Stibnite Mine Air Quality Permit

November 7, 2025 — Advocates for the West and our partners filed our opening brief in our state court case challenging the air pollution permit issued for the Stibnite Gold Mine.

September 18, 2025 — An Ada County judge ruled in favor of Advocates for the West and our partners, denying DEQ’s motion to dismiss our state court challenge to the air pollution permit issued for the proposed Stibnite Gold Mine. DEQ sought dismissal of the lawsuit on procedural grounds. The ruling means our case will proceed.

July 23, 2025 — Advocates for the West filed suit in Idaho state court representing the Idaho Conservation League (ICL) and Save the South Fork Salmon against the Idaho Department of Environmental Quality (DEQ) for failing to protect public health in issuing an air quality permit to Perpetua Resources for the proposed Stibnite Gold Mine, an open-pit cyanide leach gold mine in Valley County, Idaho.

The permit is intended to verify the project meets federal Clean Air Act and state air quality requirements to protect public health and the environment but fails to include adequate monitoring and other safeguards that ensure particulate pollution is kept to safe levels. The permit allows Perpetua to emit arsenic at levels that would exceed the yearly limit DEQ itself set to protect the public from this carcinogen. The permit also exempts the Stibnite Road—which the public will be allowed to use during mining—from having to comply with Idaho’s air pollution protections.

Conservation groups and the Nez Perce Tribe raised repeated concerns during the permitting process about particulate and arsenic pollution that would result from the project, which DEQ failed to address when it issued the permit in June 2022. ICL, Save the South Fork Salmon, and the Nez Perce Tribe appealed the permit to the Idaho Board of Environmental Quality. The Board ruled in favor of the conservation groups and the tribe in 2024, faulting DEQ for manufacturing an exception to Idaho’s arsenic pollution standards to permit the mine. In May 2025, however, the Board signed off on the permit, even though it still fails to ensure arsenic-laden dust is kept to safe levels.

In the lawsuit, ICL and Save the South Fork Salmon, also represented by Julia Thrower of Mountain Top Law, seek to revoke the air permit unless and until the mine can be permitted in a way that protects public health and complies with law.

October 4, 2024 — Advocates for the West and our partners filed two expert declarations in our case challenging the air pollution permit issued, and later invalidated, for the proposed Stibnite Gold Mine. The Idaho Board of Environmental Quality has remanded the permit to a hearing officer for additional consideration of Idaho Department of Environmental Quality’s analyses of ambient air arsenic and carcinogenic risks.

May 9, 2024 — The Idaho Board of Environmental Quality issued a written decision invalidating Perpetua Resources’ air pollution permit for the proposed Stibnite Gold Mine in Valley County. Blasting and hauling operations at the proposed mine would emit massive amounts of arsenic-laden dust. The Board found that the Department of Environmental Quality failed to follow Idaho air pollution rules designed to protect people from exposure to toxic and carcinogenic pollutants when it issued a permit to Perpetua.

May 1, 2024 — In an official oral decision, the Idaho Board of Environmental Quality invalidated Perpetua Resources’ air pollution permit for the proposed Stibnite Gold Mine. The Board struck down the “creative” approach used by the Idaho Department of Environmental Quality (DEQ) to assess cancer risks from the Stibnite Gold Mine, which would have allowed Perpetua to emit massive amounts of arsenic-laden dust in quantities that exceed state law limits designed to protect the public from exposure to carcinogens. The Board’s decision sends a critical component of Perpetua Resources’ ill-conceived proposal back to the drawing board, requiring an administrative hearing officer to re-address arsenic emission and cancer risks from the proposed mine.

January 17, 2024 — Advocates for the West filed our opening brief before the Idaho Board of Environmental Quality in support of an Amended Petition for Review of the Preliminary Orders, challenging the Idaho Department of Environmental Quality’s approval of the air quality permit for the proposed Stibnite Gold Project.

September 21, 2023 — Advocates for the West presented oral argument along with Julie Thrower from Save the South Fork Salmon during a summary judgment hearing in our contested case.

June 9, 2023 — Advocates for the West filed a brief in response to the Idaho Department of Environmental Quality’s cross-motion for summary judgment and intervenor Perpetua Resources’ motion for summary judgment, along with standing declarations.

April 14, 2023 — Advocates for the West filed our motion for summary judgment and supporting brief in this case. When the Idaho Department of Environmental Quality issued the air quality permit to Perpetua Resources, the agency failed to account for a large portion of the project’s course particulate matter and arsenic emissions, and underestimated the degree to which they will degrade ambient air quality and threaten public health and the environment.

July 22, 2022 — Advocates for the West appealed an air quality permit issued by the Idaho Department of Environmental Quality (DEQ) to Perpetua Resources Idaho, Inc. for its proposed Stibnite Gold Project. We represent the Nez Perce Tribe and Idaho Conservation League in this appeal, which was filed together with Save the South Fork Salmon. Over the prior two years, the groups raised repeated concerns during the permitting process about particulate and arsenic pollution that would result from the project. Still, Idaho DEQ failed to address these concerns when it issued the Permit to Construct in June 2022.

The Stibnite Gold Project is a massive gold mine proposed in the headwaters of the East Fork of the South Fork Salmon River adjacent to the Frank Church River of No Return Wilderness Area. The area within and surrounding the proposed mine is part of the aboriginal homelands of the Nez Perce Tribe who have reserved the right to fish, hunt, gather, and pasture at traditional places in their 1855 Treaty with the United States.

The proposed mining activities would result in large quantities of dust or particulate matter being emitted into the air, which can cause serious health problems including premature death, heart attacks, aggravated asthma, and other respiratory issues. The rocks, soils, and dust at Stibnite are also known to be very high in arsenic, a human carcinogen known to cause developmental effects, diabetes, pulmonary disease, and cardiovascular disease.

Controlling dust from mining operations is critical to protect public health, but the permit fails to include basic monitoring and other safeguards to ensure dust levels are kept to safe levels.