Center for Biological Diversity: Hermosa Mine Arizona ESA Challenge Filed

• The Center for Biological Diversity and Patagonia Area Resource Alliance filed a lawsuit challenging the expansion of the South32 Hermosa mine in southern Arizona.
• The lawsuit alleges federal agencies violated the Endangered Species Act and National Environmental Policy Act by failing to protect imperiled species and conduct adequate environmental analysis.
• The mine expansion threatens a critical 120-mile migration corridor for endangered jaguars and ocelots in the Patagonia Mountains.
• The project involves a 113-year timeline, a 225-acre tailings facility, and could cause significant groundwater depletion, impacting local communities.
• Conservationists argue the Patagonia Mountains are a vital ecosystem whose value far exceeds that of mining operations.

Once these mountains are carved up and their aquifers depleted, restoration is impossible, asserting that the Patagonia Mountains hold far greater value as a thriving ecosystem than they ever will to a large mining corporation.

A significant legal challenge has been mounted against the expansion of a heavy metal mine in southern Arizona, with conservation groups alleging federal agencies failed to adequately protect endangered species and critical habitats. The Center for Biological Diversity, joined by the Patagonia Area Resource Alliance, filed a lawsuit on Tuesday, targeting the Trump administration's approval of the South32 Hermosa mine expansion. This legal action, an Arizona mining environmental lawsuit, contends that the U.S. Forest Service and U.S. Fish and Wildlife Service disregarded environmental safeguards in their decision-making process.

The approved expansion, which encompasses 52,438 acres, involves mineral extraction operations by Australian company South32 Hermosa, with construction currently underway. The project is situated within the Patagonia Mountains, specifically impacting Flux Canyon and the Hermosa Mine Project Area. Conservationists argue that this development will irrevocably alter one of Arizona's most ecologically vital mountain ranges, bringing industrial activity deep into public forest lands. The Center for Biological Diversity lawsuit highlights concerns that the federal agencies downplayed the project's potential environmental devastation.

Central to the legal challenge is the assertion that federal agencies violated the Endangered Species Act (ESA) by neglecting to properly assess and mitigate the impacts of the South32 Hermosa mine expansion on listed species and their designated critical habitats. The lawsuit specifically points to endangered jaguars and ocelots, whose last remaining migration corridor for approximately 120 miles across the U.S.-Mexico border would be directly threatened by the project. Agencies' own assessments reportedly acknowledge this threat to the corridor, which is crucial for these imperiled felines; a rare ocelot was last observed via trail camera in the Patagonia Mountains in July 2025, and jaguars are frequently sighted in adjacent ranges. Beyond these iconic predators, the Patagonia Mountains provide vital habitat for threatened Mexican spotted owls and western yellow-billed cuckoos, alongside significant populations of other imperiled flora and fauna, including Bartram’s stonecrop, beardless chinchweed, Gila topminnow, and northern Mexican gartersnakes.

Further compounding the environmental concerns, the plaintiffs also allege a violation of the National Environmental Policy Act (NEPA). They claim the U.S. Forest Service failed to conduct an adequate analysis of the project's threats, particularly its effects on groundwater resources and other public assets. The mine expansion is projected to cause massive water drawdowns in the Patagonia Mountains, potentially lowering the water table by as much as 250 feet and reducing or eliminating surface water flows. This could also impact the municipal water supply for nearby communities, including the town of Patagonia, Arizona. The project's infrastructure includes a 225-acre tailings facility designed to hold up to 38 million tons of mining waste, a 7.6-mile permanent access road, 7.2 miles of new power transmission lines, hundreds of exploratory drill holes, and six groundwater wells, all contributing to habitat destruction and fragmentation over a 113-year construction, operation, and closure timeline. The company itself acknowledges that without a new waste dump, current operations would cease within a decade due to existing facility capacity limitations, yet the Forest Service approved the expansion.

The Hermosa Mine Arizona ESA challenge underscores the profound ecological value of the Patagonia Mountains. Russ McSpadden, Southwest conservation advocate at the Center for Biological Diversity, emphasized the irreversible nature of the proposed development, stating that federal agencies are planning to sacrifice one of the most important wildlife corridors in the Southwest. He highlighted that once these mountains are carved up and their aquifers depleted, restoration is impossible, asserting that the Patagonia Mountains hold far greater value as a thriving ecosystem than they ever will to a large mining corporation.

This Endangered Species Act litigation and National Environmental Policy Act challenge represent a critical effort to ensure Patagonia Mountains habitat protection. The lawsuit seeks to hold federal agencies accountable for their obligations under environmental law, particularly concerning large-scale mining projects in ecologically sensitive regions. The outcome of this case could set important precedents for future resource extraction endeavors, emphasizing the need for rigorous environmental impact assessments and robust species protection measures.

This case highlights the significant legal risks and compliance burdens associated with large-scale mining projects in environmentally sensitive areas, particularly concerning federal agency adherence to the Endangered Species Act and NEPA. Lawyers advising resource extraction companies or environmental organizations should monitor this litigation for precedents regarding environmental impact assessments and species protection.

Source: Original reporting via Courthouse News