the same effect as though fully set forth at this place.

IN WITNESS WHEREOF, Union Electric Company has caused this Bond to be signed in its name by its Chairman of the Board or President or a Vice President by manual signature or a facsimile thereof, and its corporate seal (or a facsimile thereof) to be hereto affixed and attested by its Secretary or an Assistant Secretary by manual signature or a facsimile thereof.

Dated,
UNION ELECTRIC COMPANY,

[CORPORATE SEAL]

Attest:

[FORM OF TRUSTEE'S CERTIFICATE]

This Bond is one of the Bonds, of the series designated therein, described in the within-mentioned Amended Indenture and Supplemental Indenture of February 1, 2004.

THE BANK OF NEW YORK, as Trustee

[FORM OF REVERSE OF NEW BOND]

This Bond is one of a duly authorized issue of Bonds of the Company (herein called the "Bonds"), limited to an aggregate principal amount of $42,585,000, of the series hereinafter specified, all issued under and equally secured by the Indenture of Mortgage and Deed of Trust, dated June 15, 1937, executed by the Company to The Bank of New York (successor trustee to Bank of America, National Association, formerly Boatmen's Trust Company), as trustee (herein called the "Trustee"), as amended by indentures supplemental thereto dated May 1, 1941, April 1, 1971, February 1, 1974, July 7, 1980, February 1, 2000 and August 15, 2002, between the Company and the Trustee (said mortgage and deed of trust, as so amended, being herein called the "Amended Indenture"), to which Amended Indenture and all indentures supplemental thereto reference is hereby made for a description of the properties mortgaged and pledged, the nature and extent of the security, the rights of the bearers or registered owners of the Bonds and of the Trustee in respect thereto, and the terms and conditions upon which the Bonds are, and are to be, secured. To the extent permitted by, and as provided in, the Amended Indenture, modifications or alterations of the Amended Indenture, or of any indenture supplemental thereto, and of the rights and obligations of the Company and of the holders of the Bonds may be made with the consent of the Company by an affirmative vote of not less than 60% in amount of the

Bonds entitled to vote then outstanding, at a meeting of Bondholders called and held as provided in the Amended Indenture, and by an affirmative vote of not less than 60% in amount of the Bonds of any series entitled to vote then outstanding and affected by such modification or alteration, in case one or more but less than all of the series of Bonds then outstanding under the Amended Indenture are so affected. Additionally, the Company may amend the Amended Indenture, as supplemented, by an appropriate written consent of not less than 60% in aggregate principal amount of the Bonds outstanding (and, if the rights of one or more, but less than all, series of Bonds then outstanding are to be affected by action taken pursuant to such consent, then also by consent of the holders of at least 60% in principal amount of each series of Bonds so to be affected and outstanding hereunder) without a meeting of such Bondholders. No such modification or alteration shall be made which will affect the terms of payment of the principal of, or interest on, this Bond, which are unconditional. The Bonds may be issued in series, for various principal sums, may mature at different times, may bear interest at different rates and may otherwise vary as in the Amended Indenture provided. This Bond is one of a series designated as the "First Mortgage Bonds, Environmental Improvement Series 2004G (1991 Bonds)" (herein called the "Bonds of this Series") of the Company, issued under and secured by the Amended Indenture and described in the indenture (hereinafter called the "Supplemental Indenture") dated February 1, 2004, between the Company and the Trustee, supplemental to the Amended Indenture.

The Bonds of this Series are not entitled to the benefit of any improvement, maintenance or analogous fund.

This Bond is, subject to the provisions of the Amended Indenture, subject to redemption in the amounts, at the times, at the prices and under the circumstances under which the Authority Bonds are subject to redemption under the same terms and circumstances set forth in the Authority Bond Indenture for the redemption of the Authority Bonds.

This Bond is also subject to mandatory redemption at the principal amount hereof plus accrued interest to the date fixed for redemption if the Trustee or the Company is notified that an "Event of Default" under the Authority Bond Indenture has occurred and is continuing and the Authority Bond Trustee has declared the principal amount of all Authority Bonds then outstanding due and payable in accordance with the Authority Bond Indenture.

The Company may, by notice to the Trustee at least 60 days prior to any date on which any principal amount is due on this Bond, elect to receive a credit in respect of such principal payment (a) for any Bonds of this Series then due which have been redeemed prior to such principal payment date or otherwise acquired and delivered to the Trustee for cancellation by said Trustee prior to the giving of such notice, or (b) for any Authority Bonds which have been purchased, delivered for cancellation or previously redeemed, which in each case have not theretofore been applied as a credit against such principal payment. Each Bond with respect to which the Company elects to receive a credit will be credited by the Trustee at 100% of the principal amount thereof against such principal payment, provided further that in the case of a credit with respect to any Authority Bonds, the principal amount thereof shall be established by an officers' certificate (as defined in the Amended Indenture) concurred in by the Authority Bond Trustee, included with the above-mentioned notice to the Trustee. The principal amount of Bonds to be paid on the due date of such principal payment will be reduced by the amount of any such credit or credits in respect of Bonds previously redeemed or delivered as provided above.

Upon cancellation in full or in part of any of the Authority Bonds (or provision for payment thereof having been made in accordance with the provisions of the Authority Bond Indenture) and payment of all fees and charges of the trustee thereunder, such trustee shall deliver to the Trustee, for cancellation a corresponding amount of Bonds remaining in its possession.

Such redemption in every case shall be effected upon notice delivered by the Company at least 60 days prior to the date of redemption, to the registered owner of the Bonds at its address as the same shall appear on the transfer register of the Company, all subject to the conditions of, and as more fully set forth in, the Amended Indenture and Supplemental Indenture.

In case an event of default, as defined in the Amended Indenture, shall occur, the principal of all the bonds at any such time outstanding under the Amended Indenture may be declared or may become due and payable, upon the conditions and in the manner and with the effect provided in the Amended Indenture. The Amended Indenture provides that such declaration may in certain events be waived by the holders of a majority in principal amount of the bonds outstanding.

This Bond shall not be assignable or transferable except as permitted or required by Section 12.13 of the Authority Bond Indenture. This Bond is exchangeable by the registered owner hereof, in person or by duly authorized attorney, on the books of the Company to be kept for that purpose at the office of the Company in the City of St. Louis, Missouri, upon surrender and cancellation of this Bond and on presentation of a duly executed written instrument of transfer, and thereupon a new Bond or Bonds of the same series, of the same aggregate principal amount and in authorized denominations will be issued to the transferee or transferees in exchange herefor, without payment of any charge other than stamp taxes and other governmental charges incident thereto; and this Bond with or without others of like series, may in like manner be exchanged for one or more new Bonds of the same series of other authorized denominations but of the same aggregate principal amount; all subject to the terms and conditions set forth in the Amended Indenture.

As provided in Section 7.04 of the Authority Bond Indenture, from and after the Release Date (as defined in the Authority Bond Indenture), the obligations of the Company with respect to this Bond shall be deemed to be satisfied and discharged, this Bond shall cease to secure in any manner the Company's obligations under the Agreement with respect to the payment of any Authority Bonds outstanding under the Authority Bond Indenture, and, pursuant to Section 7.04 of the Authority Bond Indenture, the Authority Bond Trustee shall forthwith deliver this Bond to the Company for cancellation.

No recourse shall be had for the payment of the principal of, or the interest on, this Bond, or for any claim based hereon or on the Amended Indenture or any indenture supplemental thereto, against any incorporator, or against any stockholder, director or officer, past, present or future, of the Company, or of any predecessor or successor corporation, either directly or through the Company or any such predecessor or successor corporation, whether for amounts unpaid on stock subscriptions or by virtue of any constitution, statute or rule of law, or by the enforcement of any assessment or penalty or otherwise, all such liability, whether at common law, in equity,

by any constitution, statute or otherwise, of incorporators, stockholders, directors or officers being released by every owner hereof by the acceptance of this Bond and as part of the consideration for the issue hereof, and being likewise released by the terms of the Amended Indenture.

[END OF FORM OF REVERSE OF NEW BOND]

ARTICLE II

ISSUE OF THE NEW BONDS

Section 2.1. The principal amount of the New Bonds which may be authenticated and delivered hereunder is limited to an amount equal to the principal amount of Forty-Two Million Five-Hundred Eighty-Five Thousand Dollars ($42,585,000) consisting of Bonds maturing on December 1, 2020.

Section 2.2. The New Bonds in the aggregate principal amount set forth above, may forthwith be executed by the Company and delivered to the Trustee and shall be authenticated by the Trustee and delivered (either before or after the filing or recording hereof) to or upon the order of the Company, upon compliance by the Company with the applicable provisions of Article III and Article XVIII of the Original Indenture.

Section 2.3. As provided in Section 7.04 of the Authority Bond Indenture, from and after the Release Date (as defined in the Authority Bond Indenture), the obligations of the Company with respect to the New Bonds shall be deemed to be satisfied and discharged, the New Bonds shall cease to secure in any manner the Company's obligations under the Agreement with respect to the payment of any Authority Bonds outstanding under the Authority Bond Indenture, and, pursuant to
Section 7.04 of the Authority Bond Indenture, the Authority Bond Trustee shall forthwith deliver the New Bonds to the Company for cancellation.

ARTICLE III

REDEMPTION OF THE NEW BONDS

Section 3.1. The New Bonds are, subject to the provisions of the Original Indenture, subject to redemption in the amounts, at the times, at the prices and under the circumstances under which the Authority Bonds are subject to redemption, under the same terms and conditions set forth in the Authority Bond Indenture for the redemption of the Authority Bonds. In the event that less than all the New Bonds are to be redeemed, the New Bonds to be redeemed shall be determined by lot in such manner as the Trustee in its discretion shall deem proper, as in the Original Indenture provided.

The New Bonds are also subject to mandatory redemption as set forth in the form of New Bonds in Section 1.3 of Article I of this Supplemental Indenture.

Section 3.2. Subject to the provisions of Article V of the Original Indenture, notice of redemption shall be delivered by the Company at least 60 days prior to the date of redemption, to the registered owner of such Bonds at its address as the same shall appear on the transfer register of the Company.

Section 3.3. As provided in the Authority Bond Indenture, any amounts of money held in the Bond Fund provided in said Indenture and available for such purpose, which are at the request of the Company applied to the payments of the principal of, premium, if any, and interest on the Authority Bonds on any payment or redemption date, shall be applied as a credit on amounts otherwise due under the New Bonds; provided that the amount of such credit shall be established by an officers' certificate (as defined in the Amended Indenture), concurred in by the Authority Bond Trustee which shall be filed with the Trustee prior to the application of any such credit.

Upon cancellation in full or in part of any of the Authority Bonds (or provision for payment thereof having been made in accordance with the provisions of the Authority Bond Indenture) and payment of all fees and charges of the trustee thereunder, such trustee shall deliver to the Trustee, for cancellation a corresponding amount of New Bonds remaining in its possession or shall request such Trustee to issue a New Bond reflecting any such cancellation

ARTICLE IV

COVENANTS

The Company hereby covenants, warrants and agrees;

Section 4.1. That the Company is lawfully seized and possessed of all of the mortgaged property described in the granting clauses of this Supplemental Indenture; that it has good right and lawful authority to mortgage the same as provided in this Supplemental Indenture; and that such mortgaged property is, at the actual date of the issue of the New Bonds, free and clear of any deed of trust, mortgage, lien, charge or encumbrance thereon or affecting the title thereto prior to the Original Indenture, except as set forth in the granting clauses of the Original Indenture or this Supplemental Indenture.

Section 4.2. That, so long as any of the New Bonds are outstanding, whenever any officers' certificate is required to be filed or deposited with the Trustee pursuant to Section 3(b) of Article III of the Original Indenture upon an application for the authentication of additional Bonds pursuant to Article III of the Original Indenture, such officers' certificate shall include, in addition to the matters required to be stated therein by said Section 3(b), the statement with respect to the net earnings of the Company available for interest after property retirement appropriations required by Section 2 of Article V of the Supplemental Indenture of July 1, 1956.

Section 4.3. That, so long as any of the New Bonds are outstanding, the Company will not apply for the authentication and delivery of additional Bonds pursuant to Section 4 of Article III of the Original Indenture or the withdrawal of cash from the trust estate or the reduction of the amount of cash required to be paid into the trust estate or to satisfy the

maintenance and improvement funds under any provision of the Original Indenture or the Supplemental Indentures creating prior series of Bonds, on the basis of the amount of $15,000,000 excluded from net bondable value of property additions not subject to an unfunded prior lien pursuant to Section 3 of Article V of the Supplemental Indenture of October 1, 1945, or on the basis of the amount of $7,500,000 excluded from net bondable value of property additions not subject to an unfunded prior lien pursuant to Section 3 of Article V of the Supplemental Indenture of July 1, 1956.

Section 4.4. That, so long as any of the New Bonds are outstanding, the Company will not issue or permit to be issued any prior lien bonds secured by an unfunded prior lien in addition to the prior lien bonds secured by such unfunded prior lien at the time of first acquisition by the Company of property subject thereto (other than in lieu of lost, stolen or mutilated bonds or on the exchange for bonds already outstanding of an equal principal amount of other bonds of the same issue and the same series, if any, and of the same maturity), except upon compliance with the provisions of Section 16 of Article IV of the Original Indenture, nor unless the net earnings of the Company available for interest after property retirement appropriations (determined as provided in
Section 2 of Article V of the Supplemental Indenture of July 1, 1956), for any 12 consecutive calendar months during the period of 15 calendar months immediately preceding the first day of the month in which the additional prior lien bonds are to be issued, have been, in the aggregate, equal to not less than twice the annual interest charges on the indebtedness specified in subparagraphs
(i) and (ii) of paragraph (1) of Section 2(a) of said Article V; provided that, if the application for the issue of such additional prior lien bonds is upon the basis of payment at maturity of prior lien bonds theretofore sold or otherwise disposed of or the redemption or purchase thereof after a date two years prior to the date of maturity, the additional requirement imposed by this Section 4 with respect to net earnings of the Company available for interest after property retirement appropriations shall not apply. Any officers' certificate with respect to net earnings of the Company, required to be filed with the Trustee as a condition precedent to the issue of such additional prior lien bonds, shall include, in addition to the matters otherwise required to be stated therein, the matters required to be stated in an officers' certificate pursuant to paragraphs (1) and (2) of Section 2(a) of said Article V.

Section 4.5. That, so long as any of the New Bonds are outstanding, the Company will not acquire, by purchase, merger or otherwise, any property subject to a lien or liens which will on acquisition be an unfunded prior lien or prior liens, except upon compliance with the provisions of Section 14 of Article IV of the Original Indenture, nor unless the net earnings of such property available for interest after property retirement appropriations (determined in the manner provided in Section 2 of Article V of the Supplemental Indenture of July 1, 1956), for any 12 consecutive calendar months during the period of 15 calendar months immediately preceding the first day of the month in which the first acquisition of property subject to such lien or liens occurs, have been, in the aggregate, equal to not less than twice the amount of annual interest charges, on all outstanding indebtedness secured by such lien or liens. Any officers' certificate with respect to net earnings of such property, required to be filed with the Trustee as a condition precedent to the acquisition of such property, shall include, in addition to the matters otherwise required to be stated therein, the matters required to be stated in an officers' certificate pursuant to Section 2 of said Article V applicable, however, only to the net earnings of such property and to the indebtedness secured by such liens to which such property is subject.

ARTICLE V

THE TRUSTEE

The Trustee hereby accepts the trusts hereby declared and provided, and agrees to perform the same upon the terms and conditions in the Original Indenture and in this Supplemental Indenture set forth, and upon the following terms and conditions:

The Trustee shall not be responsible in any manner whatsoever for or in respect of the validity or sufficiency of this Supplemental Indenture or the due execution hereof by the Company or for or in respect of the recitals contained herein, all of which recitals are made by the Company solely.

ARTICLE VI

MISCELLANEOUS PROVISIONS

Section 6.1. Except as otherwise defined herein, all terms contained in this Supplemental Indenture shall, for all purposes thereof, have the meanings given to such terms in Article I of the Original Indenture.

Section 6.2. This Supplemental Indenture may be simultaneously executed in any number of counterparts, each of which when so executed shall be deemed to be an original; but such counterparts shall together constitute but one and the same instrument.

IN WITNESS WHEREOF, said Union Electric Company has caused this Supplemental Indenture to be executed on its behalf by its Chairman of the Board or President or one of its Vice Presidents and its corporate seal to be hereto affixed and said seal and this Supplemental Indenture to be attested by its Secretary or one of its Assistant Secretaries; and said The Bank of New York, in evidence of its acceptance of the trust hereby created, has caused this Supplemental Indenture to be executed on its behalf by its President or one of its Vice Presidents, and its corporate seal to be hereto affixed and said seal and this Supplemental Indenture to be attested by its Secretary, or one of its Assistant Secretaries; all as of the 1st day of February, Two thousand and four.

Attested:                              UNION ELECTRIC COMPANY,
                                         1901 Chouteau Avenue
                                         St. Louis, Missouri  63103


/s/ G. L. Waters                       By:  /s/ Jerre E. Birdsong
-------------------------------           --------------------------------------
    G. L. Waters                       Name:  Jerre E. Birdsong
 Assistant Secretary                   Title: Vice President and Treasurer


Signed, sealed and delivered by
       UNION ELECTRIC COMPANY
       in the presence of:


/s/ D. Bradley
-------------------------------
             Daphyne Bradley


/s/ Wayne K. Forbes
-------------------------------
             Wayne K. Forbes

As Witnesses

Attested:                                 THE BANK OF NEW YORK,
                                            911 Washington Avenue
                                            St. Louis, Missouri  63101


/s/ Belinda Brown                         By:  /s/ Robert J. Dunn
-------------------------------              -----------------------------------
Belinda Brown                             Name:    Robert J. Dunn
As Agent                                  Title:   As Agent

Signed, sealed and delivered by
THE BANK OF NEW YORK
in the presence of:

/s/ Daniel G. Dwyer
-------------------------------
Daniel G. Dwyer


/s/ Richard F. Novosak
-------------------------------
Richard F. Novosak

As Witnesses

STATE OF MISSOURI          )
                           )  SS:
CITY OF ST. LOUIS          )

On this 18th day of March 2004, before me appeared JERRE E. BIRDSONG, to me personally known, who, being by me duly sworn, did say that he is Vice President and Treasurer of UNION ELECTRIC COMPANY, a corporation, and that the seal affixed to the foregoing instrument is the corporate seal of said corporation, and that said instrument was signed and sealed in behalf of said corporation by authority of its Board of Directors, and said JERRE E. BIRDSONG acknowledged said instrument to be the free act and deed of said corporation.

IN TESTIMONY WHEREOF, I have hereto set my hand and affixed my official seal at my office, in the City and State aforesaid, the day and year last above written.

 /s/ S.A. Kitchens
--------------------------------------

STATE OF MISSOURI          )
                           )  SS:
CITY OF ST. LOUIS          )

On this 18th day of March 2004, before me appeared Robert J. Dunn, to me personally known, who, being by me duly sworn, did say that he is an Agent of THE BANK OF NEW YORK, a corporation, and that the seal affixed to the foregoing instrument is the corporate seal of said corporation, and that said instrument was signed and sealed in behalf of said corporation, as the trustee thereunder by authority of its Board of Directors, and said Vice President, acknowledged said instrument to be the free act and deed of said corporation as the trustee under said instrument.

IN TESTIMONY WHEREOF, I have hereto set my hand and affixed my official seal at my office, in the City and State aforesaid, the day and year last above written.

/s/ Renee Beard
---------------------------------------------

Exhibit 4.8

WHEN RECORDED
MAIL TO:

Executed in 35 Counterparts, No. 35

SUPPLEMENTAL INDENTURE

DATED FEBRUARY 1, 2004

UNION ELECTRIC COMPANY

TO

THE BANK OF NEW YORK,
AS TRUSTEE

(SUPPLEMENTAL TO THE INDENTURE OF MORTGAGE AND DEED OF
TRUST DATED JUNE 15, 1937, AS AMENDED, EXECUTED BY

UNION ELECTRIC COMPANY
TO THE BANK OF NEW YORK, AS TRUSTEE)

First Mortgage Bonds, Environmental Improvement Series 2004H (1992 Bonds)

This instrument was prepared by Steven R. Sullivan, Senior Vice President Governmental/Regulatory Policy, General Counsel and Secretary of Union Electric Company, 1901 Chouteau Avenue, St. Louis, Missouri 63103, (314) 554-2098.

