HELENA — A magistrate judge scheduled a May trial in a lawsuit accusing the owners of a Montana power plant of violating the federal Clean Air Act and state laws.
The Sierra Club and the Montana Environmental Information Center allege the Colstrip coal-fired plant discharges an excessive amount of pollution.
They accuse the owners of making changes to the plant without proper permits, and want to block it from operating until it is in compliance.
Colstrip serves markets across the Pacific Northwest.
The six companies that own the 2,100-megawatt plant say its emissions fall within federal and state regulations.
They acknowledge making changes to the plant, but say the work was routine and did not require permits.
On Tuesday, U.S. Magistrate Judge Jeremiah Lynch scheduled a May 31 bench trial in Missoula.