Bay Study Links Drain Outlets, Swimmer Illness
An unprecedented health survey shows that Santa Monica Bay beach-goers who swim near storm drains are almost 50% more likely to contract colds, sore throats, diarrhea and other illnesses than those who swim farther away in cleaner water.
Scheduled to be released today, the research by USC epidemiologist Robert W. Haile confirms for the first time anecdotal evidence that Los Angeles’ most popular recreational resource makes some people sick.
But the Santa Monica Bay Restoration Project and other sponsors said the exhaustive survey of swimmers gives reason for some optimism, since the risk of illness decreases dramatically for those who swim 100 yards or more from the dozen drains that typically empty into the bay year-round.
Swimmers outside the drainage areas were far less likely to fall ill, perhaps little more than if they had swum in a pool or stayed out of the water altogether.
“The good news is that, of the bay’s 50-plus-mile coastline, less than two miles are problematic,” a summary of the report said.
The Santa Monica Bay Restoration Project--a consortium of cities, businesses, environmental groups and government agencies--commissioned the survey as one of the top priorities in its five-year plan to clean up the bay.
The epidemiology study, the first of its kind in the nation, surveyed 15,492 people who went into the water last summer at three locations--Surfrider Beach in Malibu, Will Rogers State Beach in Pacific Palisades and Santa Monica State Beach, one mile south of the Santa Monica Pier. Interviewers reached most of the participants a week or two later to determine how many had become ill.
In response to the survey’s findings, Los Angeles County officials are printing more adamant warning signs to be placed near storm drains, and county lifeguards are pledging to issue stronger admonitions against swimming in polluted waters. The findings also could push ahead stalled talks among 85 cities on how best to clean urban runoff that flows into drains and thus into the bay.
Haile suggested that the study may have national implications.
“There are a lot of beaches subject to urban runoff,” Haile said. “Are those beaches having some increased risk? The answer is probably yes, because the beaches we studied are not unique.”
Swimmers and surfers long have reported getting sick after plunging into the surf from Malibu to Torrance. Researchers had confirmed that pollution, including human waste, flowed out of some storm drains. But without a health survey, the source of the illnesses had never been confirmed.
Haile enlisted dozens of college students last summer to comb the three beaches, interviewing anyone who had put their face underwater in either the ocean or at various points near storm water streams. A control group of swimmers was interviewed about 400 yards away from the drains, locations at which the levels of bacteria and human viruses usually were found to be negligible.
The study found that those who swam near the drains were well over 50% more likely to suffer fever or vomiting, for example, than those who kept their distance from the polluted runoff.
In raw numbers, the survey projects that 373 of every 10,000 people (about 4%) swimming near drains will contract at least one symptom--cough, ear ailment, sore throat, fever, chills or some gastrointestinal disorder.
“To put it another way, that means that if you bring a classroom of 25 kids out there to swim in that polluted water, one of them is going to get at least one of these symptoms. That’s what this study shows,” said Mark Gold, executive director of the environmental group Heal the Bay and a driving force behind the study.
While the survey used the swimmers nearly a quarter of a mile from storm drains as a control group, it found that the levels of illness dropped off dramatically even 100 yards from the mouths of the drains.
Too few swimmers were questioned in the study to compare the relative risks at the three beaches. Malibu Surfrider, which receives runoff from Malibu Creek, generally had the highest levels of contamination.
Pending an announcement today, results of the study have been closely held.
But officials at the Los Angeles County Department of Health Services already have been briefed and have begun printing signs that will be posted near storm drains. They are more emphatic than previous messages, said Catherine Tyrrell, executive director of the Santa Monica Bay Restoration Project.
The new signs say: “Warning! Storm Drain Water May Cause Illness. No Swimming.” Previously, the signs cautioned bathers that storm water “may be contaminated” and urged no swimming. Health officials have agreed to post flags near the signs to attract the public’s attention.
The warnings also will be printed in Spanish, an important consideration because the survey found that Latinos, particularly children, are more likely to swim in and near the polluted water. Officials speculated that the difference in usage of the contaminated water might be linked to the dearth of publicity in the Latino community about storm water pollution.
While county lifeguards will not order bathers out of polluted areas, they plan to “do our darndest to keep the people from playing or swimming in that water,” said Steve Saylors, a captain with the agency.
Researchers believe that their results have identified a pollution measure that will be more useful, in the future, in predicting when the ocean is unhealthful.
In the past, public health officials have relied heavily on measuring the concentration of coliforms, ubiquitous bacteria present in lawn clippings, pet droppings, human waste and many other plants and animals. Because many of those sources are not associated with human diseases, however, high coliform readings do not always mean high risk to swimmers.
Haile’s study found, however, that illness is far more likely when a high percentage of the bacteria comes from human waste. When 50% or more of the coliforms were fecal coliforms, the number of swimmers contracting respiratory illnesses more than doubled.
The survey does have its limitations.
Because it was intended to link public health to water quality on particular days, swimmers who went in the ocean more than once in 10 days were not questioned. If the frequent swimmers had become ill, interviewers would not have been able to link the sickness to a particular locale and pollution condition, researchers said.
That meant that the survey necessarily excluded surfers and lifeguards. “The presumption would be that those people are at a higher risk from additional exposures,” Haile said. “There is a chance, on the other hand, that they would build up immunities. But I doubt that, because you would have to build up resistance to so many different pathogens in the water.”
Researchers did not examine possible health effects on people who wade in or otherwise did not put their faces into the water, nor did they study any of the dozens of urban storm drains that only flow into the ocean during the rainy season. Health officials have long recommended against swimming in the bay for at least 48 hours after significant rainfall.
Santa Monica Bay Restoration Project officials already are suggesting more studies, perhaps of surfers and lifeguards, targeting the health effects of repeated exposure to polluted waters.
The organization also is urging that the research be used to bolster efforts to investigate and eliminate the sources of storm water pollution. That might include the diversion of some polluted runoff to sewage treatment plants, where disease-causing organisms could be eliminated, before discharging the effluent into the ocean.
Los Angeles City Council members Ruth Galanter and Michael Feuer are expected today to introduce a motion calling for the diversion of more storm water to the city’s sewage treatment plant and requesting increased funding for public education.
Activists such as Heal the Bay’s Gold said they hope that the findings will help 85 cities in the county come to some agreement on a plan to clean up the drains. That plan is due for adoption July 15 but has been stalled by bickering among the cities.
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Santa Monica Bay beachgoers who swim near storm drains face a significantly higher risk of becoming ill than those who swim farther away in cleaner water. Here are the approximate locations of storm drains that typically flow year-round into the ocean:
1. Malibu Creek and Lagoon, Malibu
2. Topanga Creek, at Topanga Canyon Boulevard
3. Santa Monica Canyon, at Chautauqua Boulevard and West Channel Road
4. Montana Avenue, Santa Monica
5. Santa Monica Pier
6. Ashland Avenue, Santa Monica
7. Windward Avenue, Venice
8. Ballona Creek, Marina del Rey
9. 28th Street, Hermosa Beach
10. 16th Street, Hermosa Beach
11. Herondo Street, Redondo Beach
12. Avenue I, Redondo Beach
Note: A 13th year-round storm drain at the base of Pico Boulevard in Santa Monica already is diverted to a sewage plant, rather than flowing directly into the ocean.
Source: Santa Monica Bay Restoration Project