Enviros challenge Forest Service’s environmental review of South 32 Hermosa mine

More than a dozen environmental organizations urged the Forest Service to reconsider an environmental analysis of South32’s Hermosa Mine, arguing federal officials failed to consider how the mine would impact the “sensitive and ecologically rich” Patagonia Mountains of Southern Arizona.

The criticism comes just days before the Forest Service will close public comments on the draft plan, and the public has until midnight on Monday, June 23, to weigh in.

Australian company South32 acquired the Hermosa project in 2013 when it bought Arizona Minerals, and has pushed to develop what company officials call a “modern, state-of-the-art” mine that will extract high-grade zinc-lead-silver and “battery-grade” manganese, central to building high-capacity batteries for electric cars. South32 said it would invest $2.16 billion to develop the mine, including funding to build key infrastructure projects, including water management systems, power, site facilities, underground shaft sinking, and other work.

The mine will also extract silver and lead “essential for harnessing renewable energy,” the company said. Unlike the pit mines expected for copper mining like the long-controversial Rosemont or Copper World projects, the Hermosa mine will sink two shafts and use remote-controlled vehicles to extract the minerals.

The project was fast-tracked for federal permits in 2023 after federal
officials declared minerals like zinc and manganese “critical minerals”
under a process known as FAST-41, but a final decision is still not
expected until late 2026.

The mine will occupy around 750 acres, and South32 has said the mine will use advanced technology to minimize air pollution and use 75 percent less water than other mines. The company has said it will create about 900 jobs the area, including a control facility dubbed Centro in Nogales, Ariz.

So far, the mine has faced sharp opposition from local groups, including the Tucson-based Center for Biological Diversity and the Patagonia Area Resource Alliance.

South32 needs a federal permit for “ancillary infrastructure” on Forest Service land to fully develop the project. Company officials said construction is about 40 percent complete, but said they need federal permission to full-develop the project, including a 138kv power-line, the construction of a new road, a new dry-stack tailing facility, and a plan to direct water discharge in the Patagonia Mountains.

South 32 already holds state permits to construct and operate on private
land, however, the Forest Service needs to complete a new EIS and
consider a range of alternatives for infrastructure on land in the Coronado National Forest, As part of the process, the public
had 45 days to submit comments and feedback on the Forest Service’s own
draft document.

The draft EIS is based on the mine’s plan of operations, and company officials said the plan has been updated with “greater environmental protections” which includes analysis for a “range of alternatives for power, access, tailings and water management to minimize impacts to the surrounding environment.”

On Thursday, the Patagonia Area Resource Alliance and 15 other organizations, published a 221-page document criticizing how the Forest Service approached the draft EIS.

In a letter to Kerwin S. Dewberry, the forest supervisor for Coronado National Forest, the groups argued Thursday the draft EIS and the proposed mine “violates various federal laws and regulations” including the National Environmental Policy Act and the Endangered Species Act.

“The proposed operation of the Hermosa Project on USFS Public Lands requires the highest level of environmental protections because the impacted public lands in the Patagonia Mountains are part of the Madrean Pine Oak Woodland, a global biodiversity hotspot identified by scientists as one of the top regions in the world most in need of research and protection for species survival,” the groups said.

The groups said the Forest Service failed to “fully analyze baseline environmental conditions of the sensitive and ecologically rich Patagonia region ” and did not “adequately examine the direct and indirect impacts of the Hermosa Project, as well as the effects of other nearby past, present, and foreseeable future projects.”

The groups added federal officials ignored the “cumulative impacts to the landscape, wildlife, and communities” and did not “properly evaluate” alternatives.

“It is our responsibility to protect our air, water, public health, and the health of all human and non-human lifeforms that live in the Patagonia Mountains from the reality of 21st century industrialized mining,” said Carolyn Shafer, mission coordinator at PARA.

