8-K

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d) of the

Securities Exchange Act of 1934

Date of report (Date of earliest event reported):

July 7, 2006

Commission File Number	Exact Name of Registrant as Specified in Charter; State of Incorporation; Address and Telephone Number	IRS Employer Identification Number
1-14756	Ameren Corporation (Missouri Corporation) 1901 Chouteau Avenue St. Louis, Missouri 63103 (314) 621-3222	43-1723446
1-2967	Union Electric Company (Missouri Corporation) 1901 Chouteau Avenue St. Louis, Missouri 63103 (314) 621-3222	43-0559760
1-3672	Central Illinois Public Service Company (Illinois Corporation) 607 East Adams Street Springfield, Illinois 62739 (217) 523-3600	37-0211380
333-56594	Ameren Energy Generating Company (Illinois Corporation) 1901 Chouteau Avenue St. Louis, Missouri 63103 (314) 621-3222	37-1395586
2-95569	CILCORP Inc. (Illinois Corporation) 300 Liberty Street Peoria, Illinois 61602 (309) 677-5271	37-1169387

1-2732	Central Illinois Light Company (Illinois Corporation) 300 Liberty Street Peoria, Illinois 61602 (309) 677-5271	37-0211050
1-3004	Illinois Power Company (Illinois Corporation) 370 South Main Street Decatur, Illinois 62523 (217) 434-6600	37-0344645

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

[ ] Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

[ ] Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

[ ] Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

[ ] Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

ITEM 1.02 Termination of a Material Definitive Agreement.

Reference is made to Note 2 - Rate and Regulatory Matters and Note 7 - Related Party Transactions to the financial statements under Part I, Item 1, Outlook under Part I, Item 2. Management’s Discussion and Analysis of Financial Condition and Results of Operations, and Risk Factors under Part II, Item 1A in the Form 10-Q for the quarterly period ended March 31, 2006, of registrant Ameren Corporation (“Ameren”) and its registrant subsidiaries, Union Electric Company, doing business as AmerenUE (“UE”), Central Illinois Public Service Company, doing business as AmerenCIPS (“CIPS”), Ameren Energy Generating Company (“Genco”), CILCORP Inc., Central Illinois Light Company, doing business as AmerenCILCO ("CILCO") and Illinois Power Company, doing business as AmerenIP (“IP”) (collectively, the “registrants”), for a discussion of the joint dispatch agreement among UE, CIPS and Genco and the Illinois power procurement auction. Reference is also made to Note 14 - Related Party Transactions to the financial statements under Part II, Item 8 in the registrants’ Annual Report on Form 10-K for the fiscal year ended December 31, 2005, for a discussion of the joint dispatch agreement. The joint dispatch agreement as last amended and restated effective January 10, 2006 (filed as Exhibit 10.1 to the Current Report on Form 8-K of Ameren, UE, CIPS and Genco dated January 9, 2006) (“JDA”), under which UE and Genco jointly dispatch electric generation, provides each affiliate the option to serve its load requirements from its own generation first and then to allow access to any available remaining generation to its affiliate at incremental cost. Any excess generation not used by UE or Genco to serve load requirements is sold to third parties on a short-term basis. Under the provisions of the JDA, the margins from third party sales are allocated between UE and Genco based on generation output. CIPS is no longer an active participant under the JDA due to the transfer of its power plants to Genco in 2000. The JDA established no specific termination date for the agreement but provided any party the right to terminate it on one year’s notice. The JDA may be terminated earlier by mutual consent of the parties.

On July 7, 2006, UE, CIPS and Genco mutually consented to waive the one year termination notice requirement and agreed to terminate the JDA on December 31, 2006. This action with respect to the JDA will require acceptance by the Federal Energy Regulatory Commission (“FERC”).

