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Colorado challenges EPA rejection of regional haze plan
ColoradoBiz Staff //March 5, 2026//
DENVER — Phil Weiser filed a petition in the U.S. Court of Appeals for the Tenth Circuit challenging the Trump administration’s rejection of Colorado’s regional haze plan aimed at reducing air pollution in national parks and wilderness areas.
In Brief:
- Colorado filed a lawsuit challenging the EPA’s rejection of the state’s regional haze plan under the Clean Air Act.
- The plan included air pollution rules and expected retirement dates for several coal-fired power plants.
- EPA rejected the plan, citing concerns about relying on voluntary coal plant closures.
- If the decision stands, the EPA could impose a federal implementation plan for Colorado.
The lawsuit follows the U.S. Environmental Protection Agency’s decision to reject Colorado’s regional haze state implementation plan, which the state submitted under the Clean Air Act and the federal Regional Haze Rule.
The plan adopted by the Colorado Air Quality Control Commission included regulations to reduce air pollution and accounted for the expected retirement of several coal-fired power plants. The closure dates were included in the state implementation plan submitted to the EPA for approval.
In a notice published Jan. 26 in the Federal Register, the EPA rejected the plan, saying Colorado failed to provide assurances it could implement all elements of the proposal because it relied on voluntary coal plant closure dates. The agency said those closures could raise concerns about uncompensated takings.
Weiser said the decision interferes with state authority to regulate air quality.
“EPA’s decision to disapprove Colorado’s regional haze state implementation plan is based on policy objections to closing coal plants and it is another example of the Trump administration intruding on state authority without any basis in law,” Weiser said.
The state’s plan cited utilities’ decisions to retire coal plants as a cost-effective way to comply with state and federal environmental laws.
If the rejection stands, the EPA would be required to issue a federal implementation plan for Colorado unless the state submits a new plan that the agency approves.
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