On Wednesday August 5, 2015, during an EPA mine site investigation of the Gold King Mine near Silverton, CO, heavy equipment disturbed loose material around a soil “plug” at the mine entrance. Apparently, acid mine drainage had built up behind the plug, which unexpectedly gave way due to the weight of the water pressure in the tunnel, and a torrent of water gushed out of the tunnel.
This accident resulted in the release of approximately 3 million gallons of contaminated water into Cement Creek which flows into the Animas River. The water contains a number of heavy metals such as lead and arsenic. The spill has affected waterways throughout the Colorado River Basin, which impacts 6 states and 12 tribes. This area in Colorado has a history of mining since the 1800’s and there is a history of toxic leaks going into the river (Church et al., 2007). However, this may be one of the largest toxic spills in this region.