Amanda Pampuro

DENVER (CN) — The Clean Air Act gives Wyoming wide discretion in designing plans to retrofit small coal-powered plants in efforts to reduce regional haze, the 10th Circuit found in an order published Tuesday that rejected separate critiques filed by the U.S. Environmental Protection Agency and several conservation groups.

Vast swaths of Wyoming are protected as national parks, including Grand Teton and Yellowstone, which sit adjacent to haze-producing coal-powered plants. As mandated by the Clear Air Act, the EPA implemented the 1999 Regional Haze Rule and the 2001 Best Available Retrofit Technology (BART) guidelines directing states to clean up the air, particularly around national parks.

The BART program allows polluting coal plants to remain online with modifications, and directs states to lead the way.

In 2011, Wyoming submitted plans to retrofit five coal plants to control sulfur dioxide and nitric oxide, two compounds largely responsible for smog. The EPA approved Wyoming’s plan for four units but rejected the plan for the Wyodak plant in the northeast corner of the state, an hour away from Devils Tower National Monument.

Wyoming petitioned the 10th Circuit for review in 2014. Power company PacifiCorp, which runs the utility in question, joined. The Sierra Club and other environmental groups petitioned the court to reject Wyoming’s plan for two other PacifiCorp units, Naughton I and II.

Although litigation began under Obama-era EPA administrator Gina McCarthy, Wyoming asked the court to stay proceedings under Trump-era administrator Scott Pruitt, hoping to work out a deal. A settlement did not manifest and the case passed on to Biden-nominated administrator Michael Regan.

A 10th Circuit panel heard oral arguments this past May.

Ultimately the panel found the Clean Air Act leaves states like Wyoming relatively free to adopt or ignore the guidelines for small coal plants like Wyodak which produces 335 annual megawatts when designing state implementation plans, or SIPs.

"Certainly, the guidelines are helpful while not binding, and ordinarily no problem presents itself when the EPA references them in reviewing Wyoming’s SIP,” U.S. Circuit Judge Timothy Tymkovich wrote in a 23-page opinion.

“The problem arises, however, when the EPA’s rejection of the state’s BART determination — supposedly for unreasonable cost and visibility analyses — is grounded in a strict application of the nonbinding guidelines,” the George W. Bush appointee added.

Rather than approve Wyoming’s plan outright, the court remanded it to the EPA for review in light of the panel’s clarification.

Under a similar rational of deference, the court denied a request submitted by the Sierra Club and other conservation groups to send plans for the Naughton plants back to the drawing board.

"This balancing means that although the ‘B’ stands for ‘best,’ BART is not necessarily the most stringent or effective technology. That is because the statutory balancing is aimed at allowing a state to generate a SIP that addresses each source’s site-specific characteristics,” Tymkovich wrote.

Haze is caused by sulfates, nitrates and particulate matter like sea salt, soot and soil. The number of annual hazy days around Wyoming’s national parks has fluctuated over the last decade per the National Park Service’s IMPROVE program, which collects air quality data.

A paper published in Atmospheric Environment found Clean Air Act regulation along with reductions in coal power have successfully cut average haze in half across the country, with the greatest decreases measured in the East.

The court additionally settled two questions of mootness to footnotes. First, the panel asked whether the whole review was moot since a planning deadline had long passed, but found the contemporary retrofit plan held implications for future policy. In a separate footnote, the panel rejected PacifiCorp’s request to dismiss the conversationists’ argument as moot since the Naughton plants are scheduled to be decommissioned in 2025.

U.S. Circuit Judge Robert Bacharach, a Barack Obama appointee, and U.S. Circuit Judge Joel M. Carson, appointed by Donald Trump, rounded out the panel.

Earthjustice represented the Sierra Club, the National Parks Conservation Association and the Powder River Basin Resource Council on appeal. The organization called the 10th Circuit decision a setback.

“Excessive pollution from Wyoming coal plants is both harmful to the air we breathe and unnecessary in light of modern technology currently in use at other plants across the country,” said Jenny Harbine, managing attorney for Earthjustice’s Northern Rockies Office in a statement. “Today's decision is a temporary setback in our fight to clean up the skies, but now EPA must act urgently to ensure PacifiCorp takes the necessary steps to reduce harmful emissions from the Wyodak and Naughton plants.”

PacifiCorp applauded the ruling.

“PacifiCorp agrees with the court that the state of Utah and EPA correctly approved the current regional haze plan,” said PacifiCorp spokesperson David Eskelsen via email.

The Wyoming Attorney General’s office did not immediately respond to a press inquiry.