Growing up on both sides of the Arizona-Mexico border, Denise Moreno Ramírez got respite from the border town bustle by hiking through sycamore and juniper trees in the mountains near her home. These isolated mountains – known as the Sky Islands – provide a crucial habitat for native plants and animals, but also played a special role in Moreno Ramírez’s family history: like many in the area with Indigenous Yaqui or Mayo origins, her ancestors once mined the mountains for precious metals.
Moreno Ramírez’s great-grandfather, Alberto Moreno, dug for copper when he first came to Arizona from Mexico in the early 1900s. He found that the mining industry powered the state economy and put food on his table; eventually his son – Moreno Ramírez’s grandfather – followed suit and worked in the mines, too.
So Moreno Ramírez wasn’t surprised when she heard an Australian mining company, South32, planned to open a manganese, zinc, lead and silver operation in the same area where her family had worked.
“We from the US-Mexico border are used to this,” she said, describing how the region, brimming with biodiversity, attracts the boom and bust of extractive industries.
But this latest proposed mine was alarming, she said, because Biden is fast-tracking it in the name of the energy transition – potentially compromising the mountain’s delicate ecosystems, many of which have begun to be restored as mines have shut down. “The Patagonia mountains are the heart of the Sky Islands. If those mountains go, a lot of other things are going to go, period,” said Moreno Ramírez, an environmental scientist and postdoctoral fellow at the University of Arizona.
A growing network of Arizona residents say that allowing the mine to proceed as planned could introduce a grave new layer of environmental injustices.
The grasslands, woodlands, swamps and prairies of south-east Arizona’s Sky Islands are home to more than 100 species of large mammals: the greatest number north of Mexico. Residents from the borderlands area have long dealt with the health impacts of pollution linked with earlier industrial activity, including mining – from lupus to cancer. And in spite of it all, they have managed to preserve a patch of one of the most biodiverse, and imperiled, ecosystems in the world.
“Biodiversity is the foundation of a lot of our health. The western perspective has made it so that we’re very disconnected from that reality,” said Moreno Ramírez. “But the fact is that we do not have technological tools that will compensate.”
No existing standards
The lithium boom has received the bulk of attention amid calls to electrify everything – but another mineral, manganese, has been earmarked by the US as a critical element to ramp up the production of electric vehicle batteries.
Manganese hasn’t been mined in the US since 1973. Amid an expected surge in new demand, the mine proposed in south-east Arizona appears to be the crown jewel in the Biden administration’s ambitions to introduce domestic supply of the mineral, which is abundant in the US south-west. The project received expedited status under Fast-41, a 2015 program that coordinates the environmental review process for infrastructure investments over $200m, many of them clean energy projects.
But experts say state and federal environmental standards around manganese are lagging. Overexposure to the chemical when airborne can cause Parkinson’s-like symptoms: from tremors and stiffness to depression. Air quality standards set by the Environmental Protection Agency (EPA) do not include any limit for manganese, though the agency suggests that adverse health effects may begin at 0.05mg per cubic meter. The state of Arizona has no legal standard either.
The Occupational Safety and Health Administration (Osha) sets the limit at 5mg per cubic meter, recommending that workers not exceed 3mg per cubic meter during any five-minute work period. But a study led by Brad Racette, a leading researcher on clinical manganese exposure, suggests manganese can cause adverse health effects at exponentially lower levels.
When Racette’s team studied more than 600 residents living adjacent to a manganese smelter in South Africa, they found Parkinson’s-like motor symptoms in residents living with 0.00075-0.0026mg per cubic meter of ambient manganese.
“Since we do not know the level at which manganese exposure is safe, it is critical that every effort be made to keep occupational and environmental exposures as low as possible,” Racette said, noting that his primary concerns over the south-east Arizona mine is the safety of workers and unexpected aquifer contamination.
There are other risks associated with mining in this region of Arizona, according to experts. Extraction can liberate additional neurotoxic and endocrine-disrupting metals such as lead and zinc, which are both embedded in the deposits South32 is seeking to mine, said C Loren Buck, a biology professor at Northern Arizona University.
Buck’s research shows that manganese and other toxic metal dust can travel in the air for at least a radius of 20km (12.5 miles), affecting people and wildlife in that vicinity.
