Two environmental organizations that have previously challenged the construction of a new power plant are suing the Montana Department of Environmental Quality accusing the state agency of failing to follow the state Supreme Court’s order to consider the station’s impact on human and environmental health.

The suit is the second the Montana Environmental Information Center and the Northern Plains Resource Council have filed on the Yellowstone County Generation Station, and it raises similar issues because it alleges state officials ignored court orders to meaningfully assess the risks to human health as well as address climate change.

The lawsuit leans heavily upon the landmark Held vs. Montana case, and is one of the first to use it in new litigation. The Held case gained national attention by becoming one of the first lawsuits in the country, filed by a group of youth plaintiffs, who said that the Montana Constitution protects a “clean and healthful environment” and that state leaders were derelict in their duty to protect the state’s environment for current and future generations.

The lawsuit filed Monday in Yellowstone County District Court said the DEQ failed to look at how the plant’s emissions would affect the residents and the environment.

The power generation station, which sits approximately 300 feet from the Yellowstone River near Laurel, has been the subject of multiple lawsuits and challenges, as residents have balked at the 18 natural gas generators.  Attorneys for the two groups argue that the plant will contribute much to climate change and increase health risks for Montanans living in the state’s most populated county.

Furthermore, they allege that the state DEQ failed to consider the individual and cumulative effects of the plant, and instead just estimated the amount of pollutants, including carbon dioxide, that would be released without requiring any action to curb the effects.

“The final environmental assessment fails to adequately evaluate the environmental impacts of the Yellowstone County Generation Station’s greenhouse gas emissions despite the Montana Supreme Court’s clear direction to DEQ in January 2025 to consider and disclose such information,” the lawsuit reads.

Earthjustice attorneys E. Lars Phillips and Melissa Hornbein of the Western Environmental Law Center are representing the groups.

NorthWestern Energy, the owner of the plant and the state’s largest public utility, more than doubled its methane-fired electricity capacity when the plant went online. Court records said NorthWestern plans on keeping the plant operational until at least 2057, while emitting 769,706 tons of carbon monoxide year, translating to more than 25 million metric tons during the course of its estimated lifespan.

The lawsuit also outlines how the Montana economy will increasingly feel the effects of climate change, including more wildfires, smoke-related health problems, including respiratory and cardiopulmonary issues. Furthermore, it alleges recreation, agriculture, and tourism will wane, caused by a variety of factors including, “decreased snowpack and water levels in summer and fall, extreme spring flooding events, accelerating forest mortality, and increased drought, wildfire, water temperatures and heal waves.”

Crops are also predicted to suffer.

“Decreasing snowpack is forecasted to lead to decreased streamflow and less reliable irrigation capacity, during the late growing season, which would have the greatest impact on hay, sugar, barley, market garden, and potato producers across Montana,” the lawsuit said. “Increased temperatures are forecasted to allow winter annual weeds, like cheatgrass, to increase in distribution and frequency in winter wheat cropland and rangeland, resulting in decreased crop yields and forage productivity and increased rangeland wildfire frequency.”

The lawsuit also attempts to quantify the costs of the plant by using the Social Cost of Carbon calculator — a tool which helps experts measure the economic cost of carbon.

Using a rate of $190 per ton of carbon dioxide release, the lifetime estimate of the plant’s impact is pegged at $132,078,050.

“The (Montana Supreme) court directed DEQ to evaluate the direct, secondary and cumulative impacts of the Yellowstone County Generation Station,” the lawsuit said. “DEQ’s brief discussion (of) potential mitigation measures, consisting entirely of summary references to geological carbon sequestration, industrial carbon sequestration, and biological sequestration, completely fails to analyze and disclose emissions control technologies and operational limitations that could reduce the (plant’s) greenhouse gas emissions and related climate impacts.”

Nearby residents say they’re already feeling the impacts of the operational power generation station.

“It is deeply disappointing that the Montana DEQ granted NorthWestern Energy an air quality permit based on a flawed and misleading assessment that ignored the daily harms this plant inflicts on Laurel’s community,” said Steve Krum, member of Northern Plains Resource Council and Laurel resident. “Our families see the brown clouds, feel the vibrations, and live with the hidden toxins every day, proof that a full environmental impact statement is required, not a superficial review. This plant should never have been sited in a populated area, and certainly not without constitutional protections for our community’s health and safety.”