OEHHA Issues First State Fish Advisory for Sierra Nevada, and Fish Advisory for Black Butte Reservoir

Dec 16, 2003

SACRAMENTO -- The California Environmental Protection Agency's Office of Environmental Health Hazard Assessment (OEHHA) has issued two fish advisories concerning elevated levels of mercury in certain fish from five reservoirs and portions of the Bear and South Yuba rivers and Deer Creek in the Northern Sierra Nevada foothills (Nevada, Placer and Yuba counties), and from Black Butte, Stony Gorge and East Park reservoirs (Glenn, Tehama and Colusa counties).

The Northern Sierra advisory is the first state fish advisory ever issued for water bodies in the Sierra Nevada.

“It is safe in most cases to eat limited amounts of fish from these areas. But people – especially women of childbearing age and children – should keep track of how much they eat,” OEHHA Director Dr. Joan Denton said. “Miners began releasing mercury into the environment during the Gold Rush, and the substance is still showing up today inside these fish.”

The Northern Sierra foothills advisory contains guidelines for consumption of bass, channel catfish, trout and other fish species from Camp Far West Reservoir, Lake Combie, Lake Englebright, Rollins Reservoir, Scotts Flat Reservoir and portions of the South Yuba River, Deer Creek and Bear River.

The guidelines call for females of childbearing age and children age 17 and younger (who are particularly sensitive to methylmercury, the most prevalent form of mercury in fish) to refrain from eating all bass from Camp Far West Reservoir; limit their consumption of bass and channel catfish from the other water bodies to 1 to 2 meals per month, depending on where the fish were caught; and limit their consumption of trout from Deer Creek to 2 meals per month and from the Bear and So. Yuba rivers to 4 meals per month. Females beyond childbearing years and adult males should limit their consumption of bass and channel catfish to 2 to 4 meals per month, depending on where the fish were caught; and limit consumption of Deer Creek trout to 8 meals per month.

The Black Butte Reservoir advisory recommends that women of childbearing age and children age 17 and younger limit consumption of all bass to 1 meal per month, and consumption of channel catfish, carp and crappie to 2 meals per month. Females beyond childbearing years and adult males should limit consumption of bass to 2 meals per month, and channel catfish, carp and crappie to 4 meals per month. OEHHA also recommends that people follow the same consumption guidelines for fish taken from nearby Stony Gorge and East Park reservoirs.

Both advisories also include OEHHA's general recommendations for freshwater sport fish in California. Women of childbearing age and children should limit consumption of other species not mentioned in the advisories to 4 meals per month, while females beyond childbearing years and adult males should limit consumption to 12 meals per month.

The Northern Sierra advisory is based on fish samples from the five reservoirs and 14 stream sites in the watersheds taken by the U.S. Geological Survey (USGS) in 1999. OEHHA completed an initial analysis of the sampling results in 2000 and assisted local health offices in Nevada, Placer and Yuba counties in developing interim health advisories. OEHHA conducted a more extensive evaluation of the USGS data and issued a draft advisory for public review and comment in January 2003. The new advisory replaces all earlier advisories.

The Black Butte advisory is based on a 1999 OEHHA study of the lake's fish that was funded by the U.S. Environmental Protection Agency. The advisory replaces interim advisories issued by Glenn and Tehama counties with OEHHA's assistance in 1999.

As far back as the Gold Rush, mercury was discharged into streams either from mercury mines or from the use of inorganic mercury to extract gold from mined materials. Bacteria converted inorganic mercury in the sediment into the more toxic methylmercury, which fish take in from their diet. Methylmercury can accumulate in fish to concentrations many thousands of times greater than mercury levels in the surrounding water.

Women can pass methylmercury on to their fetuses through the placenta, and to infants through breast milk. Excessive exposure to methylmercury may affect the nervous system in children, leading to subtle decreases in learning ability, language skills, attention and/or memory. These effects may occur through adolescence as the nervous system continues to develop. In adults, the most subtle symptoms clearly associated with methylmercury toxicity are numbness or tingling sensations in the hands and feet or around the mouth. Other symptoms at higher levels of exposure could include loss of coordination and vision problems.

Visit www.oehha.ca.gov for more information, or for Fish Advisories for other California waterbodies.