SUPPLEMENTAL INDENTURE, dated the 1st day of February, Two thousand and four (2004) made by and between UNION ELECTRIC COMPANY, a corporation organized and existing under the laws of the State of Missouri (hereinafter called the "Company"), party of the first part, and The Bank of New York (successor trustee to Bank of America, National Association, formerly Boatmen's Trust Company), a bank existing under the laws of the State of New York (hereinafter called the "Trustee"), as Trustee under the Indenture of Mortgage and Deed of Trust dated June 15, 1937, hereinafter mentioned, party of the second part:

WHEREAS, the Company has heretofore executed and delivered to the Trustee its Indenture of Mortgage and Deed of Trust, dated June 15, 1937, as amended May 1, 1941, April 1, 1971, February 1, 1974, July 7, 1980, February 1, 2000 and August 15, 2002 (said Indenture of Mortgage and Deed of Trust as so amended, being hereinafter referred to as the "Original Indenture"), to secure the payment of the principal of and the interest (and premium, if any) on all bonds at any time issued and outstanding thereunder, and indentures supplemental thereto dated June 15, 1937, May 1, 1941, March 17, 1942, April 13, 1945, April 27, 1945, October 1, 1945, April 11, 1947, April 13, 1949, September 13, 1950, December 1, 1950, September 20, 1951, May 1, 1952, March 1, 1954, May 1, 1955, August 31, 1955, April 1, 1956, July 1, 1956, August 1, 1957, February 1, 1958, March 1, 1958, November 5, 1958, March 16, 1959, June 24, 1959, December 11, 1959, August 17, 1960, September 1, 1960, October 24, 1960, June 30, 1961, July 1, 1961, August 9, 1962, September 30, 1963, November 1, 1963, March 12, 1965, April 1, 1965, April 14, 1966, May 1, 1966, February 17, 1967, March 1, 1967, February 19, 1968, March 15, 1968, August 21, 1968, April 7, 1969, May 1, 1969, September 12, 1969, October 1, 1969, March 26, 1970, April 1, 1970, June 12, 1970, January 1, 1971, April 1, 1971, September 15, 1971, December 3, 1973, February 1, 1974, April 25, 1974, February 3, 1975, March 1, 1975, June 11, 1975, May 12, 1976, August 16, 1976, April 26, 1977, October 15, 1977, November 7, 1977, December 1, 1977, August 1, 1978, October 12, 1979, November 1, 1979, July 7, 1980, August 1, 1980, August 20, 1980, February 1, 1981, October 8, 1981, August 27, 1982, September 1, 1982, December 15, 1982, March 1, 1983, June 21, 1984, December 12, 1984, June 11, 1985, March 1, 1986, May 1, 1986, May 1, 1990, December 1, 1991, December 4, 1991, January 1, 1992, September 30, 1992, October 1, 1992, December 1, 1992, February 1, 1993, February 18, 1993, May 1, 1993, August 1, 1993, October 1, 1993, January 1, 1994, February 1, 2000, August 15, 2002, March 5, 2003, April 1, 2003, July 15, 2003, October 1, 2003 and the seven indentures supplemental each dated as of February 1, 2004, respectively, have heretofore been entered into between the Company and the Trustee; and

WHEREAS, Bonds have heretofore been issued by the Company under the Original Indenture as follows:

(1) $80,000,000 principal amount of First Mortgage and Collateral Trust Bonds, 3-3/4% Series due 1962, all of which have been redeemed prior to the date of the execution hereof;

(2) $90,000,000 principal amount of First Mortgage and Collateral Trust Bonds, 3-3/8% Series due 1971, which are described in the Supplemental Indenture dated

May 1, 1941 (hereinafter called the "Supplemental Indenture of May 1, 1941"), all of which have been paid at maturity prior to the date of the execution hereof;

(3) $13,000,000 principal amount of First Mortgage and Collateral Trust Bonds, 2-3/4% Series due 1975 (herein called the "Bonds of 1975 Series"), which are described in the Supplemental Indenture dated October 1, 1945 (hereinafter called the "Supplemental Indenture of October 1, 1945"), all of which have been paid at maturity prior to the date of the execution hereof;

(4) $25,000,000 principal amount of First Mortgage and Collateral Trust Bonds, 2-7/8% Series due 1980 (herein called the "Bonds of 1980 Series"), which are described in the Supplemental Indenture dated December 1, 1950 (hereinafter called the "Supplemental Indenture of December 1, 1950"), all of which have been paid at maturity prior to the date of the execution hereof;

(5) $30,000,000 principal amount of First Mortgage and Collateral Trust Bonds, 3-1/4% Series due 1982 (herein called the "Bonds of 1982 Series"), which are described in the Supplemental Indenture dated May 1, 1952 (hereinafter called the "Supplemental Indenture of May 1, 1952"), all of which have been paid at maturity prior to the date of the execution hereof;

(6) $40,000,000 principal amount of First Mortgage Bonds, 3-3/4% Series due 1986 (herein called the "Bonds of 1986 Series"), which are described in the Supplemental Indenture dated July 1, 1956 (hereinafter called the "Supplemental Indenture of July 1, 1956"), all of which have been paid at maturity prior to the date of the execution hereof;

(7) $35,000,000 principal amount of First Mortgage Bonds, 4-3/8% Series due 1988 (herein called the "Bonds of 1988 Series"), which are described in the Supplemental Indenture dated March 1, 1958 (hereinafter called the "Supplemental Indenture of March 1, 1958"), all of which have been paid at maturity prior to the date of the execution hereof;

(8) $50,000,000 principal amount of First Mortgage Bonds, 4-3/4% Series due 1990 (herein called the "Bonds of 1990 Series"), which are described in the Supplemental Indenture dated September 1, 1960 (hereinafter called the "Supplemental Indenture of September 1, 1960"), all of which have been paid at maturity prior to the date of the execution hereof;

(9) $30,000,000 principal amount of First Mortgage Bonds, 4-3/4% Series due 1991 (herein called the "Bonds of 1991 Series"), which are described in the Supplemental Indenture dated July 1, 1961 (hereinafter called the "Supplemental Indenture of July 1, 1961"), all of which have been paid at maturity prior to the date of the execution hereof;

(10) $30,000,000 principal amount of First Mortgage Bonds, 4-1/2% Series due 1993 (herein called the "Bonds of 1993 Series"), which are described in the

Supplemental Indenture dated November 1, 1963 (hereinafter called the "Supplemental Indenture of November 1, 1963"), all of which have been redeemed prior to the date of the execution hereof;

(11) $35,000,000 principal amount of First Mortgage Bonds, 4-1/2% Series due 1995 (herein called the "Bonds of 1995 Series"), which are described in the Supplemental Indenture dated April 1, 1965 (hereinafter called the "Supplemental Indenture of April 1, 1965"), all of which have been paid at maturity prior to the date of the execution hereof;

(12) $30,000,000 principal amount of First Mortgage Bonds, 5-1/2% Series due 1996 (herein called the "Bonds of 1996 Series"), which are described in the Supplemental Indenture dated May 1, 1966 (hereinafter called the "Supplemental Indenture of May 1, 1966"), all of which have been paid at maturity prior to the date of the execution hereof;

(13) $40,000,000 principal amount of First Mortgage Bonds, 5-1/2% Series due 1997 (herein called the "Bonds of 1997 Series"), which are described in the Supplemental Indenture dated March 1, 1967 (hereinafter called the "Supplemental Indenture of March 1, 1967"), all of which have been paid at maturity prior to the date of the execution hereof;

(14) $50,000,000 principal amount of First Mortgage Bonds, 7% Series due 1998 (herein called the "Bonds of 1998 Series"), which are described in the Supplemental Indenture dated March 15, 1968 (hereinafter called the "Supplemental Indenture of March 15, 1968"), all of which have been redeemed prior to the date of the execution hereof;

(15) $35,000,000 principal amount of First Mortgage Bonds, 7-3/8% Series due 1999 (herein called the "Bonds of May 1999 Series"), which are described in the Supplemental Indenture dated May 1, 1969 (hereinafter called the "Supplemental Indenture of May 1, 1969"), all of which have been redeemed prior to the date of the execution hereof;

(16) $40,000,000 principal amount of First Mortgage Bonds, 8-1/4% Series due 1999 (herein called the "Bonds of October 1999 Series"), which are described in the Supplemental Indenture dated October 1, 1969 (hereinafter called the "Supplemental Indenture of October 1, 1969"), all of which have been redeemed prior to the date of the execution hereof;

(17) $100,000,000 principal amount of First Mortgage Bonds, 9.95% Series due 1999 (herein called the "Bonds of November 1999 Series"), which are described in the Supplemental Indenture dated November 1, 1979 (hereinafter called the "Supplemental Indenture of November 1, 1979"), all of which have been redeemed prior to the date of the execution hereof;

(18) $60,000,000 principal amount of First Mortgage Bonds, 9% Series due 2000 (herein called the "Bonds of 2000 Series"), which are described in the Supplemental Indenture dated April 1, 1970 (hereinafter called the "Supplemental Indenture of April 1, 1970"), all of which have been redeemed prior to the date of the execution hereof;

(19) $50,000,000 principal amount of First Mortgage Bonds, 7-7/8% Series due 2001 (herein called the "Bonds of January 2001 Series"), which are described in the Supplemental Indenture dated January 1, 1971 (hereinafter called the "Supplemental Indenture of January 1, 1971"), all of which have been redeemed prior to the date of the execution hereof;

(20) $50,000,000 principal amount of First Mortgage Bonds, 7 5/8% Series due 2001 (herein called the "Bonds of April 2001 Series"), which are described in the Supplemental Indenture dated April 1, 1971 (hereinafter called the "Supplemental Indenture of April 1, 1971"), all of which have been redeemed prior to the date of the execution hereof;

(21) $60,000,000 principal amount of First Mortgage Bonds, 8 1/8% Series due 2001 (herein called the "Bonds of October 2001 Series"), which are described in the Supplemental Indenture dated September 15, 1971 (hereinafter called the "Supplemental Indenture of September 15, 1971"), all of which have been redeemed prior to the date of the execution hereof;

(22) $70,000,000 principal amount of First Mortgage Bonds, 8-3/8% Series due 2004 (herein called the "Bonds of 2004 Series"), which are described in the Supplemental Indenture dated February 1, 1974 (hereinafter called the "Supplemental Indenture of February 1, 1974"), all of which have been redeemed prior to the date of the execution hereof;

(23) $70,000,000 principal amount of First Mortgage Bonds, 10-1/2% Series due 2005 (herein called the "Bonds of 2005 Series"), which are described in the Supplemental Indenture dated March 1, 1975 (hereinafter called the "Supplemental Indenture of March 1, 1975"), all of which have been redeemed prior to the date of the execution hereof;

(24) $70,000,000 principal amount of First Mortgage Bonds, 8-7/8% Series due 2006 (herein called the "Bonds of 2006 Series"), which are described in the Supplemental Indenture dated August 16, 1976 (hereinafter called the "Supplemental Indenture of August 16, 1976"), all of which have been redeemed prior to the date of the execution hereof;

(25) $27,085,000 principal amount of First Mortgage Bonds, 5.80% Environmental Improvement Series 1977, which are described in the Supplemental Indenture dated October 15, 1977 (hereinafter called the "Supplemental Indenture of October 15, 1977"), all of which have been redeemed prior to the date of the execution hereof;

(26) $60,000,000 principal amount of First Mortgage Bonds, 8 5/8% Series due 2007 (herein called the "Bonds of 2007 Series"), which are described in the Supplemental Indenture dated December 1, 1977 (hereinafter called the "Supplemental Indenture of December 1, 1977"), all of which have been redeemed prior to the date of the execution hereof;

(27) $55,000,000 principal amount of First Mortgage Bonds, 9.35% Series due 2008 (herein called the "Bonds of 2008 Series"), which are described in the Supplemental Indenture dated August 1, 1978 (hereinafter called the "Supplemental Indenture of August 1, 1978"), all of which have been redeemed prior to the date of the execution hereof;

(28) $60,000,000 principal amount of First Mortgage Bonds, Environmental Improvement Series 1980, which are described in the Supplemental Indenture dated August 1, 1980 (hereinafter called the "Supplemental Indenture of August 1, 1980"), all of which have been redeemed prior to the date of the execution hereof;

(29) $150,000,000 principal amount of First Mortgage Bonds, 15-3/8% Series due 1991 (herein called the "Bonds of February 1991 Series"), which are described in the Supplemental Indenture dated February 1, 1981 (hereinafter called the "Supplemental Indenture of February 1, 1981"), all of which have been redeemed prior to the date of the execution hereof;

(30) $125,000,000 principal amount of First Mortgage Bonds, 15% Series due 1992 (herein called the "Bonds of 1992 Series"), which are described in the Supplemental Indenture dated September 1, 1982 (hereinafter called the "Supplemental Indenture of September 1, 1982"), all of which have been redeemed prior to the date of the execution hereof;

(31) $100,000,000 principal amount of First Mortgage Bonds, 13% Series due 2013 (herein called the "Bonds of 2013 Series"), which are described in the Supplemental Indenture dated March 1, 1983 (hereinafter called the "Supplemental Indenture of March 1, 1983"), all of which have been redeemed prior to the date of the execution hereof;

(32) $100,000,000 principal amount of First Mortgage Bonds, 9-3/8% Series due 2016 (herein called the "Bonds of 2016 Series"), which are described in the Supplemental Indenture dated March 1, 1986 (hereinafter called the "Supplemental Indenture of March 1, 1986"), all of which have been redeemed prior to the date of the execution hereof;

(33) $100,000,000 principal amount of First Mortgage Bonds, 8-7/8% Series due 1996 (herein called the "Bonds of 1996 Series"), which are described in the Supplemental Indenture dated May 1, 1986 (hereinafter called the "Supplemental Indenture of May 1, 1986"), all of which have been redeemed prior to the date of the execution hereof;

(34) $60,000,000 principal amount of First Mortgage Bonds, Environmental Improvement Series 1990A, which are described in the Supplemental Indenture dated May 1, 1990 (hereinafter called the "Supplemental Indenture of May 1, 1990"), all of which have been redeemed prior to the date of the execution hereof;

(35) $125,000,000 principal amount of First Mortgage Bonds, 8-3/4% Series due 2021 (herein called the "Bonds of 2021 Series"), which are described in the Supplemental Indenture dated December 1, 1991 (hereinafter called the "Supplemental Indenture of December 1, 1991"), all of which have been redeemed prior to the date of the execution hereof;

(36) $75,000,000 principal amount of First Mortgage Bonds, 8.33% Series due 2002 (herein called the "Bonds of 2002 Series"), which are described in the Supplemental Indenture dated December 4, 1991 (hereinafter called the "Supplemental Indenture of December 4, 1991"), all of which have been paid at maturity prior to the date of the execution hereof;

(37) $100,000,000 principal amount of First Mortgage Bonds, 7.65% Series due 2003 (herein called the "Bonds of 2003 Series"), which are described in the Supplemental Indenture dated January 1, 1992 (hereinafter called the "Supplemental Indenture of January 1, 1992"), all of which have been paid at maturity prior to the date of the execution hereof;

(38) $204,000,000 aggregate principal amount of First Mortgage Bonds, consisting of $100,000,000 principal amount of 6-3/4% Series due 1999 and $104,000,000 principal amount of 8-1/4% Series due 2022 (herein called the "Bonds of 1999 Series" and "Bonds of 2022 Series", respectively), which are described in the Supplemental Indenture dated October 1, 1992 (hereinafter called the "Supplemental Indenture of October 1, 1992"), of which the Bonds of 1999 Series have been paid at maturity prior to the date of execution hereof and the Bonds of 2022 Series have been redeemed prior to the date of the execution hereof;

(39) $170,000,000 aggregate principal amount of First Mortgage Bonds, consisting of $85,000,000 principal amount of 7-3/8% Series due 2004 and $85,000,000 principal amount of 8% Series due 2022 (herein called the "Bonds of December 2004 Series" and "Bonds of December 2022 Series", respectively, which are described in the Supplemental Indenture dated December 1, 1992, (hereinafter called the "Supplemental Indenture of December 1, 1992"), of which the Bonds of December 2022 Series have been redeemed prior to the date of the execution hereof and the Bonds of December 2004 Series are outstanding at the date of the execution hereof;

(40) $188,000,000 principal amount of First Mortgage Bonds, 6-7/8% Series due 2004 (herein called the "Bonds of August 2004 Series"), which are described in the Supplemental Indenture dated February 1, 1993 (hereinafter called the "Supplemental Indenture of February 1, 1993"), all of which are outstanding at the date of the execution hereof;

(41) $148,000,000 principal amount of First Mortgage Bonds, 6-3/4% Series due 2008 (herein called the "Bonds of May 2008 Series"), which are described in the Supplemental Indenture dated May 1, 1993 (hereinafter called the "Supplemental Indenture of May 1, 1993"), all of which are outstanding at the date of the execution hereof;

(42) $75,000,000 principal amount of First Mortgage Bonds, 7.15% Series due 2023 (herein called the "Bonds of 2023 Series"), which are described in the Supplemental Indenture dated August 1, 1993 (hereinafter called the "Supplemental Indenture of August 1, 1993"), all of which have been redeemed prior to the date of the execution hereof;

(43) $44,000,000 principal amount of First Mortgage Bonds, Environmental Improvement Series 1993 (herein called the "Bonds of 2028 Series"), which are described in the Supplemental Indenture dated October 1, 1993 (hereinafter called the "Supplemental Indenture of October 1, 1993"), all of which are outstanding at the date of the execution hereof;

(44) $100,000,000 principal amount of First Mortgage Bonds, 7% Series due 2024 (herein called the "Bonds of 2024 Series"), which are described in the Supplemental Indenture dated January 1, 1994 (hereinafter called the "Supplemental Indenture of January 1, 1994"), all of which are outstanding at the date of the execution hereof;

(45) $173,000,000 principal amount of First Mortgage Bonds, Senior Notes Series AA (herein called the "Bonds of 2012 Series"), which are described in the Supplemental Indenture dated August 15, 2002 (hereinafter called the "Supplemental Indenture of August 15, 2002"), all of which are outstanding at the date of the execution hereof;

(46) $184,000,000 principal amount of First Mortgage Bonds, Senior Notes Series BB (herein called the "Bonds of 2034 Series"), which are described in the Supplemental Indenture dated March 5, 2003 (hereinafter called the "Supplemental Indenture of March 5, 2003"), all of which are outstanding at the date of the execution hereof;

(47) $114,000,000 principal amount of First Mortgage Bonds, Senior Notes Series CC (herein called the "Bonds of 2015 Series"), which are described in the Supplemental Indenture dated April 1, 2003 (hereinafter called the "Supplemental Indenture of April 1, 2003"), all of which are outstanding at the date of the execution hereof;

(48) $200,000,000 principal amount of First Mortgage Bonds, Senior Notes Series DD (herein called the "Bonds of 2018 Series"), which are described in the Supplemental Indenture dated July 15, 2003 (hereinafter called the "Supplemental Indenture of July 15, 2003"), all of which are outstanding at the date of the execution hereof;

(49) $200,000,000 principal amount of First Mortgage Bonds, Senior Notes Series EE (herein called the "Bonds of 2013 Series"), which are described in the Supplemental Indenture dated October 1, 2003 (hereinafter called the "Supplemental Indenture of October 1, 2003"), all of which are outstanding at the date of the execution hereof;

(50) $60,000,000 principal amount of First Mortgage Bonds, Environmental Improvement Series 2004A (1998A Bonds) (herein called the "Bonds of 2033 (Series 1998A)"), which are described in the Supplemental Indenture dated February 1, 2004 (hereinafter called the "Supplemental Indenture of February 1, 2004 (2004A)"), all of which are outstanding at the date of the execution hereof;

(51) $50,000,000 principal amount of First Mortgage Bonds, Environmental Improvement Series 2004B (1998B Bonds) (herein called the "Bonds of 2033 (Series 1998B)"), which are described in the Supplemental Indenture dated February 1, 2004 (hereinafter called the "Supplemental Indenture of February 1, 2004 (2004B)"), all of which are outstanding at the date of the execution hereof;

(52) $50,000,000 principal amount of First Mortgage Bonds, Environmental Improvement Series 2004C (1998C Bonds) (herein called the "Bonds of 2033 (Series 1998C)"), which are described in the Supplemental Indenture dated February 1, 2004 (hereinafter called the "Supplemental Indenture of February 1, 2004 (2004C)"), all of which are outstanding at the date of the execution hereof;

(53) $63,000,000 principal amount of First Mortgage Bonds, Environmental Improvement Series 2004D (2000B Bonds) (herein called the "Bonds of 2035 (Series 2000B)"), which are described in the Supplemental Indenture dated February 1, 2004 (hereinafter called the "Supplemental Indenture of February 1, 2004 (2004D)"), all of which are outstanding at the date of the execution hereof;

(54) $63,500,000 principal amount of First Mortgage Bonds, Environmental Improvement Series 2004E (2000A Bonds) (herein called the "Bonds of 2035 (Series 2000A)"), which are described in the Supplemental Indenture dated February 1, 2004 (hereinafter called the "Supplemental Indenture of February 1, 2004 (2004E)"), all of which are outstanding at the date of the execution hereof;

(55) $60,000,000 principal amount of First Mortgage Bonds, Environmental Improvement Series 2004F (2000C Bonds) (herein called the "Bonds of 2035 (Series 2000C)"), which are described in the Supplemental Indenture dated February 1, 2004 (hereinafter called the "Supplemental Indenture of February 1, 2004 (2004F)"), all of which are outstanding at the date of the execution hereof; and

(56) $42,585,000 principal amount of First Mortgage Bonds, Environmental Improvement Series 2004G (1991 Bonds) (herein called the "Bonds of 2020 (Series 1991)"), which are described in the Supplemental Indenture dated February 1, 2004 (hereinafter called the "Supplemental Indenture of February 1, 2004 (2004G)"), all of which are outstanding at the date of the execution hereof; and

WHEREAS, the Company on August 31, 1955 acquired all of the properties of Union Electric Power Company, the Subsidiary as defined in Article I of the Original Indenture, upon the dissolution of the Subsidiary; the Company, by Supplemental Indenture dated August 31, 1955, conveyed all of the properties so acquired (other than property of the character defined as excepted property in the granting clauses of the Original Indenture) to the Trustee upon the terms and trusts in the Original Indenture and the indentures supplemental thereto set forth for the equal and proportionate benefit and security of all present and future holders of the Bonds and coupons issued and to be issued thereunder, all the shares of stock of the Subsidiary were released from the lien of the Original Indenture; and the Company became entitled to change the general designation of the Bonds so as to omit the words "and Collateral Trust"; and

WHEREAS, the Articles of Incorporation of the Company were duly amended on April 23, 1956, to change its corporate name from "Union Electric Company of Missouri" to "Union Electric Company"; and

WHEREAS, the Articles of Agreement of the Trustee were duly amended effective on January 4, 1982 to change its corporate name from "St. Louis Union Trust Company" to "Centerre Trust Company of St. Louis", and further amended on December 9, 1988, to change its corporate name from "Centerre Trust Company of St. Louis" to "Boatmen's Trust Company"; and

WHEREAS, that on March 13, 1998, Boatmen's Trust Company merged into NationsBank, National Association and effective July 5, 1999, changed its name to Bank of America, National Association; and

WHEREAS, that on February 1, 2000, The Bank of New York, as transferee of the corporate trust business of Bank of America, National Association (formerly known as Boatmen's Trust Company), Trustee under the Original Indenture, became successor Trustee under the Original Indenture; and

WHEREAS, the Company is entitled at this time to have authenticated and delivered additional Bonds on the basis of property additions upon compliance with and pursuant to the provisions of Article III, Section 4 of the Original Indenture; and

WHEREAS, the Company has entered into a Loan Agreement dated as of December 1, 1992 (the "Original Loan Agreement") with the State Environmental Improvement and Energy Resources Authority of the State of Missouri (the "Authority") pursuant to which the Authority agreed to issue $47,500,000 aggregate principal amount of its Environmental Improvement Revenue Refunding Bonds (Union Electric Company Project) Series 1992 (the "Authority Bonds"), all of which are presently outstanding and loan the proceeds thereof to the Company; and

WHEREAS, the Authority Bonds were issued pursuant to an Indenture of Trust dated as of December 1, 1992 (the "Original Authority Bond Indenture") between the Authority and UMB Bank & Trust, N.A., as successor to Mercantile Bank of St. Louis National Association, as trustee (the "Authority Bond Trustee"); and

WHEREAS, the Company has determined it to be necessary and desirable to further secure rights of the owners of the Authority Bonds to the payment of principal and interest on the Authority Bonds by obtaining a Financial Guaranty Insurance Policy with respect to the Authority Bonds (the "Authority Bond Insurance Policy") from MBIA Insurance Corporation and in furtherance thereof
(i) the Authority and the Authority Bond Trustee will enter into an Amended and Restated Indenture of Trust dated as of February 1, 2004 (the "Authority Bond Indenture") which amends and restates the Original Authority Bond Indenture, and
(ii) the Authority and the Company will enter into the First Amendment to Loan Agreement dated as of February 1, 2004 (the "First Amendment to Loan Agreement"), which amends the Original Loan Agreement (the Original Loan Agreement as so amended is referred to herein as the "Agreement"); and

