Colorado Attorney General Phil Weiser and several environmental organizations have filed separate petitions in the U.S. Court of Appeals for the Tenth Circuit, challenging the U.S. Environmental Protection Agency’s decision to reject Colorado’s regional haze plan.

The plan included proposals to retire coal plants and impose emission limits on industrial sources to improve visibility in national parks, including Rocky Mountain National Park.

Weiser filed a petition on March 4 contesting the EPA’s Jan. 26 rejection of the 2022 state implementation plan. On the same day, the National Parks Conservation Association and the Sierra Club, represented by Earthjustice, filed their own challenge, describing the EPA action as an illegal effort to prop up coal.

The plan, adopted by the Colorado Air Quality Control Commission, included utilities’ proposed deadlines for retiring certain coal-fired units by 2029 and set emission limits on dozens of other major sources, such as the Suncor oil refinery and cement plants. State officials said the plan would deliver significant reductions in statewide emissions.

Colorado has met its reasonable progress obligations under the federal Regional Haze Rule since 2018 and it continues to satisfy visibility protection requirements, independent of the disputed state implementation plan (SIP) elements, according to the EPA.

“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 in a release. “Colorado included the closure of several coal-fired power plants in its plan based on utilities’ independent decisions to close them. Those decisions in turn were based on the utilities’ judgment that closure was the best and most cost-effective way to comply with a range of state and federal laws.”

The agency objected to including specific coal-closure dates, arguing that the state improperly sought to mandate early shutdowns using the haze program, despite the state’s ongoing compliance.

“Colorado chose clean air. The EPA chose pollution,” said Tracy Coppola, Colorado senior program manager for the National Parks Conservation Association. “We’re taking legal action to protect Rocky Mountain National Park, and all Coloradans, from the EPA’s reckless decision.”

The EPA rejected the plan, ruling it lacked “necessary assurances” of enforceability under the Clean Air Act.

The agency raised concerns about potential uncompensated takings —government action that deprives private property owners (in this case, utilities) of economic value or use without just compensation, as prohibited by the Fifth Amendment.

“Reliable baseload energy sources are essential to powering the Great American Comeback and ensuring families have cost-effective energy,” EPA Administrator Lee Zeldin said in a release. “The Trump EPA has repeatedly demonstrated that we can achieve our statutory obligations, support baseload power, and improve visibility within our national parks.”

Sarah Tresedder, senior climate and energy organizer at Colorado Sierra Club, said, “This can’t be seen any other way; it’s a handout to the coal industry and a disservice to Coloradan communities and our environment.”

The Colorado Mining Association supported the EPA’s decision.

“Today’s decision by EPA is prudent given the state’s failure to sufficiently or reasonably consider the energy impacts of its plan to require the retirement of the coal fleet and the negative effects for grid reliability,” said Adam Eckman, president and CEO of the Colorado Mining Association.

Environmental attorney Paul Seby noted that most current haze impairment comes from wildfires and international sources, not power plants.

“There is a standalone SIP for visibility,” Seby said. “The majority of the impairment now is coming from forest fires, from the management of public lands or international emissions … (including) Africa and China.”

Grid reliability worries prompted a U.S. Department of Energy order in December to keep Craig Station Unit 1 available through March 2026 amid regional energy shortfalls.

The full disapproval obligates the EPA to issue a federal implementation plan unless Colorado submits an approvable revision or the court overturns the decision.