Research Areas > Regional Monitoring > Bight Regional Monitoring > Shoreline Microbiology
Project Group: Shoreline Microbiology
SCCWRP Research
The Shoreline Microbiology component of the Southern California Bight (Bight) Regional Monitoring Program was added in 1998, and represented the first cooperative study ever conducted among the 26 organizations that routinely monitor beach water quality in southern California. It is now a consistent part of the Bight Regional Monitoring Program and is conducted at five-year intervals.
The 1998 program assessed how much of the southern California shoreline meets microbiological water quality standards. While southern California has extensive beach monitoring, most of this is targeted at areas with known water quality concerns. In contrast, the Bight program used a stratified random sampling design to assess overall condition, finding that 95% of beaches were in good condition. However, conditions close to urban runoff outlets were considerably worse. More than 60% of the samples collected in the immediate vicinity of runoff outlets were below water quality standards. Overall conditions worsened considerably following rainstorms, with about two-thirds of the shoreline failing standards during the 48 hours after a storm.
In 2003, the Shoreline Microbiology program focused on assessing whether measurements collected at ankle depth (where samples are currently collected in California’s routine beach monitoring programs) are protective of surfers who spend most of their time in deeper water. Paired samples were collected at both ankle depth and at the line-up area where surfers sit while waiting for a wave. This was done at 12 beaches in the summer dry season and 9 beaches following winter rainstorms. Concentrations of enterococci were found to be higher in the ankle depth samples than offshore, with the difference being nearly three-fold under dry conditions and only 25% higher under wet conditions. Based on these findings, the local health agencies concluded that the routine samples were conservative and protective of exposure to surfers.
The 2008 program is focusing on assessing what percentage of beaches with chronic microbial water quality problems result from human fecal contributions versus the number that have high enterococcus counts from environmental sources, such as birds or other wildlife. The program uses a combination of techniques to make this assessment, including use of alternative fecal indicators and enterococcal species identification. It will also include a typing analysis to assess whether high fecal bacteria levels might result from regrowth of enterococcus in beach sands.
In addition to these core objectives, the regional monitoring study has been used to evaluate new environmental assessment methods. In 1998, the IDEXX-defined substrate method was incorporated into the laboratory intercalibration studies as part of the regional monitoring quality assurance exercises. The findings from this evaluation led to adoption of the IDEXX method, initially in California, and ultimately the nation. In 2008, special studies were conducted to evaluate which methods for measuring bacteria in sand were most appropriate for application in southern California.
The main project in this group is:
This page was last updated on: 4/5/2011