BOISE, Idaho— A coalition of local and national conservation organizations today filed an appeal with the 9th U.S. Circuit Court of Appeals seeking to reverse federal approval of the Stibnite Gold Project and halt Perpetua Resources’ initial mine construction.

The proposed open-pit cyanide leach gold mine would threaten public health and clean water, harm wildlife protected under the Endangered Species Act, and permanently scar thousands of acres of public land in the headwaters of the Idaho’s South Fork Salmon River.

Perpetua has insisted on moving forward with mine construction — including cutting a new access road through protected roadless and riparian areas and habitat for threatened species — despite ongoing legal challenges.

“The Stibnite mine would leave a massive industrial footprint in one of Idaho’s wildest and most ecologically important landscapes, threatening clean water, fish and wildlife, and world-class recreation,” said John Robison, public lands and wildlife director of the Idaho Conservation League. “We will continue to protect the South Fork Salmon River watershed from a high-risk open-pit mine whose impacts would last far longer than its operations.”

Despite Perpetua’s claim that the mine is needed to provide the U.S. military with antimony — a mineral with several potential military uses — the project would only meet U.S. demand for antimony for two years, and one of the mine’s three pits is not expected to yield any antimony at all. Almost all of the project’s value comes from gold mining, not antimony.

In addition, it will take several years at best for antimony from the Stibnite project to be available to military manufacturers, and even then, because the antimony is low-grade, it may not be suitable for military use.

“I’m hopeful the appeals court will step in to halt this toxic gold mine that has no place in the wilds of central Idaho,” said Marc Fink, a senior attorney at the Center for Biological Diversity. “The mine would spew pollution into the South Fork Salmon River watershed, destroying vital habitat for imperiled salmon and bull trout. These waters and the wildlife that depend on them need our protection.”

In February 2025 the conservation groups filed suit in federal district court against the U.S. Forest Service for violating the National Environmental Policy Act and other bedrock environmental laws in approving the mine, which would be located mostly on National Forest lands. The lawsuit is also against the U.S. Fish and Wildlife Service for violating the Endangered Species Act by failing to protect threatened bull trout, wolverine and whitebark pine.

While the district court found in an Aug. 18 decision that the Fish and Wildlife Service’s Incidental Take Statements for wolverine and bull trout failed to adequately specify required protections and are legally deficient under the Endangered Species Act, it did not issue a stop-work order as conservation groups requested.

The conservation groups previously appealed the court’s denial of a preliminary injunction, and today’s appeal asks the appeals court to review additional legal violations raised in the case.

“When we fail to protect sensitive habitats from irresponsible mines, future generations pay the price,” said Jared Naimark, Western mining senior manager at Earthworks. “Perpetua Resources’ insistence on building a second access road to its gold mine through protected roadless areas and streams could cause permanent harm. We will use every legal tool to make sure that company profits don’t take priority over our public lands and endangered species.”

“We are pleased that the court ordered the U.S. Fish and Wildlife Service to add protections for wolverine and bull trout to reduce the amount of harm that the Stibnite Gold Mine would cause to these threatened species,” said Bryan Hurlbutt, staff attorney at Advocates for the West and counsel for the conservation groups. “But allowing initial mine construction to proceed presents unacceptable risks to the South Fork Salmon River watershed, our public national forest lands, and the fish and wildlife that live there.”

Perpetua has long claimed that it will clean up the mine site. But the Forest Service’s own analysis shows that the environment in the project area would be worse off if the Stibnite Gold Project proceeds.

“We believe this appeal is essential to prevent long-term damage to this cherished part of Idaho,” said Sydney Luvaas, mining and policy manager for Idaho Rivers United. “The stakes for local water quality, wildlife and surrounding public lands are simply too high to ignore.”

Beyond the federal approval at issue in this case, the Stibnite Gold Project continues to face multiple legal challenges.

Separate challenges contest Idaho's issuance of key permits — including the project's Clean Water Act Section 401 water quality certification, water pollutant discharge permit and air quality permit — reflecting ongoing concerns about the project's threats to water quality, fish and wildlife habitat, and surrounding communities.

In addition, the Nez Perce Tribe has filed a lawsuit in federal court challenging the Forest Service’s approval of the Stibnite Gold Project.

The Stibnite site is 45 air miles from McCall, Idaho, adjacent to the Frank Church–River of No Return Wilderness Area, and is within the homelands of the Nez Perce Tribe.

Perpetua’s massive mine plan entails excavating three open pits. It would create 280 million tons of waste rock and include constructing a 475-foot tall, 120-million-ton tailings storage facility — more than 1.5 times taller than the Statue of Liberty. One of the open pits would extend more than 720 feet beneath the riverbed of the East Fork South Fork Salmon River. Perpetua would also build an extensive web of roads, power lines and other industrial infrastructure across public lands to reach the remote mine site.