On 5 August 2015, United States Environmental Protection Agency personnel, along with EPA consultants from Environmental Restoration LLC, working under EPA contract, caused a release of wastewater and tailings from the closed Gold King Mine near Silverton, Colorado.  They were attempting to investigate and mitigate tailings pollution by tapping a tailing pond when their actions destroyed the dam holding back the tailings and released over three-million gallons of water containing heavy metals and toxic elements, including lead and arsenic, into Cement Creek, a tributary of the Animas River.  The resulting flood turned the Animas River a shocking yellow-orange, and flowed for miles, eventually into the San Juan River in New Mexico and Utah.  The spill closed downstream tourism industries, especially rafting and fly-fishing operations, and forced municipal and agricultural water users to cease operations. 

Outraged communities from Durango, Colorado, to the Navajo Nation in New Mexico, along with the states of Colorado, New Mexico, and Utah, were left to question EPA’s actions, motivations, and ability to clean up the rivers or compensate affected parties.  EPA’s initial response and communications about the spill were clumsy—it waited to tell some nearby communities about the spill and failed to release critical data until many days later.  Although EPA accepted responsibility, the spill led to Colorado and the New Mexico declaring disasters, litigation (the Navajo Nation announced it would sue the agency and New Mexico and the Colorado Attorney General have publicly considered doing so) and inquisitions (the House Science Committee held a hearing on 9 September 2015, in which its members grilled EPA, and public outrage prompted widespread criticism of EPA and former mine owners).

The spill is indicative of a larger problem: state and federal agencies, along with local communities such as Silverton and Durango, are now debating how to address ongoing wastewater leaks associated with hundreds of closed and abandoned mines that cumulatively release—usually in trickles and streams rather than deluges—millions of gallons of pollutants into watersheds throughout the West, and have been for many years.  The most controversial question is whether to designate any of the legacy mines in southwestern Colorado (approximately 30 or more are near the Gold King Mine) a Superfund site under CERCLA.  Doing so would place the area on the national priority list for hazardous-waste cleanup and provide funding, but bring with it a stigma that could undermine the area’s critical tourism industry. In addition, the spill has renewed debate over reforming the General Mining Act of 1872 and passing Good Samaritan legislation to protect groups who clean up mines from long-term liability.