- Associated Press - Thursday, August 11, 2016

BOISE, Idaho (AP) - Federal land managers on Thursday approved 10 more years of mining and a 500-acre expansion mostly on public land in central Idaho for one of the largest molybdenum mines in the world.

The U.S. Bureau of Land Management and U.S. Forest Service each issued decisions allowing the work at Thompson Creek Mine about 20 miles southwest of Challis.

“It’s been a long time coming,” said Jim Kopp, site manager for Thompson Creek Mining Co., noting work stopped in December 2014 as the company waited for approval of its 2008 request. “We’re happy that there’s a decision.”

He said the mine to date has produced about 452 million pounds of molybdenum and the expansion will allow the mining of 93 million more pounds. Kopp said the mine is currently in a care and maintenance mode with about 50 workers but won’t immediately restart because of low molybdenum prices. At full production, the mine is rural Custer County’s largest employer with about 400 workers.

The oval-shaped open pit is about a mile long, nearly three-quarters of a mile wide and 2,000 feet deep. It’s the fourth largest mine producing primarily molybdenum, though it falls a few notches when mines that also produce copper are included.

Thursday’s decisions mean the open pit will be made slightly wider as material is removed from the sides starting at the top and working down. Kopp said the molybdenum deposits become richer deeper in the mine. Molybdenum has a variety of uses but mainly as an alloy to make steel, cast iron and other metals.

More than 90 percent of the mining operations are on private land, including the entirety of the open pit. But mine owners needed federal approval to use additional public land for the expansion that will produce more waste rock and tailings.

The waste rock will be put on both BLM and Forest Service land, while the tailings will be placed on Forest Service land. The 500-acre expansion includes about 200 acres of BLM land, 185 acres is Forest Service land, and 110 acres is private land.

The mine started operating in 1981, but additional molybdenum deposits led mine owners to seek an expansion.

“They found more ore they didn’t know about back then so they want to enlarge the pit,” said Ken Gardner, a geologist with the BLM and the project lead for the Thompson Creek Mine federal review.

The BLM and Forest Service decisions follow the March 2015 publication of an environmental impact statement analyzing the expansion of the mine and offering various alternatives.

The Idaho Conservation League has participated in the public process, noting its concerns about the mine’s proximity to the Salmon River, which supports populations of federally protected salmon and steelhead.

The group is concerned about what happens when the mine eventually closes and that the company sets aside enough money for reclamation.

“These funds are critical to ensure that the mine is on a clear path for successful operations and closure, that the Salmon River is protected now and for future generations, and that taxpayers don’t have to pay expensive cleanup costs,” John Robison, the group’s public lands director, said in a statement.

Meanwhile, another company, British Columbia-based American CuMo Mining Corp., wants to start a different molybdenum mine in the Boise National Forest in central Idaho.

But that plan is on hold after the Idaho Conservation League and other environmental groups filed a lawsuit and a federal judge ordered the Forest Service to re-evaluate how the mining company’s exploratory drilling might harm a rare plant called Sacajawea’s bitterroot.

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