Roles of EPA and Other Responders After the 2015 Gold King Mine Release

The content on this page is no longer maintained.

On this page:

How did EPA Respond?

EPA worked closely with response agencies and state and local officials to ensure the safety of citizens, respond to concerns and evaluate impact to water contaminated by the spill.

Response Resources

  • EPA personnel from across the country, in coordination with supporting federal, tribal, state, and local agencies, continued response and recovery work throughout the watershed from Colorado to Lake Powell, Utah.
  • EPA’s toll-free call center (844-607-7600) responded to community questions related to the spill.
  • EPA released data, information and documents to the public as quickly as they became available.

Water Monitoring, Sampling and Data Collection

EPA teams deployed throughout the Animas and San Juan Rivers corridor collecting data. Teams sampled surface water in the Animas River as well as groundwater in private wells in Colorado and New Mexico.

The majority of samples indicated water quality was trending to pre-event conditions, allowing drinking water intakes to reopen and recreational and agricultural use of the Animas River to resume. EPA collected sediment samples along several points of the river.

The Navajo Nation reopened the San Juan River for irrigation. EPA continued to share sampling results as soon as they became available, with data and interactive maps posted to the Data from Gold King Mine Response Web page.

Mine Discharge Treatment

Mine water was treated in a series of settling ponds constructed near the portal. The treatment appears to have been effective. We decreased the acidity of the water (raising the pH level) with the addition of lime and sodium hydroxide solution to facilitate sedimentation of the metals in the ponds. The treated water that was discharged to Cement Creek has a pH of about 5.0 to 5.5.

Coordination among EPA Offices and with State, Local and Tribal Governments

EPA's Region 8 office in Denver, which is responsible for the implementation of our programs within Colorado, Utah and Southern Ute Tribe, worked in close coordination with:

  • EPA's Region 6 office in Dallas, which implements our programs in New Mexico
  • EPA's Region 9 office in San Francisco, which implements our programs in the Navajo Nation within , Arizona
  • the states of Colorado, New Mexico, Utah
  • the Southern Ute Tribe, Ute Mountain Ute and the Navajo Nation
  • County and city governments throughout the watershed.

Outreach and Communication

Sampling data consistently showed that environmental conditions were trending to pre-event conditions. EPA continued sharing updated information on response activities, sampling results, impacts to public health, and other related information as quickly as possible.

For more details, see the section below, and our regular updates on the response, which will be published as they become available.

Top of Page

Which Other Organizations were Involved in the Response?

  • U.S. Geological Survey (USGS) – USGS measured increased flows using a stream gauge for 6+ hours on August 9. This resulted in a provisional calculated flow volume of 3,043,067 gallons discharged from the Gold King Mine. EPA’s original estimate of one million gallons discharged from the Gold King Mine was based on an estimate of the size of the adit. A stream gauge is an instrument that measures volume by measuring flow, which is much more precise.
  • U.S. Agency for Toxic Substances and Disease Registry (ATSDR) – we coordinated with ATSDR in response to public health concerns/questions associated with the mine waste plume. ATSDR was in communication with local health officials at San Juan Basin Health in La Plata County (Durango) and the San Juan County Health Department in Silverton, Colorado.
  • New Mexico Environment Department – we worked closely with the New Mexico Environment Department (NMED) to evaluate possible impacts in New Mexico. Potentially impacted water systems were notified and precautions put in place to ensure drinking water in homes is protected. With NMED, we provided free water quality testing for private drinking water well owners in the affected area as well as providing water quality monitoring for the five drinking water systems with intakes from the river.
  • Colorado Fish and Wildlife Conservation Office monitored the effects of the spill on terrestrial and aquatic wildlife since the incident began. CPW watched for any impacts on wildlife, whether they are acute or chronic. Fish are especially sensitive to changes in water quality. CPW also monitored a control station on a clean tributary. The Colorado Department of Public Health and the Environment assisted with drinking water concerns. They indicated they are optimistic that the effects of the spill on terrestrial wildlife will be minimal.
  • Navajo Nation and the Bureau of Indian Affairs - Our Region 9 office in San Francisco worked with the Navajo Nation and the Bureau of Indian Affairs. The discharge moved quickly and was in the vicinity of the Navajo Nation boundary, near Kirtland, New Mexico. Navajo officials reacted quickly, assessed their well fields and drinking and irrigation water intake systems and issued a precautionary "do not use" public service announcement regarding water from potentially impacted sources. The Navajo EPA surface water monitoring program (Shiprock office) collected water and sediment samples from the San Juan River, prior to the impact of the release. Region 9 provided two contractors and four additional personnel to coordinate and conduct increased sample collection and lab analysis.
  • Southern Ute Indian Tribe Water Quality Program - The Southern Ute Water Quality Program responded to the Gold King Mine release to the Animas River that occurred on August 5, 2015. The plume of sediment and metals from the mine crossed the Reservation boundary in the early morning hours of August 7, 2015. Before the plume reached the border, the Water Quality Program (WQP) collected several samples to establish baseline conditions immediately prior to the plume. The WQP provided over five years of pre-GKM historical data in order to understand baseline conditions. WQP staff monitored water quality in the Animas River at four locations, and, working with EPA/CDPHE, determined the most appropriate assessment methods. In coordination with an EPA contractor, the WQP staff assessed Tribal drinking water wells. The Tribe’s Incident Management Team supported the EPA’s Area and Incident Command throughout the event.

Top of Page