The benefits of the JDA to UE and Genco have changed recently due to the emergence of transparent wholesale markets, the dispatching of generation being conducted by the Midwest Independent Transmission System Operator, Inc. (“MISO”), and changes to the Illinois regulatory framework, among other things. As a result, UE believes the benefit it will receive from retaining the power it was transferring under the JDA to Genco at incremental cost will exceed the benefit it would have received from being able to call upon Genco’s generation under the JDA at

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incremental cost. Since UE was prepared to immediately provide Genco with one year notice of termination, Genco believes the potential benefit it could receive from being able to call upon UE’s generation through June 2007 is outweighed by, among other things, the negative consequences associated with the continued existence of the JDA past December 31, 2006. In particular, Genco believes that the JDA is no longer necessary or effective in dispatching Genco’s generation jointly with that of UE due to changes in the marketplace for the sale of electricity, including the MISO Day Two Energy Market, and the centralized dispatching of generation by MISO.  Additionally, the JDA is based on a combined control area for the UE and CIPS transmission facilities located in Missouri and Illinois, respectively.  This combined control area creates operational inefficiencies for Genco to effectively participate through Ameren Energy Marketing Company (“Marketing Company”) in the Illinois power procurement auction for power beginning January 1, 2007.  In conjunction with terminating the JDA, Ameren’s transmission-owning entities intend to restructure their control areas so as to have one control area in Missouri for UE’s transmission facilities and one in Illinois for the transmission facilities of CIPS, CILCO and IP.

As a result of the termination of the JDA on December 31, 2006, UE and Genco will no longer have the obligation to provide power to each other. In 2005, Genco received from UE under the JDA net transfers of 8.7 million megawatthours of power at an average price of $18 per megawatthour and generated 14.2 million megawatthours of power from its plants at an average cost of approximately $18 per megawatthour. This power, along with 1.2 million megawatthours purchased from Electric Energy, Inc. (“EEI”), which is 40% owned by UE and 40% owned by Ameren Energy Development Company, was used in 2005 to supply CIPS’ load and other wholesale and retail customers at an average selling price of $35 per megawatthour. In 2005, Genco also sold 3.3 million net megawatthours of power in the interchange market at $47 per megawatthour. Upon termination of the JDA, Genco will no longer receive the margins on sales that were supplied with power from UE. However, Genco will still have access to its own generation and expects to be able to sell this power at higher average prices than this power was sold for in 2005 because of the expiration of its power supply contract with CIPS and the expiration of contracts to supply other wholesale and retail customers on or before December 31, 2006. Genco currently expects to generate approximately 17.5 million megawatthours of power in 2007. By 2007, only 5.2 million megawatthours of power covered by wholesale and retail electric power supply agreements that were in effect in 2005 will remain outstanding. These agreements have an average embedded selling price of $36 per megawatthour. All other power supply agreements in effect in 2005 will expire by the end of 2006 and any available generation will be sold at prevailing market prices. Genco and AmerenEnergy Resources Generating Company (“AERG”) (a subsidiary of CILCO) through their affiliate Marketing Company and UE will have the opportunity to participate in the Illinois power procurement auction for 2007. However, they would be subject to a limitation of 35% of CIPS’, CILCO’s and IP’s annual load, or about 13 million megawatthours, which is an auction restriction imposed on any single supplier providing power to CIPS, CILCO and IP through the auction. Ameren affiliated companies will be considered one supplier for purposes of this limitation.

Ameren’s earnings will be affected by the termination of the JDA when UE’s rates are adjusted by the Missouri Public Service Commission (MoPSC). As noted in the press release (Exhibit 99.1 hereto) incorporated by reference under Item 8.01 below, UE announced on July 7, 2006, that it had filed a request with the MoPSC to increase its electric rates by $361 million. UE’s requested increase is net of the decrease in its revenue requirement resulting from increased margins expected to result from the termination of the JDA. UE’s proposed rate increase is subject to review and approval by the MoPSC.

 In 2007, Ameren’s earnings are also expected to be impacted by the expiration on December 31, 2006, of the contract for AERG to supply CILCO with power. AERG currently expects to generate approximately 7 million megawatthours of power in 2007 compared to 5.9 million megawatthours of power that was generated in 2005 at an average cost of approximately $15 per megawatthour. In 2005, this power was sold principally to CILCO at an average price of $32 per megawatthour. In addition, AERG sold 1 million net megawatthours of power in the interchange market at $38 per megawatthour in 2005. In 2007, all of AERG’s power will be sold at prevailing market prices. On December 31, 2005, a power supply agreement with EEI for UE, CIPS (whose entitlement was resold to Marketing Company) and IP expired. Power supplied under the agreement by EEI to UE, Marketing Company and IP was priced at EEI’s cost-based rates. Power previously supplied under this agreement to UE, Marketing Company and IP is being sold at market prices in 2006, which are above EEI’s cost-based rates and will continue to be sold at market prices in 2007. However, in 2006, UE, Genco (which supplies Marketing Company) and IP are replacing power previously received from EEI either through the use of their own higher-cost generation or higher-cost power purchases. In 2005, EEI generated 7.9 million megawatthours of power. UE, CIPS (which

