Sunday, July 5 Page A1
http://www.sfgate.com/science/article/Fears-of-mercury-in-Shasta-Lake-fish-surface-6366668.php
By Ted Andersen
Photos by Terray Sylvester
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| Will Epperson of Big Bend, CA, fishes on Lake Shasta on Thursday, July 2, 2015. Mercury levels in bass and catfish in Lake Shasta may be higher than reported in state fishing guidelines, posing a threat to human health. |
SHASTA LAKE — Secrets are lurking hundreds of feet beneath the murky emerald surface of Shasta Lake. Legends of giant sturgeon and catfish persist, and an American Indian tribe’s ancestral village still rests at the lake’s bottom. But there is another secret that lies in sediment of the lake bed: mercury.
Dammed in 1944, Shasta provides water from Sacramento to the crop-irrigating breadbasket of the San Joaquin Valley more than 300 miles south. It is California’s largest reservoir and a treasured jewel for anglers, many unaware of the poison in the lake and in the fish they catch.
Mercury, a legacy of the Gold Rush, has worked its way into Shasta’s food chain, state tests have found, revealing levels beyond what is considered safe by the Environmental Protection Agency. But no advisory to people who fish the lake has been put in place.
While sparsely populated — Shasta County has about 180,000 residents — the lake draws 1.4 million visitors a year and is one of the state’s top fishing destinations.
“To me it seems like clean, good water,” said Sage Baker, who has fished the lake for more than two decades and continues to go out several times a week.
“I never got sick,” said Mike Thomas, store manager at Phil’s Propeller and Fishing Tackle in the town of Shasta Lake. “In the fish and game regulation there is information, but to be honest, I’ve never read up on Shasta.”
Even if Thomas had glanced through the California Department of Fish and Wildlife’s Sport Fishing booklet, he wouldn’t have found any mention of Shasta’s toxicity. For years scientists have known about the lake’s high levels of toxicity and the State Water Resources Control Boardhas even listed it as mercury-impaired, but still no warning has been specifically issued about the lake’s fish.
Tests to be re-evaluated
Change may come this summer when officials at the California Office of Environmental Health Hazard Assessment, the state’s lead agency for environmental health risks, begins re-evaluating 2007 state tests to determine whether the reservoir’s game fish pose a danger to human health. Bob Brodberg, chief of the agency’s Fish and Water Quality Evaluation Unit, said the earlier data proved inconclusive. “It needed more data,” he said.
If change does come, two things could happen: an advisory would be listed in the booklet given to all anglers who obtain a California freshwater fishing license, and the U.S. Bureau of Reclamation could then consider posting warning signs along the lake.
Runoff from sites once active with gold mining is the main cause for the presence of mercury in the lake. Gold mining requires mercury, and there are many shuttered mines around the lake. But the widespread practice of placer mining, or gold panning, is most to blame for leftover mercury in streams that feed into Shasta, said Jay Thompson of the Shasta Historical Society.
During the Gold Rush, while countless miners chopped down trees to make sluices and cabins, an estimated 7,600 tons of mercury were dumped into California’s once-clear waters. Thompson said that every placer miner had a bottle of mercury to separate the gold from rock, and its unregulated use also polluted the Shasta watershed with a large amount of it.
“If people knew how much mercury was in the creeks up here they would be surprised,” he said.
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| Jay Thompson, an employee at the Shasta Historical Society, poses for a portrait in the society's archives in Redding, CA, on Thursday, July 2, 2015. Scientists have blamed historic gold mining for some of the mercury pollution in Lake Shasta. |
Recent mercury deposits
The lake is also coping with more recent mercury intrusion. Upstream volcanic geothermal springs along with atmospheric industrial pollution that crosses the Pacific Ocean from Asia both deposit mercury into the lake, said Philip Woodward, an engineering hydrologist at the Central Valley Regional Water Quality Control Board in Redding. It’s unknown how much mercury comes from each source.
“That’s an area that could bear some research, but it would be some meticulous work,” Woodward said.
Methylmercury poisoning causes central nervous system damage, and many of its symptoms are similar to those seen in cerebral palsy. In aquatic systems it moves from bacteria to plankton to fish, and at each step in the food chain it compounds, typically with older and larger predatory fish having the highest concentrations. The National Academies’ National Research Councilestimated that about 60,000 children are born each year in the U.S. with neurological problems because of exposure to methlymercury in utero.
There are no recorded cases of methylmercury poisoning from Shasta Lake because local government does not collect data on it, said Vanessa Vidovich, supervising nurse at Shasta County Public Health. However, she said she generally advises pregnant women against eating fish from any source. She said she hadn’t heard of any contamination issues with the lake.
“We’ve never been given the green light to advise against eating the fish in Shasta Lake specifically,” she said. “But they might be keeping a tight lid on that one because that’s a big political issue I’m sure. Recreation is a huge industry for us up here, and they probably don’t want to scare people away. We have throngs of fishermen coming up here.”
