By Hermosa President Pat Risner
At South32 Hermosa, our goal is to be as open and transparent with our community as possible. We want to clearly explain what we’re doing, why we’re doing it, and how it all works – all in a way that helps you understand what our goals are for both here and the broader Southern Arizona region. Your feedback is incredibly important to our long-term success and plays a big role in making sure we continue to build strong relationships with our neighbors.
Now’s another opportunity to provide input into Hermosa. Earlier this month, the U.S. Forest Service (USFS) released South32 Hermosa’s Draft Environmental Impact Statement (EIS), a document that evaluates and details the project’s potential environmental effects on federal land.
South32 has secured all state permits required to construct and begin operations from the Arizona Department of Environmental Quality. We are deep into our construction phase, nearing the 40% completion mark, and remain on target for first zinc production by mid-2027. This construction and initial mine operation occurs on private land.
To fully bring the project to life and maximize its potential, all with a strong focus on sustainability, we’ll also need some additional infrastructure on nearby federal land, which we outlined in our Mine Plan of Operations (MPO). That includes things like a 138kv power line, a primary access road, a system for water discharge, and a second dry-stack tailings facility. This part of the project is what the federal permitting process—under a law called NEPA—is all about.
NEPA (short for the National Environmental Policy Act) is a US federal law that has been in place since the 1970s that requires federal agencies to consider the reasonably foreseeable environmental and related social and economic impacts of their proposed actions prior to making permitting decisions.
As a part of Hermosa’s federal permitting process, the USFS conducted a thorough, independent analysis of our MPO, released in 2024 and recently updated, along with our baseline data we’ve been collecting for years, and considered public input gathered during last year’s scoping process. The result is the Draft EIS, a publicly available document that reflects community input, environmental data, and careful consideration of alternative solutions now available for public comment.
The Draft EIS shows that the USFS’s “preferred alternatives” reduce the project’s environmental and community impacts in several areas over other alternatives.
Balancing the Best Outcomes
In the Draft EIS, the USFS cites as a preferred alternative Unisource’s (UNSE) proposal to construct a 138kv power line to enable greater access to renewable energy sources for Hermosa. Without this alternative, the project would generate all power required for the mine on private lands using natural gas-fired generators.
This preferred alternative means less truck traffic needed to deliver natural gas to the site and cleaner air emissions for the surrounding communities.
The transmission line would have the added benefit of supporting service reliability for UNSE customers in the San Rafael Valley, Washington Camp, and Lochiel areas of southern Arizona – so homes and other services can keep the lights on with a more reliable energy source.
UNSE conducted a thorough analysis of the tradeoffs of burying the line as part of their line siting process and approval from the Arizona Corporation Commission. Placing the line underground – as some in the community have called for – would actually increase the environmental toll of the proposal by causing increased land disturbances not only for its initial construction but also compounded when UNSE needs to conduct routine maintenance on the equipment. If buried, the power line would need to be two miles longer and the surface disturbance would have doubled.
Burying the transmission line would also decrease the reliability of the line, one of the main community benefits from its construction. The Draft EIS alternatives analysis indicated that an underground line would result in much more extended service outages for community members in Washington Camp, the San Rafael Valley, and Lochiel due to the line being on a radial system. This prevents alternative power from being rerouted to these users and a more extended timeframe to diagnose faults as the line is underground.
Moving forward with the line as proposed, therefore, is part of that balance to achieve the best environmental and reliability outcome.
The proposed primary access road (PAR) has a similar story as the transmission line.
We understand that how materials travel to and from Hermosa is a concern for the community. Since our early days, we’ve actively sought out, and have already incorporated, feedback on the planning and design of the project. The PAR was originally proposed in response to community feedback and has gone through multiple iterations of re-alignment to reflect community input.
In the Draft EIS, the USFS identifies construction of the PAR as its preferred alternative because it will completely bypass the Town of Patagonia, Harshaw Road, and areas of greater population in favor of more rural areas. This will allow bikers, people that recreate in the area around the Hermosa site, and eco-tourists to continue enjoying Harshaw Road and surrounding areas. It also is aligned to avoid residential areas in Flux Canyon.
The Draft EIS indicates that the PAR also would reduce total heavy truck miles on state and federal highways, reduce air emissions and reduce potential wildlife conflicts.
