Stibnite Mine Pollutant Discharge Permit

February 27, 2026 — Representing Idaho Conservation League, Idaho Rivers United, Earthworks, and Save the South Fork Salmon, Advocates for the West along with co-counsel at the Western Environmental Law Center filed a petition for review with the Idaho Department of Environmental Quality (DEQ) challenging a permit the agency issued early this year to Perpetua Resources for the proposed Stibnite Gold Mine, located 12 miles east of Yellow Pine, Idaho. DEQ failed to comply with the Clean Water Act in developing the permit, which, if uncorrected, would allow the mine to unlawfully discharge toxic pollutants, including arsenic and mercury, into water bodies that are already suffering from the effects of past mining.

In addition, the permit would allow the company to heat up nearby creeks home to threatened bull trout. The East Fork of the South Fork of the Salmon River and Meadow Creek are each already formally listed as impaired for high temperature, arsenic, and antimony pollution. DEQ also failed to require the most up-to-date treatment technology for 120 million tons of tailings the mine is expected to create.

The proposed mine site is adjacent to the Frank Church–River of No Return Wilderness Area and within the homelands of the Nez Perce Tribe. The sprawling operation would include three open pits, ore processing facilities, roads, transmission lines, and on-site worker housing. It would clear thousands of acres of vegetation, destroy hundreds of acres of wetlands, eliminate fish and wildlife habitat, generate billions of pounds of toxic mine waste, and impair surface water and groundwater regimes well past the life of the mine.

Under the proposed action plan, Perpetua would spend the first three years constructing infrastructure and preparing for mining operations. The operational construction and mining activities would take place over an estimated 15 years, while mine closure and reclamation would take place during years 16 to 25. According to Perpetua, gold accounts for 96% of the project profits and antimony only 4%.

The operation footprint extends across areas in the North Fork Payette River and South Fork Salmon River subbasins. The project proposes discharging into the East Fork of the South Fork Salmon River (EFSFSR) and Meadow Creek. As part of the systems associated with these proposed discharges, Perpetua intends to construct surface water and stormwater diversions, a tunnel diversion for the EFSFSR, a tunnel diversion for Meadow Creek, a diversion for West End Creek, water storage ponds, open pit dewatering wells, active and passive water treatment systems, and various water conveyance pipelines and storage tanks.

Idaho Conservation League, Idaho Rivers United, Save the South Fork Salmon, and Earthworks submitted joint written comments for the proposed permit on July 21, 2025. The petitioners raised numerous concerns, including that DEQ failed to (1) develop the necessary and appropriate technology based effluent limitations for the facility; (2) to properly document and explain in its fact sheet how it calculated those limits and thus prevented the petitioners from providing meaningful public comment on those limitations; (3) develop the necessary and appropriate water quality based effluent limitations for the facility; (4) develop the necessary and appropriate effluent limitations to protect threatened bull trout; and (5) develop effluent limits on the total mass of each pollutant discharged from the facility. On January 30, 2026, DEQ issued the final permit, with no changes in response to the petitioners’ comments.