In the criticisms, the groups argued the Forest Service failed to consider how the mine and its operations would negatively affect a range of species, including ocelots, monarch butterflies, the Mexican grey wolf, and the northern jaguar.

In part, the groups noted the Forest Service ignored how the construction of the border wall just five miles to the south,

“We still have a chance to protect this refuge for jaguars, Sonoran tiger salamanders and Mexican spotted owls,” said Russ McSpadden, southwest conservation advocate at the Center for Biological Diversity. “Anyone who’s spent time in the Patagonia Mountains knows they pulse with life and the wild songs of the Sky Islands. This is a precious place for Arizonans and everyone needs to speak up for these mountains before it’s too late. The Forest Service is sacrificing precious habitat and people’s health by allowing a toxic mine in this biodiverse landscape.”

Company officials said the mine is the only advanced mining
 project in the United States “capable of producing two federally designated critical minerals –
zinc and manganese.”

“We are designing Hermosa from the ground up so that it is safer, more efficient and less 
impactful to the environment, combining state-of-the-art technology with best-in-class mining
techniques, to deliver minerals America needs for its national and energy security,” said Pat 
Risner, Hermosa president in a statement published in May.

“As our Draft EIS shows, South32’s approach to managing environmental risks advances the project in a way that protects public health and safety, biodiversity and water, and honors the cultural and Tribal legacy of the region,” Risner said.

“As USFS finalizes its review, we look forward to continue working with our federal, state, local and Tribal stakeholders to deliver on our aim of setting a new standard for sustainable mining and developing a project that benefits the region now and for generations to come,” said Brent Musslewhite, the mine’s project director of environmental and permitting.

Earlier this week, the Southern Arizona Business Coalition asked members to weigh-in on the draft plan, calling it a “key milestone in the federal permitting process to approve the submitted mine plan of operations.”

“By submitting a comment by June 23, 2025, you can help show what Hermosa means to the people who know it best: those who live and work in this region,” the group wrote. “Your comment doesn’t have to be technical, but it should respond directly to the Draft EIS – whether that’s by supporting its findings, sharing how they reflect your own experience, or suggesting improvements.”

The group encouraged members to support the mine’s plan, including how the Forest Service’s proposal for a distributed discharge of treated water into existing creek beds to maximize recharge in the Patagonia Mountains, as well as the joint Tucson Electric Power and UniSource effort to build a new 138KV powerline to power the site. “This will greatly enhance the project’s ability to use renewable energy and lower the traffic impact significantly by taking natural gas delivery vehicles off the road,” the group said.

They also encouraged members to write about the Forest Service recommendation for a permanent access road from the site to State Route 82 near the Nogales Airport, which they said will “largely follow the new power line to allow for its maintenance and minimize new disturbance.”

“Traffic will completely bypass the Town of Patagonia, Harshaw Road, and areas of greater population in favor of more rural areas,” the group added. They also noted the South 32 project has “redesigned and slightly moved” a proposed tailings storage area to protect a population of bearded chinchweed, a sensitive plant species.

Earlier this summer, the mine’s air quality permit was rejected by the EPA because it does not comply with the Clean Air Act.

On May 30, the EPA ruled the permit for the proposed mine owned by South32 did not meet federal air quality regulations. The ruling comes almost a year after state regulators had issued the permit. The Arizona Department of Environmental Quality was ordered to revise the permit to comply with the federal Clean Air Act within 90 days.

The agency said anonymous comments will be accepted and considered, however, “anonymous comments will not provide the respondent with standing to participate in subsequent administrative or judicial reviews.”

These comments can submitted on the Forest Service’s webpage: https://hermosaproject.commentinput.com/

Comments can also be emailed to: [email protected]

The Forest Service will accept comments mailed to:

Kerwin S. Dewberry
Forest Supervisor, Coronado Nation Forest
ATTN: Hermosa Critical Minerals Project
300 West Congress Street
Tucson, AZ 85701