SACRAMENTO -- Elevated mercury levels dating from the California Gold Rush 150 years ago are a potential danger in fish from certain Sierra reservoirs and rivers, according to a draft fish advisory that will be the first ever issued by the state for Sierra Nevada waterways.
"We are using 21st Century science to evaluate potential health threats from eating fish containing mercury that was released into Sierra streams as far back as the Gold Rush," said Joan Denton, director of the California Environmental Protection Agency's Office of Environmental Health Hazard Assessment.
Most people can safely eat limited amounts of the contaminated fish, but children and women of childbearing age should be careful how much they consume, she said. Excessive mercury levels can damage the nervous system.
The advisory, now in draft form, will warn of elevated mercury levels in fish in five reservoirs -- Camp Far West, Lake Combie, Lake Englebright, Rollins and Scotts Flat -- as well as in portions of the Bear and South Yuba rivers and Deer Creek.
The waterways are all in Nevada, Placer and Yuba counties, at the heart of the Mother Lode area where gold miners used mercury to separate gold from sand and gravel. The toxic mercury was allowed to flow into rivers and streams, where it accumulated in the soil.
Over the generations, bacteria convert the inorganic mercury to more dangerous methylmercury, which fish then eat. The department warns that the methylmercury can accumulate in fish in concentrations thousands of times greater than in the surrounding water.
The warning is based on fish samples taken in 1999 from the five reservoirs and from 14 stream sites. An initial analysis in 2000 led state and local health officials to issue interim health advisories that people eat bass from the waterways no more than once a month, and eat catfish and other fish no more than once a week.
The new proposed warning suggests that children and women of childbearing age not eat any bass from Camp Far West Reservoir; eat bass and catfish from the other waterways no more than once or twice a month, depending on where the fish are caught; and eat trout from Deer Creek no more than twice a month.
Adult men and women beyond their childbearing years should eat bass and catfish from the waterways no more than two to four times a month, depending where they're caught, and eat Deer Creek trout no more than four times a month, the advisory says.
The department is soliciting public comments through Feb. 27, and plans a Feb. 27 public hearing in Grass Valley.
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On the Net:
Read the draft report at http://www.oehha.ca.gov
