Is the largest proposed mine in the U.S. an environmental bust?

Campers enjoy the scenery at Oak Flat. This area will become inaccessible when the mine is operational. (Photo by Ashley McGowan)
Campers enjoy the scenery at Oak Flat. This area will become inaccessible when the mine is operational. (Photo by Ashley McGowan)

Nearly 100 people left Superior High School disappointed and anxious after a long night of grueling questions and harsh realities at a public meeting in April. Many lived nearby and came to tell the Tonto National Forest Service their concerns over a proposed copper mine a few miles away in Oak Flat.

Some were members of the San Carlos Apache Nation who came to defend their tradition and heritage closely tied with Chich’il Biłdagoteel, the Apache name for Oak Flat.

But everyone was outraged over the federal government’s forced land exchange that may well destroy a unique area once used for recreation, traditional ceremonies and ecological research.

Land Exchange

Congress and President Barack Obama approved the Carl Levin and Howard P. “Buck” McKeon National Defense Authorization Act, which included a land exchange in Arizona with the mining company Resolution Copper, in December of 2014.
 Hundreds of pages of the act address military spending, but Section 3003 directs the Secretary of Agriculture to “authorize, direct, facilitate, and expedite the exchange of land between Resolution Copper and the United States.”

The land exchange will trade 2,400 acres of land in the protected Oak Flat campground in the Tonto National Forest to Resolution Copper Mining in exchange for eight parcels of previously private land in Gila, Yavapai, Maricopa, Coconino, Pinal and Santa Cruz Counties, totaling 5,300 acres.

Map provided by the Tonto National Forest Service
Map provided by the Tonto National Forest Service. Click to enlarge.

The parcels offered by Resolution Copper, a conglomerate of Rio Tinto Group, a British-Australian multinational mining cooperation, include miles along the San Pedro River, archeological sites and rock-climbing areas. Still, critics of the land exchange feel that the eight parcels of scattered land do not have the same cultural or ecological value as what will be lost when mining causes the area to become a huge hole.

“We shouldn’t be attaching those unrelated measures to a National Defense Act,” said Cyndi Tuell, a leader in the Tucson Supports Oak Flat movement. “It’s sneaking something through they couldn’t pass on its own merit.”

The land exchange was proposed two times previously to the House of Representatives and was not passed. Putting the land exchange in a National Defense Act, that was described as a “must pass” bill because it addressed military spending, successfully circumvented the House of Representatives’ decision.

The Oak Flat campground was protected from mining by an executive order passed in 1955 by then President Dwight Eisenhower, but the 2014 National Defense Act removed its protection and officially opened the area to copper mining.

Section 3003 also instructs the Tonto National Forest Service to conduct an Environmental Impact Study (EIS) of the Oak Flat campground and the eight parcels of land to “ensure that the non-federal lands are acceptable through an appraisal process,” said Carrie Templin, a Public Affairs Specialist with the Tonto National Forest Service.

However, if the appraisal process finds Oak Flat to be worth more than what Resolution Copper has offered, they can either offer more land or pay the difference in cash to the federal government.

According to federal law, the land must be exchanged with the intention of building a mine.

Unless the mine proposal violates existing environmental standards and regulations, the Tonto National Forest Service will have no choice but to allow Resolution Copper to build its copper mine on the Oak Flat campground and National Forest Service land.

The General Mining Law of 1872 allows corporations access to federal land for mineral extraction and forces the Forest Service to comply.

“Congress has essentially tied the National Forest Service’s hands,” Tuell said.

After the EIS is complete and the public has an opportunity to comment, the exchange will go through.

The public will lose access to a once popular ecotourism spot, the Native American nations in the area will lose access to traditionally important land and a larger than life copper mine will be built.

Proposed Mine Plan

Resolution Copper, if authorized by the National Forest Service, would build the largest copper mine in the country. The area affected by the mine, including treatment facilities, pipelines, and the actual mine site will operate on a combination of private land, acquired through the land exchange, public, and federal land. The mine is estimated to disturb almost 7,000 square acres on the surface.

Map provided by the Tonto National Forest Service.
Map provided by the Tonto National Forest Service. Click to enlarge.

