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Gold King Mine Data, August 21, 2015

Data from Gold King Mine Response

EPA sediment samples collected on August 11, 2015 and August 14, 2015 along the Animas and San Juan Rivers in New Mexico have been validated.  Data from sediment samples collected on August 12, 2015 and August 13, 2015 were posted to this website on August 19, 2015.

EPA has done a review of the data which included a comparison to screening levels for exposure during recreational use to determine if the metal concentrations are consistent with pre-event levels.

The metal concentrations of the samples were below soil / sediment recreational screening levels. Based upon the sediment sampling results, sediment sample concentrations are trending toward pre-event conditions.



EPA sediment samples collected on August 13 & 14, 2015 from irrigation ditches along the Animas and San Juan Rivers in New Mexico have been validated.

EPA has done a review of the data which included a comparison to screening levels for exposure during recreational use to determine if the metal concentrations are consistent with pre-event levels. 

The metal concentrations of the samples were below soil / sediment recreational screening levels. Based upon the sediment sampling results, sediment sample concentrations are trending toward pre-event conditions.


 EPA has released additional water quality data collected on August 13, 2015 and August 14, 2015 from along the Animas and San Juan Rivers in New Mexico. Based upon the surface water sample results in New Mexico surface water concentrations are trending toward pre-event conditions.
Background information:

To assess the impacts of the release at the Gold King Mine, water quality samples were collected from Navajo Nation at numerous intervals beginning on August 7, 2015. The August 7, 2015 data was collected for baseline purposes to understand river conditions at the Hogback, New Mexico monitoring location prior to the impact of the upstream contaminants from the Gold King Mine release. 

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.

Surface water samples were collected on Friday, August 7, 2015, at four (4) locations prior to arrival of the plume along the Animas and San Juan Rivers in New Mexico. On Saturday, August 8, 2015, nine (9) locations were sampled after arrival of the plume.

EPA has continued to take additional samples to document the change in the concentration of metals in the river. EPA has shared this data with state, local and tribal officials in New Mexico to assist them in their decisions regarding the on-going use of water resources. These results are based on validated sampling data collected from August 7, 2015 to August 8, 2015. 

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