This 2010 file photos showa that the Santa Rita Mountains would be the backdrop for the proposed Rosemont Mine site in the Coronado National Forest near Sonoita, Ariz. The Forest Service released a report on the mine plan on Friday.

Greg Bryan/Arizona Daily Star, 2010

The proposed Rosemont Mine meets all federal environmental laws, poses no jeopardy to endangered species and should be approved, the U.S. Forest Service said Monday.

But that's not a final conclusion because reports on endangered species issues, tribal cultural resources such as archaeological sites, and U.S. Clean Water Act compliance remain unfinished, cautioned a top service official, Jim Upchurch.

In its long-awaited final draft of a crucial environmental impact statement, the Forest Service also continued to say it can't legally stop the mine if it meets all environmental laws.

Coronado National Forest proposes to approve Rosemont Copper's plan of operations for construction and operation "with concurrent reclamation" of its open-pit copper, molybdenum and silver mine in the Santa Rita Mountains southeast of Tucson, the new report says. The mine would operate for 24 to 30 years, the report says.

This is the first time, after years of study, that the service has said the mine will meet federal air-quality standards.

It is also the first time it has said the mine won't jeopardize the existence of or seriously damage critical habitat for the jaguar and nine other endangered and otherwise imperiled species that live in or near the proposed mine site, which covers more than 4,600 acres of federal, private and state land in the Santa Ritas.

However, a final opinion on that point isn't expected for another 10 days, at least, until various agencies complete a draft biological opinion on the species, Coronado Forest Supervisor Upchurch emphasized in an interview Monday.

The Forest Service released the new draft Monday to 17 local, state and federal agencies that are cooperating in preparing the document. It discussed the report with agency officials in a three-hour conference call, and posted the document on the Coronado National Forest website. Agencies have 30 days to comment before the service publishes a final environmental impact statement and decides on the six-year-old mine proposal.

This report comes a year, nine months and about 25,000 written public comments since the Forest Service's initial draft environmental impact statement. The earlier statement in 2011 drew the wrath of the U.S. Environmental Protection Agency and environmental groups, but was welcomed by Rosemont Copper and mine supporters as a key step toward getting the project on line.

The latest draft repeats past Forest Service statements that it can "reasonably regulate mining activities to protect surface resources," but faces both statutory and constitutional limits on its ability to veto a mining plan.

"This means that the Forest Service cannot categorically prohibit mining or deny reasonable and legal mineral operations under the law," the new statement said.

Specifics include:

• The service still prefers the Barrel Alternative, which would cover much of upper Barrel Canyon and lower Wasp Canyon with waste rock and mine tailings but leaves alone the adjoining McCleary Canyon. Rosemont Copper's original proposal would have covered much of McCleary and Barrel canyons with mine waste.

• The 2011 environmental report said the project's dust emissions could cause violations of air quality standards for particulates at the mine site boundary and possibly in Saguaro National Park East. After doing additional computer modeling and after Rosemont added more mitigation measures, the Forest Service says the mine will meet federal particulate standards. The mine could, however, cause ozone levels in the Tucson area to meet or exceed federal "thresholds," but Upchurch said those are guidelines, not formal laws.

• On groundwater supplies, the report said the mine's operations would drop the water table 100 feet near the mine pit several years after operations begin. Nearby springs could experience 10 feet of groundwater drawdown while mining occurs. The water table isn't likely to drop much underneath Davidson Canyon and Cienega Creek, which state and county officials say are highly valued sites due to their streams and lush vegetation. But the Empire Gulch area could experience several feet of water table decline starting 50 years or more after the mine closes.

• West of the Santa Ritas, the water table could decline 1.5 to 3.5 feet per year due to pumping for the mine. Rosemont, due to its plan to extract most liquids from its tailings, will use five to six times less water than the Freeport McMoRan Copper & Gold Sierrita Mine now operating in the Sahuarita/Green Valley area.

But the effectiveness is not known at this time of Rosemont Copper's much-publicized plan to offset pumping by recharging Central Arizona Project water in that area, the new report says. That's because the mine's exact recharge site is unknown although one has been proposed.

• As for groundwater quality, the report says the mine's dry tailings will reduce tailings seepage into the aquifer to a maximum of eight gallons a minute. Computer models have predicted that tailings seepage wouldn't exceed state water standards, even without dry tailings. Due to other mitigation measures, the report says it's likely the mine will avoid or reduce impacts to groundwater quality by factors such as acid rock drainage.

• By holding back stormwater flows by various means, the mine is expected to reduce annual flows into neighboring washes by 17 percent after the mine is closed. The service says this loss will be offset by the company's purchase of restrictive covenants, water rights and conservation easements in lower Davidson Canyon, Cienega Creek and the Sonoita Creek Ranch south of the Santa Ritas in Santa Cruz County.

Contact reporter Tony Davis at or 806-7746.