Tracking a toxic trail / Long-closed mine identified as largest source of mercury in San Francisco Bay
Published 4:00 am, Sunday, December 22, 2002
For the first time, scientists have identified the single largest source of mercury in San Francisco Bay, tracing a path of contamination to an old mine in a Silicon Valley park.
Mercury from the long-closed New Almaden Quicksilver Mine in the hills above San Jose has flowed for decades through the local watershed and into the bay, making fish unsafe to eat and endangering bird species.
But until scientists recently conducted a widespread sampling of mercury contamination in the bay, they had no idea just how much of the mercury in the estuary originated with New Almaden.
And soon, local governments including Santa Clara County, which purchased part of the mine property for parkland in the 1970s, could find themselves on the hook for part of a multimillion-dollar cleanup effort as the state focuses on tough new requirements imposed by the federal Clean Water Act.
Laws making owners of pollution sources responsible for cleanup mean the county, a local water agency and the city of San Jose, through which the highly toxic metal moves via the Guadalupe River, could all have to pay to stem the movement of mercury to the bay -- and they could also be assessed additional millions of dollars for harm the mercury has done to wildlife, regulators say.
"The mine is the single most significant source of mercury to the bay," said Tom Mumley, senior water resources control engineer at the San Francisco Bay Regional Water Quality Control Board in Oakland.
Along with PCBs from power transformers, mercury is the bay's worst pollutant. Studies show mercury from the mine is killing bird embryos in the eggs and most likely killing fish hatchlings. Among the affected species are black-necked stilts, avocets, snowy plovers and Caspian terns.
The endangered California clapper rail, a wetland bird whose population has shrunk to 1,200 worldwide, has a high rate of eggs that fail to hatch and more than half of those eggs contain harmful mercury levels. Nearly three-quarters of the black-crowned night heron's eggs, gathered in the Guadalupe watershed for a study, contained enough mercury to kill embryos.
"Pretty much consistently, birds nesting in the bay have more mercury in their eggs than birds outside the bay," said Steve Schwarzbach, biologist with the U.S. Geological Survey.
The highest mercury levels found, he said, were in the eggs of birds that nest in Cargill salt ponds near where the Guadalupe River enters the bay. One- fourth of the 16,500 acres of Cargill ponds the state and federal governments intend to restore as wetlands contain the mine's mercury.
When mercury gets into waterways and wetlands, it binds with proteins in plants and animals and forms methylmercury, which can be fatal.
The California Environmental Protection Agency recommends children and pregnant or nursing women limit consumption of fish caught in the bay to one meal per month.
Most of the mercury pollution in the United States comes from smokestacks on coal and oil-fueled power plants and garbage incinerators. It drifts through the atmosphere and falls into oceans, bays and lakes.
But in the bay, scientists have traced the worst of the mercury problems to New Almaden, which operated for more than 120 years in the hills 12 miles above San Jose, starting in the mid-19th century.
Miners at the then-biggest such mine in North America dug up the mercury deposits, broke up the rock and transferred it to furnaces. The ore was heated to 1,200 degrees, then the vapor was condensed and captured as mercury, the only common metal that is liquid at room temperature.
Until the mid-1930s, miners discharged furnace dust into Alamitos Creek. Other wastes were used as road base or dumped into the creek. Erosion transported debris to the Guadalupe River and on to the bay. Construction of dams, gravel quarries, urbanization and flood control projects changed its course, but the mercury still reached the bay.
Before the mine was closed in 1975, New Almaden encompassed seven separate mines on 8,580 acres with 45 miles of tunnels.
Its legacy embodies foot-deep layers of contaminated sediments trapped in reservoirs and accumulating behind dams, piles of old tailings, or crushed waste rock, along Alamitos Creek and Guadalupe River banks laden with mercury.
Tetra Tech Inc., consultant for the Santa Clara Valley Water District, estimated that of the 84 million pounds of mercury produced by the mine, nearly a fifth, or 17 million pounds, were left behind in the environment.
In the Guadalupe River in the center of San Jose, mercury levels are five times higher than those found in the bay, which in turn has mercury levels 100 times greater than in Puget Sound or other estuaries not contaminated by streams carrying mine waste.
During most of the years of the mine's operation, "the backyard was the local waste disposal," said geologist Michael Cox, an amateur historian and mine buff who owns an historic cabin in the town of New Almaden.
"Everything got dumped in the creek. Here we are 100 years later. But we're no longer looking at one source. The mercury that was released is all throughout the whole system. There are basins where it's been trapped in the sediments. But anywhere you go in the south bay watershed, you're going to find mercury. It's just flushing itself out. It's heading out to the ocean. It's an extremely slow process."
Geological Survey measurements of mercury levels around tributaries to the bay have found it moves around the watershed like ink spilled in a glass of water.
"After a big rainfall, all of a sudden we'd get a big spike of mercury in the sediment. In the bay, the wind blows every day and mixes up the sediments. Within a month or two, the spikes disappear. They get mixed up in the bay," said U.S.G.S. research hydrologist Sam Luoma.
By the 1970s, mercury was a documented pariah in the Bay Area. Mercury- contaminated fish had been found in Almaden, Calero and Guadalupe reservoirs and south bay streams. Warnings of the danger were posted.
