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California Gulch (OUs 9 and 11)
Leadville, Colorado

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Site Description

The California Gulch site is comprised of approximately 16.5 square miles of mountainous terrain in Lake County, Colorado, approximately 100 miles southwest of Denver. Mining, mineral processing and smelting activities in the area have produced gold, silver lead and zinc since 1859, when prospectors working in the channels of the Arkansas River tributaries discovered gold at the mouth of California Gulch. Wastes generated during the mining and ore processing activities contain naturally occurring chemicals at levels that pose a threat to human health and the environment. These wastes remain on the land surface and move through the environment by washing into streams and leaching contaminants into surface water and groundwater. The site was added to the National Priorities List in 1983 and is divided into 12 Operable Units. Operable Unit (OU) 9 addresses lead contamination in the residential areas of Leadville and Lake County. OU11 is the Arkansas River Floodplain portion of the site.

Current Site Status and Cleanup Actions to Date

  • From 2000 through Jun 2006, one of the Potentially Responsible Parties (PRP) at the site ran a program for OU9 that provided information about lead and educated the community about reducing young children's exposure to lead.
  • EPA completed a cleanup plan in 2005 for OU11 and is coordinating with mining companies and state and federal natural resource trustees to agree on a settlement pertaining to Superfund and natural resource damages. EPA also is continuing a revegetation project in some of the areas affected by mine waste deposits.
  • Two operating water treatment plants address acid mine drainage at the site.
  • 788,947 cubic yards of soil have been treated, stabilized, or removed (roughly equivalent to 148 football fields, covered 1 yard deep). 172,100,054 gallons of water have been treated, stabilized, or removed (roughly equivalent to 3 supertankers). Two people were provided alternative drinking water to prevent them from drinking contaminated water.

Current Funding Status

  • In 2006, $1.5 million was provided for OU9 to conduct the cleanup of 52 residential properties program in Leadville and Lake County.
  • In 2006, EPA provided $20,000 for OU11 to procure and transport soil amendments to be used for the cleanup of the Arkansas River Floodplain and the irrigated meadows areas.

For more information on the projects at this site, please read the California Gulch Fact Sheet on the Region 8 Superfund Web site.

Key Accomplishments

  • Since 1995, EPA and the potentially responsible parties have conducted removal and remedial activities to consolidate, contain and control more than 350,000 yards of contaminated soils, sediments and mine-processing wastes.
  • The ROD for OU11 was signed in 2005.


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