3-day waiting rule after rain may not be adequate at all sites, UCLA students find
SANTA MONICA, CA (Monday, March 3, 2014) – Ocean users at California beaches located near stormdrain outfalls should avoid water contact for five days after a rain event, according to new water quality data analysis released today by UCLA environmental science students in conjunction with Santa Monica-based nonprofit Heal the Bay.
On the heels of recent significant rainfall in the Los Angeles area, the recommendation marks a significant change from current advisories issued by local health departments, which have traditionally urged swimmers to wait three days before entering the ocean following rainfall.
The new report, which analyzed Heal the Bay’s beach water quality data for the past seven years, reveals that many popular beaches near stormdrains in Southern California remain riddled with bacterial pollution up to five days after rain and pose a health risk. There are more than 100 stormdrain-impacted beaches in Southern California.
Malibu Surfrider, Santa Monica Pier, and Doheny are among the iconic Southland beaches located near flowing storm drain outfalls. These outfalls carry bacteria-laden urban runoff directly from city streets into the sea.
The main source of pollution to Santa Monica and San Pedro bays is urban runoff carried through the county’s 5,000 mile-long storm drain system. Unlike sewage, this runoff typically receives no treatment and flows freely onto shorelines and the sea through the network of open channels, catch basins and streams.
Exposure to bacteria from runoff can cause a variety of illnesses, most frequently respiratory infection and stomach flu. Human pathogens of unknown origins can also be carried down gutters.
Separately, enclosed beaches located near harbors and marinas often did not meet beach water quality standards for 10 days after a rain, according to findings from UCLA undergraduates participating in a program with the school’s Institute of the Environment and Sustainability.
Students analyzed water quality data gathered weekly by Heal the Bay with the goal to re-evaluate the California Department of Public Health advisories. More than 87,000 data points from the 32 most frequently monitored beaches in California were analyzed for levels of harmful bacterial pollution.
UCLA students attempted to determine the relationship between beach fecal bacteria densities and rainfall, and use the results to develop recommendations to better protect the health of swimmers and surfers. The water quality data included bacteria concentrations measured at each beach site.
“The UCLA study indicates that the 3-Day Rule may not be adequate to protect the health of all ocean swimmers,” said Amanda Griesbach, a Heal the Bay staff scientist. “Until the rule is modified, swimmers are better protected by avoiding storm drain impacted and enclosed beaches for 5-10 days after a storm.”
Enclosed beaches, such as Marina del Rey’s Mother’s Beach or L.A.’s Cabrillo Harbor, do not have the strong currents and breakers of open-ocean beaches. The lack of waves may be reassuring to some parents but it leads to very poor ocean circulation.
California’s coastal economy is valued at $43 billion, with Southern California receiving a large portion of its revenue from tourism and coastal recreation activities.
“Accurate beach advisories play an essential role in maintaining this thriving economy, as well as protecting the health of those who visit California’s beaches,” said Lily Tsukayama, a UCLA student researcher. Thousands of surfers use the water year-round, she noted, so more protective advisories are warranted during the winter rainy season.
Open ocean beaches, which do not have storm drain outfalls or enclosing jetties, were also included in the study. But the research showed that three days is a sufficient advisory period for this beach type.
The 32 beach sites most frequently monitored in California (all in Los Angeles County and Orange County) were examined for a given rain day and the following 10 dry runoff days for seven years of beach water quality data (2005-2012).
The students analyzed the impacts of various storm intensities and found that rainfall over a half inch increased the proposed advisory period for stormdrain impacted and enclosed beaches. These classified larger storms had only a small impact on open beaches.
Heal the Bay and UCLA student researchers also recommended that a standardized beach monitoring program is essential for California.
Many beaches are not monitored adequately (at least weekly) during the winter. Some counties monitor beaches right in front of stormdrains and creeks (point zero) while others monitor at 50 yards, 100 yards, or even based on the distance from a river mouth up to a mile away. A standardized monitoring program at point zero in front of stormdrains and creeks would be far more protective of public health.
Heal the Bay urges beachgoers to check the latest water quality grades for more than 400 beaches statewide, based on the latest samples, each week at beachreportcard.org.
The full UCLA-Heal the Bay report can be found here.
About UCLA and Heal the Bay
The UCLA Institute of the Environment and Sustainability (IoES) has a unique, graduate-level practicum project in which senior undergraduate students are paired with an outside agency.
Heal the Bay is an environmental group with over 15,000 members dedicated to making Southern California coastal waters and watersheds safe and healthy for people and aquatic life.