Lava Cap Mine
The Lava Cap Mine is an abandoned gold mine in Nevada County, California. The mine is located southeast of Nevada City. The site is undergoing cleanup by the United States Environmental Protection Agency for arsenic contamination. History. Gold and silver mining began on site in 1861, with an inactive period from 1918 to 1934. In 1934 mining restarted under the Lava Cap Gold Mining Corporation. Beginning in 1940, a gold cyanidation plant operated on site to leech residual gold from the mine tailings. The gold cyanidation process increased yield to 95 percent of the gold contained in  the mine's ore. At the time of its closure, the Lava Cap Mine was the most productive in California, with over 300 men. From 1934 to 1943 the mine produced of gold and of silver. In 1943 mining ceased due to World War II and did not resume. In 1952, Lava Cap Gold Mining Corporation, including the mine itself, was acquired by Sterling CentreCorp, and in 1989 the site was acquired by developer Stephen Elder. A dam failure in 1997 caused a spill of arsenic-rich tailings, leading to an investigation by the EPA. Remedial action began in 2005 . In 2018, a $32 million judgement was obtained against Elder and Sterling CentreCorp, related to cleanup costs. Environmental issues. Waste slurry from the gold extraction was stored behind a high log dam located at the mouth of a nearby ravine. During a January 1997 storm, the log dam collapsed, releasing 10,000 cubic yards of arsenic-rich tailings downstream into the Little Clipper Creek and watershed, including Lost Lake. Samples of contaminated material contained 100 to 2,200 milligrams of arsenic per kilogram Health concerns. EPA tests revealed elevated levels of arsenic in Little Clipper Creek, Lost Lake, shallow groundwater, and  in drinking water wells. Arsenic has been classified as a carcinogen and causes other severe health issues, including thickening skin, pain, nausea, paralysis, and blindness. Residents are advised to limit their exposure to mine tailings, and to wash their shoes and pets after walking in contaminated areas. Superfund designation. In February 1999, the Lava Cap Mine was added to the EPA's National Priorities List, allowing Superfund resources to be allocated for the site's cleanup. The cleanup was divided into 4 operable units (OUs)