Dozens of residents have voiced their opposition to the proposed large-scale land readjustment, fearing it would turn the area into an operational hub for a zinc and manganese mine that Australian company South 32 hopes to build in the nearby Patagonian Mountains.

During nearly two hours of public comment, the county board of oversight heard concerns about health risks, pollution, water depletion, heavy truck traffic, and destruction of natural areas in the Santa Cruz River community, about 90 miles south of Tucson.

At issue is a request from prominent local landlord Andrew Jackson for a major zoning change along a nine-mile strip along Interstate 19 through Rio Rico, permitting mixed commercial, residential, and industrial development on vacant land currently used for ranching and agriculture near the river.

“Rio Rico has something special,” one local resident told county supervisors. “If you let South 32 and Andrew Jackson destroy it, you will destroy it.”

The barrage of negative feedback preceded the presentation by Pat Lisner, president of South32’s Hermosa Project in the Patagonian Mountains.

Rizner said he came on Tuesday to give an update on the project and clear up some misconceptions about the company’s plans for Rio Rico and elsewhere.

The “next-generation mine,” he said, will be the only U.S. operation of its kind and the only location outside of China that can produce the types of manganese needed to make batteries for electric vehicles and other renewable energy initiatives.

“This project aims to build a domestic supply chain for that,” Lisner said.

Billion Mine: An approximately 5-acre office building that houses a remote operations center for mine automation equipment and a 250-acre office building that houses a 250-acre processing plant to produce battery-grade manganese.

The company has promised to locate both facilities somewhere in Santa Cruz County to maximize employment and tax benefits for the mine’s host county, but Lissner said the facilities could be located elsewhere if residents didn’t want them.

“We have not made a decision to put these anywhere, much less at Rio Rico,” he said.

As for Jackson’s rezoning plan, Lissner said South 32 was not involved. “It’s not what we asked for, it’s not what we need,” he said.

Rizner promised to host community meetings in the coming months to address questions and concerns about the mining operations and the materials produced there.

He said Rio Rico is the preferred location for the company’s remote operations center because people who want to be trained to work at the facility now live there. A battery-grade manganese facility, on the other hand, isn’t something you could put “right next to the Santa Cruz River” or near your home or school, Lissner said.

He added that South 32 “wouldn’t select a processing plant site without dialogue with the local community, and the reason it hasn’t happened yet is that we’re early in the process.”

Artist renderings of the facility on display during Tuesday’s conference included three enclosed processing structures: a warehouse, a substation, an administrative building, a product bagging plant and an “emergency service center.”

Rizner said the ore will be shipped to the facility in sealed containers made to remain intact in the event of a truck accident. Manganese processing will take place in a building that is shielded from the outside air, but renderings show mountains of outdoor ‘dry deposition’ running the length of the facility.

Rizner said South 32 has a number of environmental protection measures in place, including monitoring dust along transportation routes to and from the mine.

Actual mining on site in the mountains above Patagonia is still years away, assuming the project overcomes the many legal issues already underway.

In May, the Hermosa project was approved for a federal program aimed at streamlining critical infrastructure reviews, although the mine permit process is expected to continue until 2026.

On Friday, eight environmental groups asked a federal judge to block South 32 and another mining company from exploratory drilling in Patagonia while a lawsuit surrounding the project is pending.

The group, mostly from Tucson, is suing the US Forest Service for approval of the exploration effort. As a result, they argue, 24-hour drilling could take place for up to seven years in sensitive habitats that are home to the endangered Mexican spotted owl and spotted open-billed cuckoo.

“Road building and excavation should not proceed in the Patagonia Mountains before court day arrives,” said Scott Stern, an associate attorney for EarthJustice’s Biodiversity Defense Program, who represents the eight groups. “We are asking judges to prevent environmental damage that threatens endangered wildlife and irreplaceable natural areas.”

Conservationists have also filed a notice stating they intend to sue the Biden administration for violating the Endangered Species Act unless the exploration project’s approval is revoked within 60 days.

At a meeting of county supervisors in Nogales on Tuesday, only one person spoke in favor of South 32’s mining proposal, which he said would provide much-needed job opportunities for young people in Santa Cruz County, especially in the Hispanic community.

Several speakers argued that the economic benefits would not be sufficient to risk jeopardizing the health and safety of residents.

Many Rio Rico residents have complained of being blindsided by Andrew Jackson’s massive rezoning plan, which was reviewed by the County Planning and Zoning Commission on June 22, less than a week after many said they had never heard of it.

The regulator was due to consider Mr. Jackson’s proposal on July 11, but that hearing has since been postponed until August 15.

It’s still too early for some county commentators.

One speaker at Tuesday’s conference said the speed with which county officials are believed to be pushing the proposal “is nothing short of criminal.”

“Turning slowly,” said the man.