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resold the power to Marketing Company) and IP purchased 3.0 million, 2.0 million and 1.2 million megawatthours, respectively, from EEI at an average price of $20 per megawatthour. The remaining generation was sold to EEI’s minority owner. The expiration of this agreement and the resulting decrease in UE’s margins and increase in its revenue requirement was also reflected in UE’s July 7, 2006, request to the MoPSC to increase electric rates discussed above.

The ultimate impact of all of the matters mentioned above on the registrants’ results of operation, financial position, or liquidity cannot be predicted at this time.

ITEM 8.01 Other Events.

On July 7, 2006, UE issued press releases announcing that it had filed requests with the MoPSC for increases in electric and natural gas rates. The press releases are attached as Exhibits 99.1 and 99.2 and are incorporated herein by reference.

ITEM 9.01 Financial Statements and Exhibits.

(d) Exhibits

Exhibit Number:Title:

99.1                              Press release dated July 7, 2006 regarding electric rate increase request

99.2                              Press release dated July 7, 2006 regarding natural gas rate increase request

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This combined Form 8-K is being filed separately by each registrant. Information contained herein relating to any individual registrant has been filed by such registrant on its own behalf. No registrant makes any representation as to information relating to any other registrant.

FORWARD-LOOKING STATEMENTS

Statements in this report not based on historical facts are considered “forward-looking” and, accordingly, involve risks and uncertainties that could cause actual results to differ materially from those discussed. Although such forward-looking statements have been made in good faith and are based on reasonable assumptions, there is no assurance that the expected results will be achieved. These statements include (without limitation) statements as to future expectations, beliefs, plans, strategies, objectives, events, conditions, and financial performance. In connection with the “safe harbor” provi-sions of the Private Securities Litigation Reform Act of 1995, the registrants are providing this cautionary statement to identify important factors that could cause actual results to differ materially from those anticipated. The following factors, in addition to those discussed elsewhere in this report and in the registrants’ other filings with the SEC, could cause actual results to differ materially from management expectations suggested in such forward-looking statements:

·   regulatory actions, including changes in regulatory policies and ratemaking determinations;

·   changes in laws and other governmental actions, including monetary and fiscal policies;

·   the effects of increased competition in the future due to, among other things, deregulation of certain aspects of the registrants’ business at both the state and federal levels, and the implementation of deregulation, such as when the current electric rate freeze and current power supply contracts expire in Illinois at the end of 2006;

·   the effects of participation in the MISO;

·   the availability of fuel such as coal, natural gas and enriched uranium used to produce electricity; the availability of purchased power and natural gas for distribution; and the level and volatility of future market prices for such commodities, including the ability to recover the costs for such commodities;

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·   the effectiveness of the registrants’ risk management strategies and the use of financial and derivative instruments;

·   prices for power in the Midwest;

·   business and economic conditions, including their impact on interest rates;

·   disruptions of the capital markets or other events that make the registrants access to necessary capital more difficult or costly;

·   the impact of the adoption of new accounting standards and the application of appropriate technical accounting rules and guidance;

·   actions of credit rating agencies and the effects of such actions;

·   weather conditions and other natural phenomena;

·   generation plant construction, installation and performance, including costs associated with UE’s Taum Sauk pumped-storage hydroelectric plant incident and its future operation;

·   operation of UE’s nuclear power facility, including planned and unplanned outages, and decommissioning costs;

·   the effects of strategic initiatives, including acquisitions and divestitures;

·   the impact of current environmental regulations on utilities and power generating companies and the expectation that more stringent requirements will be introduced over time, which could have a negative financial effect;

·   labor disputes and future wage and employee benefits costs, including changes in returns on benefit plan assets;

·   the inability of the registrants’ counterparties to meet their obligations with respect to contracts and financial instruments;

·   the cost and availability of transmission capacity for the energy generated by the registrants’ facilities or required to satisfy energy sales made by the registrants;

·   legal and administrative proceedings; and

·   acts of sabotage, war, terrorism or intentionally disruptive acts.

