Gold King Mine

Read EPA Press Release–(3/16/19)
Visit 2015 Release Pages

DEQ and USGS sampling the San Juan River at Mexican Hat on March 16, 2019

Spring 2019 Untreated Water Release

Extreme weather conditions and heavy snow knocked out power to the Gladstone Interim Water Treatment Plant (IWTP) at the Gold King Mine on March 13, 2019. Several avalanches along the road leading to the treatment plant prevented the operator from accessing the plant for several days. Snowpack in the San Juan Mountains near Silverton is 150 percent of normal, and avalanches have been common in recent weeks.

The IWTP plant operator monitored and ran the plant remotely on an emergency backup generator and intermittent line power following the storm. The pumps were able to run for roughly 20 hours before running out of fuel on the evening of March 14, 2019. The plant shut down, and untreated mine water began to flow at a rate of approximately 264 gallons per minute (gpm) into Cement Creek, then to the Animas River and on to the San Juan River.

Upon receiving the news of the plant shutdown, employees from the Utah Department of Environmental Quality (DEQ) along with teams from the U.S. Geological Survey (USGS) field offices in New Mexico and Moab headed to the Four Corners region to collect water samples.

Approximately 800,000 gallons of untreated mine water was released from the Gold King Mine between the evening of March 14, 2019, and the afternoon of March 16, 2019, when the plant went back online. The release was smaller than the 2015 release that deposited 3 million gallons of metal-laden mine water into the San Juan watershed over a shorter period of time.

The Environmental Protection Agency (EPA) has collected and treated discharge from the Gold King Mine at the water treatment plant since October 2015. The IWTP is located in the Cement Creek drainage basin and removes metals in the mine-impacted water through lime neutralization, precipitation, and flocculation.

A series of monitoring gages were installed along the Animas and San Juan Rivers following the 2015 mine release. Since 2015, Utah DEQ and its partner agencies have collected sediment and water samples in the San Juan River watershed on a regular basis to monitor water quality and assess impacts to the watershed.

Update March 18, 2019

On the evening of March 15, 2019, San Juan County cleared one lane of the county road leading to the IWTP. On the morning of March 16, 2019, the operator was granted permission to drive up to the plant. The operator was able to get the treatment plant successfully operating by early afternoon on March 16, 2019. The EPA Region 8 Bonita Peak Mining District team continues to coordinate with the plant operator to ensure the continued operation of the treatment plant.

At this time, the EPA anticipates that there will be no impacts to downstream drinking water or agricultural users from the short-term shutdown. Any impacts are expected to be localized and largely limited to aquatic life in the Animas River Canyon south of Silverton, Colorado.


Teams from DEQ, the U.S. Geological Survey (USGS), and New Mexico were dispatched immediately after receiving the news of the release and have been on site since March 16, 2019, to monitor the release and gather water and sediment samples. DEQ and USGS scientists collected samples on March 16, 2019, before the release reached the San Juan River. Results from these samples are expected by March 20, 2019.

Teams remain on site to sample and monitor the release, which is anticipated to reach the San Juan River between Sunday afternoon (March 17, 2019) and Tuesday morning (March 19, 2019). A DEQ team began additional sampling on the afternoon of March 18, 2019.

DEQ plans to visit four sites twice daily on March 19 and 20, 2019, to collect grab samples and sediment samples. DEQ is coordinating this sampling effort with USGS scientists who will collect depth-integrated samples at the same sites at the same time. The use of different sampling methods at the same sites is anticipated to produce a richer dataset.

Sample sites on the San Juan River match the 2015 sample locations, with the addition of a replicate sample for quality-control purposes:

  1. Four Corners (state line)
  2. Montezuma Creek
  3. Sand Island
  4. Sand Island (replicate for quality control)
  5. Mexican Hat

EPA collected weather-limited water samples at the bridge on Cement Creek below the water treatment plant and along the Animas River below Silverton and in Durango on March 15, 2019. These sample results are expected to be available on March 21, 2019.

Recreational Users:

The BLM has been in contact with the San Juan County Health Department, who is working with the Utah Division of Water Quality to monitor the San Juan River. The diluted waste water is expected to reach the Utah border on Tuesday, March 19 and flow through the Bureau of Land Management (BLM)-managed recreational boating segment of the San Juan River between Montezuma Creek and Clay Hills over the following several days. Based on available information, the river segment remains open to boaters and no BLM recreation closures are currently in effect. The BLM always recommends that recreational users bring all of their drinking water while visiting the river and not rely on personal devices for filtration/purification of river water.

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