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Officials Trying to Solve Mystery of Harbor Bacteria

September 5, 2008

By Julia Scott

PRINCETON-BY-THE-SEA — The sun-dappled waters of Pillar Point Harbor look bright and beautiful on a hot afternoon, but the bacteria that lies below the surface is as much of a mystery as where it’s coming from.

County Environmental Health officials have known for years that the inner harbor’s waters contain dangerously high levels of fecal coliform bacteria. It accumulates on Capistrano Beach, leading the county to post a permanent warning sign to keep visitors away.

Officials have also long suspected that the inner harbor functions like a bathtub, its breakwall impeding the natural flow of water and trapping the bacteria. They’ll test that hypothesis with an ambitious, wide-scale, real-time water circulation study on Saturday, Sept. 27.

The San Mateo County Resource Conservation District is seeking several volunteers for the daylong event, part of a larger study to determine the origins of the fecal bacteria in the harbor and to propose some solutions.

Researchers’ creative approach to revealing the secrets of how water circulates inside Pillar Point will be to turn it red and blue with a kind of dye used in science experiments but invisible to the human eye. A flotilla of volunteers on strategically-placed kayaks will take water samples at regular intervals, and scientists will examine them under a fluorometer to observe the color changes and understand how the water travels around the harbor.

“Let’s say there is a storm drain dumping into the harbor. We will want to know how it will be distributed in the harbor and how it will wind up on the beach. It’s our approach to solving the riddle as to where the sources are coming from and how much is coming from a particular source,” said UC Davis professor Stefan Wuertz, an expert in bacterial and viral pathogens who has been hired on a lead researcher for the project.

The harbor circulation study is one of several state-of-the art techniques Wuertz’s team is using to test out its hypotheses as to where the bacteria is coming from. Two creeks flow into the harbor via culverts near Capistrano Beach, and with them the possibility of fecal contamination from broken sewer lines and horse waste. Alternately, birds and dogs could be causing the bulk of the problem right at the beach itself. Then again, the live-aboards — boats with full-time occupants anchored in the inner harbor — might not be disposing of their waste in violation of the law, in which case it could be washing up on shore.

The Resource Conservation District expects to have test results ready early in 2009 along with a plan of action it will share with locals via several public meetings.

“The ultimate goal is to develop a plan to reduce the number of beach closures,” said Kellyx Nelson, executive director of the district. “Depending on what we find, the recommendation might be as widely ranging as repairing some sewer lateral lines or an education campaign for dog walkers.”

Researchers are also testing out another hypothesis that could make finding a long-term solution difficult.

Recent studies have shown that certain kinds of fecal bacteria can survive out in the atmosphere on their own by latching onto seaweed at the water’s edge, where it multiplies. That raises the possibility that it can turn up on beaches anywhere without first entering the water column, and suggests it will be harder to defeat, said Wuertz.

That raises major questions about the way the state tests for fecal indicators like E.coli, focusing just on water content.

“We’re usually worried about fecal indicator bacteria in water. There are no regulations that require authorities to sample sediments or sands,” said Wuertz. “Anytime we sample the water column, it’s possible we are simply sampling indicator bacteria that were attached to sand and have become resuspended because of the wave motion.”

Wuertz will test bacteria found in the seaweed and match it to its sources using genetic markers for fecal bacteria derived from specific animals, and the results will provide some clues on how to proceed.

In the meantime, few visitors seem to heed the warning signs on Capistrano Beach.

“I think because it’s permanently posted some people are numb to it. You’ll see families clamming and dogs running around,” said Nelson.

To volunteer for the Sept. 27 study, contact the Resource Conservation District at (650) 712-7765.

Staff writer Julia Scott can be reached at (650) 348-4340 or at julia.scott@bayareanewsgroup.com.

Originally published by Julia Scott, San Mateo County Times.

(c) 2008 Oakland Tribune. Provided by ProQuest LLC. All rights Reserved.




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