Initial Stream Diversion Activities Completed - Contributing To Water Quality Improvements At Historic Mine Site

BOISE, ID - Perpetua Resources Corp. reported that the summer 2022 field program to initiate water quality improvements in the historical Stibnite mining district is complete. After 100 years of mining activity, the millions of tons of unconstrained tailings and mine waste left behind by previous operators has been degrading water quality for decades. Perpetua was granted permission to take action to address the most pressing water quality concerns through an agreement signed in 2021 between the Company, the Environmental Protection Agency (EPA) and the United States Department of Agriculture (USDA).

The 2022 field program included: 1) Lining and improving the existing Hennessy Creek diversion channel around the Northwest Bradley Waste Rock Dumps to prevent leakage into the dumps and the resulting uptake of metals. 2) Removing legacy waste from the Defense Minerals Exploration Administration (DMEA) waste rock dump from within and along a tributary to the East Fork of the South Fork of the Salmon River and restoring the original streamflow course. 3) Creating a lined diversion for surface water that previously contacted with legacy contamination around Smelter Flats, the former mill and smelter site used by past operators.

The next environmental improvements are expected to include the relocation of at least 325,000 tons of historical tailings and mine waste away from the East Fork of the South Fork of the Salmon River in 2023.

"We did not create the contamination that has degraded water quality in the historic Stibnite Mining District for decades, but are committed to be part of the solution," said Laurel Sayer, CEO. "Isolating streams away from historically contaminated material is a first step in fulfilling our goal of leaving the area better than it is today and demonstrates that responsible partnerships with private industry can benefit the environment and people of Idaho."