UNION ELECTRIC CO

ITEM 1A. RISK FACTORS.

The Form 10-K includes  a detailed discussion of our risk factors. The information presented below updates, and should be read in conjunction with, the risk factors and in, see the information disclosed in Part I, Item 1A, of the Form 10-K.

In connection with the resolution of the NSR and Clean Air Act litigation relating to the Rush Island Energy Center, Ameren and Ameren Missouri could be required to implement additional mitigation relief measures, the costs of which could be material and could adversely impact Ameren and Ameren Missouri's results of operations and financial position.

In January 2011, the United States Department of Justice, on behalf of the EPA, filed a complaint against Ameren Missouri in the United States District Court for the Eastern District of Missouri alleging that projects performed in 2007 and 2010 at the coal-fired Rush Island Energy Center violated provisions of the Clean Air Act and Missouri law. In January 2017, the district court issued a liability ruling against

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Ameren Missouri and, in September 2019, entered a remedy order that required Ameren Missouri to install a flue gas desulfurization system at the Rush Island Energy Center and a dry sorbent injection system at the Labadie Energy Center. Following an appeal from Ameren Missouri, in August 2021, the United States Court of Appeals for the Eighth Circuit affirmed the liability ruling and the district courts remedy order as it related to the installation of a flue gas desulfurization system at the Rush Island Energy Center, but reversed the order as it related to the installation of a dry sorbent injection system at the Labadie Energy Center. In September 2023, the district court granted Ameren Missouris request to modify the remedy order to allow the retirement of the Rush Island Energy Center in advance of its previously expected retirement date of 2039 in lieu of installing a flue gas desulfurization system. In its amended remedy order, the district court established an October 15, 2024 retirement date to allow for the completion of various transmission reliability projects and, in the interim, authorized Ameren Missouri to operate the energy center only as needed and as directed by the MISO. The United States Department of Justice is seeking an order from the district court providing for additional mitigation relief related to prior emissions. Ameren Missouri contends that the retirement of the Rush Island Energy Center, which eliminates all future emissions from the energy center, mitigates claims relating to prior emissions. In March 2024, the district court ordered Ameren Missouri and the United States Department of Justice to file proposed draft orders outlining additional mitigation relief. In May 2024, Ameren Missouri filed a proposed draft order that includes retiring the Rush Island Energy Center, a program to provide electric buses and charging stations to schools in the metro St. Louis area, a program to provide air filters to eligible Ameren Missouri electric residential customers, and the retirement of SO2 allowances. Excluding the accelerated retirement of the Rush Island Energy Center, these programs are estimated to cost approximately $20 million. Also in May 2024, the United States Department of Justice filed a proposed draft order that includes a program to provide electric buses and charging stations to schools in the metro St. Louis area and a program to provide air filters to eligible Ameren Missouri electric residential customers. These programs include a significantly greater number of buses, charging stations, and air filters than Ameren Missouris proposal and the United States Department of Justice estimates these programs would cost approximately $120 million. A mediation proceeding related to the potential additional mitigation relief is scheduled for September 2024. As of June 30, 2024, Ameren and Ameren Missouri recorded a $20 million liability related to the cost of potential additional mitigation, which represents the estimated minimum liability, as no other amount within the range was a better estimate. Ameren Missouri could be required to implement some or all of the additional mitigation relief programs included in the United States Department of Justices proposed draft order, the costs of which could be material and could adversely impact Ameren and Ameren Missouris results of operations and financial position. Depending on the scope and basis of any final order issued by the district court, which is expected by the end of 2024, Ameren Missouri or the United States Department of Justice could appeal any additional mitigation relief ordered.