Shasta County Board of Supervisors Chair Leonard Moty, who said he was not aware of any of the mercury issues affecting the lake, said tourism to Shasta contributes to the roughly $2 million per year in sales tax revenue for the county, but that this is just a fraction of the $16 million generated by property tax.
“I would have no inclination to hide something like that from the public, even if it meant (losing) tourism dollars,” he said. “It is what it is, and if that is an issue we have to deal with, then we’ll just have to do it.”
No warning signs
Because there are no warning signs around the lake, anyone seeking to investigate mercury in the water would have to do some sleuthing around the Environmental Protection Agency and State Water Resources Control Board websites to detect there is an environmental problem.
One could follow the “Water Quality Assessment” link to an interactive map showing all impaired water bodies across California. In 2008, the EPA listed Shasta as impaired by mercury based on a scientific calculation called “maximum total daily loads,” which means the amount of a pollutant a body of water can receive and still safely meet quality standards.
But this designation does not include mercury levels in fish and is simply not strong enough for people such as Chief Caleen Sisk of the Winnemem Wintu American Indian tribe, whose historic lands were flooded by the building of the reservoir in the early 1940s. She said her tribe has unsuccessfully lobbied the U.S. Bureau of Reclamation, which manages the reservoir, to notify the public of the risk posed by the fish.
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| Will Epperson of Big Bend holds a spotted bass after hooking it from Lake Shasta, CA, on Wednesday, July 1, 2015. |
Lurking problem
“You have this monster festering underneath that we know is there,” she said. “You’ve got a problem here because they’ve already studied the fish, and the fish in Shasta Lake have mercury poisoning. But they are not posting that. We said, ‘In how many languages will you post that the fish in Shasta Lake have mercury poisoning?’ ... That was like eight years ago.”
The Bureau of Reclamation is not opposed to erecting warning signs for fishermen around the lake, said Michael Mosley, the agency’s regional water quality coordinator, but to do that, it would need to follow proper protocol. A mercury program led by the State Water Resources Control Board is currently collecting more data, which could then prompt an official advisory from the state’s health hazard assessment office and finally a posting of warning signs on the lake.
“We are going along with that and waiting for that process,” Mosley said. “If they came up with some things like that, we would most certainly do our best to comply.”
The decision to issue health warnings for Shasta’s fish is up to the Office of Environmental Health Hazard Assessment. To develop the advisories, the agency will use fish data, much of which has been collected or funded by the state water board. It will then make the information available online to the public and in the California Fish and Wildlife Sportfishing Regulations booklet, which displays all site-specific fishing advisories throughout the state.
The advisories include information about the fish that can be eaten without harm or should be avoided altogether. There are 77 site-specific advisories throughout the state, but none at Shasta.
The re-evaluation of state tests will likely begin in July and could take up to three years, Brodberg said. He said a lack of comprehensive fish species testing is what has held back an advisory.
High levels in bass, catfish
The 2007 study of mercury contamination in Shasta Lake found that both spotted bass and catfish larger than 14 inches exceeded safe state and federal methylmercury levels, with the highest concentrations found in the catfish. But the findings were never made public in the California Fish and Wildlife Sport Fishing booklet.
“I thought they put Shasta Lake in there but I guess not,” said Monty Currier, environmental scientist in charge of reservoir sport fish at the California Department of Fish and Wildlife. “I thought they were going to add that in the book for sure.”
A great variability exists in mercury levels for different fish species, and based on certain norms, the state’s health hazard assessment agency emphasizes eating rainbow trout. Bass, catfish and brown trout are typically the fish most prone to high levels of mercury because of their predatory nature.
EPA methlymercury limits for safe eating are 0.3 milligram per kilogram. Data from the 2007 state tests reveal bass with levels just under 0.5 milligram per kilogram and catfish at more than double the limit. On the other hand, testing of rainbow trout from 2002 and 2006 shows safe levels between 0.1 and 0.2 milligram per kilogram. Brown trout, a commonly eaten predatory fish typically higher in mercury than rainbow trout, could prove to be the deciding species if the lake’s fish are to be listed as contaminated.
Fish tests
“That’s why we need more testing,” Brodberg said.“We don’t like to issue an advisory for one fish. We like to have at least three species of fish and nine samples of each of them.”
If the data are sufficient, Shasta will be added to the advisory section of the California Fish and Wildlife Sport Fishing booklet, said Margy Gassel, a research scientist with the state’s health hazard office. But in terms of posting signs, that is out of the organization’s hands, and would be up to the Bureau of Reclamation.
For now, fishermen will be left guessing as to the safety of their catch. In his two decades of fishing Shasta Lake, Sage Baker said he has heard about the mercury issue in conversation but has never seen any proof.
“It’s kind of crazy that you don’t hear more about this mercury stuff. It seems it could damage your health,” he said. “I just assumed that if it was that bad, I would have heard more about it.”
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