Key Takeaways
- The U.S. Forest Service supports the Hermosa mine expansion in southern Arizona, announced on March 6, 2026.
- The project involves extending mining infrastructure from private to federal land in the Coronado National Forest, with critical mineral deposits.
- The environmental review includes a Draft Record of Decision and a Final Environmental Impact Statement analyzing South32’s Mine Plan of Operations.
- Infrastructure plans include a primary access road, a dry-stack tailings facility, and a power transmission line, designed to minimize impact on nearby communities.
- The project enters a 45-day objection period for stakeholders, with final determination expected around July 2026.
The U.S. Forest Service released a draft decision supporting the Hermosa mine expansion in southern Arizona. The project is operated by Australian mining company South32. The decision was announced on March 6, 2026. The expansion would allow mining infrastructure to extend from private land onto federal land in the Coronado National Forest. The Hermosa mine expansion involves mineral deposits classified as critical minerals by the U.S. government.
Environmental Review for the Hermosa Mine Expansion
The agency issued two key documents related to the Hermosa mine expansion. These are a Draft Record of Decision and a Final Environmental Impact Statement. The documents summarize the environmental analysis of the project.
The environmental review examined South32’s Mine Plan of Operations submitted in 2024. Federal officials reviewed environmental data and public comments collected during the assessment period.
The selected development option aims to meet the project goals while limiting environmental impacts. The evaluation covered potential effects on water resources, wildlife habitats, air quality, recreation areas, and nearby communities.
Infrastructure Planned Under the Hermosa Mine Expansion
The Hermosa mine expansion includes several infrastructure components on federal land. South32 plans to construct a primary access road and a dry-stack tailings facility. A portion of a 138-kilovolt power transmission line would also cross forest land.
The access road design is intended to avoid heavy traffic near the nearby town of Patagonia. The project design also includes a water discharge system intended to support aquifer recharge in the surrounding area.
Approval Process and Timeline for the Hermosa Mine Expansion
The Hermosa project is included in the U.S. FAST-41 permitting program. This federal program accelerates the review of major infrastructure projects considered strategically important.
The Hermosa mine expansion will now enter a 45-day objection period. Only stakeholders who previously submitted comments can file objections. After this stage, the Forest Service will review any objections before issuing a final decision.
The agency expects the final determination around July 2026.
South32 has already secured permits from the Arizona Department of Environmental Quality for infrastructure located on private land. The Hermosa project contains deposits of zinc, silver, and manganese. The operation is located in Santa Cruz County, Arizona.
