Tailings, chat and other waste from mining operations have contributed significantly to the exposure of humans and wildlife to high levels of lead. The waste, commonly referred to as “chat” from dry mining operations or “tailings” from wet operations, is usually a dust, or a sand and gravel like substance that contains very high concentrations of heavy metals (e.g. lead, mercury, zinc, etc.). This waste is often left in piles or ponds at or around the operative or abandoned mining sites.
This mining waste is considered hazardous waste. In one instance, the mining town of Picher, Oklahoma, was declared uninhabitable due to the high levels of lead in the area associated with residual waste piles. In California alone, there are estimated to be between 39,000 to 47,000 abandoned mines, with 4,300 of these presenting significant risks to the environment, and many being declared EPA Superfund sites due to the extent of environmental hazards posed by the toxic waste (California Department of Conservation, 2000).
In California, the Black Bob Mine in Los Padres National Forest is an abandoned gold mine with significant amounts of lead and arsenic in the tailings. The Black Bob Mine is located within the California condor zone where the endangered species is located. The lead tailings are situated at the tributary to Salt Wash Creek, immediately upstream from the Wildlands Conservancy. The U.S. Forest Service has acknowledged that the tailings are contaminated and have already removed 205 cubic yards of waste, but more waste remains. Wildlife in the area, including the California condor, are exposed to lead in both the soil and water and are at risk from either ingesting grit or water, or dermal absorption from dust baths.
Old mining operation sites have released significant amounts of lead into the environment, and continue to be a source of lead exposure to humans and wildlife alike.