The EPA, Pima County and environmental groups have criticized Hudbay Minerals Inc.’s latest mitigation plan for the Rosemont Mine because it wouldn’t restore land within the Cienega Creek watershed.

It’s believed the mine’s most serious impacts will occur on that watershed southeast of Tucson. Cienega Creek, designated an “Outstanding Water” by the state, is fed by tributaries from the proposed mine site in the Santa Rita Mountains.

But Hudbay says it couldn’t find acceptable parcels inside the Cienega watershed to buy, preserve or restore. It gave these reasons:

  • The vast majority of lands in that watershed are publicly owned and not available for purchase.
  • A number of private lands packages within the watershed were examined, but several sites lay within the urban core of Pima County and are too small or too far away from washes and streams to be used for mitigation.
  • Rosemont also sought opportunities for water-based mitigation projects at the federal Las Cienegas National Conservation Area east of the mine, and Pima County’s Cienega Creek Natural Preserve northeast of it. None were available or feasible.
  • Rosemont bought 545 acres near Davidson Canyon and the mine site that have springs. But since the mine site lies in the headwaters of the Davidson drainage area, Army Corps of Engineers officials expressed concerns the mine construction would impact these lands, so they were dropped from the mitigation plan.

The company’s comments came in a proposed, 859-page mitigation plan that is a legal requirement for the $1.9 billion mine project to secure a federal Clean Water Act, from the Army Corps, for mine construction.

The September 2017 plan proposes to restore and upgrade sections of Sonoita Creek on a ranch Hudbay owns in Santa Cruz County. The Sonoita Creek Ranch lies in a separate watershed lying 12.5 miles south of the mine site in the Santa Ritas in Pima County.

The Environmental Protection Agency’s concern about the lack of mitigation lands inside the Cienega Creek watershed is detailed in a 26-page set of comments it sent the Corps in November 2017.

Hudbay’s account is contradicted in a letter Pima County Administrator Chuck Huckelberry wrote in December to the Corps. He wrote that Hudbay and its predecessor on the mine project, Augusta Resource Corp., rejected many opportunities to mitigate impacts within the Cienega watershed.

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Not only are there many private and state land parcels in the Cienega watershed outside the Davidson Canyon watershed that could be purchased, the county provided a list to the Forest Service in December 2009 and a map of available parcels to the Corps four years later, Huckelberry wrote.

In 2014, county officials suggested that Rosemont consider an available parcel on Apache Springs along Gardner Canyon, a Cienega Creek tributary lying south of the mine site and flowing out of the Santa Ritas, he wrote. While Gardner is a significant source of surface water and groundwater for upper Cienega, Augusta Resource’s subsidiary Rosemont Copper declined to buy the property after investigating its cost, Huckelberry said. The 131-acre Apache Springs Ranch has since been sold to another party.

The county also proposed that Rosemont preserve or rehabilitate streams in three areas the company owns in the Santa Ritas west of the mine site. The company rejected that idea because it wished to keep them open for future exploitation, Huckelberry wrote.

Those areas, Broadtop Butte, Copper World and Peach-Elgin, have long been thought by Rosemont critics to be future mining sites. In 2015, Hudbay officials told the county that there’s not enough information about these properties to make any commitments regarding their future development or conservation.

“Hudbay has an obligation to its shareholders to not make this type of decision prematurely and without adequate information,” the company said at the time.

Contact reporter Tony Davis at tdavis@tucson.com or 806-7746. On Twitter@tonydavis987