Contact: Adam McMahon, Cyanidation Program Manager, adam.mcmahon@deq.idaho.gov
BOISE – The Idaho Department of Environmental Quality (DEQ) is issuing a cyanidation permit modification to Perpetua Resources Idaho, Inc (Perpetua Resources) for the Stibnite Gold Project (SGP).
Perpetua Resources is the operator of the SGP, a proposed gold mine located in Valley County, approximately 12 miles east of Yellow Pine, Idaho. The SGP is located on private and public lands within the Boise and Payette National Forests. Perpetua Resources has 29,827 acres of mining claims comprised of both unpatented (28,477 acres) and patented (1,350 acres) claims. The mine is also located within the historical Stibnite Mining District, an area impacted by previous mining activities including underground mine workings, rock dumps, tailings deposits, and open pits, including the Yellow Pine Pit.
Cyanidation is the process of extracting precious metals from ores by treating them with a solution of sodium cyanide or calcium cyanide. The cyanidation permit establishes the procedures and requirements to construct, operate, and close the portion of a cyanidation facility that is intended to contain, control, or treat process water, process-contaminated water, or cyanidation pollutants. The permit modification incorporates the grinding and flotation components of the ore processing area as Phase II. Additional cyanidation facility components and operating plans will be incorporated as subsequent phases in permit modification applications.
DEQ issued a draft permit modification and initiated a 60-day public comment period on February 19, 2026. A public meeting was held on March 1, 2026. Following this review period, DEQ determined the application for the grinding and flotation phase of the ore processing facility meets the requirements of Idaho Code § 39-118A. Therefore, DEQ is making a final permit decision to issue a modified permit to Perpetua Resources.
Individuals may be entitled to appeal this action pursuant to the “Contested Case Rules and Rules for Protection and Disclosure of Records” (IDAPA 58.01.23). For more information, see DEQ’s Petitions for Review and Precedential Orders web page.
For more information on the final permit, including the permit, fact sheet, and responses to comments, see DEQ’s Issued Permits and Water Quality Certifications web page.