A spokesperson for South32 said the company uses “conservative occupational exposure standards and community guidance values for manganese”, though they did not further specify which standard.
South32 is the largest producer of manganese globally, with mines in South Africa and Australia. There is no specific mention of manganese dust limits in the 185-page draft air-quality permit South32 submitted, which has residents worried. A representative of the Arizona department of environmental quality noted that while there is no manganese standard to apply in the permit, any manganese air emissions from the South32 facility “will be entrained in particulate matter for which the draft permit does include requirements”.
Like Racette, Moreno Ramírez worries about workers in her home town. She says the South32 mining and processing jobs are likely to be appealing, especially to working-class people. She characterizes the current opportunities for those without a college education as: produce, police or border patrol. Her research on exposure at Arizona superfund sites suggests that, as with prior environmental injustices, disparities in mining-related exposure in Santa Cruz county are slated to occur disproportionately along race and class lines.
“The workers that are actually doing the hard mining who are more than likely to have impacts to their health are more than likely going to be the people in my community,” she said.
‘Dewatering’ the mountain
Residents like Carolyn Schafer are also worried about the mine further polluting the region’s streams, rivers, lakes and aquifers. Schafer has been working with the Patagonia Area Resource Alliance (Para), an Arizona-based environmental watchdog, for over a decade.
The communities around the proposed manganese mine are already at an elevated risk of exposure to downstream water pollution. According to the EPA’s environmental justice screening tool, census tracts in the surrounding 12 miles (20km) are in the 40th to 89th percentile for wastewater discharge.
Conservationists say they worry that South32 is seeking to use water irresponsibly amid long-term drought. According to a draft permit, the company would discharge up to 6.48m gallons (24.5m liters) a day of “treated mine drainage water, tailings seepage, groundwater, core cutting water, drilling water, and stormwater” into Harshaw Creek, in the Santa Cruz watershed.
Pumping out groundwater to clear the way for extraction, known as “dewatering”, is of concern given Arizona’s overall susceptibility to the impacts of the climate crisis.
While much of Arizona is arid and deals with crippling drought, the Patagonia mountains are lush with vegetation that rely on underground sources. Dewatering is likely to worsen extremities: the dramatic absence of water in some places, and excess in others, said Robert Proctor, director of the local conservation group Friends of Sonoita Creek.
“You wonder where all [the water] is gonna go, and what’s going to happen to the mountain,” Proctor said, noting that the creeks he used to play in here have all dried up since he was a child. “It’s a mess.”
Grassroots groups, including Para, are pursuing legal actions, including appealing two water permits issued by the Arizona department of environmental quality, one of which allows the company to discharge into a stream already found by the agency itself to be impaired with metals, including lead. They have also sued the US Forest Service for failing to take into account the cumulative effects of South32’s exploratory drilling at another nearby site, including the impact that proposed 24/7 activity would have on endangered species such as jaguars and ocelots.
“If you’re going to force mining on us in what is a global biodiversity hotspot, it must also be mitigated to the highest science possible and monitored on an ongoing basis,” said Schafer.
A moment to restructure?
Alida Cantor is an associate professor of geography at Portland State University who studies emerging conflicts over decarbonization. She said that communities should have the right to reject a project they deem too harmful.
Cantor argues there is much room for energy transition projects to be completed equitably, such as through community ownership and rigorous community benefit agreements. The energy transition is also a moment to restructure, she said, including through policies that expand public transit and decrease dependence on private vehicles, rather than encourage the one-to-one replacement of gas-powered cars with electric ones. Modeling has shown such alternatives to hold great potential to lower the demand for critical minerals.
“We need to rethink this dynamic – we can’t just keep sacrificing local communities in the name of energy security or decarbonization,” Cantor said.
The South32 proposal, as the first mining project to be granted Fast-41 approval, will in many ways set a precedent for energy transition projects. Advocates remain hopeful that such development can occur at the speed and scale needed to address the climate crisis, without creating other outsized social and environmental problems along the way. But much remains to be seen in Arizona; last month, South32 announced an investment of over $2bn into the development of the zinc-lead-silver deposit in the Patagonia mountains, signaling at least part of the company’s plans are moving forward.
“We are the guinea pigs in the whole country on this,” Schafer said.
