Colstrip Coal Plant Granted Two-Year Exemption from EPA Emissions Rule

Washington, D.C. — Colstrip Steam Electric Station Units 3 and 4 have been granted a two-year exemption from the Environmental Protection Agency’s (EPA) Mercury and Air Toxics Standards (MATS), following a directive from President Donald Trump aimed at supporting American energy infrastructure during a declared national energy emergency.

The exemption was confirmed on April 14, just days after President Trump’s Regulatory Relief for Certain Stationary Sources proclamation. Congressman Troy Downing (MT-02) praised the decision, calling it a victory for affordable, reliable energy in Montana.

“Overreaching regulation is the greatest hurdle to increasing access to affordable, reliable energy,” said Downing. “Unleashing American energy promises to lower costs, protect American jobs, and bolster U.S. national security.”

The move follows a March 31 letter from Montana’s congressional delegation to EPA Administrator Lee Zeldin. Signed by Senators Steve Daines and Tim Sheehy, and Representatives Troy Downing and Ryan Zinke, the letter criticized the Biden-era MATS rule as economically and technologically infeasible for Colstrip.

According to the delegation, the rule would force Colstrip to install a $500 million emissions control system that combined fabric filters with existing wet scrubbers—an untested configuration with uncertain results. The lawmakers argued that construction could not be completed in time to meet the rule’s deadlines, rendering compliance “unavailable” from both a technological and timing standpoint.

The EPA acknowledged in internal analysis that Colstrip alone would bear 42% of the rule’s compliance burden.

In February, the U.S. Senate voted to affirm Executive Order 14156, declaring a national energy emergency. The order cited threats to grid reliability and economic security. The Trump administration’s April 8 proclamation invoked this authority to allow targeted exemptions for coal and oil-fired power plants deemed critical to U.S. energy stability.

Colstrip Units 3 and 4 are among the largest coal-fired plants in the Western U.S., supplying baseload power across Montana and the Pacific Northwest. Supporters say the exemption will preserve jobs, stabilize regional energy prices, and allow more time to plan for the plant’s future.

“With this executive order, President Trump delivered on a hallmark promise: to protect and unleash Made-In-America energy,” said Senator Steve Daines. “The Colstrip Power Plant keeps the lights on for Montanans and provides jobs and revenue for the state. It’s refreshing to finally have an administration that puts the needs of our communities first, rather than pandering to woke environmentalists.”

Daines said he looks forward to working with the administration on further ways to support Montana’s energy sector.

Governor Greg Gianforte praised the President and the EPA Administrator and is slated to launch an Unleashing Energy Task Force group in the coming weeks. The task force is said to be focusing on developing long-term solutions to ensure Montana has affordable, reliable energy.

“Thanks to President Trump and EPA Administrator Lee Zeldin, America’s coal-fired power plants can continue to support thousands of jobs and power our homes, schools, and businesses,” Gov. Gianforte. “With coal in our energy portfolio, we can stabilize our energy grid and reduce costs for consumers. In Montana, we’ll continue to support an all-of-the-above approach to energy to keep the lights on across the region.”

Critics, including environmental health advocates, warn the exemption prolongs exposure to toxic pollutants such as mercury and arsenic and delays needed energy transitions. EPA findings have shown that Colstrip is among the highest total emitters of mercury and other hazardous air pollutants in the country, though the last publicly available EPA emissions profile was compiled several years ago. The plant’s operators have not published emissions reductions since that period, and the new rule targeted untested upgrades many say would be cost-prohibitive.

Supporters of the exemption argue the EPA’s MATS updates functioned as a de facto shutdown order. The combination of pollution controls required by the 2024 revision—fabric filters and wet scrubbers—had not been commercially demonstrated at a facility like Colstrip, which operators said made compliance technologically and economically unfeasible.

The Colstrip plant remains one of the few dispatchable power sources in the Northwest capable of providing steady baseload power during peak demand. Critics of the MATS rule argued it risked triggering grid instability, higher energy prices, and mass job losses without any stable and reliable generation to take its place.

Though emissions are high in absolute terms, some argue this is due to Colstrip’s size and importance. When adjusted for total energy output, its emissions rate may be more comparable to other facilities.

The MATS exemption runs for two years beyond the rule’s original compliance date, July 8, 2027.