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Clear Lake
California has some of the oldest lakes in the world.
Many lakes formed in ancient volcanic cones, or calderas. Clear Lake is such a lake. It is one of the oldest lakes of this type in North America and possibly the second oldest in the world.
Clear Lake is the largest natural lake entirely in California and has the largest surface area of any freshwater lake entirely in California. It is located in Lake County and is fed by many streams. Its sole outlet is Cache Creek. There is a dam on Cache Creek to increase the lake’s capacity and to regulate outflow.
Studies indicate that the water coming out of this caldera and flowing into the Central Valley and the San Francisco Bay (Cache Creek basin and Yolo Bypass) is extremely high in nutrients. This nutrient-rich water also indicates the existence of large veins of minerals, like mercury, in the Clear Lake area.
Since most of the past efforts to resolve the spread of contamination have failed, an increased public awareness of these phenomena will bring attention to the complexities of the ecosystem in the area. For instance, we should begin to look toward non-polluting technologies that provide a more holistic effort to clean the environment as well as give life to a better economy.
Sulphur Bank Mercury Mine
Sulphur Bank Mercury Mine is located on the shores of Clear Lake. Mining activity at Sulphur Bank started in the mid 1800s when settlers began mining sulphur for gun powder. They soon found that the sulfur was contaminated with cinnabar – an ore containing mercury, essential in extracting gold from ore. The owners dug mine shafts to facilitate removal of mercury-laden ore and the area became a full-scale open pit in the 1920s.
The mine was closed in 1957, leaving a hole 90 feet deep that began filling with water from creeks and geothermal springs. Dubbed the Herman Impoundment, the “lake” covers 23 acres amid 120 acres of mine tailings and waste rock.
During the 1970s and 1980s, catfish and bass were found in Clear Lake with elevated levels of mercury.
In 1990, the mine site was designated an EPA Superfund Site and is currently the largest mercury Superfund site in the nation.
Today, the entire impound is fenced off from the public. The EPA has instituted a number of remedial projects at the site that have helped, but not fixed, the problems. A long-term cleanup plan has been delayed by funding cutbacks as well as disputes on how to solve the problem. While this goes on, the mercury continues to contaminate Clear Lake.
Tribal Communities
There are several tribal communities in the Clear Lake area. In particular, members of the Elem Indian Tribe were tested and found to have elevated levels of mercury in their systems. They reside directly adjacent to the Sulphur Bank Mine.
Thirty years ago the Bureau of Indian Affairs provided housing for tribe members. They used dirt and/or tailings from the mine site to level the area where they built the residences. No tests on the soil were performed at the time and, therefore, no one in the tribe was made aware of the potential risks.