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Fighting Beach Pollution in the Lab

Microbial tracking helps to pinpoint elusive sources of coastal contamination. Use of the method is growing, but experts cite limits.

January 29, 2006|Tim Reiterman | Times Staff Writer

SANTA BARBARA — With stately multimillion-dollar homes, miles of shade-dappled bridle trails and a private beach below steep bluffs, Hope Ranch is a place of uncommon wealth and serenity. But like other California coastal communities, it has wrestled for years with a mysterious problem that may be rooted in runoff from its own land.

County officials have posted dozens of health warnings on the beach since 1998. And parents routinely shoo their children away from a tiny creek that drains the 1,900-acre enclave and empties onto the shoreline.

Residents had hoped they had the problem under control several years ago after fixing a septic system and taking measures to keep horse manure out of the creek.

But when surfers and swimmers later got sick, the community turned to the emerging science of microbial source tracking to try to pin down the elusive origin of the pollution. In recent years, a growing number of government agencies and local communities have used the technology to pinpoint whether they need to fix sewage systems, relocate wildlife or capture waste from livestock.

Rather than simply confirming the presence of fecal bacteria, the tracking methodology often uses genetic fingerprinting to detect what species produced it. Without knowing the origin of such pollution, experts say, stopping it can be a matter of guesswork. A community could waste millions of dollars upgrading a sewer system, for example, if it later turns out that the pollution comes from ranch lands or from seabirds flying overhead.

Scientists using microbial source tracking in San Luis Obispo County identified birds, humans, cattle and dogs as contributors to bacterial pollution that restricted shellfish harvesting in Morro Bay. And they discovered that decaying sewer pipes in Avalon on Catalina Island were polluting the shoreline with human bacteria.

Beach pollution poses a persistent threat to one of the state's most valuable assets. Although government officials cannot precisely quantify the health effects, polluted runoff in seaside communities is widely believed to cause numerous illnesses each year among beachgoers and put popular stretches of the coast off-limits to residents and tourists.

The State Water Resources Control Board requires health warnings to be posted when bacteria levels exceed standards for swimming and other water contact.

Records show that from 2000 through 2004, warnings were posted for the equivalent of 150 miles of beach for 10 days each year on average -- mostly in Los Angeles, Orange and San Diego counties. In addition, sewage spills and leaks from 2001 through 2004 caused beach closures that annually averaged the equivalent of about 65 miles of beach for the same duration.

As is the case at many beaches, the bacterial pollution in San Diego's Mission Bay was long presumed to be human. Yet it continued even after the city spent about $130 million on sewer and storm drain upgrades between 1985 and 1996.

Fearing that more costly work might be needed, officials arranged two microbial source tracking studies in 2002 and concluded that bird droppings were the primary pollutant. The city now is changing its bayside irrigation to avoid washing bird waste from the grass into the water.

"Any technique that gives you reliable answers on how you spend public funds is worthwhile," said Deborah Castillo, spokeswoman for the city's storm water program. "The beauty of this study was we were able to target the problem and be specific about how we approached a solution."

Most microbial source tracking tries to match the bacterial strains removed from water to a host species. These genetic fingerprinting techniques are largely dependent on collecting a "library" of samples for comparison.

Other methods test for the presence or absence of signature genes carried by specific warm-blooded animals, especially humans. Experts say detecting human waste is important because it generally is considered more likely to contain pathogens that can produce illnesses.

Many Southern California beaches are near creeks and storm drains, which collect runoff from residential developments, agricultural land and open space.

"In a watershed with ... residents, pets, rodents, birds, urban wildlife and all the sewer lines and septics, God knows what we have got," said Mansour Samadpour, the owner of a consulting company who pioneered a genetic fingerprinting technique and has performed about 170 pollution studies, using a library that now exceeds 120,000 samples.

"Then you get into an estuarine environment with marine mammals and an abundance of birds," he added. "And you have beaches where humans swim, and humans become sources" of fecal bacteria....

"These are complex issues."

Santa Barbara County -- with its popular beaches, tourist economy and environmental activism galvanized by a disastrous oil spill in 1969 -- has become a laboratory of sorts for pollution tracking.

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