BILLINGS – Montana environmental regulators said Monday they want more details about potential water contamination before they will consider approving an underground copper mine that opponents fear could harm the Smith River and its acclaimed trout fishery.
The $218 million Black Butte Copper Project is proposed by Tintina Resources, Inc. in the Little Belt Mountains north of White Sulphur Springs.
An application submitted by the company in December lacked key details about its potential impacts on groundwater supplies and two Smith River tributaries — Sheep Creek and Coon Creek, according to officials from the Montana Department of Environmental Quality.
Tintina vice president Jerry Zieg said the company would respond to the agency in the near future and remains confident its project won’t be harmful.
Among the state’s chief concerns is whether Tintina’s proposal to leave about half of the mine’s tailings underground and encase them in concrete would be effective, said DEQ director Tom Livers.
Tailings are waste ore from mining that can contain heavy metals and other toxins. Cracks, shrinking or other unforeseen changes to any tailings left behind at Black Butte could allow groundwater to pass through, leaching out contaminants, state officials said.
Another concern is that treated water from above-ground tailings piles could make its way to the surface downhill of the mine operation and enter the Smith River tributaries. That would require an additional permit for the project, officials said.
“We don’t have enough information at this point to have a sense of whether this is a fatal flaw or is there a clear path forward,” Livers said. “Most of our analysis is in the immediate vicinity of the mine, but recognizing that if there are certain impacts on the tributaries, there will be derivative impacts to the Smith River itself.”
Tintina was asked in a 62-page letter issued March 10 to submit more geochemical data to back up its contention that mining would not harm the environment. The mine would be about 13 miles from the Smith River, according to the company.
Zieg said Black Butte was designed to be protective of water supplies and the requested details were being collected to ease the state’s concerns.
“This is not unexpected. It is a normal part of the process and we fully expected an ample letter from DEQ,” Zieg said. “We may have some small tweaks (to the application) to accommodate any concerns. I think a good deal of it can easily be better explained.”
Derf Johnson, an attorney with the Montana Environmental Information Center, said the concerns raised by regulators showed they were taking seriously a project that could forever alter the Smith River.
Promotional material from Tintina mentions the potential for a mining district across a much broader area of the Little Belt Mountains, with enough copper to last 50 years. “They need to tell Montanans the full truth about the project,” Johnson said.
Zieg said there were no immediate expansion plans, which would require additional permits.
Tintina is majority-owned by Sandfire Resources of Australia. Black Butte would be located on private land that contains one of the highest-grade copper deposits in the world, according to the company.