August 12, 2015: To assess the impacts of the release at the Gold King Mine near Silverton, Colorado, water quality samples were collected at numerous intervals beginning on Aug. 5, 2015. Samples were taken prior to the plume’s arrival to establish a baseline for water quality comparisons. Each surface water sample was analyzed for 24 metals, including arsenic, cadmium, lead and mercury.

Analysis now shows that water quality for the Animas River from the Silverton, Colo. area to the Durango municipal water intake has returned to pre-event water quality levels. These results are based on validated sampling data collected from Aug. 5 to Aug. 9, 2015.

EPA has shared this data with state, local and tribal officials in Colorado to assist them in their decisions regarding the on-going use of water resources. EPA plans to continue to monitor, analyze and share data for downstream river segments as it becomes available.

Go to the data.