Given these uncertainties, undue reliance should not be placed on these forward-looking statements. Except to the extent required by the federal securities laws, the registrants undertake no obligation to publicly update or revise any forward-looking statements to reflect new information or future events.

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, each registrant has duly caused this report to be signed on its behalf by the undersigned thereunto duly authorized. The signature for each undersigned company shall be deemed to relate only to matters having reference to such company or its subsidiaries.

AMEREN CORPORATION

(Registrant)

/s/ Martin J. Lyons                  

Martin J. Lyons

Vice President and Controller

(Principal Accounting Officer)

UNION ELECTRIC COMPANY

(Registrant)

/s/ Martin J. Lyons                  

Martin J. Lyons

Vice President and Controller

(Principal Accounting Officer)

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CENTRAL ILLINOIS PUBLIC SERVICE COMPANY

(Registrant)

/s/ Martin J. Lyons                  

Martin J. Lyons

Vice President and Controller

(Principal Accounting Officer)

AMEREN ENERGY GENERATING COMPANY

(Registrant)

/s/ Martin J. Lyons                  

Martin J. Lyons

Vice President and Controller

(Principal Accounting Officer)

CILCORP Inc.

(Registrant)

/s/ Martin J. Lyons                   

Martin J. Lyons

Vice President and Controller

(Principal Accounting Officer)

CENTRAL ILLINOIS LIGHT COMPANY

(Registrant)

/s/ Martin J. Lyons                  

Martin J. Lyons

Vice President and Controller

(Principal Accounting Officer)

ILLINOIS POWER COMPANY

(Registrant)

/s/ Martin J. Lyons                  

Martin J. Lyons

Vice President and Controller

(Principal Accounting Officer)

Date: July 7, 2006

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Exhibit Index

Exhibit Number:Title:

99.1                              Press release dated July 7, 2006 regarding electric rate increase request

99.2                              Press release dated July 7, 2006 regarding natural gas rate increase request

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EX-99.1

Exhibit 99.1

                       One Ameren Plaza

                         1901 Chouteau Avenue

                            St. Louis, MO 63103

 [GRAPHIC INSERTED]

                                                                                                                                                      0;                                                                                                             

Contact:

MediaAnalysts                                                                Investors

Erica Abbett                                        Mike Cleary                                             Bruce Steinke                     Investor Services

(314) 206-0646                                     (573) 681-7137                                          (314) 554-2574                                                       (800) 255-2237

                bsteinke@ameren.com                                         invest@ameren.com

For Immediate Release

To Cover Rising Costs and Energy Infrastructure Investments, Maintain System

Reliability and Invest in Environmentally Friendly Generation Technologies,

AmerenUE Seeks Electric Rate Increase

Would be First Increase in 20 Years For Rates That Are Approximately

30 Percent Below National Average

St. Louis, MO, July 7, 2006 -- AmerenUE, an operating company of Ameren Corporation (NYSE:AEE), today filed a request for an increase in base rates for electric service with the Missouri Public Service Commission (MoPSC). If approved, it would mark the first electric rate increase for AmerenUE in almost 20 years.

Overview of Electric Rate Filing

The company’s filing includes a proposed average increase in electric rates of 17.7 percent or $361 million. The company is also proposing to limit the increase on residential rates to 10 percent, allocating revenue amounts above that level to other customer classes. Under the application, a typical residential customer using 1,000 kilowatt-hours a month would see the electric bill rise from approximately $66 per month to $72 per month, excluding taxes. Even with this increase, a typical AmerenUE residential electric customer would be paying rates that would be below AmerenUE’s 1991 levels.

In addition to the proposed limit on the residential rate increase, the company has committed to working with key stakeholders during the rate review process to develop low income energy assistance and energy conservation programs to help address customers’ needs.

