Environmental groups filed suit in a Meagher County district court Monday challenging mining exploration near the headwaters of the Smith River.

The Montana Environmental Information Center and Earthworks, represented by Earthjustice, filed the complaint against the Montana Department of Environmental Quality and Tintina Alaska Exploration Inc. based out of Vancouver, British Columbia. The complaint alleges that DEQ failed to conduct an adequate environmental analysis of the Black Butte Copper Project near Sheep Creek, a tributary of the Smith.

Sheep Creek originates in the Little Belt Mountains about 15 miles northeast of White Sulphur Springs before flowing west to the Smith. DEQ performed an environmental assessment of the proposed exploration, which hinged on Tintina mitigating any issues with contamination or in-stream flow.

“The environmental assessment didn’t do enough to look at the impacts of dewatering and water quality from mine discharges,” Bonnie Gestring of Earthworks said. “The department should have done an environmental impact statement instead to do a more rigorous assessment.”

On Jan. 14, DEQ approved an exploration permit for Tintina to build a “decline,” or ramp that would survey the Johnny Lee copper deposit. The permit would give Tintina permission to remove 10,000 tons of rock for sampling. Preliminary economic reports indicate the mine could net 47 million pounds of copper per year. That could put values at almost $2 billion over the next 14 years if the price of copper remains near $3 per pound.

Earthworks and MEIC contend that Tintina’s proposal goes well beyond typical mining exploration. The decline will go a mile deep and well below the water table. In order to explore, Tintina will need to pump water out, which could contain contaminates. Removing groundwater could also impact in-stream flow for Sheep Creek, Gestring said.

Vice president of exploration for Tintina Jerry Zieg said they are still evaluating the lawsuit.

“In general we feel that DEQ went through a pretty thorough and exhaustive process,” Zieg said. “As a company and a group of people we’re as highly concerned with water quality in Sheep Creek and the Smith as anyone else.”

Communications director for DEQ Chris Saeger said the agency had received the lawsuit and its attorneys were reviewing it, but did not comment further.

DEQ received nearly 4,000 public comments on the environmental assessment.