Diversified miner South32 has moved a step closer to securing federal approval for the development of its Hermosa project in Arizona, after the US Forest Service released the project’s final environmental impact statement (EIS) and a draft record of decision (RoD) indicating support for the development.

The draft RoD signals the agency’s intent to authorise the project’s expansion onto National Forest Service land following years of environmental review, public consultation and interagency engagement.

Final approval would allow South32 to fully develop Hermosa beyond its privately held land, including the construction of key infrastructure such as a primary access road, a dry-stack tailings facility and a portion of a 138 kV power line to be built by UniSource Energy Services on Coronado National Forest land.

Hermosa will produce several federally designated critical minerals, including zinc, silver and manganese. The project is the first mining development to be included in the federal FAST-41 permitting programme.

“This draft RoD reflects years of listening, collaboration, and real changes shaped by community input,” said South32 Hermosa president Pat Risner.

“This draft decision affirms our design and development approach including mitigation measures as described in the final EIS that were informed through agency and public consultation.”

As part of the federal permitting process, the US Forest Service conducted a review of the project’s mine plan of operations, released in 2024, alongside baseline environmental data and submissions received during the public comment period under the National Environmental Policy Act.

The final EIS concluded that the selected development alternative would meet the project’s objectives while minimising environmental impacts. Measures include construction of a primary access road designed to avoid traffic near the town of Patagonia, development of a dry-stack tailings facility and the discharge of treated water high in the Patagonia Mountains to help recharge local aquifers and support wildlife.

South32 has already secured the required state permits from the Arizona Department of Environmental Quality for initial infrastructure development on private land.

“This outcome reflects a thorough, transparent process that affirms South32's Hermosa’s design and commitments are compatible with the long-term management of public lands and sets the stage for the final authorisation process ahead,” said Hermosa environment and permitting director Brent Musslewhite. “The findings show the federal government’s independent review is working as intended and produced a decision grounded in science and public input.”

The draft RoD triggers a 45-day objection period, followed by a further 45-day resolution phase before the Forest Service can issue a final decision, which is expected in July.

South32 said the project had been designed to minimise environmental impacts and projected water use about 90% lower than many other mines in the region.

Once operational, the Hermosa project is expected to create up to 900 jobs at peak operations and contribute to long-term economic growth in the region.