Research Areas > Regional Monitoring > Bight '98 to '03 Shoreline Microbiology

Project: Bight '98 to '03 Shoreline Microbiology

Background and Objectives

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. While Southern California has extensive beach monitoring, most target specific areas with known water quality concerns. In contrast, the Bight program uses a stratified random sampling design to assess overall condition.

Primary goals for the survey were:

• To determine the percent of shoreline mile-days in the Bight that exceeded bacterial indicator thresholds in August 1998;
• To compare the response among three bacterial indicators commonly used in California;
• To determine how well these bacterial indicator measures correlated with detection of human enteric virus genetic material; and
• To assess how well shallow water sampling characterizes conditions in deeper waters.

Status

This ongoing program was initiated in 1998.

Methods

The 1998 program assessed how much of the Southern California shoreline meets microbiological water quality standards. Samples were collected on a weekly basis at 307 sites between Point Conception, California, and Punta Banda, Mexico, beginning August 2, 1998 and continuing for five weeks. Sampling sites were selected using a stratified random design, with six sampling strata: high- and low-use sandy beaches and rocky shoreline, and ephemeral and perennial freshwater outlets. Samples were collected using standardized protocols. Total and fecal coliforms were analyzed for all samples, and enterococci were measured in approximately 70% of the samples. Molecular analyses to measure the presence of human enteric virus genetic material were performed on samples collected from 15 randomly selected perennial freshwater outlet locations.

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. Beaches selected for study all had a flowing freshwater creek, surfers present at the site and a history of microbial water quality standards exceedences.

In addition to these core objectives, the regional monitoring study has been used to evaluate new environmental assessment methods. In 1998, for example, the IDEXX-defined substrate method was incorporated into the laboratory intercalibration studies as part of the regional monitoring quality assurance exercises. This evaluation led to regulatory adoption of the IDEXX method, initially in California, and ultimately the nation.

Findings

The 1998 program found 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 the 2003 study, 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.

Partners

This project was conducted in collaboration with more than 40 different participating agencies.

Data

• Data from Bight '03
• Data from Bight '98