WHEREAS, in connection with obtaining the Authority Bond Insurance Policy, the Company desires by this Supplemental Indenture to provide for the issuance to the Authority Bond Trustee of a new series of Bonds under the Original Indenture as security for the Company's obligations under the Agreement with respect to the payment of the Authority Bonds, to have the designation provided in Article I, Section 1 hereof (herein called the "New Bonds"), and the Original Indenture provides that certain terms and provisions, as determined by the Board of Directors of the Company, of the Bonds of any particular series may be expressed in and provided by the execution of an appropriate supplemental indenture; and

WHEREAS, the Original Indenture provides that the Company and the Trustee may enter into indentures supplemental to the Original Indenture specifically to convey, transfer and assign to the Trustee and to subject to the lien of the Original Indenture additional properties acquired by the Company; and

WHEREAS, the Company, in the exercise of the powers and authority conferred upon and reserved to it under the provisions of the Original Indenture and pursuant to appropriate resolutions of the Board of Directors, has duly resolved and determined to make, execute and deliver to the Trustee a Supplemental Indenture in the form hereof for the purposes herein provided; and

WHEREAS, all conditions and requirements necessary to make this Supplemental Indenture a valid, binding and legal instrument have been done, performed and fulfilled and the execution and delivery hereof have been in all respects duly authorized;

NOW, THEREFORE, THIS INDENTURE WITNESSETH:

That, in consideration of the premises and of the mutual covenants herein contained and of the acceptance of this trust by the Trustee and of the sum of One Dollar duly paid by the Trustee to the Company at or before the time of the execution of this Supplemental Indenture, and of other valuable considerations, the receipt whereof is hereby acknowledged, and in order further to secure the payment of the principal of and interest (and premium, if any) on all Bonds at any time issued and outstanding under the Original Indenture, according to their tenor and effect, and to secure the Company's obligations under the Agreement with respect to the payment of the Authority Bonds, the Company has executed and delivered this Supplemental

Indenture and has granted, bargained, sold, warranted, aliened, remised, released, conveyed, assigned, transferred, mortgaged, pledged, set over and confirmed and by these presents does grant, bargain, sell, warrant, alien, remise, release, convey, assign, transfer, mortgage, pledge, set over and confirm unto The Bank of New York, as Trustee, and to its successors in trust under the Original Indenture forever, all and singular the following described properties (in addition to all other properties heretofore subjected to the lien of the Original Indenture and not heretofore released from the lien thereof) - that is to say:

FIRST

ALL power houses, plants, buildings and other structures, dams, dam sites, substations, heating plants, gas works, holders and tanks, together with all and singular the electric, heating, gas and mechanical appliances appurtenant thereto of every nature whatsoever, now owned by the Company, including all and singular the machinery, engines, boilers, furnaces, generators, dynamos, turbines and motors, and all and every character of mechanical appliance for generating or producing electricity, steam, gas and other agencies for light, heat, cold, or power or other purposes, and all transmission and distribution systems used for the transmission and distribution of electricity, steam, gas and other agencies for light, heat, cold or power or any other purpose whatsoever, whether underground or overhead, surface or otherwise, now owned by the Company, including all poles, towers, posts, wires, cables, conduits, manholes, mains, pipes, tubes, drains, furnaces, switchboards, transformers, conductors, insulators, supports, meters, lamps, fuses, junction boxes, regulator stations, and other electric, steam and gas fixtures and apparatus; all of the aforementioned property being located in the City of St. Louis, the counties of Adair, Audrain, Benton, Bollinger, Boone, Butler, Caldwell, Callaway, Camden, Cape Girardeau, Clark, Clay, Clinton, Cole, Cooper, Crawford, Daviess, Dunklin, Franklin, Gasconade, Howard, Iron, Jefferson, Knox, Lewis, Lincoln, Livingston, Macon, Madison, Maries, Marion, Miller, Mississippi, Moniteau, Montgomery, Morgan, New Madrid, Osage, Pemiscot, Perry, Pettis, Phelps, Pike, Pulaski, Ralls, Randolph, Ray, Reynolds, Ripley, St. Charles, St. Francois, Ste. Genevieve, St. Louis, Saline, Schuyler, Scott, Stoddard, Warren, Washington, and Wayne, Missouri, the counties of Adams, Alexander, Calhoun, Franklin, Hancock, Henderson, Jackson, Jersey, Macoupin, Madison, Massac, Monroe, Perry, Pike, Pulaski, St. Clair, Union, and Washington, Illinois, and the counties of Des Moines, Henry, Johnson, Lee, and Washington, Iowa, upon real estate owned by the Company, or occupied by it under rights to so occupy, which real estate is described in the Indenture of Mortgage and Deed of Trust dated June 15, 1937, in the Supplemental Indentures dated May 1, 1941, March 17, 1942, April 13, 1945, April 27, 1945, October 1, 1945, April 11, 1947, April 13, 1949, September 13, 1950, December 1, 1950, September 20, 1951, May 1, 1952, March 1, 1954, May 1, 1955, August 31, 1955, April 1, 1956, July 1, 1956, August 1, 1957, February 1, 1958, March 1, 1958, November 5, 1958, March 16, 1959, June 24, 1959, December 11, 1959, August 17, 1960, September 1, 1960, October 24, 1960, June 30, 1961, July 1, 1961, August 9, 1962, September 30, 1963, November 1, 1963, March 12, 1965, April 1, 1965, April 14, 1966, May 1, 1966, February 17, 1967, March 1, 1967, February 19, 1968, March 15, 1968, August 21, 1968, April 7, 1969, May 1, 1969, September 12, 1969, October 1, 1969, March 26, 1970, April 1, 1970, June 12, 1970, January 1, 1971, April 1, 1971, September 15, 1971, December 3, 1973, February 1, 1974, April 25, 1974, February 3, 1975, March 1, 1975, June 11, 1975, May 12, 1976, August 16, 1976, April 26, 1977, October 15, 1977, November 7, 1977,

December 1, 1977, August 1, 1978, October 12, 1979, November 1, 1979, July 7, 1980, August 1, 1980, August 20, 1980, February 1, 1981, October 8, 1981, August 27, 1982, September 1, 1982, December 15, 1982, March 1, 1983, June 21, 1984, December 12, 1984, June 11, 1985, March 1, 1986, May 1, 1986, May 1, 1990, December 1, 1991, December 4, 1991, January 1, 1992, September 30, 1992, October 1, 1992, December 1, 1992, February 1, 1993, February 18, 1993, May 1, 1993, August 1, 1993, October 1, 1993, January 1, 1994, February 1, 2000, August 15, 2002, March 5, 2003, April 1, 2003, July 15, 2003, October 1, 2003 and in this Supplemental Indenture and the seven other Supplemental Indentures each dated February 1, 2004, or attached to or connected with such real estate or transmission or distribution systems of the Company leading from or into such real estate.

SECOND

ALSO, (except as in the Original Indenture expressly excepted) all franchises and all permits, ordinances, easements, privileges, immunities and licenses, all rights to construct, maintain and operate overhead, surface and underground systems for the distribution and transmission of electricity, steam, gas or other agencies for the supply to itself or others of light, heat, cold or power, all rights-of-way, all waters, water rights and flowage rights and all grants and consents, now owned or, subject to the provisions of Article XII of the Original Indenture, which it may hereafter acquire.

ALSO, (except as in the Original Indenture expressly excepted) all inventions, patent rights and licenses of every kind now owned by the Company or, subject to the provisions of Article XII of the Original Indenture, which it may hereafter acquire.

THIRD

ALSO, subject to the provisions of Article XII of the Original Indenture, all other property, real, personal and mixed (except as therein or herein expressly excepted) of every nature and kind and wheresoever situated now or hereafter possessed by or belonging to the Company, or to which it is now, or may at any time hereafter be, in any manner entitled at law or in equity.

TO HAVE AND TO HOLD all said properties, real, personal and mixed, mortgaged, pledged and conveyed by the Company as aforesaid, or intended so to be, unto the Trustee and its successors and assigns forever;

SUBJECT, HOWEVER, to the exceptions and reservations and matters hereinabove recited, to existing leases, to existing liens upon rights of way for transmission or distribution line purposes, as defined in Article I of the Original Indenture, and any extensions thereof, and subject to existing easements for streets, alleys, highways, rights-of-way and railroad purposes over, upon and across certain of the property hereinbefore described, and subject also to all the terms, conditions, agreements, covenants, exceptions and reservations expressed or provided in the deeds or other instruments respectively under and by virtue of which the Company acquired

the properties hereinabove described, and to undetermined liens and charges, if any, incidental to construction or other existing permitted liens as defined in Article I of the Original Indenture;

IN TRUST, NEVERTHELESS, upon the terms and trusts in the Original Indenture and the indentures supplemental thereto, including this Supplemental Indenture, set forth, for the equal and proportionate benefit and security of all present and future holders of the Bonds and coupons issued and to be issued thereunder, or any of them, without preference of any of said Bonds and coupons of any particular series over the Bonds and coupons of any other series, by reason of priority in the time of the issue, sale or negotiation thereof, or by reason of the purpose of issue or otherwise howsoever, except as otherwise provided in
Section 2 of Article IV of the Original Indenture.

AND IT IS HEREBY COVENANTED, DECLARED AND AGREED, by and between the parties hereto, for the benefit of those who shall hold the Bonds and coupons, or any of them to be issued under the Original Indenture, as follows:

ARTICLE I

DESCRIPTION OF THE NEW BONDS

Section 1.1. There is hereby created a new series of Bonds to be executed, authenticated and delivered under and secured by the Original Indenture which shall, subject to the provisions of Section 1 of Article II of the Original Indenture, be designated as "First Mortgage Bonds, Environmental Improvement Series 2004H (1992 Bonds)" (the "New Bonds") of the Company. The New Bonds shall be executed, authenticated and delivered in accordance with the provisions of, and shall in all respects be subject to all of the terms, conditions and covenants of, the Original Indenture and shall be issued to, and registered in the name of, the Authority Bond Trustee under the Authority Bond Indenture to secure any and all obligations of the Company under the Agreement with respect to the payment of the Authority Bonds.

The New Bonds shall mature, subject to prior redemption, on December 1, 2022, and shall bear interest at the same rate or rates of interest as the Authority Bonds which, in turn, shall be determined by the methods set forth in the Authority Bond Indenture, which provides for a Short-Term Auction Rate, a Long-Term Auction Rate, a Bond Interest Term Rate, a Weekly Rate or a Long-Term Interest Rate (each as defined in the Authority Bonds Indenture). Reference is made to the provisions of the Authority Bond Indenture concerning the methods by which such interest rates are determined, and the means by which the method of determining such interest rates may be changed, and such provisions are included in this Supplemental Indenture as if fully set forth herein. Interest on the New Bonds is payable on the same dates as interest on the Authority Bonds is paid, until the principal sum of the New Bonds is paid in full. The New Bonds shall be payable as to principal and interest in any coin or currency of the United States of America which at the time of payment is legal tender for public and private debts, and shall be payable, in immediately available funds, at the office of the Authority Bond Trustee.

Section 1.2. The New Bonds shall not be assignable or transferable except as permitted or required by Section 12.13 of the Authority Bond Indenture. Any such transfer shall be effected at the principal office or place of business of the Trustee under the Original Indenture. The New Bonds are exchangeable for the New Bonds of other denominations, as in the Original Indenture provided, except that payment of a service charge therefor will not be required by the Company.

Notwithstanding the provisions of Section 6 of Article II of the Original Indenture, the New Bonds shall be dated their date of authentication and shall bear interest from the interest payment date to which interest on the New Bonds has been paid next preceding the date thereof, unless such date is an interest payment date to which interest has been paid, in which case they shall bear interest from the date thereof.

Upon any payment of the principal of and interest on, all or any portion of the Authority Bonds, whether at maturity or otherwise or upon provision for the payment thereof having been made in accordance with Section 7.01 of the Authority Bond Indenture, the New Bonds in a principal amount equal to the principal amount of such Authority Bonds shall, to the extent of such payment of principal and interest, be deemed paid and the obligation of the Company thereunder to make such payment shall be discharged to such extent and, in the case of the payment of principal, such New Bonds shall be surrendered to the Company for cancellation as provided in and subject to the terms of Section 7.04 of the Authority Bond Indenture. The Trustee may at any time and all times conclusively assume that the obligation of the Company under the Agreement to make payments with respect to the principal of and interest on the Authority Bonds, so far as such payments at the time have become due, has been fully satisfied and discharged pursuant to the foregoing sentence unless and until the Trustee shall have received a written notice from the Authority Bond Trustee signed by one of its officers stating (i) the timely payment of principal or interest on, the Authority Bonds has not been made, (ii) that the Company is in arrears as to the payments required to be made by it to the Authority Bond Trustee pursuant to the Agreement, and (iii) the amount of the arrearage.

                           [Form of Face of New Bond]

No. ____                                                             $________

                              Ill. C. C. No. 6313

NOTWITHSTANDING ANY PROVISIONS HEREOF OR IN THE ORIGINAL INDENTURE THIS BOND IS NOT ASSIGNABLE OR TRANSFERABLE EXCEPT AS PERMITTED OR REQUIRED BY SECTION 12.13 OF THE AMENDED AND RESTATED INDENTURE OF TRUST DATED AS OF FEBRUARY 1, 2004, BETWEEN THE STATE ENVIRONMENTAL IMPROVEMENT AND ENERGY RESOURCES AUTHORITY OF THE STATE OF MISSOURI AND UMB BANK & TRUST, N.A., AS SUCCESSOR TO MERCANTILE BANK OF ST. LOUIS NATIONAL ASSOCIATION, AS TRUSTEE

UNION ELECTRIC COMPANY
(Incorporated under the laws of the State of Missouri)

First Mortgage Bonds, Environmental Improvement Series 2004H (1992 Bonds)

Illinois Commerce Commission Identification No. 6313

UNION ELECTRIC COMPANY, a corporation organized and existing under the laws of the State of Missouri (hereinafter called the "Company," which term shall include any successor corporation as defined in the Amended Indenture referred to on the reverse hereof), for value received, hereby promises to pay to UMB Bank & Trust, N.A., as successor to Mercantile Bank of St. Louis National Association, as trustee under the Authority Bond Indenture hereinafter referred to, or registered assigns, the sum of _________________________ Dollars, on the 1st day of December, 2022, subject to prior redemption, in any coin or currency of the United States of America which at the time of payment is legal tender for public and private debts, and to pay interest thereon, in like coin or currency, at the same rate or rates of interest as the Authority Bonds (as determined in accordance with the Authority Bond Indenture referred to below), but in no event shall the interest rate on this Bond exceed twelve percent (12%) per annum. Interest on overdue principal premium, if any, and, to the extent permitted by law, on overdue interest, shall be payable at the interest rate payable on the Authority Bonds. Interest on this Bond is payable on the same dates as interest on the Authority Bonds, or, if this Bond shall be duly called for redemption, until the redemption date, or if the Company shall default in the payment of the principal hereof, until the Company's obligation to pay principal shall be discharged as provided in the Amended Indenture is paid, until the principal sum is paid in full. The principal of, and interest on, this Bond are payable, in immediately available funds, at the office of the Authority Bond Trustee hereinafter referred to.

Under an Indenture of Trust dated as of December 1, 1992, as amended and restated by the Amended and Restated Indenture of Trust dated as of February 1, 2004 (as so amended and restated, the "Authority Bond Indenture") between the State Environmental Improvement and Energy Resources Authority of the State of Missouri (the "Authority") and UMB Bank & Trust, N.A., as successor to Mercantile Bank of St. Louis National Association, as trustee (the "Authority Bond Trustee"), the Authority has issued its Environmental Improvement Revenue

Refunding Bonds (Union Electric Company Project) Series 1992 in the aggregate principal amount of $47,500,000 (the "Authority Bonds"). The Company has agreed to pay the principal of and interest on the Authority Bonds pursuant to a Loan Agreement dated as of December 1, 1992, as supplemented and amended by the First Amendment to Loan Agreement dated as of February 1, 2004 (as so amended, the "Agreement") between the Company and the Authority. Pursuant to the Granting Clause of the Authority Bond Indenture, this Bond is issued to the Authority Bond Trustee to secure any and all obligations of the Company under the Agreement with respect to payment of the Authority Bonds. Payment of principal of, or interest on, the Authority Bonds shall constitute payments on this Bond as further provided herein and in the Supplemental Indenture dated February 1, 2004 pursuant to which this Bond has been issued (the "Supplemental Indenture").

Upon any payment of the principal of, and interest on, all or any portion of the Authority Bonds, whether at maturity or otherwise or upon provision for the payment thereof having been made in accordance with Section 7.01 of the Authority Bond Indenture, a principal amount of this Bond equal to the principal amount of such Authority Bonds shall, to the extent of such payment of principal and interest, be deemed paid and the obligation of the Company thereunder to make such payment shall be discharged to such extent and, in the case of the payment of principal, such Bonds shall be surrendered to the Company for cancellation as provided in Section 7.04 of the Authority Bond Indenture. The Trustee (as hereinafter defined) may at any time and all times conclusively assume that the obligation of the Company to make payments under the Agreement with respect to the principal of, and interest on, the Authority Bonds, so far as such payments at the time have become due, has been fully satisfied and discharged pursuant to the foregoing sentence unless and until the Trustee shall have received a written notice from the Authority Bond Trustee signed by one of its officers stating (i) that timely payment of principal of, or interest on, the Authority Bonds has not been made, (ii) that the Company is in arrears as to the payments required to be made by it to the Authority Bond Trustee pursuant to the Agreement, and (iii) the amount of the arrearage.

This Bond shall not be entitled to any benefit under the Amended Indenture or any indenture supplemental thereto, or become valid or obligatory for any purpose, until The Bank of New York, the Trustee under the Amended Indenture, or a successor trustee thereto under the Amended Indenture, or an agent therefor, shall have signed the form of certificate endorsed hereon.

The provisions of this Bond are continued on the reverse hereof and such continued provisions shall for all purposes have the same effect as though fully set forth at this place.

IN WITNESS WHEREOF, Union Electric Company has caused this Bond to be signed in its name by its Chairman of the Board or President or a Vice President by manual signature or a facsimile thereof, and its corporate seal (or a facsimile thereof) to be hereto affixed and attested by its Secretary or an Assistant Secretary by manual signature or a facsimile thereof.

Dated,
UNION ELECTRIC COMPANY,

[CORPORATE SEAL]

Attest:

[FORM OF TRUSTEE'S CERTIFICATE]

This Bond is one of the Bonds, of the series designated therein, described in the within-mentioned Amended Indenture and Supplemental Indenture of February 1, 2004.

THE BANK OF NEW YORK, as Trustee

[FORM OF REVERSE OF NEW BOND]

This Bond is one of a duly authorized issue of Bonds of the Company (herein called the "Bonds"), limited to an aggregate principal amount of $47,500,000, of the series hereinafter specified, all issued under and equally secured by the Indenture of Mortgage and Deed of Trust, dated June 15, 1937, executed by the Company to The Bank of New York (successor trustee to Bank of America, National Association, formerly Boatmen's Trust Company), as trustee (herein called the "Trustee"), as amended by indentures supplemental thereto dated May 1, 1941, April 1, 1971, February 1, 1974, July 7, 1980, February 1, 2000 and August 15, 2002, between the Company and the Trustee (said mortgage and deed of trust, as so amended, being herein called the "Amended Indenture"), to which Amended Indenture and all indentures supplemental thereto reference is hereby made for a description of the properties mortgaged and pledged, the nature and extent of the security, the rights of the bearers or registered owners of the Bonds and of the Trustee in respect thereto, and the terms and conditions upon which the Bonds are, and are to be, secured. To the extent permitted by, and as provided in, the Amended Indenture, modifications or alterations of the Amended Indenture, or of any indenture supplemental thereto, and of the rights and obligations of the Company and of the holders of the Bonds may be made with the consent of the Company by an affirmative vote of not less than 60% in amount of the

Bonds entitled to vote then outstanding, at a meeting of Bondholders called and held as provided in the Amended Indenture, and by an affirmative vote of not less than 60% in amount of the Bonds of any series entitled to vote then outstanding and affected by such modification or alteration, in case one or more but less than all of the series of Bonds then outstanding under the Amended Indenture are so affected. Additionally, the Company may amend the Amended Indenture, as supplemented, by an appropriate written consent of not less than 60% in aggregate principal amount of the Bonds outstanding (and, if the rights of one or more, but less than all, series of Bonds then outstanding are to be affected by action taken pursuant to such consent, then also by consent of the holders of at least 60% in principal amount of each series of Bonds so to be affected and outstanding hereunder) without a meeting of such Bondholders. No such modification or alteration shall be made which will affect the terms of payment of the principal of, or interest on, this Bond, which are unconditional. The Bonds may be issued in series, for various principal sums, may mature at different times, may bear interest at different rates and may otherwise vary as in the Amended Indenture provided. This Bond is one of a series designated as the "First Mortgage Bonds, Environmental Improvement Series 2004H (1992 Bonds)" (herein called the "Bonds of this Series") of the Company, issued under and secured by the Amended Indenture and described in the indenture (hereinafter called the "Supplemental Indenture") dated February 1, 2004, between the Company and the Trustee, supplemental to the Amended Indenture.

The Bonds of this Series are not entitled to the benefit of any improvement, maintenance or analogous fund.

This Bond is, subject to the provisions of the Amended Indenture, subject to redemption in the amounts, at the times, at the prices and under the circumstances under which the Authority Bonds are subject to redemption under the same terms and circumstances set forth in the Authority Bond Indenture for the redemption of the Authority Bonds.

This Bond is also subject to mandatory redemption at the principal amount hereof plus accrued interest to the date fixed for redemption if the Trustee or the Company is notified that an "Event of Default" under the Authority Bond Indenture has occurred and is continuing and the Authority Bond Trustee has declared the principal amount of all Authority Bonds then outstanding due and payable in accordance with the Authority Bond Indenture.

The Company may, by notice to the Trustee at least 60 days prior to any date on which any principal amount is due on this Bond, elect to receive a credit in respect of such principal payment (a) for any Bonds of this Series then due which have been redeemed prior to such principal payment date or otherwise acquired and delivered to the Trustee for cancellation by said Trustee prior to the giving of such notice, or (b) for any Authority Bonds which have been purchased, delivered for cancellation or previously redeemed, which in each case have not theretofore been applied as a credit against such principal payment. Each Bond with respect to which the Company elects to receive a credit will be credited by the Trustee at 100% of the principal amount thereof against such principal payment, provided further that in the case of a credit with respect to any Authority Bonds, the principal amount thereof shall be established by an officers' certificate (as defined in the Amended Indenture) concurred in by the Authority Bond Trustee, included with the above-mentioned notice to the Trustee. The principal amount of Bonds to be paid on the due date of such principal payment will be reduced by the amount of any such credit or credits in respect of Bonds previously redeemed or delivered as provided above.

