State Near Finish on Yellowstone-Area Mine Cleanup

The McLaren Mine processed gold and copper ore from 1934 to 1953

By Lisa Baumann, Associated Press

COOKE CITY — A creek that ran with orange-tinged water for years looked clear Monday as a project to clean up waste from an abandoned gold mine just east of Yellowstone National Park neared completion a year ahead of schedule.

Gov. Steve Bullock toured the mine site near Cooke City with a team of people from state and local agencies and private companies who worked on the project, which is estimated to cost about $22 million. That’s about $2 million under budget, Bullock said.

“Knowing that legacy problems aren’t going to destroy our park or the beautiful area we’re in is pretty amazing,” Bullock said.

The McLaren Mine processed gold and copper ore from 1934 to 1953. Since then, the tailings, which consist of ground rock and water contaminated with heavy metals, have flowed from the 30-acre site into Soda Butte Creek and through Yellowstone.

In the 1960s, the creek was recognized as the most contaminated creek entering a national park, according to reclamation specialist Tom Henderson with the Montana Department of Environmental Quality.

He said pollution was easily visible in the water flowing through the creek due to a layer of iron coating it.

“It was a mess,” Henderson said. “It was acidic water rich in metals with poor quality of water discharging out of the tailings.”

After the 1988 fires in Yellowstone, Henderson said the tailings dam to Soda Butte Creek became a concern because high runoff could have caused the dam to fail and release a large amount of the toxic tailings into the creek at once. Because of that, the U.S. Environmental Protection Agency designated it an Emergency Response Action site in 1988 and efforts were made to stabilize the dam, Henderson said.

Work on the tailings, with grant money from the federal Office of Surface Mining, began in 2010 after two years of preparation. In four years, Henderson estimates up to 1 billion pounds of tailings have been removed and stored in an underground facility next to the site.

He said the work was expensive because the remote location of the mine made it challenging to haul and move equipment and because of the amount of water, more than 100 million gallons, that had to be pumped out and treated. About 40 percent more tailings also were found than had been anticipated, he added.

Even with the added challenges, the project will be finished in about three weeks, about a year ahead of schedule thanks mostly to how well the pumping system worked, allowing workers to more easily find the tailings, Henderson said.

He also said it’s been a good surprise that the creek’s water quality is already close to pristine, and he’s hearing reports that cutthroat trout are beginning to return.

“We’re very happy it’s turning out the way it is,” Henderson said.

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