Washington sues EPA over mercury emissions rollback

WA Attorney General News Releases

Filed March 31st, 2026

Detected April 4th, 2026

Summary

Washington State Attorney General Nick Brown joined a multistate coalition filing federal lawsuit against the EPA challenging the repeal of the Mercury and Air Toxics Standards (MATS) Rule. The coalition argues the EPA violated the Administrative Procedure Act by reverting to 2012 emission standards without providing a reasoned basis or adequately considering technological developments. The lawsuit seeks reversal of the rollback affecting emissions of mercury, arsenic, lead, and other toxic pollutants from coal- and oil-fired power plants.

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What changed

Washington AG filed federal lawsuit challenging EPA's repeal of the Mercury and Air Toxics Standards (MATS) Rule, which limited emissions of mercury, arsenic, lead, toxic metals, and acid gases from coal- and oil-fired power plants since 2012. The EPA updated standards in 2024 but reverted to the 2012 standards last month. The coalition, led by Illinois and Minnesota AGs, argues the repeal is unlawful because EPA failed to provide a reasoned basis and failed to adequately consider developments in pollution control technologies and practices. The lawsuit specifically notes Washington has one remaining coal-fired power plant, the TransAlta generating station in Centralia.

Compliance teams at affected power plants should monitor this litigation as it may determine whether current emission standards stand or revert to 2012 levels. The case could affect operations at coal- and oil-fired facilities nationwide. If the court rules in plaintiffs' favor, EPA would be required to reinstate updated standards. The coalition is asking the court to determine the rule is unlawful and must be reversed.

What to do next

Monitor this litigation as it may determine whether MATS emission standards stand or revert to 2012 levels
Review current emissions compliance status at any coal- or oil-fired power plant operations
Assess potential operational implications if updated standards are reinstated following court ruling

Source document (simplified)

FOR IMMEDIATE RELEASE:

Mar 31 2026

(Updated March 31, 2026, to include additional plaintiffs.)

The Environmental Protection Agency (EPA) has violated the law by repealing nationwide standards on emissions of mercury and other toxic air pollutants, Washington and a multistate coalition argued in a new federal lawsuit filed today.

Since 2012, the Mercury and Air Toxics Standards (MATS) Rule has limited emissions of toxic air pollutants from coal- and oil-fired power plants, including mercury, arsenic, lead, and other toxic metals, in addition to acid gases, such as hydrogen chloride and formaldehyde. In 2024, following significant developments in the technologies used to control pollution, the EPA updated the standards for emissions of these hazardous air pollutants from power plants. Last month, EPA reverted to the 2012 emission standards, allowing for more of these dangerous emissions to be released into the air.

“From the San Juan Islands to the Columbia River Gorge and the Palouse, our state depends on sensible regulation to prevent dangerous pollutants like mercury from damaging the environment and Washingtonians’ health,” Attorney General Nick Brown said. “No one wants to breathe dirty air or drink unsafe water. That’s why I’m determined to challenge this administration’s unlawful rollback of protections against toxic pollutants that jeopardize our health and well-being.”

Washington has one remaining coal-fired power plant that was scheduled for closure at the end of 2025, the TransAlta generating station in Centralia. The Department of Energy, however, has ordered the coal plant to remain operational based on an alleged “energy emergency,” invoking emergency authority under the Federal Power Act. Washington state is challenging that action in court. If the Centralia coal plant reopens, Washington residents are at even greater risk for exposure to mercury and other toxic air emissions resulting from the lax standards at issue in this case.

While mercury and other hazardous air pollutants disproportionately harm people who live near coal- and oil-fired power plants, the emissions can also travel great distances and be deposited into other states. Mercury is a potent neurotoxin that poses serious dangers to public health, especially for pregnant women and children. Exposure in unborn babies and small children can lead to lifelong developmental harms and neurological disorders such as seizures, vision and hearing loss, or delayed development. In adults, mercury exposure increases the risk of cardiovascular disease, diabetes, and autoimmune dysfunction.

Mercury emissions from power plants are also a major contributor to mercury contamination in U.S. waterways. Mercury pollution in lakes and rivers harms the local commercial and recreation fishing economies, as well as tribal nations and indigenous peoples who rely on fishing for subsistence.

Brown and the coalition argue that the repeal is unlawful because the EPA has failed to provide a reasoned basis for it and failed to adequately consider developments in practices, processes, and control technologies in its attempt to revert to outdated standards. The attorneys general are asking the court to determine that the rule is unlawful and must be reversed.

Illinois Attorney General Kwame Raoul and Minnesota Attorney General Keith Ellison are leading the coalition. Joining Raoul, Ellison, and Brown in filing the legal challenge are the attorneys general of Arizona, Connecticut, Delaware, the District of Columbia, Maine, Maryland, Massachusetts, Michigan, New Jersey, New Mexico, New York, Oregon, Rhode Island, Vermont, and Wisconsin, along with Harris County, Texas, and the cities of Chicago and New York.

A copy of the petition to the U.S. Court of Appeals for the District of Columbia Circuit is available here.

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