A Montana judge Thursday vacated a state air permit for a $275 million gas-fired power plant being built by NorthWestern Energy, halting construction in a dispute over its significance that would trigger a full environmental review.
The Montana Department of Environmental Quality failed during its environmental review to assess greenhouse gas emissions from the Laurel, Montana, power plant, Michael Moses, a judge at the Montana district court for Yellowstone County, said in the ruling.
The DEQ improperly reasoned that it does not need to consider the plant’s future GHG emissions because Montana law bars reviews of environmental impacts beyond the state’s borders, according to Moses.
“They must take a hard look at the greenhouse gas effects of this project as it relates to impacts within the Montana borders,” Moses said.
When the DEQ issued the air quality permit for the project in 2021 it determined it would not have a significant effect on the environment and therefore only needed an environmental assessment rather than a more robust environmental impact statement.
Moses said it was premature to say whether the project is “significant” under the Montana Environmental Policy Act, a finding that would trigger an EIS. However, he said the project is 15 miles from Billings, Montana’s largest city, will release close to 770,000 tons of carbon dioxide a year and is next to the “pristine” Yellowstone River.
“To most Montanans who clearly understand their fundamental constitutional right to a clean and healthful environment, this is a significant project,” Moses said.
The judge dismissed other challenges to the DEQ’s review involving a pipeline, water quality, sulfur dioxide emissions and noise. But he said the agency must further assess how light from the power plant would affect the area.
The court decision requires NorthWestern to stop building the power plant, according to the Montana Environmental Information Center and the Sierra Club, groups that sued over the air permit.
The power plant grew out of an all-source solicitation NorthWestern issued in January 2020 for peaking and flexible capacity.
The utility company started building the power plant in April 2022 with the expectation it would be operating by next year, according to NorthWestern’s most recent quarterly report with the Securities and Exchange Commission. The lawsuit, as well as other legal challenges related to the power plant, could delay its construction, NorthWestern said. The company had spent $154.9 million on the project as of Dec. 31.
NorthWestern didn’t respond immediately to a request for comment.
The legal dispute comes as NorthWestern is preparing to take at no charge Avista Corp.’s 222-MW share of the coal-fired Colstrip power plant in 2026, a move the utility says will satisfy its capacity needs for at least five years.