The proposed copper mine is so large that concerned citizens at the public meeting were directed to look at copper mines in Chile for comparison by Mine Environmental Specialist Mark Nelson. Nothing in the U.S. is comparable.

At the East Plant Site, where the underground mine will be located, Resolution Copper intends to use a mining technique called “panel mining,” which entails constructing a network of shafts and tunnels below the ore body, and then using explosives to fracture the ore so that it can be transported underground to the West Plant Site, located at the old Magma Mine in Superior, for processing.

After the ore is processed into copper concentrate it will be pumped to a “filter/loadout” facility near Magma. In order to transport the copper concentrate to Magma, Resolution Copper plans to construct an upgraded rail line, new water pipelines, new utility lines, pump stations and 30 new ground wells.

From the filter/loadout facility the copper concentrate will be sent to market.

The production of copper also produces tailings, or “the waste material left-over after processing,” according to the National Forest Service. Tailings do not contain any minerals of economic value but are potentially dangerous for human and environmental health. So they must be stored safely to protect air, water and wildlife quality.
 Tailings will be transported from the West Plant Site to a storage facility that will operate on about 4,400 acres of national forest land.

The tailings will be stored in an embankment with precautions in place to minimize seepage and prevent dangerous materials from entering surrounding areas and water systems.

The construction of the mine and its components is estimated to take 10 years after the acquisition of all necessary permits and authorizations, which could also take years.

Once built, Resolution Copper predicts the mine will have an operational life span of 40 years. After the mine is closed, the company expects that “reclamation” of the land will take between five and 10 years.

Environmental Impacts on Land

The most obvious effect from such an enormous copper mine will be a huge hole caused by the panel mining technique. Mining creates a void beneath the surface so large that the earth above gradually collapses, through a process called subsidence.

The National Forest Service predicts the surface area affected by subsidence could fall up to 1,000 ft., and encompass many square miles of the Oak Flat area.

Subsidence is a concern for environmentalists because essentially it will leave an expansive uninhabitable crater in an area with a unique and delicately balanced ecosystem, explains Sandy Bahr, the director of the Sierra Club’s Grand Canyon Chapter.

“There are mature oak trees in Oak Flat which is unusual and not part of the desert,” Bahr said.

The impact of subsidence is the permanent loss of a vast area where tourists, ecologists, and Native American nations frequent and numerous species of plants and animals inhabit.


In order to construct the underground shafts and tunnels necessary for the copper mine, Resolution must “dewater” the Oak Flat area.

Although they intend to use and recycle the water many times in the mining process, “anytime you have even a little bit of water in such an arid place it’s hugely important to plants and animals,” Bahr said.

Once Resolution removes the groundwater in the Oak Flat area, which is mostly stored in wet sand underground, it will not be replenished for many life times, said Kelly Mott Lacroix with the Water Resources Research Center at the University of Arizona.

“Extraction of groundwater could also make springs in the area disappear. Springs are part of a riparian ecosystem, which are the rarest ecosystems that we have in Arizona. About 2 percent of the land area in our state is riparian,” she said.

Riparian ecosystems are made up of the plants and animals located on the edges of springs and are distinctly different than the surrounding areas.

Wildflowers bloom on the Oak Flat Campground. Much of the plant life in this area is unique because of the spring-fed ecosystem. (Photograph by Ashley McGowan)
Wildflowers bloom on the Oak Flat Campground. Much of the plant life in this area is unique because of the spring-fed ecosystem. (Photo by Ashley McGowan)

In addition to concerns over dewatering, there is always a possibility that tailings, which contain acidic chemicals and trace metals, can enter surrounding water systems, including drinking water.

Over the 40-year operational period, Resolution predicts that the mine will produce around 1.5 billion tons of tailings that have to be permanently stored.

The embankment method of storage will create a tailings pond. Tailings ponds have been described as one of the worst environmental disasters of modern history, because their massive size makes them difficult to contain.

Roger Featherstone, the director of the Arizona Mining Reform Coalition, is particularly concerned about Resolution’s tailings storage method because “they are not going to line 
it, putting toxic chemicals on bare ground,” Featherstone said.

