An official website of the United States government.

We've made some changes to EPA.gov. If the information you are looking for is not here, you may be able to find it on the EPA Web Archive or the January 19, 2017 Web Snapshot.

Gold King Mine Data, October 14, 2015

Data from Gold King Mine Response

Surface water and sediment concentrations are now below recreational screening levels. The river system as a whole is being maintained at pre-event conditions.

It is important to keep in mind that metal concentrations in water and sediment may fluctuate. Fluctuations occur because of weather and other events that change water flow rates or volume. They can also occur if sediments are accumulating at a higher than normal rate at a particular site, before being washed away by the next high water event. 

As the response to the mine release transitions to long-term evaluations, EPA will continue to monitor for any abnormal occurrences of metal concentration exceedances of risk-based screening levels.

EPA surface water and sediment samples collected on 9/30 and 10/1 from locations along the Animas River in New Mexico.


EPA sediment samples collected on 9/28 and 10/1 from locations along the Animas River in Colorado.


EPA surface water samples collected on 10/1 from locations along the Animas River in Colorado.


This data submission presents data for sediment samples collected on 9/24 from the San Juan River.

This data submission presents data for surface water samples collected on 9/24 from the San Juan River.

Surface water sample results have been compared to pre-event conditions as well as recreational screening levels. The concentration of several metals in some sampling locations have shifted higher than pre-event levels and are also higher than the recreational screening levels. In particular, aluminum, cobalt, iron, manganese and thallium concentrations are above the recreational screening levels. The concentration of lead at one sampling location is near the recreational screening level, but did not exceed the level. Field logs do indicate thunderstorm activity in the area on the day prior to sampling. This may be a cause for the high metal concentrations. Sampling activity will continue in this area.

Top of Page