Colorado is still recovering from an August 5 toxic waste spill that turned the Animas River a bright orange color. The leak, which amounted to 3 million gallons, was caused when the U.S. Environmental Protection Agency used heavy machinery to investigate pollutants at the Gold King Mine, north of Silverton.
Much of the ire over the mishap has been directed at the EPA, especially after the federal agency's own internal review revealed that it hadn't performed a key safety test. According to the report: "Although difficult and therefore expensive and technically challenging, this procedure may have been able to discover the pressurized conditions that turned out to cause the blowout."
But regardless of what actually caused the blowout, the Gold King Mine accident also calls attention to a much bigger problem that confronts Colorado and other western states. According to a 2011 report by the federal Government Accountability Office, there are at least 161,000 abandoned hardrock mine sites in 12 western states and Alaska. At least 33,000 of those are causing environmental problems, including contamination of surface water and groundwater.
EPA also has estimated that mine drainage has contaminated 40 percent of western watersheds. In Colorado alone, state Department of Public Health and Environment officials told the Denver Post that 230 old mines have contaminated 1,645 miles of rivers and streams.
And the problem could get worse. EPA estimated that the 161,000 sites had at least 332,000 features - an average of more than two per site - that raised the risk of an environmental mishap, such as unstable or decaying mine structures that might collapse and cause a toxic waste-water leak.
Earthworks Action, an environmental group, has compiled this state-by-state breakdown of known sites of abandoned mines and environmental hazards that they cause.
The problem is largely the result of many years of lax or even non-existent regulation of mining in the west. As miners drilled through the rocks in mines, they dislodged iron sulfide, which reacted with air and pyrite in the Earth to create sulfuric acid. That acid ate through the mine, dissolving heavy metals such as copper and lead, and forming a toxic stew in the mine's waste water. For years, they weren't required to do anything to mitigate that risk.
"In the old days, there was very little control, and not much attention paid to control," Ronald Cohen, an environmental engineer at the Colorado School of Mines, explained to public radio station KUNC.
Cleaning up these hazards could cost as much as $72 billion, according to Earthworks Action. And taxpayers are likely to foot most, if not all, of the bill, since in many cases the owners of the mines are long gone.
The recent accident isn't even the worst one that's occurred on the Animas River. In 1975, a dam failure dumped 50,000 tons of metal tailings, leaving the river looking "like aluminum paint," according the High Country News.