Upon cancellation in full or in part of any of the Authority Bonds (or provision for payment thereof having been made in accordance with the provisions of the Authority Bond Indenture) and payment of all fees and charges of the trustee thereunder, such trustee shall deliver to the Trustee, for cancellation a corresponding amount of Bonds remaining in its possession.

Such redemption in every case shall be effected upon notice delivered by the Company at least 60 days prior to the date of redemption, to the registered owner of the Bonds at its address as the same shall appear on the transfer register of the Company, all subject to the conditions of, and as more fully set forth in, the Amended Indenture and Supplemental Indenture.

In case an event of default, as defined in the Amended Indenture, shall occur, the principal of all the bonds at any such time outstanding under the Amended Indenture may be declared or may become due and payable, upon the conditions and in the manner and with the effect provided in the Amended Indenture. The Amended Indenture provides that such declaration may in certain events be waived by the holders of a majority in principal amount of the bonds outstanding.

This Bond shall not be assignable or transferable except as permitted or required by Section 12.13 of the Authority Bond Indenture. This Bond is exchangeable by the registered owner hereof, in person or by duly authorized attorney, on the books of the Company to be kept for that purpose at the office of the Company in the City of St. Louis, Missouri, upon surrender and cancellation of this Bond and on presentation of a duly executed written instrument of transfer, and thereupon a new Bond or Bonds of the same series, of the same aggregate principal amount and in authorized denominations will be issued to the transferee or transferees in exchange herefor, without payment of any charge other than stamp taxes and other governmental charges incident thereto; and this Bond with or without others of like series, may in like manner be exchanged for one or more new Bonds of the same series of other authorized denominations but of the same aggregate principal amount; all subject to the terms and conditions set forth in the Amended Indenture.

As provided in Section 7.04 of the Authority Bond Indenture, from and after the Release Date (as defined in the Authority Bond Indenture), the obligations of the Company with respect to this Bond shall be deemed to be satisfied and discharged, this Bond shall cease to secure in any manner the Company's obligations under the Agreement with respect to the payment of any Authority Bonds outstanding under the Authority Bond Indenture, and, pursuant to Section 7.04 of the Authority Bond Indenture, the Authority Bond Trustee shall forthwith deliver this Bond to the Company for cancellation.

No recourse shall be had for the payment of the principal of, or the interest on, this Bond, or for any claim based hereon or on the Amended Indenture or any indenture supplemental thereto, against any incorporator, or against any stockholder, director or officer, past, present or future, of the Company, or of any predecessor or successor corporation, either directly or through the Company or any such predecessor or successor corporation, whether for amounts unpaid on stock subscriptions or by virtue of any constitution, statute or rule of law, or by the enforcement of any assessment or penalty or otherwise, all such liability, whether at common law, in equity,

by any constitution, statute or otherwise, of incorporators, stockholders, directors or officers being released by every owner hereof by the acceptance of this Bond and as part of the consideration for the issue hereof, and being likewise released by the terms of the Amended Indenture.

[END OF FORM OF REVERSE OF NEW BOND]

ARTICLE II

ISSUE OF THE NEW BONDS

Section 2.1. The principal amount of the New Bonds which may be authenticated and delivered hereunder is limited to an amount equal to the principal amount of Forty-Seven Million Five-Hundred Thousand Dollars ($47,500,000) consisting of Bonds maturing on December 1, 2022.

Section 2.2. The New Bonds in the aggregate principal amount set forth above, may forthwith be executed by the Company and delivered to the Trustee and shall be authenticated by the Trustee and delivered (either before or after the filing or recording hereof) to or upon the order of the Company, upon compliance by the Company with the applicable provisions of Article III and Article XVIII of the Original Indenture.

Section 2.3. As provided in Section 7.04 of the Authority Bond Indenture, from and after the Release Date (as defined in the Authority Bond Indenture), the obligations of the Company with respect to the New Bonds shall be deemed to be satisfied and discharged, the New Bonds shall cease to secure in any manner the Company's obligations under the Agreement with respect to the payment of any Authority Bonds outstanding under the Authority Bond Indenture, and, pursuant to
Section 7.04 of the Authority Bond Indenture, the Authority Bond Trustee shall forthwith deliver the New Bonds to the Company for cancellation.

ARTICLE III

REDEMPTION OF THE NEW BONDS

Section 3.1. The New Bonds are, subject to the provisions of the Original Indenture, subject to redemption in the amounts, at the times, at the prices and under the circumstances under which the Authority Bonds are subject to redemption, under the same terms and conditions set forth in the Authority Bond Indenture for the redemption of the Authority Bonds. In the event that less than all the New Bonds are to be redeemed, the New Bonds to be redeemed shall be determined by lot in such manner as the Trustee in its discretion shall deem proper, as in the Original Indenture provided.

The New Bonds are also subject to mandatory redemption as set forth in the form of New Bonds in Section 1.3 of Article I of this Supplemental Indenture.

Section 3.2. Subject to the provisions of Article V of the Original Indenture, notice of redemption shall be delivered by the Company at least 60 days prior to the date of redemption, to the registered owner of such Bonds at its address as the same shall appear on the transfer register of the Company.

Section 3.3. As provided in the Authority Bond Indenture, any amounts of money held in the Bond Fund provided in said Indenture and available for such purpose, which are at the request of the Company applied to the payments of the principal of, premium, if any, and interest on the Authority Bonds on any payment or redemption date, shall be applied as a credit on amounts otherwise due under the New Bonds; provided that the amount of such credit shall be established by an officers' certificate (as defined in the Amended Indenture), concurred in by the Authority Bond Trustee which shall be filed with the Trustee prior to the application of any such credit.

Upon cancellation in full or in part of any of the Authority Bonds (or provision for payment thereof having been made in accordance with the provisions of the Authority Bond Indenture) and payment of all fees and charges of the trustee thereunder, such trustee shall deliver to the Trustee, for cancellation a corresponding amount of New Bonds remaining in its possession or shall request such Trustee to issue a New Bond reflecting any such cancellation

ARTICLE IV

COVENANTS

The Company hereby covenants, warrants and agrees;

Section 4.1. That the Company is lawfully seized and possessed of all of the mortgaged property described in the granting clauses of this Supplemental Indenture; that it has good right and lawful authority to mortgage the same as provided in this Supplemental Indenture; and that such mortgaged property is, at the actual date of the issue of the New Bonds, free and clear of any deed of trust, mortgage, lien, charge or encumbrance thereon or affecting the title thereto prior to the Original Indenture, except as set forth in the granting clauses of the Original Indenture or this Supplemental Indenture.

Section 4.2. That, so long as any of the New Bonds are outstanding, whenever any officers' certificate is required to be filed or deposited with the Trustee pursuant to Section 3(b) of Article III of the Original Indenture upon an application for the authentication of additional Bonds pursuant to Article III of the Original Indenture, such officers' certificate shall include, in addition to the matters required to be stated therein by said Section 3(b), the statement with respect to the net earnings of the Company available for interest after property retirement appropriations required by Section 2 of Article V of the Supplemental Indenture of July 1, 1956.

Section 4.3. That, so long as any of the New Bonds are outstanding, the Company will not apply for the authentication and delivery of additional Bonds pursuant to Section 4 of Article III of the Original Indenture or the withdrawal of cash from the trust estate or the reduction of the amount of cash required to be paid into the trust estate or to satisfy the

maintenance and improvement funds under any provision of the Original Indenture or the Supplemental Indentures creating prior series of Bonds, on the basis of the amount of $15,000,000 excluded from net bondable value of property additions not subject to an unfunded prior lien pursuant to Section 3 of Article V of the Supplemental Indenture of October 1, 1945, or on the basis of the amount of $7,500,000 excluded from net bondable value of property additions not subject to an unfunded prior lien pursuant to Section 3 of Article V of the Supplemental Indenture of July 1, 1956.

Section 4.4. That, so long as any of the New Bonds are outstanding, the Company will not issue or permit to be issued any prior lien bonds secured by an unfunded prior lien in addition to the prior lien bonds secured by such unfunded prior lien at the time of first acquisition by the Company of property subject thereto (other than in lieu of lost, stolen or mutilated bonds or on the exchange for bonds already outstanding of an equal principal amount of other bonds of the same issue and the same series, if any, and of the same maturity), except upon compliance with the provisions of Section 16 of Article IV of the Original Indenture, nor unless the net earnings of the Company available for interest after property retirement appropriations (determined as provided in
Section 2 of Article V of the Supplemental Indenture of July 1, 1956), for any 12 consecutive calendar months during the period of 15 calendar months immediately preceding the first day of the month in which the additional prior lien bonds are to be issued, have been, in the aggregate, equal to not less than twice the annual interest charges on the indebtedness specified in subparagraphs
(i) and (ii) of paragraph (1) of Section 2(a) of said Article V; provided that, if the application for the issue of such additional prior lien bonds is upon the basis of payment at maturity of prior lien bonds theretofore sold or otherwise disposed of or the redemption or purchase thereof after a date two years prior to the date of maturity, the additional requirement imposed by this Section 4 with respect to net earnings of the Company available for interest after property retirement appropriations shall not apply. Any officers' certificate with respect to net earnings of the Company, required to be filed with the Trustee as a condition precedent to the issue of such additional prior lien bonds, shall include, in addition to the matters otherwise required to be stated therein, the matters required to be stated in an officers' certificate pursuant to paragraphs (1) and (2) of Section 2(a) of said Article V.

Section 4.5. That, so long as any of the New Bonds are outstanding, the Company will not acquire, by purchase, merger or otherwise, any property subject to a lien or liens which will on acquisition be an unfunded prior lien or prior liens, except upon compliance with the provisions of Section 14 of Article IV of the Original Indenture, nor unless the net earnings of such property available for interest after property retirement appropriations (determined in the manner provided in Section 2 of Article V of the Supplemental Indenture of July 1, 1956), for any 12 consecutive calendar months during the period of 15 calendar months immediately preceding the first day of the month in which the first acquisition of property subject to such lien or liens occurs, have been, in the aggregate, equal to not less than twice the amount of annual interest charges, on all outstanding indebtedness secured by such lien or liens. Any officers' certificate with respect to net earnings of such property, required to be filed with the Trustee as a condition precedent to the acquisition of such property, shall include, in addition to the matters otherwise required to be stated therein, the matters required to be stated in an officers' certificate pursuant to Section 2 of said Article V applicable, however, only to the net earnings of such property and to the indebtedness secured by such liens to which such property is subject.

ARTICLE V

THE TRUSTEE

The Trustee hereby accepts the trusts hereby declared and provided, and agrees to perform the same upon the terms and conditions in the Original Indenture and in this Supplemental Indenture set forth, and upon the following terms and conditions:

The Trustee shall not be responsible in any manner whatsoever for or in respect of the validity or sufficiency of this Supplemental Indenture or the due execution hereof by the Company or for or in respect of the recitals contained herein, all of which recitals are made by the Company solely.

ARTICLE VI

MISCELLANEOUS PROVISIONS

Section 6.1. Except as otherwise defined herein, all terms contained in this Supplemental Indenture shall, for all purposes thereof, have the meanings given to such terms in Article I of the Original Indenture.

Section 6.2. This Supplemental Indenture may be simultaneously executed in any number of counterparts, each of which when so executed shall be deemed to be an original; but such counterparts shall together constitute but one and the same instrument.

IN WITNESS WHEREOF, said Union Electric Company has caused this Supplemental Indenture to be executed on its behalf by its Chairman of the Board or President or one of its Vice Presidents and its corporate seal to be hereto affixed and said seal and this Supplemental Indenture to be attested by its Secretary or one of its Assistant Secretaries; and said The Bank of New York, in evidence of its acceptance of the trust hereby created, has caused this Supplemental Indenture to be executed on its behalf by its President or one of its Vice Presidents, and its corporate seal to be hereto affixed and said seal and this Supplemental Indenture to be attested by its Secretary, or one of its Assistant Secretaries; all as of the 1st day of February, Two thousand and four.

Attested:                               UNION ELECTRIC COMPANY,
                                         1901 Chouteau Avenue
                                         St. Louis, Missouri  63103




/s/ G. L. Waters                        By:  /s/ Jerre E. Birdsong
--------------------------------           -------------------------------------
    G. L. Waters                        Name:    Jerre E. Birdsong
 Assistant Secretary                    Title: Vice President and Treasurer


Signed, sealed and delivered by
         UNION ELECTRIC COMPANY
         in the presence of:


/s/ D. Bradley
--------------------------------
          Daphyne Bradley


/s/ Wayne K. Forbes
--------------------------------
          Wayne K. Forbes

          As Witnesses

Attested:                               THE BANK OF NEW YORK,
                                          911 Washington Avenue
                                          St. Louis, Missouri  63101


/s/ Belinda Brown                       By:  /s/ Robert J. Dunn
---------------------------------       ----------------------------------------
Belinda Brown                           Name:  Robert J. Dunn
As Agent                                Title:  As Agent

Signed, sealed and delivered by
THE BANK OF NEW YORK
in the presence of:

/s/ Daniel G. Dwyer
---------------------------------
Daniel G. Dwyer


/s/ Richard F. Novosak
---------------------------------
Richard F. Novosak

STATE OF MISSOURI          )
                           )  SS:
CITY OF ST. LOUIS          )

On this 18th day of March 2004, before me appeared JERRE E. BIRDSONG, to me personally known, who, being by me duly sworn, did say that he is Vice President and Treasurer of UNION ELECTRIC COMPANY, a corporation, and that the seal affixed to the foregoing instrument is the corporate seal of said corporation, and that said instrument was signed and sealed in behalf of said corporation by authority of its Board of Directors, and said JERRE E. BIRDSONG acknowledged said instrument to be the free act and deed of said corporation.

IN TESTIMONY WHEREOF, I have hereto set my hand and affixed my official seal at my office, in the City and State aforesaid, the day and year last above written.

/s/ S.A. Kitchens
-----------------------------------------

STATE OF MISSOURI          )
                           )  SS:
CITY OF ST. LOUIS          )

On this 18th day of March 2004, before me appeared Robert J. Dunn, to me personally known, who, being by me duly sworn, did say that he is an Agent of THE BANK OF NEW YORK, a corporation, and that the seal affixed to the foregoing instrument is the corporate seal of said corporation, and that said instrument was signed and sealed in behalf of said corporation, as the trustee thereunder by authority of its Board of Directors, and said Vice President, acknowledged said instrument to be the free act and deed of said corporation as the trustee under said instrument.

IN TESTIMONY WHEREOF, I have hereto set my hand and affixed my official seal at my office, in the City and State aforesaid, the day and year last above written.

/s/ Renee Beard
-----------------------------------------

Exhibit 4.9

FIRST AMENDMENT TO LOAN AGREEMENT

Dated as of February 1, 2004

Between

STATE ENVIRONMENTAL IMPROVEMENT AND ENERGY RESOURCES AUTHORITY

and

TABLE OF CONTENTS

(This Table of Contents is not a part of the First Amendment to Loan Agreement and is only for convenience of reference.)

SECTION                                                HEADING                                                  PAGE
ARTICLE I                  DEFINITIONS............................................................................1

       Section 1.01.       Definitions of Terms...................................................................1

ARTICLE II                 AMENDMENTS TO ORIGINAL AGREEMENT.......................................................2

       Section 2.01.       Amendments to Article V of the Original Agreement......................................2
       Section 2.02.       Amendments to Article VI of the Original Agreement.....................................4
       Section 2.03.       Amendment to Section 9.1 of the Original Agreement.....................................4

ARTICLE III                MISCELLANEOUS..........................................................................5

       Section 3.01.       Agreement Confirmed....................................................................5
       Section 3.02.       Severability...........................................................................5
       Section 3.03.       Counterparts...........................................................................5
       Section 3.04.       Applicable Provisions of Law...........................................................5
       Section 3.05.       Effective Date.........................................................................5

FIRST AMENDMENT TO LOAN AGREEMENT

THIS FIRST AMENDMENT TO LOAN AGREEMENT (this "First Amendment") is made and entered into as of February 1, 2004 between the STATE ENVIRONMENTAL IMPROVEMENT AND ENERGY RESOURCES AUTHORITY of the State of Missouri, a body corporate and politic and a governmental instrumentality of the State of Missouri (the "Issuer"), and UNION ELECTRIC COMPANY, a Missouri corporation doing business as AMERENUE (the "Company"):

WITNESSETH:

WHEREAS, on December 17, 1991 the Issuer issued its Environmental Improvement Revenue Refunding Bonds (Union Electric Company Project) Series 1991 (the "Bonds") in the original aggregate principal amount of $42,585,000 pursuant to an Indenture of Trust dated as of December 1, 1991 (the "Original Indenture") by and between the Issuer and UMB Bank & Trust, N.A., successor to Mercantile Bank of St. Louis National Association (the "Trustee"); and

WHEREAS, in connection with the issuance of the Bonds, the Issuer and the Company executed and delivered the Loan Agreement dated as of December 1, 1991 by and between the Issuer and the Company (the "Original Agreement"); and

WHEREAS, the Original Indenture is being amended and restated as the Amended and Restated Indenture of Trust of even date herewith in order to secure the Bonds with additional collateral, i.e., the Bond Insurance Policy and the Company's First Mortgage Bonds; and

WHEREAS, Section 11.02 of the Original Indenture provides that the Issuer and the Company may, with the consent of the Bondholders, enter into an agreement supplemental to the Original Agreement and Section 10.4 of the Original Agreement provides that such supplemental agreement is subject to the written consent of the Trustee; and

WHEREAS, the Issuer and the Company desire to enter into this First Amendment, as permitted by Section 11.02 of the Original Indenture and Section 10.4 of the Original Agreement, in order to amend the Original Agreement to make certain changes relating to the amendments being made to the Indenture concurrently herewith;

NOW, THEREFORE, in consideration of the foregoing and of the mutual covenants herein set forth, the parties hereto agree as follows:

ARTICLE I

DEFINITIONS

Section 1.01. Definitions of Terms. For all purposes of this First Amendment, in addition to the terms defined above in the WHEREAS clauses, unless the context clearly requires

otherwise, all terms defined in Article I of the Indenture have the same meanings in this First Amendment.

ARTICLE II

AMENDMENTS TO ORIGINAL AGREEMENT

Section 2.01. Amendments to Article V of the Original Agreement. (a) There is hereby added a new paragraph to the end of Section 5.1 of the Original Agreement to read as follows:

"The Company agrees to make all payments when due on the First Mortgage Bonds. If for any reason amounts paid to the Trustee on the First Mortgage Bonds, together with other moneys held by the Trustee and available for that purpose, would not be sufficient to make the corresponding payments of principal of, premium, if any, and interest on the Bonds corresponding to such First Mortgage Bonds when such payments become due, the Company will pay the amounts required from time to time to make up any such deficiency."

(b) Section 5.5, Section 5.6 and Section 5.7 are hereby added to the end of Article V of the Original Agreement to read as follows:

"Section 5.5. First Mortgage Bonds. The Company shall execute and deliver to the Trustee, as assignee of the Issuer, its First Mortgage Bonds. The form of the First Mortgage Bonds will be substantially as set forth in the Company's Supplemental Indenture to its Mortgage executed and delivered to the Trustee on the effective date of this First Amendment."

"Section 5.6. Payment of the Bonds from Payments of the First Mortgage Bonds and Other Amounts. Payments of principal of, and premium, if any, and interest on, the First Mortgage Bonds by the Company to the Trustee, as assignee of the Issuer, shall constitute payments of such amounts on the loan under Section
5.1(a). The Bonds shall be payable from payments made by the Company to the Trustee of principal and interest on the First Mortgage Bonds delivered hereunder. Payments of principal of or premium, if any, or interest on, the Bonds with moneys held under the Indenture for such payment shall be deemed to be like payments with respect to the First Mortgage Bonds. The obligations of the Company to make payments under the First Mortgage Bonds shall be absolute and unconditional. Whenever the Bonds are redeemable in whole or in part, the Issuer will redeem the same upon the request of the Company, and the

Company covenants and agrees to pay an amount equal to the applicable redemption price of the Bonds as a prepayment of principal of and interest due on the First Mortgage Bonds. If the Company prepays the First Mortgage Bonds, the Company's obligations under Section 5.1 will be satisfied and there will be a corresponding redemption of the Bonds. Whenever payment or provision therefor has been made in respect of the principal of or interest on all or any portion of the Bonds in accordance with the Indenture (whether at maturity or upon redemption or acceleration), the First Mortgage Bonds shall be deemed paid to the extent such payment or provision therefor has been made and is considered to be a payment of principal or interest on the Bonds. If the Bonds or any portion thereof are thereby deemed paid in full, First Mortgage Bonds in a principal amount equal to the principal amount of the Bonds so deemed to be paid shall be cancelled and returned to the Company. Subject to the foregoing or unless the Company is entitled to a credit under this Loan Agreement or the Indenture, all payments shall be in the full amount required under the First Mortgage Bonds.

The Issuer, by the terms of the Indenture, shall require the Trustee to notify in writing the Mortgage Trustee of all payments or credits with respect to the First Mortgage Bonds.

All First Mortgage Bonds shall equally and ratably secure all outstanding Bonds."

"Section 5.7. Assignment of Issuer's Rights to First Mortgage Bonds. As security for the payment of its Bonds, the Issuer hereby pledges and assigns to the Trustee the First Mortgage Bonds and the right to receive payments thereunder. The Issuer directs the Company, and the Company agrees, to pay to the Trustee at its principal corporate trust office all payments on the First Mortgage Bonds, and other payments due and payable to the Trustee hereunder. The Company will make payments directly to the Trustee without defense or set-off by reason of any dispute between the Company and the Trustee or the Issuer. The Issuer hereby agrees that the Trustee as assignee may enforce any and all rights and remedies hereunder, but retains the right to also proceed in its own name against the Company for the enforcement of the specific performance of any obligation of the Company under Sections 5.2, 7.2 and 9.3; provided, that in any such action seeking specific performance, the Issuer shall have no rights with respect to the First Mortgage Bonds and in such event the obligation of the Company to make the payments required to repay the loan hereunder and the purchase price for the Bonds and payments

required under the First Mortgage Bonds shall remain unconditional as provided in Section 5.4.

The Issuer and the Company covenant and agree that the First Mortgage Bonds will at all times be (i) in fully registered (both principal and interest) form; (ii) registered in the name of the Trustee; (iii) non-transferable except as provided in the Mortgage; and (iv) appropriately marked to indicate clearly the restrictions on the transfer thereof imposed by this Loan Agreement."

Section 2.02. Amendments to Article VI of the Original Agreement. (a) Clause (b)(i) of Section 6.1 of the Original Agreement is hereby amended to read as follows:

"(b) (i) the surviving, resulting or transferee legal entity is organized and existing under the laws of the United States, a state thereof or the District of Columbia, and (if not the Company) assumes in writing all the obligations of the Company under this Loan Agreement, the Mortgage and the First Mortgage Bonds and"

(b) Section 6.7 of the Original Agreement is hereby deleted.

