Water Use Map Resolution Copper Mine Oct 2021

A map showing potential groundwater drawdown from the proposed Resolution Copper Mine, according to a new report from James Wells and environmental consultants L. Everett & Associates. According to their estimates, groundwater depletion would occur throughout nearly all of the Superstition Vistas development area and into the Pinal AMA. Deeper drawdown of the water table of up to 1,000 feet would occur closer to the mine site. The location of the mine waste dump is also included in black at the far right.

SUPERIOR — As rivers and reservoirs dry up throughout the Southwest, Arizona is now months away from mandated cutbacks of Colorado River supplies. As sustaining groundwater becomes vital for the state, particularly in agriculture, potential projects with high water consumption have come under renewed scrutiny.

Last week, the San Carlos Apache Tribe released a report showing new estimates on water use by the proposed Resolution Copper mine just east of Superior in northern Pinal County.

The report, written by James Wells and environmental consultants at L. Everett & Associates, lays out the following analysis in the executive summary:

  • The Resolution Copper mine would use at least 250 billion gallons of water over the mine’s lifespan, much of which would come from pumping groundwater from the East Salt River Valley.
  • The goal of achieving withdrawal/recharge balance in the state’s Phoenix Active Management Area would “unquestionably not be met” if the mine were approved.
  • The original Environmental Impact Statement, which was rescinded in March, did not account for the new allocation cutbacks mandated under the Drought Contingency Plan.
  • Regional water supplies would be threatened by the mine’s tailings pond, including any potential development within the Superstition Vistas Planning Area.
  • Arizona citizens will get $80 to $120 million in tax revenue but lose $600 million worth of groundwater resources.

Wells, who was part of the working group that advised the U.S. Forest Service for its draft of the EIS, gave testimony in April to Congress about the mine’s possible environmental impacts, citing similar statistics on water consumption.

“Over the last 150 years, mining has brought certain benefits to Arizona but it also has serious costs,” Wells’ report reads. ”The legacy of open pits, acid mine drainage and huge tailings dumps are obvious to anyone who has spent time in Arizona’s Copper Triangle. The massive water requirements of modern mines is a hidden cost that has taken on greater urgency in the 20th year of drought conditions in the desert southwest.”

In the wake of the report, San Carlos Apache Tribe Chairman Terry Rambler also reiterated his opposition to the mine, which the tribe maintains would permanently damage a sacred site due to extreme land subsidence — a 1,000-foot crater would form — from the block caving process.

“Our cultural foundation is at stake here,” Rambler said in an interview with Indian Country Today. “The US’ approach to us is to dominate us and treat us like children. Our history is laced with lies, cheating, relocation and trampling our freedom of religion. Here is an opportunity for Congress to correct some of that.”

The location of the proposed mine is in an area called Oak Flat, which the tribe considers sacred.

A major point of contention between Resolution Copper and opponents to the mine are the efficacy of new technologies that the mine would employ in order to reduce water consumption.

What Resolution Copper hopes to use includes tailings thickening and filtered tailings to reclaim water and use less water per pound of copper than other operating mines in Arizona. Resolution Copper has maintained that, in addition to the new technologies, the majority of the mine’s water use will come from banked resources rather than groundwater supplies.

However, Wells’ report called the water-saving measures “unproven” and said that, if the technology wasn’t utilized as planned, the mine would require double to triple Resolution Copper’s estimates.

“We recognize the importance of water for communities in Arizona and are committed to ongoing consultation, including through the process being led by the U.S. Forest Service,” representatives with Resolution Copper said in a statement. “Resolution Copper has already spent tens of millions of dollars to store enough surface water in the ground to sustain our operations for decades, which will result in a net zero impact to the groundwater when the stored water is recovered.”

Resolution Copper says that it welcomes input from Native American communities, including the San Carlos Apache Tribe.

Those looking to read the new report can access it here.


Aaron Dorman is the Casa Grande reporter at PinalCentral, covering government, schools, business and more. He can be reached at adorman@pinalcentral.com.

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