Around 10:30 am on August 5, 2015, an Environmental Protection Agency (EPA) crew ruptured a plug of rock and soil at the Gold King Mine north of Silverton, releasing an estimated 3 million gallons of contaminated wastewater. This water ran into Cement Creek, a tributary of the Animas River, and was washed downstream through Durango to the San Juan River and eventually to Lake Powell. The contaminated runoff turned the normally green waters of the Animas River a bright orange-brown and brought national attention to southwest Colorado and the hazardous legacy of mining in the San Juan Mountains.
In the summer of 2015, the EPA was working to divert water contained within the Gold King Mine, an abandoned mine about ten miles north of Silverton. Contractors had advised the EPA that accessing the mine could result in a blowout, and the EPA’s on-scene coordinator, Steve Way, had postponed the job until the site could be inspected by the Bureau of Reclamation. While Way was away on vacation, his acting replacement, Hays Griswold, ordered the work resumed.
On the morning of August 5, a contracting crew ruptured a plug of rock and soil while using heavy equipment to access the mine, causing the contaminated water within to pour out. It is believed that the water had accumulated in the Gold King Mine after the Sunnyside Gold Corporation inserted a series of bulkheads in the nearby American Tunnel Mine between 1996 and 2003. As natural runoff flowed into the plugged mine, it began to spill into adjacent mines, including the Gold King. Sunnyside Gold maintains that its mines are not connected to the Gold King, but the federal government still considers the company as a potentially responsible party.
Three million gallons of wastewater poured from the mine into nearby Cement Creek. The wastewater contained high levels of lead, iron, arsenic, aluminum, cadmium, copper, and calcium, equivalent of what is released by the hundreds of mining sites around Silverton over a typical 300-day span. The spillage caused the water in the Animas River to rapidly become more acidic, dropping from 7.8 to 5.8 on the pH scale.
The bright orange wastewater took roughly twenty-four hours to reach the Animas River valley, just north of the city of Durango. At this point Durango and surrounding La Plata County ordered the river closed to public use and stopped pumping water for city use. The river’s pH returned to near normal levels about a day later, but the water remained a bright orange color due to sediment that had been deposited along the river and was still leaking into the river; the mine was still draining contaminated water into Cement Creek at an estimated rate of 800 gallons per minute.
The EPA held its first public meeting about the accident on August 7 in Durango. The agency accepted responsibility for the disaster and explained its initial plan for containment. It would build settling ponds where sediment could settle to the bottom and water could be treated before it ran into the Animas River.
The EPA opened an interim water treatment plant eight miles north of Silverton on October 19, 2015. Designed to treat runoff from Gold King and other mining sites in the area, the plant cost $1.5 million to open and more than $2.4 million per year to operate. As of January 2021, the interim treatment plant is still in operation and filters the estimated 300 gallons per minute of contaminated water that still drains from the Gold King Mine.
An internal investigation at the EPA, published on August 26, 2015, identified a lack of analysis of the water pressure within the Gold King Mine as the critical factor that led to the spill. Rather than drill directly into the blockage, the crew should have drilled vertically into the access tunnel from a different location to ascertain the water pressure. The report stated that proper drilling and testing could have prevented the sudden release.
In the days immediately following the disaster, Colorado Parks and Wildlife placed cages of fish into the Animas River to assess the potential damage to aquatic life. Somewhat surprisingly, few of the fish in the cages died. In fact, studies of the waterway have shown that the spill had little to no long-term effect on the river, largely because it already contained high levels of heavy metals from thousands of old mines in the region. This contamination causes stretches of the river to be virtually devoid of aquatic life and renders the fish populations inhabiting the river near Durango incapable of reproducing.
The disaster provided the impetus for the creation of the Bonita Peak Mining District Superfund Site, which facilitates access to federal funding and resources, to help deal with the problem of mine drainage. Silverton had previously opposed attempts to create a Superfund site, which it feared would dissuade companies from reopening mines that had been the foundation of the town's early economy, but this time the Silverton City Council and San Juan County Commission unanimously approved the designation in February 2016. The Superfund designation focuses on forty-eight mining sites in the mountains surrounding Silverton, with the goals of improving downstream water quality, stabilizing sites that contribute contaminants, and minimizing risks of future blowouts. As of August 5, 2020, more than $75 million had been spent on the site, but there were still no meaningful improvements to the Animas River’s water quality or aquatic life because the sources of contamination are so widespread.
Future remediation options in the Bonita Peak Mining District include the placement of additional plugs in discharging mines or the creation of a permanent water-treatment facility. Locals are concerned that the placement of additional plugs will only postpone the problem, potentially leading to another large discharge if a plugged mine becomes overly pressurized.
Local rafting companies in the Durango area were forced to close down for eight days while the contaminated water worked its way downstream. Regional politicians quickly tried to restore public confidence in the safety of the water and restore tourism to the affected communities. On August 12, 2015, Governor John Hickenlooper famously drank from the Animas River in an attempt show that the water was safe. "If that shows that Durango is open for business, I'm happy to help," Hickenlooper said.
Even after the water was cleared for public use, tourists were hesitant to return to the river and its communities. Local businesses filed millions of dollars’ worth of lost-income claims and lawsuits. None of these claims has been paid out, because the EPA claimed governmental immunity, but several lawsuits are still pending in federal court.
The contaminated runoff from the Gold King Mine spill reached the Navajo Nation, which flanks the San Juan River in New Mexico, Arizona, and Utah, in the middle of the growing season. It caused both physical damage (lost crops) and cultural damage, as the waters of the Animas carry a spiritual significance. The federal government provided tanker trucks filled with potable water for use by affected farmers, but for many this came too late as crops had already dried up without access to clean water for irrigation.
Some Indigenous communities, such as in Shiprock, New Mexico, refused to use irrigation water from the Animas River for the following year even after it had been cleared by federal officials. They harbored a long-standing distrust of the federal government owing to its history of mistreating the land and breaking treaties with Native Americans. Consumers also showed reluctance to purchase produce grown in the area. The Shiprock Farmers Market was shuttered for three years after the disaster. Upon its reopening, the market showcased flyers with both local and EPA-sponsored data demonstrating the safety of the crops.
The Gold King Mine Spill provided a graphic, high-profile reminder of the problem of acid mine drainage, an ongoing process that annually leaks more contaminants into the Animas River than were released by the disaster. The forty-eight sites designated in the Bonita Peak Mining District are the primary culprits. Five years after the disaster, the EPA is still studying the area and proposing remediation efforts. Cleanup remains years away. Across Colorado, many other waterways are similarly affected by this toxic legacy of the state’s largely unregulated nineteenth-century rush for mineral wealth.
In January 2021, Sunnyside Gold reached “no fault” settlements with New Mexico and the Navajo Nation for $11 million and $10 million, respectively. The cases were filed under the assumption the Gold King Mine was filled with overflow water from the American Tunnel Mine, and Sunnyside Gold settled to avoid the cost of ongoing litigation. Cases against the EPA and its contractor are pending in federal court and are expected to go to trial in 2022. New Mexico is seeking $130 million and the Navajo Nation $162 million. A similar case was settled between the state of Utah and the EPA for $3 million in clear water projects and $360 million in abandoned-mine remediation projects.