Jump to main content or area navigation.

Contact Us


? ?

Superfund Program Implements the Recovery Act

Sulphur Bank Mercury Mine

Clearlake Oaks, California

Site Description
The 200-acre Sulphur Bank Mercury Mine (SBMM) site is an inactive mercury mine that is located on the shores of Clear Lake in Lake County, CA.  The mine property includes a flooded open-pit mine and approximately 3,000,000 cubic yards of contaminated mine waste.  The site also includes the contaminants from the mine that are now located in Clear Lake sediments, in the wetland to the north of the mine property, and at the Elem Indian Colony (EIC).

The EIC is located on approximately 50 acres of land directly adjacent to SBMM that have been placed into Trust status for the Elem Pomo Tribe.  During construction of housing and the paved roadway system at the EIC in the 1970s, mine waste was used from the SBMM as fill on residential lots located on the western edge of the EIC, as road-base material on paved and unpaved roads throughout the EIC residential area, and as road-base material for the only paved access road to the EIC. The levels of mercury, antimony and arsenic present in EIC soils and in the exposed roadway shoulders exceed levels that are safe for residential and recreational use, based on EPA’s baseline risk assessment.

Cleanup Activities to Date
EPA listed the site on the National Priorities List  in 1990.  In 2006 and 2007, EPA excavated and removed all mine wastes and contaminated soils that were located in the residential area at the EIC, and disposed of these contaminated materials in a secure location at the adjacent SBMM.  EPA is currently evaluating long-term cleanup actions for the main mine property and expects to select a cleanup approach for this portion of the site in 2010.

Recovery Act Project Activity
EPA will use the approximately $1 million in Recovery Act funding to start the cleanup of BIA 120 mine wastes in 2009. EPA's primary efforts in 2009 will be planning and coordinating activities with the Elem Pomo Tribe; the procurement of a construction subcontractor; the initiation of work to provide temporary water supply, sewer service and access for EIC residents during the cleanup; and planning efforts to assure the early 2010 performance of mine waste excavation and disposal efforts.

EPAmodified the roadway design to provide for the relocation of permanent water supply and sewer service for surrounding residents. EPA initiated construction activities in March 2010, and completed the mine waste excavation and disposal efforts, and road construction in December 2010.

To find out more about: