DENVER — A Colorado mine that spewed 3 million gallons of contaminated wastewater into rivers in three Western states was designated a Superfund site Wednesday, clearing the way for a multimillion-dollar federal cleanup.
The U.S. Environmental Protection Agency added the inactive Gold King Mine and 47 other nearby sites to the Superfund list. It also included nine other sites in eight states and Puerto Rico.
The Colorado Superfund designation is the beginning of a years-long effort to clean up the wreckage of a once-booming mining industry in the San Juan Mountains in the southwestern corner of the state. Abandoned mining sites send millions of gallons of acidic wastewater to creeks and rivers every year.
"What a great benchmark for this community and for our downstream partners, that we got listed," said Bill Gardner, town administrator for Silverton, a mountain village not far from the Gold King.
A federal crew inadvertently triggered the Colorado spill during preliminary cleanup work at the gold mine on Aug. 5, 2015, sending out a mustard-yellow plume that tainted rivers in Colorado, New Mexico and Utah.
The EPA estimates that 880,000 pounds of metals flowed into the Animas River in Colorado, including arsenic, cadmium, copper, lead, mercury, nickel and zinc.
Utilities and farmers temporarily stopped drawing water from the rivers for drinking and irrigation. The EPA said water quality quickly returned to pre-spill levels.
The spill triggered a storm of criticism of the EPA and at least three lawsuits.
New Mexico has sued both the EPA and Colorado over the spill, while the Navajo Nation sued the federal government. Utah officials say they also plan to sue.
Acting New Mexico Environment Secretary Butch Tongate said his state and other downstream jurisdictions were excluded from some of the Superfund planning. "We will persist in our fight to protect New Mexicans and to hold EPA fully accountable," he said in a written statement.
An investigation last year by the Interior Department, which is independent of the EPA, said the cleanup crew could have avoided the spill but rushed its work.
Interior officials said they found no evidence of criminal wrongdoing. A separate criminal investigation is still underway, along with an internal EPA inquiry.
Congress has conducted multiple hearings on the spill and is considering several bills to address hundreds of old, leaking mines nationwide.
The EPA said Wednesday it's too early to say how long the cleanup will take and what it will cost.
Authorities will first gather data including water and sediment samples and assessments of fish and wildlife habitat and other information. That process will probably end next year, said Rebecca Thomas, EPA's manager for the project, known as the Bonita Peak Mining District Superfund Site.
The EPA will then study different cleanup methods, choose a preferred option and ask for public comment. Work would then start on designing and implementing the cleanup.
Fixes could include water treatment plants for acidic waste draining from the site, plugging abandoned mines that are leaking and moving mine waste piles away from streams, Thomas said.
The Superfund listing marks a dramatic shift in public sentiment in Silverton and surrounding San Juan County, where many residents first feared the designation would stamp the area with a stigma and hurt its vital tourism industry. The EPA does not designate Superfund sites without local support.
"It has been a stunning turnaround," said Mark Esper, editor of the Silverton Standard newspaper. He said he wasn't sure of all the reasons for the reversal, but others have said residents recognized that a long-term solution was urgent and only the federal government could afford it.
Esper said Silverton could become a research center for cleaning up leaking mines across the nation. The Government Accountability Office estimates that at least 33,000 abandoned mines across the West and in Alaska are contaminating water or causing other environmental problems.
The cleanup might also improve the town's finances, which have been in decline since a mine and mill closed in 1991, Esper said.
"I think people are really optimistic in the future of Silverton. I don't think we see Superfund as being a hindrance to that," he said.
The other sites added to the Superfund list Wednesday:
— Argonaut Mine, Jackson, California.
— West Vermont drinking water contamination, Indianapolis, Indiana.
— SBA Shipyard, Jennings, Louisiana.
— Anaconda Aluminum Co. reduction plant, Columbia Falls, Montana.
— Wrappinger Creek, Dutchess County, New York.
— Valley Pike volatile organic compounds, Riverside, Ohio.
— Groundwater contamination, Dorado, Puerto Rico.
— Eldorado Chemical Co., Live Oak, Texas.
— North 25th Street glass and zinc, Clarksburg, West Virginia.
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