Section 2.03. Amendment to Section 9.1 of the Original Agreement. (a) The first paragraph of Section 9.1 of the Original Agreement is hereby amended to read as follows:

"Whenever any Event of Default under the Indenture has occurred and is continuing, the Trustee may take whatever action may appear necessary or desirable to collect the payments then due and to become due or to enforce performance of any agreement of the Company in this Loan Agreement or in the First Mortgage Bonds."

(b) The last paragraph of Section 9.1 of the Original Agreement is hereby amended to read as follows:

"Except as may otherwise be provided under the Mortgage, nothing in this Loan Agreement shall be construed to permit the Issuer, the Trustee, any Bondholder or any receiver in any proceeding brought under the Indenture to take possession of or exclude the Company from possession of the Project by reason of the occurrence of an Event of Default."

ARTICLE III

MISCELLANEOUS

Section 3.01. Agreement Confirmed. Except as amended by this First Amendment, all of the provisions of the Original Agreement shall remain in full force and effect, and from and after the effective date of this First Amendment shall be deemed to have been amended as herein set forth.

Section 3.02. Severability. If any provision of this First Amendment shall be held or deemed to be or shall, in fact, be inoperative or unenforceable as applied in any particular case in any jurisdiction or jurisdictions or in all jurisdictions, or in all cases because it conflicts with any other provision or provisions hereof or any constitution or statute or rule of public policy, or for any other reason, such circumstances shall not have the effect of rendering the provision in question inoperative or unenforceable in any other case or circumstance, or of rendering any other provision or provisions herein contained invalid, inoperative, or unenforceable to any extent whatever.

Section 3.03. Counterparts. This First Amendment may be simultaneously executed in several counterparts, each of which shall be an original and all of which shall constitute but one and the same instrument.

Section 3.04. Applicable Provisions of Law. This First Amendment shall be governed by and construed in accordance with the laws of the State of Missouri.

Section 3.05. Effective Date. This First Amendment shall become effective on the date the Trustee has received the consent of the Trustee to the execution hereof.

IN WITNESS WHEREOF, the Issuer and the Company have caused this First Amendment to be executed in their respective corporate names, and the Issuer has caused its seal to be hereunto affixed and attested by its duly authorized officer, all as of the date first above written.

STATE ENVIRONMENTAL IMPROVEMENT AND
ENERGY RESOURCES AUTHORITY

                                        By:  /s/ Charles D. Banks
                                           -------------------------------------
                                                            Chairman

[SEAL]

ATTEST:


By:  /s/ Deron L. Cherry
   -------------------------------
                  Secretary

UNION ELECTRIC COMPANY, DBA AMERENUE

By:  /s/ Jerre E. Birdsong
   -------------------------------------
   Title:  Vice President and Treasurer

CONSENT OF THE TRUSTEE

Pursuant to Section 10.4 of the Loan Agreement between the State Environmental Improvement and Energy Resources Authority of the State of Missouri (the "Issuer") and Union Electric Company dba AmerenUE (the "Company"), dated as of December 1, 1991, UMB Bank & Trust, N.A., successor to State Street Bank and Trust Company of Missouri, N.A., as Trustee, hereby consents to the execution and delivery of the First Amendment to Loan Agreement dated as of February 1, 2004 between the Issuer and the Company.

UMB BANK & TRUST, N.A., successor to State Street Bank and Trust Company of Missouri, N.A.

                                    By:  /s/ R.A. Dengler
                                       -----------------------------------------
                                       Its  Authorized Officer

Date:  March 26, 2004

Exhibit 4.10

FIRST AMENDMENT TO LOAN AGREEMENT

Dated as of February 1, 2004

Between

STATE ENVIRONMENTAL IMPROVEMENT AND ENERGY RESOURCES AUTHORITY

and

TABLE OF CONTENTS

(This Table of Contents is not a part of the First Amendment to Loan Agreement and is only for convenience of reference.)

SECTION                                                HEADING                                                 PAGE
ARTICLE I                  DEFINITIONS............................................................................1

       Section 1.01.       Definitions of Terms...................................................................1

ARTICLE II                 AMENDMENTS TO ORIGINAL AGREEMENT.......................................................2

       Section 2.01.       Amendment to Article III of the Original Agreement.....................................2
       Section 2.02.       Amendments to Article V of the Original Agreement......................................2
       Section 2.03.       Amendments to Article VI of the Original Agreement.....................................5
       Section 2.04.       Amendment to Section 8.1 of the Original Agreement.....................................7
       Section 2.05.       Amendments to Article IX of the Original Agreement.....................................7
       Section 2.06.       Amendments to Article X of the Original Agreement......................................7

ARTICLE III                MISCELLANEOUS..........................................................................8

       Section 3.01.       Agreement Confirmed....................................................................8
       Section 3.02.       Severability...........................................................................8
       Section 3.03.       Counterparts...........................................................................8
       Section 3.04.       Applicable Provisions of Law...........................................................8
       Section 3.05.       Effective Date.........................................................................8

FIRST AMENDMENT TO LOAN AGREEMENT

THIS FIRST AMENDMENT TO LOAN AGREEMENT (this "First Amendment") is made and entered into as of February 1, 2004 between the STATE ENVIRONMENTAL IMPROVEMENT AND ENERGY RESOURCES AUTHORITY of the State of Missouri, a body corporate and politic and a governmental instrumentality of the State of Missouri (the "Issuer"), and UNION ELECTRIC COMPANY, a Missouri corporation doing business as AMERENUE (the "Company"):

WITNESSETH:

WHEREAS, on December 3, 1992 the Issuer issued its Environmental Improvement Revenue Refunding Bonds (Union Electric Company Project) Series 1992 (the "Bonds") in the original aggregate principal amount of $47,500,000 pursuant to an Indenture of Trust dated as of December 1, 1992 (the "Original Indenture") by and between the Issuer and UMB Bank & Trust, N.A., successor to Mercantile Bank of St. Louis National Association (the "Trustee"); and

WHEREAS, in connection with the issuance of the Bonds, the Issuer and the Company executed and delivered the Loan Agreement dated as of December 1, 1992 by and between the Issuer and the Company (the "Original Agreement"); and

WHEREAS, the Original Indenture is being amended and restated by the Amended and Restated Indenture of Trust of even date herewith in order to secure the Bonds with additional collateral, i.e., the Bond Insurance Policy and the Company's Mortgage Bonds; and

WHEREAS, Section 11.02 of the Original Indenture provides that the Issuer and the Company may, with the consent of the Bondholders, enter into an agreement supplemental to the Original Agreement and Section 10.4 of the Original Agreement provides that such supplemental agreement is subject to the written consent of the Trustee; and

WHEREAS, the Issuer and the Company desire to enter into this First Amendment, as permitted by Section 11.02 of the Original Indenture and Section 10.4 of the Original Agreement, in order to amend the Original Agreement to make certain changes relating to the amendments being made to the Indenture concurrently herewith;

NOW, THEREFORE, in consideration of the foregoing and of the mutual covenants herein set forth, the parties hereto agree as follows:

ARTICLE I

DEFINITIONS

Section 1.01. Definitions of Terms. For all purposes of this First Amendment, in addition to the terms defined above in the WHEREAS clauses, unless the context clearly requires otherwise, all terms defined in Article I of the Indenture have the same meanings in this First Amendment.

ARTICLE II

AMENDMENTS TO ORIGINAL AGREEMENT

Section 2.01. Amendment to Article III of the Original Agreement. The last clause of Section 3.5 of the Original Agreement is hereby amended to read as follows:

", provided that the Trustee and the Bond Insurer receive a Favorable Opinion of Tax Counsel prior to such abandonment."

Section 2.02. Amendments to Article V of the Original Agreement. (a) Subsection 5.1(a) of the Original Agreement is hereby amended to read as follows:

"(a) The Company will repay the loan made to it under
Section 4.1 as follows: Before the close of business (local time at the principal corporate office of the Registrar) on the day before each day on which any payment of either principal of or interest on the Bonds, or both, shall become due (whether at maturity, or upon redemption or acceleration or otherwise), the Company will pay, in immediately available funds, an amount which, together with other moneys held by the Tender Agent or by the Trustee under the Indenture and available therefor, will enable the Registrar to make such payment in full in a timely manner. If such day on which any payment shall become due is not a Business Day, then the payment required by this Section shall be made on or before the preceding Business Day. If the Company defaults in any payment required by this Section, the Company will pay interest (to the extent allowed by law) on such amount until paid at the rate provided for in the Bonds."

(b) The last paragraph of Section 5.1 of the Original Agreement is hereby amended to read as follows:

"All amounts payable under this Section by the Company are assigned by the Issuer to the Trustee pursuant to the Indenture for the benefit of the Bondholders and the Bond Insurer. The Company consents to such assignment. Accordingly, the Company will pay directly to the Registrar at its principal corporate trust office all payments payable by the Company pursuant to this Section."

(c) There is hereby added a new paragraph to the end of Section 5.1 of the Original Agreement to read as follows:

"The Company agrees to make all payments when due on the First Mortgage Bonds. If for any reason amounts paid to the

Trustee on the First Mortgage Bonds, together with other moneys held by the Trustee and available for that purpose, would not be sufficient to make the corresponding payments of principal of, premium, if any, and interest on the Bonds corresponding to such First Mortgage Bonds when such payments become due, the Company will pay the amounts required from time to time to make up any such deficiency."

(d) A new Subsection 5.2(d) is hereby added to the end of
Section 5.2 of the Original Agreement to read as follows:

"(d) Notwithstanding any provision herein to the contrary, payment to the Bond Insurer of all amounts due under the Insurance Agreement pursuant to the terms of the Insurance Agreement."

(e) Section 5.3 of the Original Agreement is hereby amended to read as follows:

"Section 5.3. Prepayments. The Company may at any time prepay to the Registrar all or any part of the amounts payable under Section 5.1. A prepayment will not relieve the Company of its obligations under this Loan Agreement until all the Bonds have been paid or provision for the payment of all the Bonds has been made in accordance with the Indenture and all amounts due the Bond Insurer have been paid. In the event of a mandatory redemption of the Bonds, the Company will prepay all amounts necessary for such redemption."

(f) Section 5.4 of the Original Agreement is hereby amended to read as follows:

"Section 5.4. Obligations of Company Unconditional. The Company agrees that the obligations of the Company to make the payments required by Sections 5.1 and 5.3 and to perform its other agreements contained in this Loan Agreement shall be absolute and unconditional. Until the principal of and interest on the Bonds shall have been fully paid, or provision for the payment of the Bonds made in accordance with the Indenture, and the Bond Insurer is paid in full, the Company (a) will not suspend or discontinue any payments provided for in Section 5.1, (b) will perform all its other agreements in this Loan Agreement and (c) will not terminate this Loan Agreement for any cause including any acts or circumstances that may constitute failure of consideration, destruction of or damage to the Project, commercial frustration of purpose, any change in the laws of the United States or of the State or any political subdivision of either or any failure of the Issuer to perform any of its agreements, whether express or implied, or any

duty, liability or obligation arising from or connected with this Loan Agreement."

(g) Section 5.5, Section 5.6 and Section 5.7 are hereby added to the end of Article V of the Original Agreement to read as follows:

"Section 5.5. First Mortgage Bonds. The Company shall execute and deliver to the Trustee, as assignee of the Issuer, its First Mortgage Bonds. The form of the First Mortgage Bonds will be substantially as set forth in the Company's Supplemental Indenture to its Mortgage executed and delivered to the Trustee on the effective date of this First Amendment."

"Section 5.6. Payment of the Bonds from Payments of the First Mortgage Bonds and Other Amounts. Payments of principal of, and premium, if any, and interest on, the First Mortgage Bonds by the Company to the Trustee, as assignee of the Issuer, shall constitute payments of such amounts on the loan under Section 5.1(a). The Bonds shall be payable from payments made by the Company to the Trustee of principal and interest on the First Mortgage Bonds delivered hereunder. Payments of principal of or premium, if any, or interest on, the Bonds with moneys held under the Indenture for such payment shall be deemed to be like payments with respect to the First Mortgage Bonds. The obligations of the Company to make payments under the First Mortgage Bonds shall be absolute and unconditional. Whenever the Bonds are redeemable in whole or in part, the Issuer will redeem the same upon the request of the Company, and the Company covenants and agrees to pay an amount equal to the applicable redemption price of the Bonds as a prepayment of principal of and interest due on the First Mortgage Bonds. If the Company prepays the First Mortgage Bonds, the Company's obligations under Section 5.1 will be satisfied and there will be a corresponding redemption of the Bonds. Whenever payment or provision therefor has been made in respect of the principal of or interest on all or any portion of the Bonds in accordance with the Indenture (whether at maturity or upon redemption or acceleration), the First Mortgage Bonds shall be deemed paid to the extent such payment or provision therefor has been made and is considered to be a payment of principal or interest on the Bonds. If the Bonds or any portion thereof are thereby deemed paid in full, First Mortgage Bonds in a principal amount equal to the principal amount of the Bonds so deemed to be paid shall be cancelled and returned to the Company. Subject to the foregoing or unless the Company is entitled to a credit under this Loan Agreement or the

Indenture, all payments shall be in the full amount required under the First Mortgage Bonds.

The Issuer, by the terms of the Indenture, shall require the Trustee to notify in writing the Mortgage Trustee of all payments or credits with respect to the First Mortgage Bonds.

All First Mortgage Bonds shall equally and ratably secure all outstanding Bonds."

"Section 5.7. Assignment of Issuer's Rights to First Mortgage Bonds. As security for the payment of its Bonds, the Issuer hereby pledges and assigns to the Trustee the First Mortgage Bonds and the right to receive payments thereunder. The Issuer directs the Company, and the Company agrees, to pay to the Trustee at its principal corporate trust office all payments on the First Mortgage Bonds, and other payments due and payable to the Trustee hereunder. The Company will make payments directly to the Trustee without defense or set-off by reason of any dispute between the Company and the Trustee or the Issuer. The Issuer hereby agrees that the Trustee as assignee may enforce any and all rights and remedies hereunder, but retains the right to also proceed in its own name against the Company for the enforcement of the specific performance of any obligation of the Company under Sections 5.2, 7.2 and 9.3; provided, that in any such action seeking specific performance, the Issuer shall have no rights with respect to the First Mortgage Bonds and in such event the obligation of the Company to make the payments required to repay the loan hereunder and the purchase price for the Bonds and payments required under the First Mortgage Bonds shall remain unconditional as provided in Section 5.4.

The Issuer and the Company covenant and agree that the First Mortgage Bonds will at all times be (i) in fully registered (both principal and interest) form; (ii) registered in the name of the Trustee; (iii) non-transferable except as provided in the Mortgage; and
(iv) appropriately marked to indicate clearly the restrictions on the transfer thereof imposed by this Loan Agreement."

Section 2.03. Amendments to Article VI of the Original Agreement. (a)
Section 6.1 of the Original Agreement is hereby amended to read as follows:

"Section 6.1. Maintenance of Existence. The Company agrees that during the term of this Loan Agreement and so long as any Bond is outstanding, it will maintain its corporate existence, will continue to be a corporation in good standing under the laws

of the State, will not dissolve or otherwise dispose of all or substantially all of its assets and will not consolidate with or merge into another legal entity or permit one or more other legal entities (other than one or more subsidiaries of the Company) to consolidate with or merge into it, or sell or otherwise transfer to another legal entity all or substantially all its assets as an entirety and dissolve, unless the Company's actions shall be permitted under the terms of the Insurance Agreement and (a) in the case of any merger or consolidation, the Company is the surviving corporation, or (b)(i) the surviving, resulting or transferee legal entity is organized and existing under the laws of the United States, a state thereof or the District of Columbia, and (if not the Company) assumes in writing all the obligations of the Company under this Loan Agreement, the Mortgage and the First Mortgage Bonds and (ii) no event which constitutes, or which with the giving of notice or the lapse of time or both would constitute an Event of Default shall have occurred and be continuing immediately after such merger, consolidation or transfer."

(b) The last sentence of Section 6.2 of the Original Agreement is hereby amended to read as follows:

"A copy of each such report, as well as each of its quarterly reports to shareholders, will be filed with the Issuer and the Bond Insurer."

(c) The second paragraph of Section 6.5 of the Original Agreement is hereby amended to read as follows:

"The Company covenants and agrees to notify promptly the Trustee, the Issuer and the Bond Insurer of the occurrence of any event of which the Company has notice and which event would require the Company to prepay the amounts due hereunder because of a redemption upon a determination of taxability."

(d) Section 6.7 of the Original Agreement is hereby deleted.

(e) Section 6.8 is hereby added to the Original Agreement to read as follows:

"Section 6.8. Purchase of Bonds by the Company. The Company shall not purchase or otherwise acquire Bonds without the prior written consent of the Bond Insurer unless the Company redeems or cancels such Bonds on the day of any such purchase."

Section 2.04. Amendment to Section 8.1 of the Original Agreement.
Section 8.1 of the Original Agreement is hereby amended to read as follows:

"The Company may assign its rights and obligations under this Loan Agreement with the prior written consent of the Issuer and the Bond Insurer, but no assignment will relieve the Company from primary liability for any obligations under this Loan Agreement."

Section 2.05. Amendments to Article IX of the Original Agreement. (a) The first paragraph of Section 9.1 of the Original Agreement is hereby amended to read as follows:

"Whenever any Event of Default under the Indenture has occurred and is continuing, the Trustee may, with the consent of the Bond Insurer and shall, upon direction of the Bond Insurer, take whatever action may appear necessary or desirable to collect the payments then due and to become due or to enforce performance of any agreement of the Company in this Loan Agreement or in the First Mortgage Bonds."

(b) The last paragraph of Section 9.1 of the Original Agreement is hereby amended to read as follows:

"Except as may otherwise be provided under the Mortgage, nothing in this Loan Agreement shall be construed to permit the Issuer, the Trustee, any Bondholder or any receiver in any proceeding brought under the Indenture to take possession of or exclude the Company from possession of the Project by reason of the occurrence of an Event of Default."

(c) Section 9.2 of the Original Agreement is hereby amended to read as follows:

"Section 9.2. Delay Not Waiver; Remedies. A delay or omission by the Issuer, the Bond Insurer or the Trustee in exercising any right or remedy accruing upon an Event of Default shall not impair the right or remedy or constitute a waiver of or acquiescence in the Event of Default. No remedy is exclusive of any other remedy. All available remedies are cumulative."

Section 2.06. Amendments to Article X of the Original Agreement.
(a) Section 10.4 of the Original Agreement is hereby amended to read as follows:

"After the issuance of the Bonds, this Loan Agreement may not be effectively amended or terminated without the written consent of the Trustee, the Bond Insurer and the Tender Agent and in accordance with the provisions of the Indenture."

(b) Section 10.10 is hereby added to the end of Article X of the Original Agreement to read as follows:

"Section 10.10. Third Party Beneficiary. The Bond Insurer is a third party beneficiary of this Loan Agreement."

Article III

Miscellaneous

Section 3.01. Agreement Confirmed. Except as amended by this First Amendment, all of the provisions of the Original Agreement shall remain in full force and effect, and from and after the effective date of this First Amendment shall be deemed to have been amended as herein set forth.

Section 3.02. Severability. If any provision of this First Amendment shall be held or deemed to be or shall, in fact, be inoperative or unenforceable as applied in any particular case in any jurisdiction or jurisdictions or in all jurisdictions, or in all cases because it conflicts with any other provision or provisions hereof or any constitution or statute or rule of public policy, or for any other reason, such circumstances shall not have the effect of rendering the provision in question inoperative or unenforceable in any other case or circumstance, or of rendering any other provision or provisions herein contained invalid, inoperative, or unenforceable to any extent whatever.

Section 3.03. Counterparts. This First Amendment may be simultaneously executed in several counterparts, each of which shall be an original and all of which shall constitute but one and the same instrument.

Section 3.04. Applicable Provisions of Law. This First Amendment shall be governed by and construed in accordance with the laws of the State of Missouri.

Section 3.05. Effective Date. This First Amendment shall become effective on the date the Trustee has received the consent of the Trustee to the execution hereof.

In Witness Whereof, the Issuer and the Company have caused this First Amendment to be executed in their respective corporate names, and the Issuer has caused its seal to be hereunto affixed and attested by its duly authorized officer, all as of the date first above written.

State Environmental Improvement and Energy Resources Authority

                                          By: /s/ Charles D. Banks
                                             -----------------------------------
                                                         Chairman

[Seal]

Attest:


By: /s/ Deron L. Cherry
   ----------------------------------
               Secretary

Union Electric Company, dba AmerenUE

By: /s/ Jerre E. Birdsong
   -----------------------------------
  Title:  Vice President and Treasurer

Consent of the Trustee

Pursuant to Section 10.4 of the Loan Agreement between the State Environmental Improvement and Energy Resources Authority of the State of Missouri (the "Issuer") and Union Electric Company dba AmerenUE (the "Company"), dated as of December 1, 1992, UMB Bank & Trust, N.A., successor to State Street Bank and Trust Company of Missouri, N.A., as Trustee, hereby consents to the execution and delivery of the First Amendment to Loan Agreement dated as of February 1, 2004 between the Issuer and the Company.

UUMB Bank & Trust, N.A., successor to State Street Bank and Trust Company of Missouri, N.A.

                                        By: /s/ R. A. Dengler
                                           -------------------------------------
                                           Its  Authorized Officer

Date:  March 26, 2004

Exhibit 4.11

FIRST AMENDMENT TO LOAN AGREEMENT

Dated as of February 1, 2004

Between

STATE ENVIRONMENTAL IMPROVEMENT AND ENERGY RESOURCES AUTHORITY

and

TABLE OF CONTENTS

(This Table of Contents is not a part of the First Amendment to Loan Agreement and is only for convenience of reference.)

