A team of USC and UC Irvine researchers Thursday blamed human waste from leaking sewer pipes for part of the mysterious bacterial pollution problems that have plagued Santa Catalina Island's picturesque Avalon Bay for years.
The findings, which were based on a unique technique that amplifies strands of bacterial DNA so they are bountiful enough to be tested, prompted Avalon officials a year ago to spend $930,000 to repair the town's sewer lines.
As a result, beach closures declined from 31 in 2001 to 15 last year. The city is now inspecting sewer pipes of private businesses and homes to ensure that there are no more leaks.
"Previously, city officials thought all the contamination came from animals and birds," said USC microbiologist Jed Fuhrman, who conducted the sanitary survey in late 2001 with UC Irvine environmental engineer Stanley Grant. "But our results suggested that some of the contamination came from leaky sewer pipes under the city."
Avalon City Manager Robert Clark praised Fuhrman and Grant for "research that put us on the right trail."
Earlier sample studies, Clark said, "came up clean for human content, so we were focusing on birds and other potential offshore sources like sea animals."
Some city officials, however, simply dismissed the pollution as the relatively harmless result of pigeon and sea gull droppings.
To prove that point, and ease concerns of tourists visiting the popular resort about 26 miles off the Southern California coast, former Avalon Mayor Hugh T. "Bud" Smith made a point of swimming in the harbor whenever health officials posted warning signs that read: "Beach Closed. No Swimming."
"I wouldn't have gone in that water when the signs were posted," Grant said. "It would have been ill-advised to be exposed to raw sewage."
Avalon diving instructor Vicky Durst, who also ignored the warning signs, found another benefit to the findings.
"The pigeons and sea gulls are going to be happy to learn they're off the hook," she said jokingly. "The city used to trap as many pigeons as it could catch and ship them off the island, without ever making a dent in the population."