Good News for Beach-Goers--With a Caveat

An unprecedented scientific study of Southern California’s ocean waters suggests that 95% of the shoreline meets health standards for swimmers in summertime but that some trouble spots persist even when it hasn’t rained for months.

Excessive bacteria counts were found at the mouths of rivers and storm water channels in well over half the tests at such sites.

The scientists did not specifically name the sites that failed. But other testing has revealed persistent problems with storm drains and channels at many of the region’s most popular swimming and surfing areas, including Malibu Creek, the Santa Monica Pier, the San Gabriel River in Seal Beach, the Santa Ana River in Newport Beach and Main Beach and Aliso Creek in Laguna Beach.

The findings support the warning that Los Angeles and Orange County health officials have issued in recent years: Avoid swimming at beaches near channels and rivers--roughly 100 yards from the mouth. The study emphasizes that the advice applies even during dry weather.

Unparalleled in scope, the study provides a snapshot of bacterial levels along the entire 690-mile coastline from Point Conception north of Santa Barbara to Ensenada, Mexico--encompassing five California counties and northern Baja California.

Because summertime is the prime season, the overall findings may reassure beach-goers and public health officials, especially in Los Angeles County, where many people fear getting sick if they swim in the ocean.

But the study also highlights the danger posed by storm drains, rivers and creeks that carry urban runoff to the sea.

“The majority of the coastline looks pretty good, and that is one of our main conclusions,” said Rachel Noble, lead scientist for the study by the Southern California Coastal Water Research Project, a scientific group based in Westminster that specializes in studying pollution in near-shore waters. “Water quality was consistently high along the Southern California shoreline.”

Mexican beaches from Tijuana to Ensenada fared worse than Southern California’s--with five times more violations of California’s bacteria standards. Still, 75% of the waters tested in Mexico met the standards.

“The message to the public is: Expect poor water quality if you’re swimming in front of a flowing drain, regardless of where you are in Southern California,” said Mark Gold, executive director of the Santa Monica-based advocacy group Heal the Bay and a leading expert in bacterial contamination of beaches.

“In general, we’re talking about very specific polluted beaches, not miles and miles of polluted beaches,” Gold added. “That’s an important message because many people write off all of Santa Monica Bay and that’s just not accurate. . . . Out of 300 or so miles of beaches, we’re talking about 10 or 15 miles that we’re really concerned about.”

The tests look for coliform and enterococci--indicators that human sewage or animal waste has contaminated the water. Contaminated water can carry pathogens that cause diarrhea, respiratory infections and other health problems.

Three years ago, a USC study of more than 15,000 adults and children in Santa Monica, Malibu and Pacific Palisades found 50% more illnesses among those who swam near storm water outlets than in those who swam in other ocean waters.

For the new project, teams were dispatched to sample water at 307 sites once a week during a five-week period that began Aug. 2. The scientists randomly selected the locations using a process to ensure that all types of locations--from popular sandy beaches to low-use rocky areas--were tested in a scale representative of the entire coastline.

Twenty-two government agencies conducted the study with help from almost two dozen environmental groups.

A wintertime study has also been conducted, but the findings will not be available for another six months. During rainy weather, when runoff from land is greater, it is likely that more beaches have high bacteria counts.

In the August tests, 5% of the shoreline--in terms of miles and days--exceeded the state’s daily or monthly limits for at least one of four bacterial tests.

But when researchers isolated only the ocean waters collected from the mouths of storm drains, rivers and other sources of runoff, they found that 60% failed the monthly averages for bacteria and 40% failed the daily limits.

Although those areas “constitute only a small fraction of the Southern California coastline,” water quality there was “consistently poor,” the study says.

The farther from the outlets, the better the water. In tests within a 100-yard radius of the outlets, bacterial limits were exceeded 15% of the time.

“It was somewhat reassuring that water quality is good overall,” said Larry Honeybourne, water quality program chief at Orange County’s environmental health agency, which tests beaches weekly for bacteria. “We suspected there were problems with areas receiving storm water runoff and this confirmed that.”

At 15 of the storm water outlets, Noble, a USC microbiologist, used special genetic tests that checked for signs of human viruses that could pose a health danger. Seven tested positive.

Even in summer, rivers and channels carry runoff from urban streets that contain sewage and animal feces that can elevate bacteria levels.

The study shows that when swimming at beaches more than 100 yards from storm water outlets, “the chances of running into bad water are significantly less,” Noble said.

The study tested the 30 major outlets responsible for nearly all the local runoff that flows into the ocean.

The study authors did not list the sites that failed because they want their results to be representative of the region as a whole, not specific spots. One five-week period last summer is not enough, Noble said, to assess whether an individual beach is safe or unsafe.

Although beach waters are sampled routinely in Southern California by public health agencies, this was the first assessment of the condition of the entire region. About 80,000 samples are collected annually, but because they are gathered by nearly two dozen different agencies using different sampling techniques, no one until now had a regional picture.

For years, environmental experts have debated what test to use when monitoring waters and deciding when to close beaches. None of the four bacterial indicators is considered foolproof for detecting human sewage. Enterococcus, for example, was the bacterial type most frequently found at high levels. As a result, using that bacterium as the test would result in the highest level of protection for the public, but also the largest number of costly beach closures.

The study authors did not provide a definitive answer as to which bacterial type would be the most accurate predictor of problems. But they urged a comprehensive evaluation to see what bacteria are the best indicators of the presence of the viruses and other pathogens that actually make people sick.

Some of the sites had never been sampled before.

“We really didn’t uncover any hot spots that we didn’t know about,” Noble said, “which is a sign that the [government] beach monitoring program is doing a good job.”

(BEGIN TEXT OF INFOBOX / INFOGRAPHIC)

Over the Limits

A summertime study of the shoreline along the Southern California Bight--from Point Conception north of Santa Barbara to Ensenada--shows almost all areas complied with state standards designed to protect swimmers. Below is the percentage of various types of shoreline that exceeded daily bacteria limits. Findings are based on 70% of the 307 sites sampled--the ones where all four bacteria tests were conducted.

Entire region: 7%

High-use sandy beaches: 7.8%

Low-use sandy beaches: 4.1%

High-use rocky shoreline: 2.4%

Low-use rocky shoreline: 2.1%

Storm water outlets: 40.0%

Source: Southern California Coastal Water Research Project, 1998 report