Bay Area Pollution Begins at Home

CASTRO VALLEY, Calif. —  As spring arrives in this Bay Area suburb, the weekend gardeners emerge--mowing lawns, tending gardens and pruning trees. Like all good gardeners, they know that there are battles to be waged in the quest for a perfect yard: The enemies are weeds, ants and other pests. Their ammunition: a $10 bag of chemicals bought at the local hardware store.

But homeowners here may be unaware that they also are waging war against San Francisco Bay, 25 miles away.

The pesticides wash off their lawns and gardens, poison local streams and creeks, and eventually wind their way to the coast.

Just a tablespoon of diazinon, the most popular residential pesticide, is powerful enough to disrupt a creek’s food chain by wiping out tiny flea-like crustaceans that are eaten by fish and other creatures.

In a Castro Valley neighborhood of 20,000 homes, scientists recently calculated that after a rain, a pound and a half of diazinon--75 times more than the lethal level for some of the bay’s aquatic life--washed into creeks that flow into San Francisco Bay.

The potent backyard pest killer is just one of at least nine pollutants that are jeopardizing the health of California’s largest estuary and the animals and people that rely on it, according to the San Francisco Estuary Institute, a scientific group that monitors the bay.

Environmental experts now consider the runoff of chemicals from developed areas to be the biggest source of contamination in San Francisco Bay, contributing 80% of its pollutants during rainy years.

Although many people assume that the largest polluters are the giant refineries, factories and sanitation plants lining the bay front, the real culprits lie in runoff--the material that washes off lawns and streets into a system of drains that empty it, untreated, into creeks and rivers headed toward the bay.

“The problem of water pollution has come home,” said Geoff Brousseau of the Bay Area Storm Water Management Assn., which represents cities and counties around the bay.

“Now that we’ve clamped down on easily identifiable sources of pollution, we have to talk to everybody and say, ‘You’re the biggest polluter.’ And that’s a big shock to people.”

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San Francisco Bay is the dumping ground not just for the Bay Area, but also for much of California. More than one-third of the state’s land--from the Oregon border to Bakersfield, to just west of Lake Tahoe--drains into rivers and creeks flowing toward San Francisco Bay. Oil leaking from cars in San Jose, copper eroding from brake pads in Fresno, pesticides washing off lawns in Oregon’s Klamath Falls and mercury seeping from old gold mines in Placer--it all winds up in the bay.

A critical ecological resource that supports wildlife, industry and tourism, San Francisco Bay is host to more than 30 endangered species and 800,000 water birds each year. Many of California’s industries rely directly or indirectly on the health of the bay.

Despite laws mandating that all U.S. waters be safe for humans and wildlife, runoff is pushing the levels of toxic compounds that endanger the bay’s health far beyond those prescribed by law.

The most serious pollutants include such toxic materials as mercury, oily wastes, cadmium and the pesticides diazinon and dieldrin.

For the people who depend on the bay for food, the chemicals found in runoff and lingering in bottom sediments pose a direct hazard.

Although San Francisco Bay no longer supports commercial fisheries, many Bay Area residents, mostly poor African Americans and Asians, still fish there to feed their families, despite state health warnings that have been posted for years.

Their catch includes kingfish, also known as white croaker, a bottom-feeding species that absorbs dangerous levels of the industrial compounds PCBs and mercury. PCBs (polychlorinated biphenyls) were banned in 1979, but the chemicals still linger in bay sediments.

Human consumption of contaminated fish may impair the mental and motor development of fetuses, infants and young children, says the California Office of Environmental Health Hazard Assessment. Ingesting the chemicals also increases one’s risk of cancer.

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Because of the risks, state officials advise adults to eat no more than two meals per month of any type of fish caught in the bay and to avoid the skin and internal organs. Children and pregnant or nursing women are advised to eat no more than half that amount. The state’s guidelines are even more stringent for some kinds of fish, such as striped bass.

Surprisingly high volumes of mercury continue to wash into the bay, not only from ordinary household items and car exhaust but also from defunct gold mines.

Water samples on a single stormy day in 1997 showed that about 70 pounds of mercury--enough for more than 31,000 thermometers--had washed down the Sacramento River into San Francisco Bay.

Roughly half of the mercury comes from abandoned gold and mercury mining operations in Northern California, according to government scientists. The Gold Rush of 150 years ago left a legacy that keeps polluting San Francisco Bay every day, especially during rainstorms.

During the Gold Rush, miners used tons of mercury to extract gold from ore. Today, rain washes the mercury toward the coast. Mercury contamination in marine animals becomes more concentrated as it moves up the food chain. That means larger fish, such as sharks and kingfish, can amass high levels of mercury from the many smaller fish they eat over their lifetime.

Concentrated exposure to mercury can be deadly to humans. At lower levels, mercury can cause birth defects, brain damage and convulsions.

The reservoir of mercury that is sitting in the bay’s sediments is vast, perhaps amounting to more than 1 million pounds. But no one has been able to accurately estimate its extent.

The concentrations of copper frequently exceed Environmental Protection Agency limits. Some organisms--particularly phytoplankton--have been wiped out entirely in the bay, throwing off its balance of life. Some experts theorize that the tiny aquatic plants died of an intolerance to the copper in runoff.

As regulators start dealing with the complexity of the systems they seek to protect, the controversy around copper is indicative of problems to come. Scientists are starting to look into the cumulative effect that many different pollutants may have on an ecosystem--and human beings--over time.

“Environmental science is a very young science and there is much we do not know about ecosystems,” said U.S. Geological Survey scientist Sam Luoma.

To reduce the flow of mercury, the U.S. Forest Service has in recent years undertaken projects to clean up old mines on public lands. But the efforts cost millions of dollars.

What’s more, much of the land surrounding the old gold mines is now owned by private individuals who do not have the funding or expertise to sustain the massive efforts needed to root out mercury.

As for copper, Bay Area advocacy groups are trying to remove it from the bay by removing it from brake pads.

Groups trying to reduce backyard pesticides are grappling with a problem even bigger in scope. One pilot project works with stores that sell diazinon to educate consumers about less toxic alternatives.

But it may be a hard sell because most customers are accustomed to the fast and easy results they get with pesticides, said Ken Preston, manager of a Rite Aid in Castro Valley that is taking part in the project.

Scientists are also treading warily in education efforts. If gardeners quit using diazinon, they may switch to compounds that turn out to be just as bad--perhaps even worse--for the creatures that call San Francisco Bay home.