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“For decades, our focus on our core energy business, cost control and operating efficiencies has resulted in our customers enjoying some of the lowest electric rates in the nation,” said Gary L. Rainwater, chairman, president and chief executive officer, Ameren Corporation. “Our customers have come to expect AmerenUE to deliver a highly reliable, environmentally friendly supply of electricity at reasonable prices. We are committed to continuing to meet their expectations—now and in the future.”

He added, “We recognize that our customers are experiencing meaningful increases in many of their monthly costs, consistent with trends we are seeing across the nation. Because we are concerned about how these increases will impact each family’s budget, our proposal seeks to develop a program to assist our most vulnerable customers who need help paying their electric bills.”

He stressed that the company will continue to give to, and encourage others to contribute to, its Dollar More program, the region’s largest private energy assistance fund for customers in need. AmerenUE will also encourage customers to participate in Budget Billing, a company program that levels monthly bill amounts.

Through this filing, AmerenUE is proposing to develop at least 100 megawatts of wind power that will benefit all AmerenUE customers and to launch a voluntary program allowing customers to support additional development of wind power and other forms of renewable energy.

AmerenUE’s filing also includes proposed economic development incentive rates for nonresidential customers who move operations into targeted urban areas where the City of St. Louis is trying to spur re-development. Eligible projects would provide social and economic benefits in areas where jobs are needed and re-development is critical to area improvement.

Finally, Rainwater added that consistent with the company’s commitment to accept full responsibility for the effects of the Dec. 14 failure of its Taum Sauk Plant, AmerenUE has not included in the rate request filed today the related costs that the company has incurred. Those costs include the clean-up of Johnson’s Shut-Ins state park, reimbursement of state costs and resolution of individual claims.

The company’s proposal is subject to the customary rate review process, which includes review and approval by the MoPSC. A decision is expected no later than June 2007.

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Perspectives on Electric Rate Increase Proposal

AmerenUE’s electric rates are among the lowest in the nation. Since 1987 (the last time the company’s base rates were increased), the company has lowered its electric rates by approximately 13 percent. In 2005, AmerenUE’s average electric rates were approximately 30 percent below the national average and 15 percent below the Midwest average and the lowest of the investor-owned utilities in the state. In addition, St. Louis has the second lowest residential electric rates in the country compared to the rates of the major metropolitan areas surveyed by the Bureau of Labor Statistics (BLS).

However, while electric rates remained low, many electric bills have grown as a result of higher electricity usage. The average electricity usage by residential customers has risen 30 percent since the late 1980s as residents have added computers, second refrigerators, home entertainment systems, multiple television sets, cell phone chargers and other electrical devices to their homes.

Since the company’s last rate case (2002), AmerenUE’s average residential electric rates have decreased 6 percent, while electric rates across the United States and Midwest rose 11 percent and 5 percent, respectively, through the end of 2005. From 2002 through 2005, regional prices for consumer products rose 10 percent, medical costs increased by 15 percent and housing costs rose 23 percent, according to BLS.

The trend in rising electric rates is continuing: Recent U.S. Department of Energy (DOE) data reflects that U.S. average electric rates in the first quarter of 2006 are already 12 percent above where they were a year ago. In addition, should the company’s proposal be approved by the MoPSC in 2007, AmerenUE average electric rates will still be more than 20 percent below the U.S. average electric rates projected by the U.S. DOE.

In addition to keeping rates low, AmerenUE remains committed to providing superior customer service—ranking among the top utility companies in customer satisfaction surveys. The company has invested in state-of-the-art technology to meet its customers’ needs. In fact, the respected global marketing information firm known for surveys of customer satisfaction, J.D. Power and Associates, recently ranked AmerenUE better than its industry peers in the Midwest in number of brief power outages, the number of lengthy outages and the average length of the longest outages. In addition, J.D. Power certified AmerenUE’s customer contactcenter, along with three other Ameren contact centers, for providing “An Outstanding Customer

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Service Experience.” AmerenUE is among a select few electric or gas utility companies in the nation to receive this certification.