SECTION                                                HEADING                                                   PAGE
ARTICLE I                  DEFINITIONS............................................................................2

       Section 1.01.       Definitions of Terms...................................................................2

ARTICLE II                 AMENDMENTS TO ORIGINAL AGREEMENT.......................................................2

       Section 2.01.       Amendment to Article III of the Original Agreement.....................................2
       Section 2.02.       Amendments to Article V of the Original Agreement......................................2
       Section 2.03.       Amendments to Article VI of the Original Agreement.....................................6
       Section 2.04.       Amendment to Section 8.1 of the Original Agreement.....................................7
       Section 2.05.       Amendments to Article IX of the Original Agreement.....................................7
       Section 2.06.       Amendments to Section 10.4 of the Original Agreement...................................8

ARTICLE III                MISCELLANEOUS..........................................................................8

       Section 3.01.       Agreement Confirmed....................................................................8
       Section 3.02.       Severability...........................................................................8
       Section 3.03.       Counterparts...........................................................................8
       Section 3.04.       Applicable Provisions of Law...........................................................9
       Section 3.05.       Effective Date.........................................................................9

FIRST AMENDMENT TO LOAN AGREEMENT

THIS FIRST AMENDMENT TO LOAN AGREEMENT (this "First Amendment") is made and entered into as of February 1, 2004 between the STATE ENVIRONMENTAL IMPROVEMENT AND ENERGY RESOURCES AUTHORITY of the State of Missouri, a body corporate and politic and a governmental instrumentality of the State of Missouri (the "Issuer"), and UNION ELECTRIC COMPANY, a Missouri corporation doing business as AMERENUE (the "Company"):

WITNESSETH:

WHEREAS, on September 4, 1998 the Issuer issued its Environmental Improvement Revenue Refunding Bonds (Union Electric Company Project) Series 1998A (the "Bonds") in the original aggregate principal amount of $60,000,000 pursuant to an Indenture of Trust dated as of September 1, 1998 (the "Original Indenture") by and between the Issuer and UMB Bank & Trust, N.A., successor to State Street Bank and Trust Company of Missouri, N.A. (the "Trustee"); and

WHEREAS, in connection with the issuance of the Bonds, the Issuer and the Company executed and delivered the Loan Agreement dated as of September 1, 1998 by and between the Issuer and the Company (the "Original Agreement"); and

WHEREAS, the Original Indenture is being amended and restated by the Amended and Restated Indenture of Trust of even date herewith in order to add provisions relating to a bond insurance policy for the Bonds and to permit the delivery to the Trustee by the Company of its mortgage bonds to further secure the Bonds; and

WHEREAS, Section 11.01 of the Original Indenture provides that the Issuer and the Company may, without notice to or the consent of any Bondholder, enter into an agreement supplemental to the Original Agreement to make changes in connection with any authorized amendment or supplement to the Indenture, and
Section 10.4 of the Original Agreement provides that such supplemental agreement is subject to the written consent of the Trustee; and

WHEREAS, the Issuer and the Company desire to enter into this First Amendment, as permitted by Section 11.01 of the Original Indenture and Section 10.4 of the Original Agreement, in order to amend the Original Agreement to make certain changes relating to the amendments being made to the Indenture concurrently herewith;

NOW, THEREFORE, in consideration of the foregoing and of the mutual covenants herein set forth, the parties hereto agree as follows:

ARTICLE I

DEFINITIONS

Section 1.01. Definitions of Terms. For all purposes of this First Amendment, in addition to the terms defined above in the WHEREAS clauses, unless the context clearly requires otherwise, all terms defined in Article I of the Indenture have the same meanings in this First Amendment.

ARTICLE II

AMENDMENTS TO ORIGINAL AGREEMENT

Section 2.01. Amendment to Article III of the Original Agreement. The last clause of Section 3.5 of the Original Agreement is hereby amended to read as follows:

", provided that the Trustee and the Bond Insurer receive a Favorable Opinion of Tax Counsel prior to such abandonment."

Section 2.02. Amendments to Article V of the Original Agreement. (a) Subsection 5.1(a) of the Original Agreement is hereby amended to read as follows:

"(a) The Company will repay the loan made to it under
Section 4.1 as follows: Before the close of business (local time at the principal corporate office of the Registrar) on the day before each day on which any payment of either principal of or interest on the Bonds, or both, shall become due (whether at maturity, or upon redemption or acceleration or otherwise), the Company will pay, in immediately available funds, an amount which, together with other moneys held by the Tender Agent or by the Trustee under the Indenture and available therefor, will enable the Registrar to make such payment in full in a timely manner. If such day on which any payment shall become due is not a Business Day, then the payment required by this Section shall be made on or before the preceding Business Day. If the Company defaults in any payment required by this Section, the Company will pay interest (to the extent allowed by law) on such amount until paid at the rate provided for in the Bonds."

(b) The last paragraph of Section 5.1 of the Original Agreement is hereby amended to read as follows:

"All amounts payable under this Section by the Company are assigned by the Issuer to the Trustee pursuant to the Indenture for the benefit of the Bondholders and the Bond Insurer. The

Company consents to such assignment. Accordingly, the Company will pay directly to the Registrar at its principal corporate trust office all payments payable by the Company pursuant to this Section."

(c) There is hereby added a new paragraph to the end of Section 5.1 of the Original Agreement to read as follows:

"The Company agrees to make all payments when due on the First Mortgage Bonds. If for any reason amounts paid to the Trustee on the First Mortgage Bonds, together with other moneys held by the Trustee and available for that purpose, would not be sufficient to make the corresponding payments of principal of, premium, if any, and interest on the Bonds corresponding to such First Mortgage Bonds when such payments become due, the Company will pay the amounts required from time to time to make up any such deficiency."

(d) A new Subsection 5.2(d) is hereby added to the end of Section 5.2 of the Original Agreement to read as follows:

"(d) Notwithstanding any provision herein to the contrary, payment to the Bond Insurer of all amounts due under the Insurance Agreement pursuant to the terms of the Insurance Agreement."

(e) Section 5.3 of the Original Agreement is hereby amended to read as follows:

"Section 5.3. Prepayments. The Company may at any time prepay to the Registrar all or any part of the amounts payable under Section 5.1. A prepayment will not relieve the Company of its obligations under this Loan Agreement until all the Bonds have been paid or provision for the payment of all the Bonds has been made in accordance with the Indenture and all amounts due the Bond Insurer have been paid. In the event of a mandatory redemption of the Bonds, the Company will prepay all amounts necessary for such redemption."

(f) Section 5.4 of the Original Agreement is hereby amended to read as follows:

"Section 5.4. Obligations of Company Unconditional. The Company agrees that the obligations of the Company to make the payments required by Sections 5.1 and 5.3 and to perform its other agreements contained in this Loan Agreement shall be absolute and unconditional. Until the principal of and interest on the Bonds shall have been fully paid, or provision for the payment

of the Bonds made in accordance with the Indenture, and the Bond Insurer is paid in full, the Company (a) will not suspend or discontinue any payments provided for in Section 5.1, (b) will perform all its other agreements in this Loan Agreement and (c) will not terminate this Loan Agreement for any cause including any acts or circumstances that may constitute failure of consideration, destruction of or damage to the Project, commercial frustration of purpose, any change in the laws of the United States or of the State or any political subdivision of either or any failure of the Issuer to perform any of its agreements, whether express or implied, or any duty, liability or obligation arising from or connected with this Loan Agreement."

(g) Section 5.5, Section 5.6 and Section 5.7 are hereby added to the end of Article V of the Original Agreement to read as follows:

"Section 5.5. First Mortgage Bonds. The Company shall execute and deliver to the Trustee, as assignee of the Issuer, its First Mortgage Bonds. The form of the First Mortgage Bonds will be substantially as set forth in the Company's Supplemental Indenture to its Mortgage executed and delivered to the Trustee on the effective date of this First Amendment."

"Section 5.6. Payment of the Bonds from Payments of the First Mortgage Bonds and Other Amounts. Payments of principal of, and premium, if any, and interest on, the First Mortgage Bonds by the Company to the Trustee, as assignee of the Issuer, shall constitute payments of such amounts on the loan under Section 5.1(a) or of the purchase price for the Bonds under Section 5.1(b). The Bonds shall be payable from payments made by the Company to the Trustee of principal and interest on the First Mortgage Bonds delivered hereunder. Payments of principal of or premium, if any, or interest on, or the purchase price for, the Bonds with moneys held under the Indenture for such payment shall be deemed to be like payments with respect to the First Mortgage Bonds. The obligations of the Company to make payments under the First Mortgage Bonds shall be absolute and unconditional. Whenever the Bonds are redeemable in whole or in part, the Issuer will redeem the same upon the request of the Company, and the Company covenants and agrees to pay an amount equal to the applicable redemption price of the Bonds as a prepayment of principal of and interest due on the First Mortgage Bonds. If the Company prepays the First Mortgage Bonds, the Company's obligations under
Section 5.1 will be satisfied and there will be a corresponding redemption of the Bonds. Whenever payment or provision therefor has been made in respect of the principal of or

interest on all or any portion of the Bonds in accordance with the Indenture (whether at maturity or upon redemption or acceleration), the First Mortgage Bonds shall be deemed paid to the extent such payment or provision therefor has been made and is considered to be a payment of principal or interest on the Bonds. If the Bonds or any portion thereof are thereby deemed paid in full, First Mortgage Bonds in a principal amount equal to the principal amount of the Bonds so deemed to be paid shall be cancelled and returned to the Company. Subject to the foregoing or unless the Company is entitled to a credit under this Loan Agreement or the Indenture, all payments shall be in the full amount required under the First Mortgage Bonds.

The Issuer, by the terms of the Indenture, shall require the Trustee to notify in writing the Mortgage Trustee of all payments or credits with respect to the First Mortgage Bonds.

All First Mortgage Bonds shall equally and ratably secure all outstanding Bonds."

"Section 5.7. Assignment of Issuer's Rights to First Mortgage Bonds. As security for the payment of its Bonds, the Issuer hereby pledges and assigns to the Trustee the First Mortgage Bonds and the right to receive payments thereunder. The Issuer directs the Company, and the Company agrees, to pay to the Trustee at its principal corporate trust office all payments on the First Mortgage Bonds, and other payments due and payable to the Trustee hereunder. The Company will make payments directly to the Trustee without defense or set-off by reason of any dispute between the Company and the Trustee or the Issuer. The Issuer hereby agrees that the Trustee as assignee may enforce any and all rights and remedies hereunder, but retains the right to also proceed in its own name against the Company for the enforcement of the specific performance of any obligation of the Company under Sections 5.2, 7.2 and 9.3; provided, that in any such action seeking specific performance, the Issuer shall have no rights with respect to the First Mortgage Bonds and in such event the obligation of the Company to make the payments required to repay the loan hereunder and the purchase price for the Bonds and payments required under the First Mortgage Bonds shall remain unconditional as provided in Section 5.4.

The Issuer and the Company covenant and agree that the First Mortgage Bonds will at all times be (i) in fully registered (both principal and interest) form; (ii) registered in the name of the Trustee; (iii) non-transferable except as provided in the Mortgage;

and (iv) appropriately marked to indicate clearly the restrictions on the transfer thereof imposed by this Loan Agreement."

Section 2.03. Amendments to Article VI of the Original Agreement. (a)
Section 6.1 of the Original Agreement is hereby amended to read as follows:

"Section 6.1. Maintenance of Existence. The Company agrees that during the term of this Loan Agreement and so long as any Bond is outstanding, it will maintain its corporate existence, will continue to be a corporation in good standing under the laws of the State, will not dissolve or otherwise dispose of all or substantially all of its assets and will not consolidate with or merge into another legal entity or permit one or more other legal entities (other than one or more subsidiaries of the Company) to consolidate with or merge into it, or sell or otherwise transfer to another legal entity all or substantially all its assets as an entirety and dissolve, unless the Company's actions shall be permitted under the terms of the Insurance Agreement and (a) in the case of any merger or consolidation, the Company is the surviving corporation, or
(b)(i) the surviving, resulting or transferee legal entity is organized and existing under the laws of the United States, a state thereof or the District of Columbia, and (if not the Company) assumes in writing all the obligations of the Company under this Loan Agreement, the Mortgage and the First Mortgage Bonds and (ii) no event which constitutes, or which with the giving of notice or the lapse of time or both would constitute an Event of Default shall have occurred and be continuing immediately after such merger, consolidation or transfer."

(b) A new sentence is hereby added to the end of Section 6.2 of the Original Agreement to read as follows:

"A copy of each such report furnished to the Trustee will be filed with the Bond Insurer."

(c) The second paragraph of Section 6.5 of the Original Agreement is hereby amended to read as follows:

"The Company covenants and agrees to notify promptly the Trustee, Issuer and the Bond Insurer of the occurrence of any event of which the Company has notice and which event would require the Company to prepay the amounts due hereunder because of a redemption upon a determination of taxability."

(d) Section 6.7 of the Original Agreement is hereby deleted.

(e) Section 6.9 of the Original Agreement is hereby amended to read as follows:

"The Company shall not purchase or otherwise acquire Bonds without the prior written consent of the Bond Insurer unless the Company redeems or cancels such Bonds on the day of any such purchase."

Section 2.04. Amendment to Section 8.1 of the Original Agreement. Section 8.1 of the Original Agreement is hereby amended to read as follows:

"The Company may assign its rights and obligations under this Loan Agreement with the prior written consent of the Issuer and the Bond Insurer, but no assignment will relieve the Company from primary liability for any obligations under this Loan Agreement."

Section 2.05. Amendments to Article IX of the Original Agreement. (a) The first paragraph of Section 9.1 of the Original Agreement is hereby amended to read as follows:

"Whenever any Event of Default under the Indenture has occurred and is continuing, the Trustee may, with the consent of the Bond Insurer and shall, upon direction of the Bond Insurer, take whatever action may appear necessary or desirable to collect the payments then due and to become due or to enforce performance of any agreement of the Company in this Loan Agreement or in the First Mortgage Bonds."

(b) The last paragraph of Section 9.1 of the Original Agreement is hereby amended to read as follows:

"Except as may otherwise be provided under the Mortgage, nothing in this Loan Agreement shall be construed to permit the Issuer, the Trustee, any Bondholder or any receiver in any proceeding brought under the Indenture to take possession of or exclude the Company from possession of the Project by reason of the occurrence of an Event of Default."

(c) Section 9.2 of the Original Agreement is hereby amended to read as follows:

"Section 9.2. Delay Not Waiver; Remedies. A delay or omission by the Issuer, the Bond Insurer or the Trustee in exercising any right or remedy accruing upon an Event of Default shall not impair the right or remedy or constitute a waiver of or acquiescence in the Event of Default. No remedy is exclusive of any other remedy. All available remedies are cumulative."

Section 2.06. Amendments to Article X of the Original Agreement. (a)
Section 10.4 of the Original Agreement is hereby amended to read as follows:

"After the issuance of the Bonds, this Loan Agreement may not be effectively amended or terminated without the written consent of the Trustee, the Bond Insurer and the Tender Agent and in accordance with the provisions of the Indenture."

(b) Section 10.11 is hereby added to the end of Article X of the Original Agreement to read as follows:

"Section 10.11. Third Party Beneficiary. The Bond Insurer is a third party beneficiary of this Loan Agreement."

ARTICLE III

MISCELLANEOUS

Section 3.01. Agreement Confirmed. Except as amended by this First Amendment, all of the provisions of the Original Agreement shall remain in full force and effect, and from and after the effective date of this First Amendment shall be deemed to have been amended as herein set forth.

Section 3.02. Severability. If any provision of this First Amendment shall be held or deemed to be or shall, in fact, be inoperative or unenforceable as applied in any particular case in any jurisdiction or jurisdictions or in all jurisdictions, or in all cases because it conflicts with any other provision or provisions hereof or any constitution or statute or rule of public policy, or for any other reason, such circumstances shall not have the effect of rendering the provision in question inoperative or unenforceable in any other case or circumstance, or of rendering any other provision or provisions herein contained invalid, inoperative, or unenforceable to any extent whatever.

Section 3.03. Counterparts. This First Amendment may be simultaneously executed in several counterparts, each of which shall be an original and all of which shall constitute but one and the same instrument.

Section 3.04. Applicable Provisions of Law. This First Amendment shall be governed by and construed in accordance with the laws of the State of Missouri.

Section 3.05. Effective Date. This First Amendment shall become effective on the date the Trustee has received the consent of the Trustee to the execution hereof.

IN WITNESS WHEREOF, the Issuer and the Company have caused this First Amendment to be executed in their respective corporate names, and the Issuer has caused its seal to be hereunto affixed and attested by its duly authorized officer, all as of the date first above written.

STATE ENVIRONMENTAL IMPROVEMENT AND
ENERGY RESOURCES AUTHORITY

                                  By /s/ Charles D. Banks
                                    --------------------------------------------
                                                   Chairman


[SEAL]

ATTEST:

By /s/ Deron L. Cherry
  ----------------------------
           Secretary
                                  UNION ELECTRIC COMPANY, DBA AMERENUE


                                  By: /s/ Jerre E. Birdsong
                                     -------------------------------------------
                                  Title:  Vice President and Treasurer

CONSENT OF THE TRUSTEE

Pursuant to Section 10.4 of the Loan Agreement between the State Environmental Improvement and Energy Resources Authority of the State of Missouri (the "Issuer") and Union Electric Company dba AmerenUE (the "Company"), dated as of September 1, 1998, UMB Bank & Trust, N.A., successor to State Street Bank and Trust Company of Missouri, N.A., as Trustee, hereby consents to the execution and delivery of the First Amendment to Loan Agreement dated as of February 1, 2004 between the Issuer and the Company.

UMB BANK & TRUST, N.A., successor to State Street Bank and Trust Company of Missouri, N.A.

                                 By /s/ Rebecca A. Dengler
                                   -----------------------------------------
                                   Its  Authorized Officer

Date:  February 24, 2004

Exhibit 4.12

FIRST AMENDMENT TO LOAN AGREEMENT

Dated as of February 1, 2004

Between

STATE ENVIRONMENTAL IMPROVEMENT AND ENERGY RESOURCES AUTHORITY

and

TABLE OF CONTENTS

(This Table of Contents is not a part of the First Amendment to Loan Agreement and is only for convenience of reference.)

SECTION                                                HEADING                                                   PAGE
ARTICLE I                  DEFINITIONS............................................................................2

       Section 1.01.       Definitions of Terms...................................................................2

ARTICLE II                 AMENDMENTS TO ORIGINAL AGREEMENT.......................................................2

       Section 2.01.       Amendment to Article III of the Original Agreement.....................................2
       Section 2.02.       Amendments to Article V of the Original Agreement......................................2
       Section 2.03.       Amendments to Article VI of the Original Agreement.....................................6
       Section 2.04.       Amendment to Section 8.1 of the Original Agreement.....................................7
       Section 2.05.       Amendments to Article IX of the Original Agreement.....................................7
       Section 2.06.       Amendments to Section 10.4 of the Original Agreement...................................8

ARTICLE III                MISCELLANEOUS..........................................................................8

       Section 3.01.       Agreement Confirmed....................................................................8
       Section 3.02.       Severability...........................................................................8
       Section 3.03.       Counterparts...........................................................................8
       Section 3.04.       Applicable Provisions of Law...........................................................8
       Section 3.05.       Effective Date.........................................................................8

FIRST AMENDMENT TO LOAN AGREEMENT

THIS FIRST AMENDMENT TO LOAN AGREEMENT (this "First Amendment") is made and entered into as of February 1, 2004 between the STATE ENVIRONMENTAL IMPROVEMENT AND ENERGY RESOURCES AUTHORITY of the State of Missouri, a body corporate and politic and a governmental instrumentality of the State of Missouri (the "Issuer"), and UNION ELECTRIC COMPANY, a Missouri corporation doing business as AMERENUE (the "Company"):

WITNESSETH:

WHEREAS, on September 4, 1998 the Issuer issued its Environmental Improvement Revenue Refunding Bonds (Union Electric Company Project) Series 1998B (the "Bonds") in the original aggregate principal amount of $50,000,000 pursuant to an Indenture of Trust dated as of September 1, 1998 (the "Original Indenture") by and between the Issuer and UMB Bank & Trust, N.A., successor to State Street Bank and Trust Company of Missouri, N.A. (the "Trustee"); and

WHEREAS, in connection with the issuance of the Bonds, the Issuer and the Company executed and delivered the Loan Agreement dated as of September 1, 1998 by and between the Issuer and the Company (the "Original Agreement"); and

WHEREAS, the Original Indenture is being amended and restated by the Amended and Restated Indenture of Trust of even date herewith in order to add provisions relating to a bond insurance policy for the Bonds and to permit the delivery to the Trustee by the Company of its mortgage bonds to further secure the Bonds; and

WHEREAS, Section 11.01 of the Original Indenture provides that the Issuer and the Company may, without notice to or the consent of any Bondholder, enter into an agreement supplemental to the Original Agreement to make changes in connection with any authorized amendment or supplement to the Indenture, and
Section 10.4 of the Original Agreement provides that such supplemental agreement is subject to the written consent of the Trustee; and

WHEREAS, the Issuer and the Company desire to enter into this First Amendment, as permitted by Section 11.01 of the Original Indenture and Section 10.4 of the Original Agreement, in order to amend the Original Agreement to make certain changes relating to the amendments being made to the Indenture concurrently herewith;

NOW, THEREFORE, in consideration of the foregoing and of the mutual covenants herein set forth, the parties hereto agree as follows:

ARTICLE I

DEFINITIONS

Section 1.01. Definitions of Terms. For all purposes of this First Amendment, in addition to the terms defined above in the WHEREAS clauses, unless the context clearly requires otherwise, all terms defined in Article I of the Indenture have the same meanings in this First Amendment.

ARTICLE II

AMENDMENTS TO ORIGINAL AGREEMENT

Section 2.01. Amendment to Article III of the Original Agreement. The last clause of Section 3.5 of the Original Agreement is hereby amended to read as follows:

", provided that the Trustee and the Bond Insurer receive a Favorable Opinion of Tax Counsel prior to such abandonment."

Section 2.02. Amendments to Article V of the Original Agreement. (a) Subsection 5.1(a) of the Original Agreement is hereby amended to read as follows:

"(a) The Company will repay the loan made to it under
Section 4.1 as follows: Before the close of business (local time at the principal corporate office of the Registrar) on the day before each day on which any payment of either principal of or interest on the Bonds, or both, shall become due (whether at maturity, or upon redemption or acceleration or otherwise), the Company will pay, in immediately available funds, an amount which, together with other moneys held by the Tender Agent or by the Trustee under the Indenture and available therefor, will enable the Registrar to make such payment in full in a timely manner. If such day on which any payment shall become due is not a Business Day, then the payment required by this Section shall be made on or before the preceding Business Day. If the Company defaults in any payment required by this Section, the Company will pay interest (to the extent allowed by law) on such amount until paid at the rate provided for in the Bonds."

(b) The last paragraph of Section 5.1 of the Original Agreement is hereby amended to read as follows:

"All amounts payable under this Section by the Company are assigned by the Issuer to the Trustee pursuant to the Indenture for the benefit of the Bondholders and the Bond Insurer. The

Company consents to such assignment. Accordingly, the Company will pay directly to the Registrar at its principal corporate trust office all payments payable by the Company pursuant to this Section."

(c) There is hereby added a new paragraph to the end of Section 5.1 of the Original Agreement to read as follows:

"The Company agrees to make all payments when due on the First Mortgage Bonds. If for any reason amounts paid to the Trustee on the First Mortgage Bonds, together with other moneys held by the Trustee and available for that purpose, would not be sufficient to make the corresponding payments of principal of, premium, if any, and interest on the Bonds corresponding to such First Mortgage Bonds when such payments become due, the Company will pay the amounts required from time to time to make up any such deficiency."

