O LEM/OSRTI Washington, DC 20460 

## N ATIONAL 

## P RIORITIES 

## L IST 

## (NPL)

*** Proposed Site *** April 2016 

### BONITA PEAK MINING DISTRICT San Juan County , C olorado San Juan County

 **Site Location :**  The Bonita Peak Mining District is located in southwest Colorado in unincorporated San Juan County, within the headwaters of the Animas River.

 **Site History:** The Bonita Peak Mining District site consists of historic and ongoing releases from mining operations in three drainages, Mineral Creek, Cement Creek and Upper Animas, which converge into the Animas River near Silverton, Colorado. Mining began in the area in the 1870s

. Forty eight mining related areas have been identified, each containing waste rock, tailings piles and/or discharging mine drainage. These areas are comprised of 35 mines, seven tunnels, four tailings impoundments and two study areas where additional information is needed to evaluate environmental concerns. The last producing mine ceased production in 1991.

 **Site Contamination/Contaminants:** Currently, the EPA has waste quantity information on 32 of the 48 identified source areas. For the 32 areas with known waste quantity information, there are approximately 2 48 ,000 cubic yards of waste rock and water discharging out of mining a dits at the cumulative rate of 3 ,740 gallons per minute (5 .4 million gallons per day). Known contaminan ts associated with both waste rock and discharges from adits are aluminum, arsenic, cadmium, copper, manganese, and zinc

. Samples collected from the waste rock piles, d ischarging adits, and from streams indicate the presence of these metals.

 **Potential Impacts on Surrounding Community/Environment :**  Contaminants have been released into Mineral Creek, Cement Creek and the Animas River

. Stretches of the Animas River and Mineral Creek support fisheries that that are harvested for huma n consumption . Additionally, Animas River, Cement Creek, and Mineral Creek have stretches of wetlands vulnerable to contaminants and t he area is hab itat known to be used by the Canada Lynx, a threatened species.

 **Response Activities (to date):** The EPA’s Superfund Emergency Response Program has been active within the study area

. In 2015, t he EPA installed

a bulkhead at the Red and Bonita mine in the Cement Creek drainage

. In response to the Gold King Mine incident in August 2015, the EPA is currently treating adit drainage discharged from the Gold King Mine

. Other parties, including the Bureau of Land Management , US Forest Service, State of Co lorad o’s Division of Reclamation, Mining and Safety, private parties, and a local stakeholder group have completed past response activiti es within the mining district including analytical sampling, rerouting of adit discharge, installing bulkheads, and waste pile consolidation.

 **Need for NPL Listing:** The documented ongoing release s of hazardous substances to surface water will require significant resources to investigate and clean up

. Therefore, adding this site to the National Priorities List would be the most effective and comprehensive approach for investigating and cleaning up contamination. The Governor of Colorado has sent EPA a letter of support for listing the Bonita Mining Dist rict on the NPL.

[The description of the site (release) is based on information available at the time the site was evaluated with the HRS. The description may change as additional information is gathered on the sources and extent of contamination. See 56 FR 5600, February 11, 1991, or subsequent FR notices.]

For more information about the hazardous substances iden tified in this narrative su mmary , including general info rmation regarding the effects of expo sure to these substances on human health, please see the Agen cy for Toxic Substances an d Disease Registry (ATSDR) ToxFAQs. ATSDR ToxFAQs can be found on the Internet at http://www.atsdr.cdc.gov/to xfaqs/index.asp or by telep ho ne at 1-888-42-ATSDR or 1- 88 8-422-8737.