Factors Contributing to Need for Electric Rate Increase

Under Missouri regulation, AmerenUE is permitted to recover from its customers its prudently incurred investments, including an appropriate return on those investments, as well as its prudently incurred costs of operating its electric operations. Since its 2002 electric rate case, AmerenUE has made significant investments in critical energy infrastructure, as well as incurred significantly higher operating expenses. For example:

·   While AmerenUE’s electric rates have decreased approximately 6 percent since the last rate case, its annual investments in energy infrastructure have risen approximately 50 percent since that time. In particular, AmerenUE has invested approximately $2.6 billion in its electric operations. Those investments included more than $700 million for 2,600 megawatts of new generation to meet growing customer demands. The company has also invested in nuclear steam generators and turbines, rail cars, transformers, major substation replacements and upgrades and the addition of 80 miles of new transmission line. In addition, the company has installed controls and employed technology to reduce emissions at its generating plants, as well as made investments in its customer service systems.

·   Costs for AmerenUE’s primary generation source—coal—have risen significantly. The cost of a ton of coal delivered to an AmerenUE plant in 2007 will be 42 percent higher than the delivered cost of a ton of coal in the 2002 electric rate case.

·   The cost of materials used in the company’s delivery system has also risen meaningfully: Aluminum overhead wire costs have grown approximately 95 percent; copper underground cable has risen approximately 145 percent, and the costs of poles and transformers have jumped approximately 35 percent and 55 percent, respectively.

·   AmerenUE has increased its tree-trimming budget by more than 20 percent to enhance the reliability of its distribution system.

·   Employee and retiree pension and medical costs have risen 56 percent.

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Looking ahead, AmerenUE expects many of these costs to continue to rise. In addition, AmerenUE intends to continue to make significant investments in its energy infrastructure, including investments in renewable generation, environmental upgrades and reliability enhancements. Without appropriate rate relief, among other things, AmerenUE would have difficulty making critical energy infrastructure investments in a timely fashion, inhibiting the company’s ability to provide reliable service on a continuous basis and increasing its borrowing costs.

“In our proposal, we are seeking recovery of investments we have made in our business since the last rate case, an appropriate return on those investments, as well as recovery of the costs of operating our business,” said Rainwater. “The ability to make timely investments in energy infrastructure is critical to meeting existing and future customer demands, which ultimately drives the economy of the state. For AmerenUE to continue to meet growing customer demand in a prudent and reliable fashion, to meet environmental standards that will require AmerenUE to invest $1.2 to $1.6 billion in environmental controls over the next 10 years, invest in environmentally friendly renewable generation and to begin preparation for its next baseload plant addition, it is essential that we receive a constructive regulatory decision that permits us to recover the investments and costs we are incurring.”

Included with this news release are supplemental charts and graphs related to AmerenUE’s electric rates. Additional information is also on our Web site, www.ameren.com.

AmerenUE is a subsidiary of St. Louis-based Ameren Corporation. The Ameren companies serve 2.4 million electric customers and nearly one million natural gas customers in a 64,000-square-mile area of Missouri and Illinois.

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Forward-Looking Statements

Statements made in this release, which are not based on historical facts, are “forward-looking” and accordingly, involve risks and uncertainties that could cause actual results to differ materially from those discussed. Although such “forward-looking” statements have been made in good faith and are based on reasonable assumptions, there is no assurance that the expected results will be achieved. These statements include (without limitation) statements as to future expectations, beliefs, plans, strategies, objectives, events, conditions and financial performance. In connection with the safe harbor provisions of the Private Securities Litigation Reform Act of 1995, the company is providing this cautionary statement to identify important factors that could cause actual results to differ materially from those anticipated. The factors discussed elsewhere in this release and the company’s past and subsequent filings with the Securities and Exchange Commission could cause actual results to differ materially from management expectations suggested in such forward-looking statements.

EX-99.2

Exhibit 99.2

                         One Ameren Plaza

                           1901 Chouteau Avenue

                            St. Louis, MO 63103

 [GRAPHIC INSERTED]

                                                                                                                                                     &# 160;                                                                                                             

Contact:

Media: Mike Cleary (573) 681-7137 mcleary@ameren.com Analysts: Bruce Steinke (314) 554-2574 bsteinke@ameren.com Investors: Investor Services invest@ameren.com

For Immediate Release

To Cover Rising Operating Costs and Investments in Critical Energy

 Infrastructure and Service Reliability, AmerenUE Files

Request for Natural Gas Rate Increase

ST. LOUIS, MO., July 7, 2006—Citing major investments in the infrastructure of its natural gas business and rising operating expenses, AmerenUE, an operating company of Ameren Corporation (NYSE:AEE), today filed a request with the Missouri Public Service Commission (MoPSC) for an $11 million increase in natural gas delivery rates for its approximately 125,000 Missouri gas customers. Since delivery rates account for only a portion of customers’ total natural gas bills—about one-third for residential customers—AmerenUE’s proposed increase of 18.3 percent in delivery rates would result in an increase in total gas revenues of about 6.4 percent.