(d) A new Subsection 5.2(d) is hereby added to the end of Section 5.2 of the Original Agreement to read as follows:

"(d) Notwithstanding any provision herein to the contrary, payment to the Bond Insurer of all amounts due under the Insurance Agreement pursuant to the terms of the Insurance Agreement."

(e) Section 5.3 of the Original Agreement is hereby amended to read as follows:

"Section 5.3. Prepayments. The Company may at any time prepay to the Registrar all or any part of the amounts payable under Section 5.1. A prepayment will not relieve the Company of its obligations under this Loan Agreement until all the Bonds have been paid or provision for the payment of all the Bonds has been made in accordance with the Indenture and all amounts due the Bond Insurer have been paid. In the event of a mandatory redemption of the Bonds, the Company will prepay all amounts necessary for such redemption."

(f) Section 5.4 of the Original Agreement is hereby amended to read as follows:

"Section 5.4. Obligations of Company Unconditional. The Company agrees that the obligations of the Company to make the payments required by Sections 5.1 and 5.3 and to perform its other agreements contained in this Loan Agreement shall be absolute and unconditional. Until the principal of and interest on the Bonds shall have been fully paid, or provision for the payment

of the Bonds made in accordance with the Indenture, and the Bond Insurer is paid in full, the Company (a) will not suspend or discontinue any payments provided for in Section 5.1, (b) will perform all its other agreements in this Loan Agreement and (c) will not terminate this Loan Agreement for any cause including any acts or circumstances that may constitute failure of consideration, destruction of or damage to the Project, commercial frustration of purpose, any change in the laws of the United States or of the State or any political subdivision of either or any failure of the Issuer to perform any of its agreements, whether express or implied, or any duty, liability or obligation arising from or connected with this Loan Agreement."

(g) Section 5.5, Section 5.6 and Section 5.7 are hereby added to the end of Article V of the Original Agreement to read as follows:

"Section 5.5. First Mortgage Bonds. The Company shall execute and deliver to the Trustee, as assignee of the Issuer, its First Mortgage Bonds. The form of the First Mortgage Bonds will be substantially as set forth in the Company's Supplemental Indenture to its Mortgage executed and delivered to the Trustee on the effective date of this First Amendment."

"Section 5.6. Payment of the Bonds from Payments of the First Mortgage Bonds and Other Amounts. Payments of principal of, and premium, if any, and interest on, the First Mortgage Bonds by the Company to the Trustee, as assignee of the Issuer, shall constitute payments of such amounts on the loan under Section 5.1(a) or of the purchase price for the Bonds under Section
5.1(b). The Bonds shall be payable from payments made by the Company to the Trustee of principal and interest on the First Mortgage Bonds delivered hereunder. Payments of principal of or premium, if any, or interest on, or the purchase price for, the Bonds with moneys held under the Indenture for such payment shall be deemed to be like payments with respect to the First Mortgage Bonds. The obligations of the Company to make payments under the First Mortgage Bonds shall be absolute and unconditional. Whenever the Bonds are redeemable in whole or in part, the Issuer will redeem the same upon the request of the Company, and the Company covenants and agrees to pay an amount equal to the applicable redemption price of the Bonds as a prepayment of principal of and interest due on the First Mortgage Bonds. If the Company prepays the First Mortgage Bonds, the Company's obligations under Section 5.1 will be satisfied and there will be a corresponding redemption of the Bonds. Whenever payment or provision therefor has been made in respect of the principal of or

interest on all or any portion of the Bonds in accordance with the Indenture (whether at maturity or upon redemption or acceleration), the First Mortgage Bonds shall be deemed paid to the extent such payment or provision therefor has been made and is considered to be a payment of principal or interest on the Bonds. If the Bonds or any portion thereof are thereby deemed paid in full, First Mortgage Bonds in a principal amount equal to the principal amount of the Bonds so deemed to be paid shall be cancelled and returned to the Company. Subject to the foregoing or unless the Company is entitled to a credit under this Loan Agreement or the Indenture, all payments shall be in the full amount required under the First Mortgage Bonds.

The Issuer, by the terms of the Indenture, shall require the Trustee to notify in writing the Mortgage Trustee of all payments or credits with respect to the First Mortgage Bonds.

All First Mortgage Bonds shall equally and ratably secure all outstanding Bonds."

"Section 5.7. Assignment of Issuer's Rights to First Mortgage Bonds. As security for the payment of its Bonds, the Issuer hereby pledges and assigns to the Trustee the First Mortgage Bonds and the right to receive payments thereunder. The Issuer directs the Company, and the Company agrees, to pay to the Trustee at its principal corporate trust office all payments on the First Mortgage Bonds, and other payments due and payable to the Trustee hereunder. The Company will make payments directly to the Trustee without defense or set-off by reason of any dispute between the Company and the Trustee or the Issuer. The Issuer hereby agrees that the Trustee as assignee may enforce any and all rights and remedies hereunder, but retains the right to also proceed in its own name against the Company for the enforcement of the specific performance of any obligation of the Company under Sections 5.2, 7.2 and 9.3; provided, that in any such action seeking specific performance, the Issuer shall have no rights with respect to the First Mortgage Bonds and in such event the obligation of the Company to make the payments required to repay the loan hereunder and the purchase price for the Bonds and payments required under the First Mortgage Bonds shall remain unconditional as provided in Section 5.4.

The Issuer and the Company covenant and agree that the First Mortgage Bonds will at all times be (i) in fully registered (both principal and interest) form; (ii) registered in the name of the Trustee; (iii) non-transferable except as provided in the Mortgage;

and (iv) appropriately marked to indicate clearly the restrictions on the transfer thereof imposed by this Loan Agreement."

Section 2.03. Amendments to Article VI of the Original Agreement. (a)
Section 6.1 of the Original Agreement is hereby amended to read as follows:

"Section 6.1. Maintenance of Existence. The Company agrees that during the term of this Loan Agreement and so long as any Bond is outstanding, it will maintain its corporate existence, will continue to be a corporation in good standing under the laws of the State, will not dissolve or otherwise dispose of all or substantially all of its assets and will not consolidate with or merge into another legal entity or permit one or more other legal entities (other than one or more subsidiaries of the Company) to consolidate with or merge into it, or sell or otherwise transfer to another legal entity all or substantially all its assets as an entirety and dissolve, unless the Company's actions shall be permitted under the terms of the Insurance Agreement and (a) in the case of any merger or consolidation, the Company is the surviving corporation, or (b)(i) the surviving, resulting or transferee legal entity is organized and existing under the laws of the United States, a state thereof or the District of Columbia, and (if not the Company) assumes in writing all the obligations of the Company under this Loan Agreement, the Mortgage and the First Mortgage Bonds and (ii) no event which constitutes, or which with the giving of notice or the lapse of time or both would constitute an Event of Default shall have occurred and be continuing immediately after such merger, consolidation or transfer."

(b) A new sentence is hereby added to the end of Section 6.2 of the Original Agreement to read as follows:

"A copy of each such report furnished to the Trustee will be filed with the Bond Insurer."

(c) The second paragraph of Section 6.5 of the Original Agreement is hereby amended to read as follows:

"The Company covenants and agrees to notify promptly the Trustee, Issuer and the Bond Insurer of the occurrence of any event of which the Company has notice and which event would require the Company to prepay the amounts due hereunder because of a redemption upon a determination of taxability."

(d) Section 6.7 of the Original Agreement is hereby deleted.

(e) Section 6.9 of the Original Agreement is hereby amended to read as follows:

"The Company shall not purchase or otherwise acquire Bonds without the prior written consent of the Bond Insurer unless the Company redeems or cancels such Bonds on the day of any such purchase."

Section 2.04. Amendment to Section 8.1 of the Original Agreement.
Section 8.1 of the Original Agreement is hereby amended to read as follows:

"The Company may assign its rights and obligations under this Loan Agreement with the prior written consent of the Issuer and the Bond Insurer, but no assignment will relieve the Company from primary liability for any obligations under this Loan Agreement."

Section 2.05. Amendments to Article IX of the Original Agreement. (a) The first paragraph of Section 9.1 of the Original Agreement is hereby amended to read as follows:

"Whenever any Event of Default under the Indenture has occurred and is continuing, the Trustee may, with the consent of the Bond Insurer and shall, upon direction of the Bond Insurer, take whatever action may appear necessary or desirable to collect the payments then due and to become due or to enforce performance of any agreement of the Company in this Loan Agreement or in the First Mortgage Bonds."

(b) The last paragraph of Section 9.1 of the Original Agreement is hereby amended to read as follows:

"Except as may otherwise be provided under the Mortgage, nothing in this Loan Agreement shall be construed to permit the Issuer, the Trustee, any Bondholder or any receiver in any proceeding brought under the Indenture to take possession of or exclude the Company from possession of the Project by reason of the occurrence of an Event of Default."

(c) Section 9.2 of the Original Agreement is hereby amended to read as follows:

"Section 9.2. Delay Not Waiver; Remedies. A delay or omission by the Issuer, the Bond Insurer or the Trustee in exercising any right or remedy accruing upon an Event of Default shall not impair the right or remedy or constitute a waiver of or acquiescence in the Event of Default. No remedy is exclusive of any other remedy. All available remedies are cumulative."

Section 2.06. Amendments to Article X of the Original Agreement. (a)
Section 10.4 of the Original Agreement is hereby amended to read as follows:

"After the issuance of the Bonds, this Loan Agreement may not be effectively amended or terminated without the written consent of the Trustee, the Bond Insurer and the Tender Agent and in accordance with the provisions of the Indenture."

(b) Section 10.11 is hereby added to the end of Article X of the Original Agreement to read as follows:

"Section 10.11. Third Party Beneficiary. The Bond Insurer is a third party beneficiary of this Loan Agreement."

ARTICLE III

MISCELLANEOUS

Section 3.01. Agreement Confirmed. Except as amended by this First Amendment, all of the provisions of the Original Agreement shall remain in full force and effect, and from and after the effective date of this First Amendment shall be deemed to have been amended as herein set forth.

Section 3.02. Severability. If any provision of this First Amendment shall be held or deemed to be or shall, in fact, be inoperative or unenforceable as applied in any particular case in any jurisdiction or jurisdictions or in all jurisdictions, or in all cases because it conflicts with any other provision or provisions hereof or any constitution or statute or rule of public policy, or for any other reason, such circumstances shall not have the effect of rendering the provision in question inoperative or unenforceable in any other case or circumstance, or of rendering any other provision or provisions herein contained invalid, inoperative, or unenforceable to any extent whatever.

Section 3.03. Counterparts. This First Amendment may be simultaneously executed in several counterparts, each of which shall be an original and all of which shall constitute but one and the same instrument.

Section 3.04. Applicable Provisions of Law. This First Amendment shall be governed by and construed in accordance with the laws of the State of Missouri.

Section 3.05. Effective Date. This First Amendment shall become effective on the date the Trustee has received the consent of the Trustee to the execution hereof.

IN WITNESS WHEREOF, the Issuer and the Company have caused this First Amendment to be executed in their respective corporate names, and the Issuer has caused its seal to be hereunto affixed and attested by its duly authorized officer, all as of the date first above written.

STATE ENVIRONMENTAL IMPROVEMENT AND
ENERGY RESOURCES AUTHORITY

                                         By /s/ Charles D. Banks
                                           -------------------------------------
                                                        Chairman


[SEAL]

ATTEST:

By /s/ Deron L. Cherry
  --------------------------------
             Secretary

UNION ELECTRIC COMPANY, DBA AMERENUE

By: /s/ Jerre E. Birdsong
   ------------------------------------
Title:  Vice President and Treasurer

CONSENT OF THE TRUSTEE

Pursuant to Section 10.4 of the Loan Agreement between the State Environmental Improvement and Energy Resources Authority of the State of Missouri (the "Issuer") and Union Electric Company dba AmerenUE (the "Company"), dated as of September 1, 1998, UMB Bank & Trust, N.A., successor to State Street Bank and Trust Company of Missouri, N.A., as Trustee, hereby consents to the execution and delivery of the First Amendment to Loan Agreement dated as of February 1, 2004 between the Issuer and the Company.

UMB BANK & TRUST, N.A., successor to State Street Bank and Trust Company of Missouri, N.A.

                                    By /s/ Rebecca A. Dengler
                                      -----------------------------------------
                                      Its  Authorized Officer

Date:  February 24, 2004

Exhibit 4.13

FIRST AMENDMENT TO LOAN AGREEMENT

Dated as of February 1, 2004

Between

STATE ENVIRONMENTAL IMPROVEMENT AND ENERGY RESOURCES AUTHORITY

and

TABLE OF CONTENTS

(This Table of Contents is not a part of the First Amendment to Loan Agreement and is only for convenience of reference.)

SECTION                                                HEADING                                                   PAGE
ARTICLE I                  DEFINITIONS............................................................................2

       Section 1.01.       Definitions of Terms...................................................................2

ARTICLE II                 AMENDMENTS TO ORIGINAL AGREEMENT.......................................................2

       Section 2.01.       Amendment to Article III of the Original Agreement.....................................2
       Section 2.02.       Amendments to Article V of the Original Agreement......................................2
       Section 2.03.       Amendments to Article VI of the Original Agreement.....................................6
       Section 2.04.       Amendment to Section 8.1 of the Original Agreement.....................................7
       Section 2.05.       Amendments to Article IX of the Original Agreement.....................................7
       Section 2.06.       Amendments to Section 10.4 of the Original Agreement...................................8

ARTICLE III                MISCELLANEOUS..........................................................................8

       Section 3.01.       Agreement Confirmed....................................................................8
       Section 3.02.       Severability...........................................................................8
       Section 3.03.       Counterparts...........................................................................8
       Section 3.04.       Applicable Provisions of Law...........................................................8
       Section 3.05.       Effective Date.........................................................................8

FIRST AMENDMENT TO LOAN AGREEMENT

THIS FIRST AMENDMENT TO LOAN AGREEMENT (this "First Amendment") is made and entered into as of February 1, 2004 between the STATE ENVIRONMENTAL IMPROVEMENT AND ENERGY RESOURCES AUTHORITY of the State of Missouri, a body corporate and politic and a governmental instrumentality of the State of Missouri (the "Issuer"), and UNION ELECTRIC COMPANY, a Missouri corporation doing business as AMERENUE (the "Company"):

WITNESSETH:

WHEREAS, on September 4, 1998 the Issuer issued its Environmental Improvement Revenue Refunding Bonds (Union Electric Company Project) Series 1998BC (the "Bonds") in the original aggregate principal amount of $50,000,000 pursuant to an Indenture of Trust dated as of September 1, 1998 (the "Original Indenture") by and between the Issuer and UMB Bank & Trust, N.A., successor to State Street Bank and Trust Company of Missouri, N.A. (the "Trustee"); and

WHEREAS, in connection with the issuance of the Bonds, the Issuer and the Company executed and delivered the Loan Agreement dated as of September 1, 1998 by and between the Issuer and the Company (the "Original Agreement"); and

WHEREAS, the Original Indenture is being amended and restated by the Amended and Restated Indenture of Trust of even date herewith in order to add provisions relating to a bond insurance policy for the Bonds and to permit the delivery to the Trustee by the Company of its mortgage bonds to further secure the Bonds; and

WHEREAS, Section 11.01 of the Original Indenture provides that the Issuer and the Company may, without notice to or the consent of any Bondholder, enter into an agreement supplemental to the Original Agreement to make changes in connection with any authorized amendment or supplement to the Indenture, and
Section 10.4 of the Original Agreement provides that such supplemental agreement is subject to the written consent of the Trustee; and

WHEREAS, the Issuer and the Company desire to enter into this First Amendment, as permitted by Section 11.01 of the Original Indenture and Section 10.4 of the Original Agreement, in order to amend the Original Agreement to make certain changes relating to the amendments being made to the Indenture concurrently herewith;

NOW, THEREFORE, in consideration of the foregoing and of the mutual covenants herein set forth, the parties hereto agree as follows:

ARTICLE I

DEFINITIONS

Section 1.01. Definitions of Terms. For all purposes of this First Amendment, in addition to the terms defined above in the WHEREAS clauses, unless the context clearly requires otherwise, all terms defined in Article I of the Indenture have the same meanings in this First Amendment.

ARTICLE II

AMENDMENTS TO ORIGINAL AGREEMENT

Section 2.01. Amendment to Article III of the Original Agreement. The last clause of Section 3.5 of the Original Agreement is hereby amended to read as follows:

", provided that the Trustee and the Bond Insurer receive a Favorable Opinion of Tax Counsel prior to such abandonment."

Section 2.02. Amendments to Article V of the Original Agreement. (a) Subsection 5.1(a) of the Original Agreement is hereby amended to read as follows:

"(a) The Company will repay the loan made to it under
Section 4.1 as follows: Before the close of business (local time at the principal corporate office of the Registrar) on the day before each day on which any payment of either principal of or interest on the Bonds, or both, shall become due (whether at maturity, or upon redemption or acceleration or otherwise), the Company will pay, in immediately available funds, an amount which, together with other moneys held by the Tender Agent or by the Trustee under the Indenture and available therefor, will enable the Registrar to make such payment in full in a timely manner. If such day on which any payment shall become due is not a Business Day, then the payment required by this Section shall be made on or before the preceding Business Day. If the Company defaults in any payment required by this Section, the Company will pay interest (to the extent allowed by law) on such amount until paid at the rate provided for in the Bonds."

(b) The last paragraph of Section 5.1 of the Original Agreement is hereby amended to read as follows:

"All amounts payable under this Section by the Company are assigned by the Issuer to the Trustee pursuant to the Indenture for the benefit of the Bondholders and the Bond Insurer. The

Company consents to such assignment. Accordingly, the Company will pay directly to the Registrar at its principal corporate trust office all payments payable by the Company pursuant to this Section."

(c) There is hereby added a new paragraph to the end of Section 5.1 of the Original Agreement to read as follows:

"The Company agrees to make all payments when due on the First Mortgage Bonds. If for any reason amounts paid to the Trustee on the First Mortgage Bonds, together with other moneys held by the Trustee and available for that purpose, would not be sufficient to make the corresponding payments of principal of, premium, if any, and interest on the Bonds corresponding to such First Mortgage Bonds when such payments become due, the Company will pay the amounts required from time to time to make up any such deficiency."

(d) A new Subsection 5.2(d) is hereby added to the end of Section 5.2 of the Original Agreement to read as follows:

"(d) Notwithstanding any provision herein to the contrary, payment to the Bond Insurer of all amounts due under the Insurance Agreement pursuant to the terms of the Insurance Agreement."

(e) Section 5.3 of the Original Agreement is hereby amended to read as follows:

"Section 5.3. Prepayments. The Company may at any time prepay to the Registrar all or any part of the amounts payable under Section 5.1. A prepayment will not relieve the Company of its obligations under this Loan Agreement until all the Bonds have been paid or provision for the payment of all the Bonds has been made in accordance with the Indenture and all amounts due the Bond Insurer have been paid. In the event of a mandatory redemption of the Bonds, the Company will prepay all amounts necessary for such redemption."

(f) Section 5.4 of the Original Agreement is hereby amended to read as follows:

"Section 5.4. Obligations of Company Unconditional. The Company agrees that the obligations of the Company to make the payments required by Sections 5.1 and 5.3 and to perform its other agreements contained in this Loan Agreement shall be absolute and unconditional. Until the principal of and interest on the Bonds shall have been fully paid, or provision for the payment

of the Bonds made in accordance with the Indenture, and the Bond Insurer is paid in full, the Company (a) will not suspend or discontinue any payments provided for in Section 5.1, (b) will perform all its other agreements in this Loan Agreement and (c) will not terminate this Loan Agreement for any cause including any acts or circumstances that may constitute failure of consideration, destruction of or damage to the Project, commercial frustration of purpose, any change in the laws of the United States or of the State or any political subdivision of either or any failure of the Issuer to perform any of its agreements, whether express or implied, or any duty, liability or obligation arising from or connected with this Loan Agreement."

(g) Section 5.5, Section 5.6 and Section 5.7 are hereby added to the end of Article V of the Original Agreement to read as follows:

"Section 5.5. First Mortgage Bonds. The Company shall execute and deliver to the Trustee, as assignee of the Issuer, its First Mortgage Bonds. The form of the First Mortgage Bonds will be substantially as set forth in the Company's Supplemental Indenture to its Mortgage executed and delivered to the Trustee on the effective date of this First Amendment."

"Section 5.6. Payment of the Bonds from Payments of the First Mortgage Bonds and Other Amounts. Payments of principal of, and premium, if any, and interest on, the First Mortgage Bonds by the Company to the Trustee, as assignee of the Issuer, shall constitute payments of such amounts on the loan under Section 5.1(a) or of the purchase price for the Bonds under Section 5.1(b). The Bonds shall be payable from payments made by the Company to the Trustee of principal and interest on the First Mortgage Bonds delivered hereunder. Payments of principal of or premium, if any, or interest on, or the purchase price for, the Bonds with moneys held under the Indenture for such payment shall be deemed to be like payments with respect to the First Mortgage Bonds. The obligations of the Company to make payments under the First Mortgage Bonds shall be absolute and unconditional. Whenever the Bonds are redeemable in whole or in part, the Issuer will redeem the same upon the request of the Company, and the Company covenants and agrees to pay an amount equal to the applicable redemption price of the Bonds as a prepayment of principal of and interest due on the First Mortgage Bonds. If the Company prepays the First Mortgage Bonds, the Company's obligations under
Section 5.1 will be satisfied and there will be a corresponding redemption of the Bonds. Whenever payment or provision therefor has been made in respect of the principal of or

interest on all or any portion of the Bonds in accordance with the Indenture (whether at maturity or upon redemption or acceleration), the First Mortgage Bonds shall be deemed paid to the extent such payment or provision therefor has been made and is considered to be a payment of principal or interest on the Bonds. If the Bonds or any portion thereof are thereby deemed paid in full, First Mortgage Bonds in a principal amount equal to the principal amount of the Bonds so deemed to be paid shall be cancelled and returned to the Company. Subject to the foregoing or unless the Company is entitled to a credit under this Loan Agreement or the Indenture, all payments shall be in the full amount required under the First Mortgage Bonds.

The Issuer, by the terms of the Indenture, shall require the Trustee to notify in writing the Mortgage Trustee of all payments or credits with respect to the First Mortgage Bonds.

All First Mortgage Bonds shall equally and ratably secure all outstanding Bonds."

"Section 5.7. Assignment of Issuer's Rights to First Mortgage Bonds. As security for the payment of its Bonds, the Issuer hereby pledges and assigns to the Trustee the First Mortgage Bonds and the right to receive payments thereunder. The Issuer directs the Company, and the Company agrees, to pay to the Trustee at its principal corporate trust office all payments on the First Mortgage Bonds, and other payments due and payable to the Trustee hereunder. The Company will make payments directly to the Trustee without defense or set-off by reason of any dispute between the Company and the Trustee or the Issuer. The Issuer hereby agrees that the Trustee as assignee may enforce any and all rights and remedies hereunder, but retains the right to also proceed in its own name against the Company for the enforcement of the specific performance of any obligation of the Company under Sections 5.2, 7.2 and 9.3; provided, that in any such action seeking specific performance, the Issuer shall have no rights with respect to the First Mortgage Bonds and in such event the obligation of the Company to make the payments required to repay the loan hereunder and the purchase price for the Bonds and payments required under the First Mortgage Bonds shall remain unconditional as provided in Section 5.4.