Mitigating Water Impacts
It’s also important to share that the Draft EIS discusses multiple aspects of an important topic in Southern Arizona: water. It’s an issue we know drives local concern, and that’s why we have spent so much time considering different water management options, understanding the baseline, and mitigating impacts.
First, we don’t anticipate any of Hermosa’s water management, whether it’s water quality or water access, to impact local residents. As the Draft EIS concludes, Hermosa’s water discharge will meet or exceed all applicable state surface water quality regulations. We are committed to everyone having safe access to water and have already deployed state-of- the-art water treatment technology and a community well-monitoring program that is expected to expand over time.
Second, building an underground mine sometimes requires removing and relocating groundwater found near the orebody or underground infrastructure to ensure safety of the underground workers. Hermosa’s water management plan is a well-understood and time-tested technique in the industry.
In fact, we put our water models through multiple rounds of independent technical review by hydrogeology experts in academia, government, and private industry – all which agreed that our groundwater model used to simulate effects from pumping is robust and consistent with industry practice. The Draft EIS analysis confirmed that those multiple rounds of reviews provide a comprehensive review of Hermosa’s water management plans.
As part of the water management process, we anticipate that as much as 83% of groundwater pumped and treated will be returned to the environment through “recharge” – the process of returning the groundwater into the aquifer.
The remaining water will be used as part of Hermosa operations. Because Hermosa will use 90% less water compared to other mines in the region, what water we do use will be consumed responsibly and efficiently.
Water has been among the most discussed aspects of the mine design with the local community, and we have tried to honor those discussions by incorporating community feedback into our plans.
Our original design included the use of Rapid Infiltration Basins to honor the community’s desire for recharging the aquifer in the mountains and reducing discharge into Harshaw Creek. The USFS selected a preferred alternative that would distribute the treated water available for recharge at two separate locations on USFS lands. It achieves the same goal, albeit in a different way.
Lastly, while Hermosa could marginally impact water available for a limited number of Patagonia Mountains’ seeps and springs, the vast majority of these seeps and springs are fed by rainfall from storm events, meaning their flow depends on weather patterns, not the deep groundwater subject to the project’s groundwater management program. Hermosa’s operations have limited impact on how much water these seeps and springs release or the wildlife and vegetation that rely on them.
We know this because we have put in place a robust water monitoring program that goes above and beyond the usual sampling and analysis techniques. This has helped us to understand the quality and sources of water for seeps and springs going back to 2016, giving us good baseline data to assess any potential impacts and inform Hermosa’s design. We are actively monitoring more than 80 seeps and springs sites across the region. This information is available on our website in our annual “seeps and springs catalogue” and has been released with the Draft EIS.
Similarly, wildlife and biodiversity monitoring has been ongoing at Hermosa since 2012, and we regularly conduct surveys for plants and animals including those that are sensitive, threatened, or endangered. These ongoing surveys have allowed us to make informed decisions on activities that might occur near sensitive biological resources and take action to avoid and minimize impacts.
And we take the results of those surveys seriously. Even prior to the preferred alternative the USFS identified in the Draft EIS regarding the location of the second dry-stack tailings facility, we proactively reworked the design to make sure we avoid the beardless chinchweed, an endangered plant in southern Arizona.
Call to Action
In order to best reflect the needs of the community and ensure success of Hermosa’s activities in the region, the most important and helpful thing community members can do is read the Draft EIS, ask questions and then submit comments on the analysis and preferred alternatives. The USFS needs to hear anything the community thinks may have been overlooked or under-evaluated in their assessment.
The Draft EIS is important because it offers another opportunity for the community to provide feedback on the USFS’s analysis and proposed alternatives before they issue the Final Environmental Impact Statement currently scheduled for February 2026.
Ultimately, the Draft EIS informs the Final EIS, which enables Hermosa’s development on federal lands. Even though the mine is moving forward on private lands, the best-case approach to sustainability involves the federal lands surrounding the project. This approach not only provides the least amount of environmental impact, it also provides long-term benefits for the community and other projects.
I encourage everyone to take the time to review the Draft EIS and provide input. Our ambition is to design a project that sets a new standard for sustainable mining and benefits the region now and for generations to come. Now is your chance to speak up.
Comments should be in response to the Draft EIS, which is publicly available via the Coronado National Forest website. They can be submitted through June 23rd, 2025 via mail, online, or in person at planned public meetings on May 27th in Patagonia and May 28th in Nogales.