For a typical residential customer, AmerenUE’s request would mean an average increase of about $6 per month, excluding taxes. But the request will not have any immediate effect on customers’ gas bills, since it must first go through the process of MoPSC review and hearings. A decision is expected no later than June 2007.

In its rate filing, AmerenUE is seeking to recover expenses associated with more than $40 million of investments in gas system improvements and expansions designed to improve service reliability and keep pace with growing customer needs. Improvements include significant replacement of old cast iron mains and unprotected steel service lines that have been completed since AmerenUE’s last gas rate case in 2003.

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Add One

“Since July 1, 2003, AmerenUE has replaced about 70 miles of old cast iron and unprotected steel gas mains and more than 3,300 service lines with modern polyethylene pipe, largely to comply with state regulations,” said Gary L. Rainwater, chairman, president and chief executive officer, Ameren Corporation.

“In addition, we have added about 215 miles of new gas mains and more than 10,000 service connections to accommodate new growth. AmerenUE customers are receiving the benefits of these expenditures, but current rates do not reflect these higher costs,” Rainwater said.

Gas delivery rates reflect the cost of constructing, operating and maintaining AmerenUE’s natural gas system, but not the cost of natural gas itself. The delivery costs usually account for about a third of a typical residential customer’s total gas bill, excluding taxes. The remainder consists of the Purchased Gas Adjustment (PGA), which reflects the commodity cost of natural gas from the company’s suppliers.

AmerenUE’s delivery charges are regulated, and any changes must be approved by the MoPSC through a rate case. Supplier costs for natural gas are not regulated, and go up or down based on supply and demand. These supplier costs are passed on to customers through the PGA without “markup” by AmerenUE. The MoPSC reviews PGA costs for prudence and accuracy, but changes do not require the filing of a formal rate case.

In its rate filing, the company is also seeking to equalize the way the PGA is calculated for all its customers. Presently, the PGA differs among the four different geographic regions of Missouri where AmerenUE provides gas service, due to differences in pipeline suppliers in these areas.

“This change is designed to benefit all of our customers by creating a common PGA rate applicable to all AmerenUE gas customers. The purpose is to more effectively integrate our centralized gas purchasing and price-hedging strategies that are designed to reduce price volatility in the cost of gas from our suppliers,” Rainwater said.

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Add Two

To help customers reduce their energy costs, AmerenUE provides a range of energy-saving tips on the Ameren Web site: www.ameren.com. AmerenUE also offers a Budget Billing Plan that enables customers to minimize the impact of rate changes and big seasonal changes in energy use by spreading their energy costs out over the entire year. Customers can sign up for Budget Billing through the Ameren Web site or by calling 1-800-55-ASK-UE (1-800-552-7583).

AmerenUE is a subsidiary of St. Louis-based Ameren Corporation. The Ameren companies serve 2.4 million electric customers and nearly one million natural gas customers in a 64,000-square-mile area of Missouri and Illinois.

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Forward-Looking Statements

Statements made in this release, which are not based on historical facts, are “forward-looking” and accordingly, involve risks and uncertainties that could cause actual results to differ materially from those discussed. Although such “forward-looking” statements have been made in good faith and are based on reasonable assumptions, there is no assurance that the expected results will be achieved. These statements include (without limitation) statements as to future expectations, beliefs, plans, strategies, objectives, events, conditions and financial performance. In connection with the safe harbor provisions of the Private Securities Litigation Reform Act of 1995, the company is providing this cautionary statement to identify important factors that could cause actual results to differ materially form those anticipated. The factors discussed elsewhere in this release and the company’s past and subsequent filings with the Securities and Exchange Commission could cause actual results to differ materially from management expectations suggested in such forward-looking statements.