An official website of the United States government.

This is not the current EPA website. To navigate to the current EPA website, please go to This website is historical material reflecting the EPA website as it existed on January 19, 2021. This website is no longer updated and links to external websites and some internal pages may not work. More information »

EPA Update on Gold King Mine Response: San Juan River Data

WASHINGTON – Today EPA released new water quality and sediment data for the San Juan River within the Navajo Nation as part of the ongoing Gold King Mine response. 

What data is EPA posting today? Today EPA is posting August 24th sampling data results from the San Juan River in the Navajo Nation. Surface water and sediment samples were collected at 11 locations and analyzed for 24 metals, including arsenic, cadmium, lead and mercury. Concentrations of iron and other metals in San Juan River water in the Navajo Nation peaked during the week of August 10th as the mine release moved through the Navajo Nation, but have since trended to pre-release conditions.

What do the sample results show? 

Based on the comparison of pre-event data with data collected over the past two weeks, the pre-event sampling data show that concentrations for all 24 metals in surface water have trended to pre-event conditions, well below Recreational Screening Levels. The metal concentrations of the samples were also below soil / sediment recreational screening levels. Based upon the sediment sampling results, sediment sample concentrations are trending toward pre-event conditions as well.

View the data here.