EPA Superfund Site

LAVA CAP MINE

CA | EPA ID CAD983618893

About this site’s exposure pathways: As of December 2024, the Lava Cap Mine Superfund site is considered ''Current Human Exposure Not Under Control'' because recreational users of the area below the mine, known as the Lost Lake Dam area or Operable Unit 3, can be exposed to mine tailings, leading to incidental ingestion of arsenic in soil and airborne particulates and skin contact with contaminated sediments that are deposited along shoreline and upland areas. In addition, residents may be exposed to arsenic and potentially other heavy metals via ingestion of contaminated fish from Lost Lake, or consumption of berries that grow wild along the shoreline, or surface water contact at the lake. These exposure pathways are considered unacceptable because although conservative assumptions were used, the human health risk assessment work indicates that cancer risks exceed EPA's acceptable risk-based criteria of 1x10-4 and risks are closer to 1x10-3. EPA's acceptable hazardous index of 1 is exceeded by three orders of magnitude for arsenic with a predicted maximum Hazard Index of 1,909 for a child resident.

Currently, EPA has carried out the following activities to address these pathways: EPA has informed all the residents in the area of concern (this is not a public area and is on private lands) that there can be exposure to arsenic from the tailings if they walk or use vehicles (bikes, motorcycles, ATVs, etc.) in the area, or eat fish from the lake or berries from the shoreline, but there is still evidence that people use the area for recreational purposes. The impacted area is a series of private properties that is too large to be fenced. We have not put signs up since the parcels are privately owned. To reduce your potential risk at this site, residents should avoid the consumption of fish from the lake and berries that grow along the shoreline. Residents should also wash hands and shoes after walking through the area and avoid directly contacting sediments within the lake. EPA currently anticipates that human exposure will be under control by 2030 because the remedy is expected to be implemented by then.