PATAGONIA, AZ — Officials promise safety with a southern Arizona mine that is on track to start production in 2027, while community health and environmental advocates raise concerns.
ABC15 listened to the sentiments of the surrounding community and took a tour of the construction happening at South32’s Hermosa Mine outside Patagonia to learn more.
The mine sits in the heart of the Patagonia Mountains along Arizona’s southern border, one of many isolated ranges in an ecologically diverse area, according to the US Forest Service.
“Our community of earth stewards and water protectors have every skillset needed to co-create a better world, and that's what we're working to do,” said Carolyn Shafer with the Patagonia Area Resource Alliance. "There are more than 100 federally endangered, threatened and sensitive species in these mountains.”
While the area has been mined before, the Hermosa Project’s goal is to pull up roughly 400,000 tons of concentrated metal annually, which eclipses historical mining production at previous area mines.
Environmentalists and local community members have been pushing back against the plans, citing air, water, and land resource concerns.
South32 is currently negotiating an agreement with surrounding municipalities to outline the community’s protections and benefits.
“We've also done a lot of baseline work on biodiversity and water to understand and make sure we're not having adverse impacts on those resources,” South32’s Pat Risner said.
A National Security Interest
The mine is an investment of more than $2 billion, that’s tapping into two main deposits of Zinc and Manganese.
While the plan is to start with the zinc deposit, South32, an international mining company, also hopes to produce manganese, which hasn’t been mined in the United States for 50 years.
Manganese is used to fortify steel and is a key component in electric car batteries, but the metal is currently completely imported from overseas.
Risner said the Hermosa mine could meet the full domestic demand for the metal.
“It touches our everyday lives, but they're two of the critical minerals where we're most reliant on foreign sources. In the case of manganese, you know, it's places like China,” Risner said. “I think the opportunity to onshore that supply chain, create a domestic supply, do it more sustainably and employ Arizonans to do it, should be a good news story for everyone.”
The US Department of Defense awarded the project $20 million last May to speed up the stateside production of battery-grade manganese.
The company expects the mine to support more than 2,300 direct and indirect jobs in Santa Cruz County, both at the site and at a remote-control “Centro” center in Nogales.
Watch an extended cut of Lillian’s interview with South32 below:
Water Use
In order to reach the deposits, the company says they need to “dewater” part of the mountain.
Per the company’s Pollutant Discharge Elimination System Permit, the mine treats all groundwater that’s brought up on site, then releases that into Harshaw Creek and Alum Gulch. ADEQ requires regular water quality testing from those discharges.
“It’s going into our fragile creek systems, spilling over the sides, it’s all over the roads,” Calabasas Alliance President Robin Lucky said. “I’m really not happy with that.”
Water remains among the top concerns for the community, as all of Santa Cruz County is in either a severe or extreme drought.
The Arizona Department of Water Resources (AWDR) said the mine’s water demand could be up to 7,000 acre-feet every year, which is enough to supply 21,000 single-family homes.
However, South32’s underground mine promises to use significantly less water than other large, open pit mines in the region. The company says they will use half a gallon of water per pound of metal produced.
“Water is an important issue for the community, it’s one we’ve heard a lot of concerns about,” Risner said.
The mine’s water demand was not included in AWDR’s recent supply and demand report for the area’s water basin.
When ABC15 asked why the agency did not take this into account, the department said it needed the final results of a federal Environmental Impact Statement (EIS). The department will review the basin’s water demand again in five years.
A draft US Forest Service EIS is in the works.
Watch an extended cut of Lillian’s interview with the Patagonia Area Resource Alliance below:
Air Quality
The Agency for Toxic Substances and Disease Registry (ATSDR) said extended manganese exposure could result in serious neurological impacts. The Barrow Neurological Institute is currently studying those effects on mine workers globally.
There are no current state or federal air quality standards for manganese, so the Arizona Department of Environmental Quality (ADEQ) cannot monitor specific airborne manganese emissions, but rather total particulate matter, like smoke and dust.
“We do not intend to be a sacrifice zone here,” Shafer said.
Hermosa project leaders said the company has promised to put up air quality monitors in town and complete voluntary air dispersion modeling for manganese to compare potential emissions with risk guidelines given by the ATSDR. ADEQ said those results showed lower projected emissions along the project’s fence line than the ARSDR’s guidance.
ABC15 is committed to finding the answers you need and holding those accountable.
Submit your news tip to Investigators@abc15.com
“Part of the advantage we have is being the largest miner of manganese in the world, we have a lot of experience with how you do this elsewhere, and so we've done a lot voluntarily that's not necessarily required by law,” Risner said.
The ADEQ granted the mine’s air quality permit in August. However, community members want to get their own data.
The Calabasas Alliance has teamed up with University of Arizona researchers to independently monitor air pollutants in Patagonia and Santa Cruz County.
“With the mine coming in and heavy metals being extracted, we're not sure what's going to happen,” Lucky said. “I pray that nothing happens, that…we don't have heavy metals in the air, but let's be sure.”
In January, the Center for Biological Diversity and the Patagonia Area Resource Alliance sued the Environmental Protection Agency over a “delay in responding to objections” to the state air quality permit.
Land Footprint
South32 project leaders say they also hope to minimize the impact on surface land when compared to open pit techniques.
“Our small footprint of only 750 acres, which is about a 95% reduction on normal mining operations, is important for that,” Risner said.
Risner said the company has remediated sites on the property from prior mines and is using lined, dry-stack tailings.
While the majority of the project sits on private land, part of it extends into the Coronado National Forest.
The company is still waiting on federal permits for the uses on that land, including building a primary access road to the north of the project to bring truck traffic away from the town of Patagonia.
South32 is also exploring other areas in the Patagonia mountains for minerals, something that is being challenged in a 2023 lawsuit by several conservation groups.
“If South32 can promise just a few things... and follow through, they'll protect our water, they'll protect our air… no citizen is harmed, no worker is harmed,” Lucky said. “If they can deliver on that, then fantastic, then they can actually call themselves a 21st-century mine.”
What's Next?
Conservation groups are waiting for updates on their two lawsuits, one aimed at the air quality permit and the other challenging mineral exploration.
The US Forest Service is expected to release the draft Environmental Impact Statement in May for the projected work on national forest land. A Record of Decision for the federal permits are expected in 2026.
South32 says they plan to start local workforce training and “Centro” building construction in Nogales this year. In 2026, the company expects to expand its battery-grade manganese test plant operations and complete the shaft construction before production would start in 2027.
Meanwhile, the Town of Patagonia, City of Nogales, Santa Cruz County, and South32 are all still negotiating the Community Protection and Benefit Agreement, recently hosting community listening sessions and currently taking online public input.