The Montana Department of Environmental Quality will have a chance on June 21 to tell the state’s high court that its review of a mine operating permit for the Black Butte Copper Project was thorough.

DEQ appealed District Court Judge Katherine Bidegaray’s 2022 ruling that the agency had erred when analyzing the White Sulphur Springs-area mine’s proposal to store and stabilize tailings using cement.

The mine is situated near the headwaters of the Smith River in the Little Belt Mountains. Tintina Montana Inc. has proposed mining for 13 years to retrieve 14.5 million tons of copper ore in the area. The company first applied for a permit in 2015, which DEQ approved in 2020.

The case against DEQ was brought by Montana Trout Unlimited, the Montana Environmental Information Center, Trout Unlimited, Earthworks and American Rivers.