AVISTA CORP

Our environmental issues and contingencies disclosures have not materially changed during the three months ended March 31, 2024 except as follows:

SEC Climate Disclosure Rules

In March 2024, the SEC adopted final rules requiring certain climate disclosures to be incorporated into SEC filings. The final rules as written are effective for our filings starting with the 2025 Annual Report on Form 10-K.

After the final rules were published by the SEC, multiple lawsuits were made, including allegations that the SEC does not have statutory rulemaking authority over climate reporting, among other various allegations. The SEC requested the cases be consolidated into one action, and the consolidated action is now before the United States Circuit Court of Appeals for the Eighth Circuit.

In April 2024, the SEC voluntarily stayed the implementation of the final rules. In the stay order, the SEC noted it intends to vigorously defend the validity of the final rules.

We are monitoring the outcome of the consolidated action and voluntary stay.

EPA Regulations for Power Plants

On April 25, 2024, the EPA released a package of final regulations addressed to electric generation facilities. These include:

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Greenhouse gas regulations for new natural gas-based turbines and existing coal-based units, pursuant to section 111 of the Clean Air Act (the “CAA Section 111 Rules”). This rule finalizes (a) the repeal of the Affordable Clean Energy (“ACE”) rule; (b) guidelines for GHG emissions from existing fossil fuel-fired steam generating electric generating units; and (c) revisions to existing performance standards for new, reconstructed or heavily modified fossil fuel-fired stationary combustion turbine electric generating units.

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Supplemental Effluent Limitations Guidelines and Standards for the Steam Electric Power Generating Point Source Category (the “ELG Rule”). The ELG Rule applies to wastewater discharges from coal-based generating units and establishes pollution control requirements. The Rule builds upon the 2015 and 2020 ELG Rules. It includes a subcategory of requirements for coal plants that will be retired or repowered by the end of 2028 and provides additional compliance pathways for coal plants that retire by the end of 2034.

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Updated Mercury and Air Tox Standards, pursuant to section 112 of the Clean Air Act (the “MATS Rule”). The MATS Rule sets emissions limits for filterable particulate matter for coal-based generating units. The Rule reduces those limits from the standards that were originally set in 2012.

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Disposal of Coal Combustion Residuals from Electric Utilities – Legacy CCR Surface Impoundments (the “CCR Rule”). The CCR Rule builds on 2015 regulations, which apply to active power plants that dispose of coal combustion residuals in surface impoundments or landfills, by regulating inactive surface impoundments at inactive power plants and CCR management units at active and inactive power plants.

We are in the process of analyzing each of these rules to assess the impact, if any, it may have on our existing generating units, including Colstrip and/or our natural gas-fired generating units. At this time, there are no indications that the implementation of these rules would impact our agreement to transfer our Colstrip ownership to Northwestern, which is planned to close on December 31, 2025. To the extent these regulations result in increased compliance costs, we expect to seek recovery of those costs through the ratemaking process.

See the 2023 Form 10-K for further discussion of our environmental issues and contingencies.