Army Corps says Rosemont Mine would violate Arizona clean water rules and seriously degrade federal washes

The Daily Star obtained a Dec. 28 letter from the Corps’ regional office in San Francisco to Hudbay that details the rationale behind the district’s recommendation. The Daily Star obtained the letter through a federal Freedom of Information Act request.

The U.S. Army Corps of Engineers Los Angeles district office, which last year recommended denial of Toronto-based Hudbay Minerals’ application for a federal Clean Water Act permit to construct the proposed Rosmont Mine, determined the project would “cause or contribute to” violations of Arizona water quality standards and trigger “significant degradation” of federally regulated washes, the Arizona Daily Star reported on Jan. 14.

The letter states the district office concluded:

  • Rosemont Copper’s plan to buy, preserve and environmentally restore more than 4,800 acres to offset its impacts is inadequate.
  • Completion of what would be the U.S.’ third-largest copper mine would negatively affect surface water quality, sediment distribution and use of the area by humans and wildlife, including federally protected species.
  • Granting the permit would be against the general public interest. To approve a permit, the Corps must find that it would be in the public interest.

Col. Pete Helmlinger, commander of the Corps’ San Francisco-based South Pacific Division, will make the next decision on the $1.5 billion mine. Hudbay is seeking state and federal permits to construct the mile-wide, half-mile deep open-pit mine in the Santa Rita Mountains on the Coronado National Forest 35 miles southeast of Tucson.

Hudbay can appeal a negative decision from Helmlinger to higher-ranking Corps officials.

The U.S. Environmental Protection Agency, which has sent letters to the Army Corps repeatedly opposing the mine, can veto Corps approval of Hudbay’s request for a Section 404 Clean Water Act permit needed to construct the mine.

EPA has determined that the Upper Santa Cruz River groundwater sub-basin, where Rosemont would be located, provides 20 percent of the total groundwater recharge for the state’s water management area covering Tucson and its suburbs, the Daily Star reported.

Helmlinger’s Dec. 28 letter also states that “among the key public interest are adverse effects on cultural resources and traditional cultural properties important to tribes.”

The Tohono O’Odham tribe and others have warned that the mine would seriously damage artifacts and other cultural resources in the Santa Ritas, although the mining company has promised extensive mitigation, the Daily Star reported.

Hudbay sent two letters (Sept. 7,  and Nov. 17) to Helmlinger last year requesting additional information concerning the district’s denial recommendation and presenting its reasoning why the permit should be approved.

“We feel strongly that we should have an opportunity to respond to any technical concerns about the Project’s impacts and proposed mitigation prior to a decision on our permit application,” Hudbay vice-president for its Arizona business unit Patrick Merrin stated in the Sept. 7 letter.

The Corps offered Hudbay an opportunity to meet sometime this month to discuss technical issues related to the district’s denial recommendation, according to Helmlinger’s Dec. 28 letter.

Hudbay has stated the company plans to release an updated feasibility study for the Rosemont mine in the first quarter of this year. The company is reportedly preparing a revised mine plan of operations which could impact its application for the Clean Water Act permit.

If Hudbay’s CWA permit application changes, it may be sent back to the Corps’ L.A. office’s district engineer for evaluation and, potentially, for more analysis which could include consulting with other agencies and obtaining additional public comment, Helmlinger’s letter states.

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