The decision requires Crown Butte and the Canadian conglomerate Noranda Inc. to come up with a cleanup plan before getting water discharge permits needed to start the mine. They may also have to pay up to $150 million in fines.
The companies had argued that the acid drainage, which has killed all aquatic life in nearby areas, is natural. The judge rejected those claims, citing earlier statements by Crown Butte president Joe Baylis that old mine sites were the source of pollutants. Under the Clean Water Act, current owners of a site are liable for pollution from past activities.
Bob Ekey, with the Greater Yellowstone Coalition - one of 10 environmental groups who filed the suit - praised the court's decision, including its rejection of Noranda's claim that only the subsidiary Crown Butte was liable for contamination. Said Ekey: "We want those deep pockets to be responsible."