The Issuer and the Company covenant and agree that the First Mortgage Bonds will at all times be (i) in fully registered (both principal and interest) form; (ii) registered in the name of the Trustee; (iii) non-transferable except as provided in the Mortgage;

and (iv) appropriately marked to indicate clearly the restrictions on the transfer thereof imposed by this Loan Agreement."

Section 2.03. Amendments to Article VI of the Original Agreement. (a)
Section 6.1 of the Original Agreement is hereby amended to read as follows:

"Section 6.1. Maintenance of Existence. The Company agrees that during the term of this Loan Agreement and so long as any Bond is outstanding, it will maintain its corporate existence, will continue to be a corporation in good standing under the laws of the State, will not dissolve or otherwise dispose of all or substantially all of its assets and will not consolidate with or merge into another legal entity or permit one or more other legal entities (other than one or more subsidiaries of the Company) to consolidate with or merge into it, or sell or otherwise transfer to another legal entity all or substantially all its assets as an entirety and dissolve, unless the Company's actions shall be permitted under the terms of the Insurance Agreement and (a) in the case of any merger or consolidation, the Company is the surviving corporation, or
(b)(i) the surviving, resulting or transferee legal entity is organized and existing under the laws of the United States, a state thereof or the District of Columbia, and (if not the Company) assumes in writing all the obligations of the Company under this Loan Agreement, the Mortgage and the First Mortgage Bonds and (ii) no event which constitutes, or which with the giving of notice or the lapse of time or both would constitute an Event of Default shall have occurred and be continuing immediately after such merger, consolidation or transfer."

(b) A new sentence is hereby added to the end of Section 6.2 of the Original Agreement to read as follows:

"A copy of each such report furnished to the Trustee will be filed with the Bond Insurer."

(c) The second paragraph of Section 6.5 of the Original Agreement is hereby amended to read as follows:

"The Company covenants and agrees to notify promptly the Trustee, Issuer and the Bond Insurer of the occurrence of any event of which the Company has notice and which event would require the Company to prepay the amounts due hereunder because of a redemption upon a determination of taxability."

(d) Section 6.7 of the Original Agreement is hereby deleted.

(e) Section 6.9 of the Original Agreement is hereby amended to read as follows:

"The Company shall not purchase or otherwise acquire Bonds without the prior written consent of the Bond Insurer unless the Company redeems or cancels such Bonds on the day of any such purchase."

Section 2.04. Amendment to Section 8.1 of the Original Agreement. Section 8.1 of the Original Agreement is hereby amended to read as follows:

"The Company may assign its rights and obligations under this Loan Agreement with the prior written consent of the Issuer and the Bond Insurer, but no assignment will relieve the Company from primary liability for any obligations under this Loan Agreement."

Section 2.05. Amendments to Article IX of the Original Agreement. (a) The first paragraph of Section 9.1 of the Original Agreement is hereby amended to read as follows:

"Whenever any Event of Default under the Indenture has occurred and is continuing, the Trustee may, with the consent of the Bond Insurer and shall, upon direction of the Bond Insurer, take whatever action may appear necessary or desirable to collect the payments then due and to become due or to enforce performance of any agreement of the Company in this Loan Agreement or in the First Mortgage Bonds."

(b) The last paragraph of Section 9.1 of the Original Agreement is hereby amended to read as follows:

"Except as may otherwise be provided under the Mortgage, nothing in this Loan Agreement shall be construed to permit the Issuer, the Trustee, any Bondholder or any receiver in any proceeding brought under the Indenture to take possession of or exclude the Company from possession of the Project by reason of the occurrence of an Event of Default."

(c) Section 9.2 of the Original Agreement is hereby amended to read as follows:

"Section 9.2. Delay Not Waiver; Remedies. A delay or omission by the Issuer, the Bond Insurer or the Trustee in exercising any right or remedy accruing upon an Event of Default shall not impair the right or remedy or constitute a waiver of or acquiescence in the Event of Default. No remedy is exclusive of any other remedy. All available remedies are cumulative."

Section 2.06. Amendments to Article X of the Original Agreement. (a)
Section 10.4 of the Original Agreement is hereby amended to read as follows:

"After the issuance of the Bonds, this Loan Agreement may not be effectively amended or terminated without the written consent of the Trustee, the Bond Insurer and the Tender Agent and in accordance with the provisions of the Indenture."

(b) Section 10.11 is hereby added to the end of Article X of the Original Agreement to read as follows:

"Section 10.11. Third Party Beneficiary. The Bond Insurer is a third party beneficiary of this Loan Agreement."

ARTICLE III

MISCELLANEOUS

Section 3.01. Agreement Confirmed. Except as amended by this First Amendment, all of the provisions of the Original Agreement shall remain in full force and effect, and from and after the effective date of this First Amendment shall be deemed to have been amended as herein set forth.

Section 3.02. Severability. If any provision of this First Amendment shall be held or deemed to be or shall, in fact, be inoperative or unenforceable as applied in any particular case in any jurisdiction or jurisdictions or in all jurisdictions, or in all cases because it conflicts with any other provision or provisions hereof or any constitution or statute or rule of public policy, or for any other reason, such circumstances shall not have the effect of rendering the provision in question inoperative or unenforceable in any other case or circumstance, or of rendering any other provision or provisions herein contained invalid, inoperative, or unenforceable to any extent whatever.

Section 3.03. Counterparts. This First Amendment may be simultaneously executed in several counterparts, each of which shall be an original and all of which shall constitute but one and the same instrument.

Section 3.04. Applicable Provisions of Law. This First Amendment shall be governed by and construed in accordance with the laws of the State of Missouri.

Section 3.05. Effective Date. This First Amendment shall become effective on the date the Trustee has received the consent of the Trustee to the execution hereof.

IN WITNESS WHEREOF, the Issuer and the Company have caused this First Amendment to be executed in their respective corporate names, and the Issuer has caused its seal to be hereunto affixed and attested by its duly authorized officer, all as of the date first above written.

STATE ENVIRONMENTAL IMPROVEMENT AND
ENERGY RESOURCES AUTHORITY

                                    By /s/ Charles D. Banks
                                      ------------------------------------------
                                                       Chairman


[SEAL]

ATTEST:

By /s/ Deron L. Cherry
  --------------------------------
             Secretary

UNION ELECTRIC COMPANY, DBA AMERENUE

By: /s/ Jerre E. Birdsong
  ------------------------------------------
Title:  Vice President and Treasurer

CONSENT OF THE TRUSTEE

Pursuant to Section 10.4 of the Loan Agreement between the State Environmental Improvement and Energy Resources Authority of the State of Missouri (the "Issuer") and Union Electric Company dba AmerenUE (the "Company"), dated as of September 1, 1998, UMB Bank & Trust, N.A., successor to State Street Bank and Trust Company of Missouri, N.A., as Trustee, hereby consents to the execution and delivery of the First Amendment to Loan Agreement dated as of February 1, 2004 between the Issuer and the Company.

UMB BANK & TRUST, N.A., successor to State Street Bank and Trust Company of Missouri, N.A.

                                    By /s/ Rebecca A. Dengler
                                      ------------------------------------------
                                      Its  Authorized Officer

Date:  February 24, 2004

Exhibit 4.14

FIRST AMENDMENT TO LOAN AGREEMENT

Dated as of February 1, 2004

Between

STATE ENVIRONMENTAL IMPROVEMENT AND ENERGY RESOURCES AUTHORITY

and

TABLE OF CONTENTS

(This Table of Contents is not a part of the First Amendment to Loan Agreement and is only for convenience of reference.)

SECTION                                                HEADING                                                   PAGE
ARTICLE I                  DEFINITIONS............................................................................2

       Section 1.01.       Definitions of Terms...................................................................2

ARTICLE II                 AMENDMENTS TO ORIGINAL AGREEMENT.......................................................2

       Section 2.01.       Amendments to Article IV of the Original Agreement.....................................2
       Section 4.07.       Credit Facility........................................................................2
       Section 2.02.       Amendment to Section 5.01 of the Original Agreement....................................6
       Section 2.03.       Amendment to Article VII of the Original Agreement.....................................6
       Section 2.04        Amendment to Section 8.01 of the Original Agreement....................................6

ARTICLE III                MISCELLANEOUS..........................................................................7

       Section 3.01.       Agreement Confirmed....................................................................7
       Section 3.02.       Severability...........................................................................7
       Section 3.03.       Counterparts...........................................................................7
       Section 3.04.       Applicable Provisions of Law...........................................................7
       Section 3.05.       Effective Date.........................................................................7

FIRST AMENDMENT TO LOAN AGREEMENT

THIS FIRST AMENDMENT TO LOAN AGREEMENT (this "First Amendment") is made and entered into as of February 1, 2004 between the STATE ENVIRONMENTAL IMPROVEMENT AND ENERGY RESOURCES AUTHORITY of the State of Missouri, a body corporate and politic and a governmental instrumentality of the State of Missouri (the "Issuer"), and UNION ELECTRIC COMPANY, a Missouri corporation doing business as AMERENUE (the "Company"):

WITNESSETH:

WHEREAS, on March 9, 2000 the Issuer issued its Environmental Improvement Revenue Refunding Bonds (AmerenUE Project) Series 2000A, Series 2003B and Series 2003C (the "Bonds") in the original aggregate principal amount of $186,500,000 pursuant to a Trust Indenture dated as of March 1, 2000 (the "Original Indenture") by and between the Issuer and UMB Bank & Trust, N.A., successor to State Street Bank and Trust Company of Missouri, N.A. (the "Trustee"); and

WHEREAS, in connection with the issuance of the Bonds, the Issuer and the Company executed and delivered the Loan Agreement dated as of March 1, 2000 by and between the Issuer and the Company (the "Original Agreement"); and

WHEREAS, the Original Indenture is being amended and restated by the Amended and Restated Trust Indenture of even date herewith (the "Indenture") in connection with a Change of Credit Facility, i.e., to secure the Bonds with the Bond Insurance Policy and the Company's First Mortgage Bonds;

WHEREAS, Section 12.05(j) of the Original Indenture provides that the Issuer and the Company may, without notice to or the consent of any Bondholder, enter into an agreement supplemental to the Original Agreement to make changes in connection with a Change of Credit Facility, and Section 9.04 of the Original Agreement provides that such supplemental agreement is subject to the written consent of the Trustee; and

WHEREAS, the Issuer and the Company desire to enter into this First Amendment, as permitted by Section 12.05(j) of the Original Indenture and
Section 9.04 of the Original Agreement, in order to amend the Original Agreement in connection with a Change of Credit Facility;

NOW, THEREFORE, in consideration of the foregoing and of the mutual covenants herein set forth, the parties hereto agree as follows:

ARTICLE I

DEFINITIONS

Section 1.01. Definitions of Terms. For all purposes of this First Amendment, in addition to the terms defined above in the WHEREAS clauses, unless the context clearly requires otherwise, all terms defined in Article I of the Indenture have the same meanings in this First Amendment.

ARTICLE II

AMENDMENTS TO ORIGINAL AGREEMENT

Section 2.01. Amendments to Article IV of the Original Agreement. (a) There is hereby added a new paragraph (c) to the end of Section 4.01 of the Original Agreement to read as follows:

"(c) The Company agrees to make all payments when due on the First Mortgage Bonds. If for any reason amounts paid to the Trustee on the First Mortgage Bonds, together with other moneys held by the Trustee and available for that purpose, would not be sufficient to make the corresponding payments of principal of, premium, if any, and interest on the Bonds corresponding to such First Mortgage Bonds when such payments become due, the Company will pay the amounts required from time to time to make up any such deficiency."

(b) Section 4.07 of the Original Agreement is hereby amended to read as follows:

"Section 4.07. Credit Facility. (a) On the Issue Date, there was no Credit Facility. The Company may at any time provide for a Change of Credit Facility, provided that the Company delivers to the Trustee, the Auction Agent and the Remarketing Agent, not less than five Business Days prior to the date on which the Trustee must notify the Owners of the applicable series of the Bonds of a Change of Credit Facility pursuant to Section 2.18 of the Indenture and prior to the effective date of any such Change of Credit Facility, the following:

(1) a notice which (A) states the effective date of the Change of Credit Facility, (B) describes the terms of the Change of Credit Facility, and (C) directs the Trustee to give notice pursuant to Section 2.18(a) of the Indenture;

(2) a Favorable Opinion of Bond Counsel with respect to such Change of Credit Facility and stating, in effect, that such change of Credit Facility is authorized under this Agreement;

(3) a certificate of an Authorized Company Representative as to whether the applicable series of Bonds are then rated by either Moody's or S&P, or both; and

(4) written evidence from Moody's, if such Bonds are then rated by Moody's, and from S&P, if such Bonds are then rated by S&P, in each case to the effect that such rating agency has reviewed the proposed Change of Credit Facility and that such Change of Credit Facility will not, by itself, result in a reduction, suspension or withdrawal of its rating or ratings of such Bonds.

(b) In lieu of satisfying the requirements of subsection (a) above, the Company may provide for a Change of Credit Facility at any time that the applicable series of Bonds are subject to optional redemption pursuant to Section 4.02(b) of the Indenture, provided that the Company delivers to the Trustee, the Auction Agent and the Remarketing Agent not less than 30 days before the effective date of the Change of Credit Facility:

(1) a notice which (A) states the effective date of the Change of Credit Facility, (B) describes the terms of the Change of Credit Facility, (C) directs the Trustee to give notice pursuant to Section 2.18 of the Indenture that the Bonds of the applicable series are subject to mandatory purchase, in whole, on or before the effective date of the Change of Credit Facility in accordance with Section 3.02(a)(iii) of the Indenture, and (D) directs the Trustee to take any other action as shall be necessary for the Trustee to take to effect the Change of the Credit Facility; and

(2) on or before the effective date of the Change of Credit Facility, the Company shall furnish to the Trustee a Favorable Opinion of Bond Counsel satisfying the requirements of Section 4.07(a)(2) above.

(c) The Company may provide for one or more extensions of a Credit Facility for any period commencing after its then-current expiration date without complying with the foregoing provisions of this Section.

(d) The Company may rescind its election to make a Change of Credit Facility at any time prior to the effective date thereof."

(c) Section 4.09, Section 4.10 and Section 4.11 are hereby added to the end of Article IV of the Original Agreement to read as follows:

"Section 4.09. First Mortgage Bonds. The Company shall execute and deliver to the Trustee, as assignee of the Issuer, its First Mortgage Bonds. The form of the First Mortgage Bonds will be substantially as set forth in the Company's Supplemental Indenture to its Mortgage executed and delivered to the Trustee on the effective date of this First Amendment."

"Section 4.10. Payment of the Bonds from Payments of the First Mortgage Bonds and Other Amounts. Payments of principal of, and premium, if any, and interest on, the First Mortgage Bonds by the Company to the Trustee, as assignee of the Issuer, shall constitute payments of such amounts on the loan under Section
4.01(a). Each series of the Bonds shall be payable from payments made by the Company to the Trustee of principal and interest on the corresponding series of First Mortgage Bonds delivered hereunder. Payments of principal of or premium, if any, or interest on, each series of the Bonds with moneys held under the Indenture for such payment shall be deemed to be like payments with respect to the corresponding series of First Mortgage Bonds. The obligations of the Company to make payments under the First Mortgage Bonds shall be absolute and unconditional. Whenever a series of the Bonds is redeemable in whole or in part, the Issuer will redeem the same upon the request of the Company, and the Company covenants and agrees to pay an amount equal to the applicable redemption price of such Bonds as a prepayment of principal of and interest due on the applicable series of First Mortgage Bonds. If the Company prepays any series of the First Mortgage Bonds, the Company's obligations under Section 4.01 will be satisfied and there will be a corresponding redemption of the applicable series of Bonds. Whenever payment or provision therefor has been made in respect of the principal of or interest on all or any portion of any series of the Bonds in accordance with the Indenture (whether at maturity or upon redemption or acceleration), the applicable series of First Mortgage Bonds shall be deemed paid to the extent such payment or provision therefor has been made and is considered to be a payment of principal or interest on the Bonds. If any series of the Bonds or any portion thereof are thereby deemed paid in full, First Mortgage Bonds of the applicable series in a principal amount equal to the principal

amount of such Bonds so deemed to be paid shall be cancelled and returned to the Company. Subject to the foregoing or unless the Company is entitled to a credit under this Agreement or the Indenture, all payments shall be in the full amount required under the First Mortgage Bonds.

If the Company has deposited moneys and/or U.S. Government Obligations and obtained the release of a series of First Mortgage Bonds pursuant to Section 8.01 and Section 8.02 of the Indenture, and thereafter the corresponding series of Bonds become subject to mandatory redemption upon a determination of taxability and there are insufficient moneys available under the Indenture to effect such redemption, the Company covenants and agrees to pay to the Trustee under the Indenture any such deficiency amount as is necessary to redeem such Bonds on the date fixed for redemption.

The Issuer, by the terms of the Indenture, shall require the Trustee to notify in writing the Mortgage Trustee of all payments or credits with respect to the First Mortgage Bonds."

"Section 4.11. Assignment of Issuer's Rights to First Mortgage Bonds. As security for the payment of its Bonds, the Issuer hereby pledges and assigns to the Trustee the First Mortgage Bonds and the right to receive payments thereunder. The Issuer directs the Company, and the Company agrees, to pay to the Trustee at its principal corporate trust office all payments on the First Mortgage Bonds, and other payments due and payable to the Trustee hereunder. The Company will make payments directly to the Trustee without defense or set-off by reason of any dispute between the Company and the Trustee or the Issuer. The Issuer hereby agrees that the Trustee as assignee may enforce any and all rights and remedies hereunder, but retains the right to also proceed in its own name against the Company for the enforcement of the specific performance of any obligation of the Company under Sections 4.04, 4.06(a), 5.03, 5.06, 5.07, 5.08 and 7.05; provided, that in any such action seeking specific performance, the Issuer shall have no rights with respect to the First Mortgage Bonds and in such event the obligation of the Company to make the payments required to repay the loan hereunder and payments required under the First Mortgage Bonds shall remain unconditional as provided in Section 4.01.

The Issuer and the Company covenant and agree that the First Mortgage Bonds will at all times be (i) in fully registered (both principal and interest) form; (ii) registered in the name of the

Trustee; (iii) non-transferable except as provided in the Mortgage; and (iv) appropriately marked to indicate clearly the restrictions on the transfer thereof imposed by this Agreement."

Section 2.02. Amendment to Section 5.01 of the Original Agreement. Clause
(I) Subsection (ii) of Section 5.01 of the Original Agreement is hereby amended to read as follows:

"(I) such entity is qualified to do business in the State and has assumed in writing all of the obligations of the Company under this Agreement, the Tax Agreement, the Mortgage and the First Mortgage Bonds and"

Section 2.03. Amendment to Article VII of the Original Agreement. (a)
Section 7.01(b) of the Original Agreement is hereby amended by the following proviso, to be added at the end of Section 7.01(b):

"; and further provided, however, that failure pursuant to
Section 4.10 shall be an automatic Event of Default upon the expiration of any grace period applicable to the First Mortgage Bonds under the Mortgage."

(b) There is hereby added a new Section 7.01(e) at the end of Section 7.01 to read as follows:

"(e) the occurrence of an acceleration for any reason of the maturity of all first mortgage bonds issued under the Mortgage."

(c) The following phrase is hereby added to the end of Section 7.03(a) of the Original Agreement as follows:

"and the Trustee may take whatever action may appear necessary or desirable to collect the payments then due and to become due or to enforce performance of the First Mortgage Bonds."

Section 2.04. Amendment to Section 8.01 of the Original Agreement. The first sentence of Section 8.01 of the Original Agreement is hereby amended to include the following phrase at the end of such sentence:

", and that a corresponding prepayment has been made or will be made, by redemption or otherwise, of the First Mortgage Bonds."

ARTICLE III

MISCELLANEOUS

Section 3.01. Agreement Confirmed. Except as amended by this First Amendment, all of the provisions of the Original Agreement shall remain in full force and effect, and from and after the effective date of this First Amendment shall be deemed to have been amended as herein set forth.

Section 3.02. Severability. If any provision of this First Amendment shall be held or deemed to be or shall, in fact, be inoperative or unenforceable as applied in any particular case in any jurisdiction or jurisdictions or in all jurisdictions, or in all cases because it conflicts with any other provision or provisions hereof or any constitution or statute or rule of public policy, or for any other reason, such circumstances shall not have the effect of rendering the provision in question inoperative or unenforceable in any other case or circumstance, or of rendering any other provision or provisions herein contained invalid, inoperative, or unenforceable to any extent whatever.

Section 3.03. Counterparts. This First Amendment may be simultaneously executed in several counterparts, each of which shall be an original and all of which shall constitute but one and the same instrument.

Section 3.04. Applicable Provisions of Law. This First Amendment shall be governed by and construed in accordance with the laws of the State of Missouri.

Section 3.05. Effective Date. This First Amendment shall become effective on the date the Trustee has received the consent of the Trustee to the execution hereof.

IN WITNESS WHEREOF, the Issuer and the Company have caused this First Amendment to be executed in their respective corporate names, and the Issuer has caused its seal to be hereunto affixed and attested by its duly authorized officer, all as of the date first above written.

STATE ENVIRONMENTAL IMPROVEMENT AND
ENERGY RESOURCES AUTHORITY

                                           By:  /s/ Charles D. Banks
                                              ----------------------------------
                                                         Chairman

[SEAL]

ATTEST:


By:  /s/ Deron L. Cherry
   ---------------------------------
               Secretary

UNION ELECTRIC COMPANY, DBA AMERENUE

By:  /s/ Jerre E. Birdsong
   ----------------------------------
Title:  Vice President and Treasurer

CONSENT OF THE TRUSTEE

Pursuant to Section 10.4 of the Loan Agreement between the State Environmental Improvement and Energy Resources Authority of the State of Missouri (the "Issuer") and Union Electric Company dba AmerenUE (the "Company"), dated as of March 1, 2000, UMB Bank & Trust, N.A., successor to State Street Bank and Trust Company of Missouri, N.A., as Trustee, hereby consents to the execution and delivery of the First Amendment to Loan Agreement dated as of February 1, 2004 between the Issuer and the Company.

UMB BANK & TRUST, N.A., successor to State Street Bank and Trust Company of Missouri, N.A.

                                   By:  /s/ R.A. Dengler
                                      ------------------------------------------
                                      Its  Authorized Officer

Date:  March 17, 2004