Poisoned fish: An old mercury mine taints California waters


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An abandoned mercury mine that for decades has sent polluted, orange waste into a creek that eventually feeds into San Francisco Bay is a threat to human health and should be added to a list of the nation’s worst polluted places, federal regulators say.

The New Idria mercury mine in remote San Benito County was shuttered by the U.S. Environmental Protection Agency in 1972 because of pollution from piles of mine waste and the site’s towering blast furnace. For decades, however, the agency refused to add it to the National Priorities List, which qualifies a site for millions of dollars in federal Superfund cleanup funding.


This week, the EPA proposed listing the site — a year and a half after the Associated Press reported that federal and state regulators had failed to clean it despite their own studies showing the mine was polluting nearby streams and making fish unsafe to eat.

“In 2010, we realized … that our previous investigations had not sampled in areas that were likely impacted [and] that the effects were likely much farther downstream than we previously thought,” a group of EPA’s mine experts said in an e-mail. “Additional research was conducted by USGS and other universities that elucidated our understanding of the fate and transport of mercury in general, and specifically from the New Idria site; and, that the local and state agency efforts were not adequate to address the impacts,” the EPA said.

Today, New Idria is an eerie ghost town tucked amid cattle ranches. The company that owned the mine when it closed sold it in the 1980s, and officials have been trying to figure out who’s responsible for it now.

The hulking iron shell of the blast furnace still looms over the wreckage of abandoned buildings and small homes where mine workers lived. Bright orange water from one of the many mine tunnels still spits into a pool that drains through hill-sized piles of mercury-tainted mine waste and into San Carlos Creek, which flows into the San Joaquin River.

Records show that in 1997, the EPA found mercury in the creek exceeding federal standards and sent a “high priority” referral to state water quality regulators warning that the toxic element could be migrating into a popular fishing area and eventually to the Delta-Mendota Canal, “a drinking water conveyance to other parts of California.”

Despite this and other evidence, neither the EPA nor state regulators conducted cleanup operations to stem the flow of pollutants into the creek. Once in a creek or river, mercury travels up the food chain through bacteria, which converts it to methylmercury — a potent toxin that can permanently damage the brain and nervous system, especially in fetuses and children.


The Centers for Disease Control and Prevention calls methylmercury a possible carcinogen and one of the nation’s most serious hazardous waste problems. The CDC says that people who regularly consume tainted fish are at risk of headaches, tingling, tremors and damage to the brain and nervous system.

Mining in California’s coastal mountains for mercury, which was used to extract gold from mines in the Sierra Nevada, ceased decades ago, but at least 550 mercury mines were left behind. One U.S. Geological Survey scientist says the total may be as high as 2,000.

Studies have found that tens of thousands of people in Northern California, especially impoverished people who fish to put food on the table, eat fish caught from the Sacramento-San Joaquin Delta and San Francisco Bay, which contains mercury in amounts that exceed federal standards.

Abandoned gold and mercury mines have been cited as the source of much of this pollution, which is expected to take decades to clean up. “Kids are still getting exposed to mercury by eating fish, and this is one of the most potent neurotoxins we know of, so it’s important for our government to protect public health and make it a priority to clean up these sites,” said Deb Self, executive director of San Francisco Baykeeper.

The EPA will make a final decision on adding the site to its priorities list after a public comment period and further review.

-- Jason Dearen/AP