Research Areas > Regional Monitoring > Bight '08 Shoreline Microbiology

Project: Bight '08 Shoreline Microbiology

Background and Objectives

Previous regional surveys found that 95% of Southern California beaches met the state’s quality standards for water contact recreation. The remaining 5% were mostly located near urban runoff outlets. Several studies have suggested that some of the indicator bacteria near these outlets may come from regrowth within the storm drain systems, rather than from human fecal sources. Other sources of fecal indicator bacteria may include regrowth on beach wrack, beach sand, or sediment.

The goal of the Bight’08 Shoreline Microbiology Component was to identify the principal sources of fecal indicator bacteria at chronically problematic beaches in the Southern California Bight. A key element in this study was the development of new methods for measuring fecal indicator bacteria in sand, storm drains, and beach wrack. Other objectives were to:

1) Determine what percentage of chronically problematic beaches has human sources of fecal indicator bacteria.
2) Identify the non-human sources of fecal indicator bacteria at those beaches without human sources.

Status

This study was initiated in 2007 and completed in 2012.

Methods

The study focused on assessing what percentage of beaches with chronic microbial water quality problems result from human fecal contributions versus those with high enterococcus counts from environmental sources, such as birds or other wildlife. It used a combination of techniques to make this assessment, including use of alternative fecal indicators and enterococcal species identification. Special studies were conducted to evaluate which methods for measuring bacteria in sand were most appropriate for application in Southern California. A study design was prepared and experiments were conducted to collaboratively develop and verify measurement protocols for beach sand. A pilot study was implemented to test these protocols using sand from Surfrider Beach in Malibu. Other studies sought to develop measurement methods for bacterial regrowth in storm drain biofilms.

Once measurement protocols were defined and validated, sampling and analysis were performed at more than 15 different problematic beaches. Sources were quantified using traditional methods for fecal indicator bacteria and speciation of Enterococcus, as well as new measurement technologies, some of which can differentiate between human and nonhuman sources of fecal contamination.

Findings

Sand and wrack contributed some, but not all of the Enterococcus to the problematic beaches studied in Bight '08. Human sources of fecal indicator bacteria were found at more than half of the contaminated beaches, and the human sources were confirmed at a subset of beaches using a second human marker. Since the study demonstrated the human/non-human marker "proof of concept," the next steps will be to refine the application and standardize the confirmation procedure for future source tracking and remediation studies. The sand and kelp methods developed through Bight '08 are now widely accepted as the industry standard. Finally, the study advanced efforts to develop standard methods for identifying human markers.

Partners

This project was conducted in collaboration with more than 18 participating organizations.

Tool

• Standard operating procedure for analyzing sand, kelp, and concrete coupons. Bight '08 Shoreline Microbiology. May 2011.

Fact Sheet

• Bight '08 Shoreline Microbiology Fact Sheet