Documents released by U.S. officials have revealed that the Environmental Protection Agency knew of the potential for a blowout of toxic wastewater from a Colorado mine more than a year before a government cleanup team accidentally triggered such a release earlier this month.
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About 3 million gallons of water from the mine flowed into Colorado's Animas River and the San Juan River in New Mexico before reaching Lake Powell on the Utah-Arizona border. Public drinking water systems were temporarily shut down and farmers from the Navajo Nation stopped using river water for irrigation.
Here are some questions and answers about the newly released documents.
WHAT DID AGENCY OFFICIALS KNOW?
A June 2014 work order from the EPA for the cleanup of the inactive Gold King Mine near Silverton, Colorado, said a partial collapse of the mine's entrance had allowed water to build up inside the mine. The order said those conditions could result in a blow-out and "cause a release of large volumes of contaminated mine waters and sediment inside the mine, which contain concentrated heavy metals."
WHAT PRECAUTIONS WERE TAKEN TO PREVENT A SPILL?
The EPA's work order called for the construction of a holding pond at the mine site to capture water so contaminants could be removed by settling out in the pond or by treatment. The pond was not completed when the accident occurred. The issue is part of investigations into the spill.
WAS A PLAN IN PLACE FOR DEALING WITH A SPILL?
The EPA documents contained only a few lines describing what to do in the event of a spill, including stopping the flow, recovering spilled materials, and alerting downstream drinking water systems.
COULD IT HAPPEN AGAIN?
The Gold King Mine has not undergone maintenance since 1991, and the impound area from which the toxic wastewater was released is not the only one at the mine. The EPA has no estimate of how much water is remaining, but agency spokesman David Gray said there is a potential for another blowout. Additional work is planned to remove other blockages holding water in the mine. There's no timeline for completion.
ARE OTHER MINES PRODUCING POLLUTION IN THAT AREA?
The Upper Animas River area contains an estimated 400 abandoned and inactive mines, and state and federal officials have been working since the 1990s to address pollution flowing into area streams. However, the EPA said water quality has not improved in the Animas since 2005 and has been worsening in some areas. Officials have noted precipitous declines in fish populations as far as 20 miles downstream.
Members of Congress have blasted the EPA's slow response to the spill, including the fact that some downstream communities were not notified until a day after it happened. They've also questioned how it happened given that the agency knew of the potential for a release. Hearings before several congressional committees are planned, including a Sept. 9 hearing before the House Science, Space and Technology Committee, chaired by Texas Republican Rep. Lamar Smith, who cited EPA negligence or incompetence for the problem.