While Resolution Copper’s proposal describes the land for the tailings storage facility as, “very small permeability, which would limit tailings water seepage and potential for migration of tailings water.” The same report also recognizes some areas with higher perme- ability where “potential for tailings water seepage and migration in the subsurface could be larger.”

Resolution intends to use dams to minimize the amount of tailings seepage but there can be no guarantee that all of the hazardous materials will be forever contained.


Mining generates dust and expels pollutants into the air.

The proposal submitted by Resolution recognizes the production of carbon, nitrogen oxides, sulfur dioxides and 48 other “hazardous air pollutants” that range from arsenic to mercury.

Nitrogen oxide is known to aggravate asthma conditions, and produces ozone by reacting with oxygen in the atmosphere.

Sulfur dioxides are linked to an array of respiratory health issues. When sulfur dioxide forms small particulates in the air it can cause emphysema, bronchitis and worsen heart disease.

The mining will cause about 59.4 tons of small particulate matter to fly into the air every year. The Air Resources Board show that particulates are so small, “about a seventh of the thickness of a human hair,” that they can be inhaled into the deepest parts of the lungs. It is “among the most harmful of all air pollutants.”

Particulate matter has a greater effect on children, elderly, exercising adults and anyone with existing respiratory conditions.

Resolution’s predictions for air pollutants are within national standards but little can be done to contain those that are emitted.

What is Happening Now

Despite the feeling of defeat after the public meeting in April, legislators are still working to undo the land exchange at the federal level.

Rodger Featherstone listens to the presentation by the Tonto National Forest Service at a public meeting in April.
Roger Featherstone listens to the presentation by the Tonto National Forest Service at a public meeting in April. (Photo by Ashley McGowan)

Sen. Bernie Sanders introduced bill S. 2242 to the U.S. Senate in November 2015 to repeal Section 3003 of the 2014 National Defense Act that authorized the land exchange.

The bill is co-sponsored by Sen. Tammy Baldwin from Wisconsin and Sen. Martin Heinrich from New Mexico.

Rep. Raúl Grijalva also introduced a companion bill in the House of Representatives in June of 2015 that now has more than 36 co-sponsors in favor of repealing the land exchange.

The bills argue that Section 3003 was passed without the support of the House of Representatives or the Senate and precluded the public from the decision.

It went on to state that a mine in the area would destroy land considered sacred by local Native American nations.

Although the Tonto National Forest Service has little choice but to exchange the land at the end of the Environmental Impact Study, Templin encourages concerned citizens to attend public meetings to voice specific concerns, submit question to the National Forest Service and continue to appeal to congressional representatives.

The Tonto National Forest Service is only the first of seven steps that must be completed before the land is officially exchanged.

The Forest Service is currently holding public meetings to inform residents and gather concerns from locals. It does not appear, however, that there have been new meetings scheduled.

For More Info

About the land exchange, the mine proposal and how to get involved, visit: or call (602) 225-5222.

To submit comments and questions to the National Forest Service email

Ashley McGowan is a reporter for Arizona Sonora News, a service provided by the School of Journalism at the University of Arizona. Contact her at

For high definition photographs click here.

2 comments Add yours
  1. I spent this morning conducting an avian survey in the area that Resolution Copper proposes to dump their tailings. This area is an avian migratory corridor. Literally hundreds, and probably thousands, of neotropical migrants are utilizing this area to move from southern Ariizona into the federal wilderness immediately adjacent to the north. It is absurd that the United States would allow anyone to dump mining waste in this incredibly important habitat.

  2. President Obama could have stopped the whole process years ago with a PLO to save the Federal public land from mining, as did Republican Presidents Eisenhower and Nixon. Instead he sat back on his golf clubs for 10 years while the swap was introduced in the Senate Energy and Natural Resources committee 8 times—and never passed out of committee. These hearings have cost the San Carlos, Ft. McDowell and Yavapai Apaches and concerned citizens time and money to go to Washington to plead their case. The travesty has been perpetrated by Senator McCain and Kyl, as well as Congress Persons Kirkpatrick and Gosar, Arizona Congresspersons who should be looking out for the welfare of the Native American values—and American public lands. I love to camp, hike and bird watch in Oak Flat campground.

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