10:00 PM PST on Monday, November 24, 2008
Tissue samples from large-mouth bass captured in Big Bear Lake show elevated levels of mercury, a toxic pollutant that can cause neurological damage, especially in young children, scientists said.
Officials are unsure of the source, saying it could be atmospheric deposits from the Los Angeles area or as far away as China.
"It could be harmful to fish, birds and humans if they consume too many of the affected fish. That's why we're concerned about the levels we've seen," said Hope Smythe, senior environmental scientist at the Santa Ana Regional Water Quality Control Board.
Some of the bass sampled contained mercury at twice the levels set by regulators as acceptable for human consumption, Smythe said.
The state has not issued any public warnings about eating the bass, a popular game fish.
From 2001 to 2005, mercury levels in tissue taken from about a dozen bass varied from 0.2 parts per million to 0.6 ppm, according to state and federal documents. A concentration of 1 ppm is equal to four drops of ink in a 55-gallon barrel of water.
The U.S. Environmental Protection Agency recommends people not eat more than 8 ounces of fish every two weeks if it contains 0.3 ppm of mercury.
At 0.44 ppm, the state's Office of Environmental Health Hazard Assessment says the fish should be avoided by the most vulnerable populations -- anyone younger than 17 and women aged 18 to 45 because mercury can built up in the blood stream and cause problems for a fetus if the woman becomes pregnant.
The most recent samples were taken in 2005. State documents show elevated mercury levels in bass in Big Bear Lake going back as far as 1984. The tests were part of routine monitoring by the water quality control board as required by the federal Clean Water Act; the lake is on the list of impaired bodies of water because of heavy growth of noxious aquatic plants that increase nutrient levels and threaten fish, Smythe said.
More thorough testing will be necessary, though it is unlikely the findings have changed since the last tests, said Robert Brodberg, senior toxicologist for the state agency that assesses health risks.
Environmentalists decried the delays.
"The agencies that have been charged with protecting health and the environment in California are underfunded, and delays are rampant," said Dr. Gina Solomon, a senior scientist with the Natural Resources Defense Council in San Francisco and a member of the EPA's Science Advisory Board. "The effects on health are serious; there are entire generations of children that are potentially being exposed to hazardous chemicals."
Smythe agreed that budget constraints hamper the agency's ability to do more frequent testing and meet federal requirements to monitor and mitigate problems in impaired lakes. She said agencies involved with the lake, including the Big Bear Municipal Water District, were aware of the findings, as was the state office that issues consumption advisories when toxins are found.
The water district's general manager said his office would not be responsible for notifying the public because the findings came from government tests. Brodberg, of the Office of Environmental Health Hazard Assessment, said he talked to the water quality board about the Big Bear Lake mercury in 2006 or 2007, but no one sent follow-up data on it.
No Drinking Water Threat
The Santa Ana Regional Water Quality Control Board will meet next month to discuss how the pollution can be monitored and whether it can be reduced, and to take public comment. The board was waiting to finish the lake's nutrient plan before it dealt with the mercury, Smythe said. As part of the process, the state will establish a mercury limit for the lake that eventually will be submitted to the U.S. EPA for approval or changes.
Other lakes in the region, including Arrowhead, Perris and Elsinore, are not listed for mercury problems.
Scott Heule, the Big Bear water district's general manager, said he fears unwarranted "scare tactics" and the impact that could have on recreation at the lake.
"I don't think the problem is so huge to warrant some kind of massive program that would unnecessarily scare people with regards to the safety of the fish in the lake," he said. "We've got to be very careful that we don't say the sky is falling on something like this, because the concentrations are not high enough to be of a concern on human consumption for drinking water."
Big Bear Lake supplies drinking water to residents of Redlands, but it is not a health threat, officials said. Tests on the water earlier this year showed mercury readings from nondetectable in the lake to 17 parts per trillion in tributaries, state documents show. The acceptable level is 50 parts per trillion.
Mercury can evaporate from natural and manmade sources and become airborne. It can travel long distances before it falls to Earth with dust or precipitation. When it lands in lakes, bacteria and chemical reactions change mercury into a more toxic form, methylmercury, which concentrates in the muscle tissue of fish and humans, Brodberg said.
Methylmercury can pass through the placenta to babies, and the developing brains of fetuses and children are especially susceptible to its effects, which include learning, attention, language and memory impairment. In adults, long-term or excessive exposure can result in memory loss and speech, vision and heart problems.
Source A Mystery
Bass are particularly susceptible to mercury accumulation because they are at the top of a lake's food chain and eat smaller fish and organisms that have the element in their systems.
Bass fisherman Mike Nemec, of Menifee, said he wasn't worried about a fish consumption warning because his sport focuses on catch and release. Mercury findings would be troubling if they involved large fish kills and affected larger lakes in the area where tournaments are held, he said.
Trout and carp sampled from the lake did not have high levels of mercury. The readings were less than 0.021 parts per million, documents show.
Fish consumption restrictions because of mercury are in effect in many Northern California bodies of water, including San Francisco Bay, the San Joaquin River, Clear Lake and Lake Nacimiento. The source in many cases is earlier mining activities, officials said.
Water district manager Heule said mining in the Big Bear area, including activity north of Baldwin Lake and in Holcomb Valley, occurred outside the Big Bear Lake watershed.
Smythe, who works for the water quality control agency, said she believes the mercury comes from atmospheric deposits from coal-fired power plants in China or industrial operations in the Los Angeles-Long Beach area.
But other air quality authorities disagree.
"We have a lot of sources," said Dimitri Stanich, a spokesman for the state Air Resources Board who dismissed China or Europe as the origin of the pollution. "Chances are it's probably from our own gold-mining days."
Sam Atwood, spokesman for the South Coast Air Quality Management District, said his agency doesn't even monitor outdoor air for mercury because the state's limitations on coal burning make such testing unnecessary.
In addition to burning fossil fuels, mercury comes from metal smelting and cement plants, and natural occurrences such as volcanoes and the weathering of rocks.
James Schauer, a professor of civil and environmental engineering at the University of Wisconsin-Madison, traced mercury from an incineration and metals reprocessing facility in the Port of Long Beach to the air in Riverside and the Los Angeles Basin.
The facility contributes more than 60 percent of atmospheric mercury in the Los Angeles area, according to Schauer's research that was published earlier this year.
Though he did not measure Big Bear Lake specifically, Schauer said the mercury there is probably from the same source. Technologies are emerging that can control such mercury emissions, he said.
Reach Janet Zimmerman at 951-368-9586 or jzimmerman@PE.com