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EPA Update on Gold King Mine Response: Navajo Nation, Additional Data, Public Records

WASHINGTON – Today EPA released an update on water quality and sediment data for Navajo Nation, as well as new data sets and additional public records on the Gold King Mine response. 

What new documents are being released?

EPA is releasing documents related to legal agreements, grant funding, contract work, and response summary from Colorado employee on Gold King Mine.

Go here to view the documents.

What data is EPA posting today?
Today EPA is posting additional 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.

EPA is also releasing sediment and water quality samples collected at locations along the Animas and San Juan Rivers. The sediment data was collected on August 15-22 and Aug 24, 2015, and the surface water samples were collected August 12-22, 2015.

These data points have also been added to the trend graphs created from pre-event and post-event data posted to the Gold King Mine response website. 

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 (RSL). 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.

Specifically for Navajo Nation, EPA’s conclusions are based on comparisons of San Juan River water and sediment data to EPA and Navajo EPA standards. Results consistent with this data set have been utilized by other jurisdictions along the Animas and San Juan Rivers to lift use restrictions for irrigation, livestock watering, and recreational purposes. Last night, Navajo Nation President Russell Begaye gave the directive to open the Fruitland Irrigation canal, which delivers water from the San Juan River for irrigation to three Navajo chapters.

All EPA samples are analyzed by a private lab accredited by the National Environmental Laboratory Accreditation Conference, an independent, non-governmental laboratory certification organization.  After the lab conducts its analyses, data reports generated are validated by an independent data validation service provider.

What do EPA trend graphs show?

For each metal, EPA trend graphs illustrate that concentrations are significantly lower than the RSL. The specific RSLs for each metal are posted on the right side of each trend graph. RSLs, established by EPA, are health-based concentrations for each metal based on exposure during recreational use.

The RSLs for both soil / sediment and surface water are based on recreational scenarios in which an adult or child hiker/camper is exposed to surface water and sediment. 

For surface water, the recreation-based screening levels assume that the adult or child would receive all of their daily water intake (2 liters/day) from the river over a continuous 64 day period. For sediment, the recreation-based screening levels are based on a hiker/camper that may become exposed to sediments alongside the riverbank over a continuous 64-day period. These RSLs are conservative, representing levels that are not expected to cause adverse effects over an extended period of time, based on a continuous 64-day exposure. These screening criteria represent the most conservative scenario for recreational users.

View the data map here.