(KPAX) A coalition of conservation groups is suing the Montana Department of Environmental Quality (DEQ) over its approval of a permit for the Black Butte Copper Project near White Sulphur Springs.

The suit claims DEQ failed to conduct a thorough environmental analysis of the project and ignored thousands of public comments opposing the copper mine, which is proposed near the headwaters of Montana's iconic Smith River.

The Montana Environmental Information Center, Earthworks, American Rivers, Trout Unlimited and its Montana chapter filed the lawsuit in state district court Thursday.

Officials with Sandfire Resources America Inc., the company proposing the Black Butte Project, said they are disappointed with the litigation.

"No major natural resource project in Montana seems to go unchallenged despite strict regulations and processes enshrined in Montana law," Sandfire CEO Rob Scargill said Friday.

Scargill credited DEQ and Gov. Steve Bullock for a thorough job of evaluating and reviewing the permit application over the past four and a half years.

"We will work with the Montana DEQ to defend this litigation vigorously," said Scargill.

The litigants contend in granting the mine's operating permit that DEQ violated both the Montana Environmental Policy Act and the Metal Mine Reclamation Act.

The lawsuit points out that the mine is proposing to use a novel approach to contain toxic mine waste, which the groups say is risky and untested.

“The Smith River watershed is no place to store toxic mine waste using unproven technology," said Bonnie Gestring, northwest program director for Earthworks. "We’re adamant that this wonderful river should be nobody’s guinea pig, especially not the mining industry’s.”

The Black Butte project became a focal point in the Montana governor's race this spring during the primary. Democrat Whitney Williams, who lost the nomination to Lt. Gov. Mike Cooney, pledged to protect the Smith River and vowed to stop the controversial mine project.

Emily's List SuperPAC purchased more than $650,000 in TV ads in the recent primary campaign, focusing on the proposed mine and Williams' opposition.

The state of Montana manages the Smith River as the only permitted recreational river in Montana, which is renown for its towering limestone canyons, and world-class trout fishery.

"The Smith River isn’t only a Blue Ribbon trout stream and Montana treasure, but also an economic driver and contributor to Montana’s $7.1 billion a year outdoor economy," said Colin Cooney with Trout Unlimited. "It is a sustainable resource that must be protected."

While the lawsuit makes its way through the courts, the company is moving forward with its construction plans this summer.

In a press release Friday, Sandfire announced it's in the process of finalizing a construction contract that will allow it to be part of the nation's economic recovery from the COVID-19 pandemic.

“This sets a clear path toward completing the Black Butte Feasibility Study and building a showcase mine that will combine local input and expertise with state-of-the-art technology,” said Sandfire America Senior Vice President Jerry Zieg.

"We’re very pleased and look forward to being part of the solution to Montana’s economic revival by providing new jobs and new opportunities.

In mid-May, the Montana DEQ established a bond of $4.65 million for the Black Butte Copper Project. The company must secure that bond before it can begin any surface construction at the mine site.