Microbial Water Quality Research Plan


2019-2020 Executive Summary


SCCWRP’s microbial water quality research is focused around three major objectives: (1) developing methods to provide same-day health warnings to ocean bathers, (2) improving the approaches used to identify sources of microbial contamination, and (3) understanding the relationships between contamination measurements and observed impacts on human health. The first two areas revolve around transitioning from decades-old culture-based analyses – in which microbes must grow overnight in a lab – to genetic methods capable of rapidly detecting and quantifying microbes via their genetic material (DNA or RNA). This genetic technology also has the potential to provide important information about the source of fecal contamination, as specific genetic targets are diagnostic of different fecal sources (e.g., humans, dogs, cows, birds). Given the trove of data that these emerging technologies can yield, SCCWRP is working to incorporate these methods into epidemiological studies that can help environmental managers better understand the health risks associated with various beaches and fecal sources. SCCWRP’s ultimate goal is to provide managers with real-time information on sources of fecal contamination and commensurate risk to public health.

This year, SCCWRP will examine the relationship between fecal bacteria used to regulate recreational shellfish waters and pathogens in shellfish tissue. SCCWRP also is examining the prevalence of antibiotic-resistant bacteria and the genes that confer resistance in wastewater treatment plants and discharges, and assessing the utility of the bacterial community found in sanitary sewer infrastructure as a marker for identifying microbial water pollution. SCCWRP’s focus for 2019-20 will be on:

  • Evaluating the SHEL water-quality standard: SCCWRP and its partners will assess whether a water-quality standard designed to protect the health of people who consume shellfish from Newport Bay in Orange County has been appropriately set, a response to a looming regulatory compliance deadline for recreational shellfishing. The study will examine whether California’s existing standard for permissible fecal coliform bacterial levels in the water correlates to potentially unsafe levels of pathogens in the tissue of bivalve shellfish harvested from Newport Bay. If the water-column bacterial measurements of indicators positively correlate with pathogen levels found in the shellfish, researchers would conclude that California’s existing standard for recreational shellfish harvesting is working as designed. However, if there is no relationship between water-quality indicators and pathogens found in the shellfish, the study could provide a scientific basis for developing a site-specific standard for Newport Bay, or trigger follow-up studies examining the appropriateness of using a fecal coliform-based standard to protect California shellfish.
  • Evaluating antibiotic-resistant bacteria and genes in wastewater: SCCWRP is collaborating with its wastewater treatment member agencies to quantify the prevalence of antibiotic-resistant bacteria in wastewater treatment plants and their discharges. The study was prompted by media reports that potentially pathogenic antibiotic-resistant bacteria and antibiotic resistance genes may persist and even multiply during the wastewater treatment process before being discharged into the environment with treated effluent. The purpose of the study is to gain information about the type and prevalence of antibiotic-resistant bacteria and antibiotic resistance genes in southern California wastewater treatment plants and their discharges.
  • Tracking microbial biofilm communities in sewer pipes: SCCWRP and collaborators are investigating whether the microbial community growing on the inner surfaces of public sewer pipes is unique to this type of infrastructure, a finding that could provide insights into the origins of human fecal contamination found in aquatic systems across Southern California. Researchers are using microbial source tracking methods to determine whether leaking sewer pipes could be responsible for the fecal contamination of Southern California waterways, or whether the contamination is coming from other sources, such as direct deposition of fecal matter into storm drain channels. The biofilm community that lines the insides of sewer pipes is theorized to be the product of unique environmental factors, including temperature, moisture, darkness and a rich nutrient supply.