Mines

Background

The State of California burst into existence with the discovery of gold in 1848 along the western slope of the Sierra Nevada on ancestral homelands of First Nation people. As word spread across America and the world in 1849, hopeful prospectors swarmed up the Sacramento River to the goldfields in the Sierra.

Today, the region is riddled with abandoned mine shafts and tunnels—and other dangers that may not be apparent at first glance. The mining and mineral-processing practices of the past were not subject to today’s environmental standards and have resulted in extensive contamination to the land and waters of California.

Using techniques including placer, hard rock, and hydraulic mining, millions of ounces of gold were extracted from the Sierra Nevada “Mother Lode” during the 19th and 20th centuries. Mining practices commonly included extensive use of mercury, millions of pounds of which still contaminate the landscape. 

Much of the land impacted by these activities is now publicly owned by state, federal, and local governments. Today, there are more than 40,000 abandoned mine sites in California, according to the California Department of Conservation (CDOC), many of which are concentrated at the epicenter of the California Gold Rush, the Sierra Nevada region. Abandoned mines have left behind toxic pits and acid mine drainage. Naturally occurring metals and minerals, like lead, arsenic and asbestos, were disturbed, crushed, and distributed throughout the region. The CDOC estimates that of the abandoned mines in California, 84% present physical safety hazards and 11% present environmental hazards (CDOD, 2000).