Roger Castillo, who has lived in downtown San Jose near the Guadalupe River all of his life, remembers catching bass, salmon, catfish and threadfin shad.
"We watched the osprey fishing in the river, and we played in the river," said Castillo. "We used to swim in it."
Then in the early 1970s, people learned of mercury's toxic threat. "They posted 'Don't eat fish' signs," he said. "And people started tossing in garbage, and stopped taking care of the river."
And the New Almaden lay at the heart of the problem. Its owner at the time, New Idria Mine and Chemical, had been warned about air pollution above San Jose as well as excessive mercury discharges to water at another operation in Hollister.
Nevertheless, Santa Clara County in 1973 bought 2,455 acres of the mine land and set it aside for horse trails and open space. Over the next two decades, the county added to its initial purchase. Eventually it spent around $10 million for nearly 4,000 acres of popular parkland, which is now called Almaden Quicksilver County Park.
"People think that the county officials were naive and stupid," said Cox, the amateur historian. "I've been through the records, and it seems as if it was driven by the Board of Supervisors. They didn't seem to realize they were buying a toxic menace."
Lisa Killough, parks director, said, "I can honestly say the county didn't fully understand the ramifications of its actions. The county was focusing on the recreational use of the park and as open space. It's a very well-loved park."
In the 1980s, the state Department of Toxics Substances Control placed the mine site and park on the state list of Superfund cleanup sites, those most in need of attention. In the mid-1990s, the county spent $6 million on a cleanup. Crews capped the main furnace area in the heart of the park. They planted vegetation, put in rock to protect stream banks from erosion and excavated mine wastes. New Almaden was removed from the Superfund list and it is considered safe for park users.
But, according to the regional water board, the leaking mercury problem was far from over. Under federal law, the state must limit the toxic chemicals that threaten the bay. Mercury heads the list.
Early next year, the board intends to adopt policies that would lead to cleaning up the Guadalupe watershed and other sources. The responsible jurisdictions will have to reduce the mercury by methods that include removing contaminated tailings and sediments from the watershed and stabilizing creek banks and other eroding sources of the poison.
"The county's in a jam," said Michael Stanley-Jones of the Silicon Valley Toxics Coalition, a San Jose environmental group.
"The county has already spent millions trying to clean up the site. But they haven't done an adequate job. Our view is that a record of decision to close a Superfund site doesn't let a polluter or landowner off the hook for their obligations under the Clean Water Act. If contamination is coming off site after the cleanup, that, too, needs to be addressed by the responsible parties."
The Santa Clara Valley Water District, which has already spent hundreds of thousands of dollars on studies to define the mercury problem, is seeking partners to share cleanup costs it estimates will go into the millions of dollars.
"We're waiting for a response from the county and the city," said Beau Goldie, district spokesman.
County parks Director Killough said, "We've invested significant resources into the cleanup of the park, and it's not apparent to us at this time what are the impacts to the watershed from mercury." More cleanup would be "a very big effort. We need to get more information before we get on board."
San Jose has told the water district that "it's not prepared to contribute funds toward the mercury study until responsibility issues are resolved," said Mary Ellen Dick, the city's division manager for watershed protection.
The local agencies could be liable for damage New Almaden mercury has done to the bay's living creatures.
Federal law requires governments and private parties to make reparation for damage to wildlife and other resources from pollution. Currently, negotiations are taking place with about a dozen of those entities, including Santa Clara County, San Jose and companies that owned or operated the mine property in the past.
Fish and Wildlife Service biologist Jim Haas has been collecting data on injury to the environment from the New Almaden mine -- be it contaminated fish,
which also feed migratory birds, or tainted endangered species.
"We found in the creeks below the historic mining district that the concentrations were about eight to 10 times higher than at other locations," said Haas. "I'd be concerned for any wildlife eating fish in that watershed."
Human symptoms and advisories:
-- Who's at risk: At greatest risk from mercury are fetuses and infants, who can get a harmful dose from their pregnant or nursing mothers. The effects can include decreased brain size, delayed physical development, mental impairment, abnormal muscle tone and coordination problems. Adults usually experience milder symptoms - abnormal sensations in the hands and feet and blurred vision. Long-term exposure can damage the kidneys. Recent studies link mercury exposure to impairment of immune and reproductive systems and cardiovascular disease.
-- What not to eat: State warnings about fish from the San Francisco Bay and the Sacramento River-San Joaquin River Delta say adults should eat no more than two 8-ounce meals a month of sport fish, including sturgeon and striped bass. Adults should not eat any striped bass over 35 inches. Women who are pregnant or may become pregnant, nursing mothers and children under age 6 shouldn't eat more than one meal a month. They shouldn't eat any striped bass over 27 inches or any shark over 24 inches. The advisory doesn't apply to salmon, anchovies, herring and smelt.
-- Where risk is highest: Mercury's presence also has prompted warnings about eating fish from these Northern California waters:
Lake Herman (Solano County)
Parts of Lake Berryessa (Napa County)
Clear Lake (Lake County)
Lake Nacimiento (San Luis Obispo County)
Guadalupe, Calero and Almaden reservoirs (Santa Clara County)
Guadalupe River and Alamitos and Guadalupe creeks (Santa Clara County) .