2018-2019 Executive Summary
With more than 233 million visits per year, Southern California’s beaches are a precious natural resource and a major economic driver for the state and region. As such, protecting beachgoers from waterborne microbes that come from a disparate array of sources is vital to maintaining the economic benefits and perception of healthful living associated with California beach culture. Although California runs the nation’s most comprehensive beach water monitoring program, the public can benefit greatly from continuing advances in how microbial water contamination is monitored. Existing methods take 24 hours or more to yield results, which isn’t fast enough to provide same-day warnings to beachgoers. Moreover, when environmental managers find fecal indicator bacteria that may be associated with potentially pathogenic microbes in water, they want to identify where the contamination is coming from to stop it at the source. Given that waterborne microbes can travel long distances, remain infectious for extended periods (as in the case of some viruses), leave behind genetic material long after being rendered non-viable via disinfection treatment processes, and come from any combination of human and animal feces, the process of identifying sources of microbial water contamination and their associated health risks can be challenging and complex – an area for which the technology is still evolving. SCCWRP has been at the forefront of efforts to more rapidly detect beach microbial contamination and to advance the breadth and accuracy of emerging source-identification technologies. Working with its collaborators, SCCWRP has evaluated methods for identifying fecal sources, created a tiered framework for investigating sources of fecal bacteria at beaches, and developed and evaluated multiple assays designed to measure pathogens in both fresh and marine water. SCCWRP also is actively involved in applying these methodologies to epidemiology and modeling studies to characterize the risk of water-contact illness.
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 prevalence of antibiotic-resistant bacteria and the genes that confer resistance in wastewater treatment plants and discharges. SCCWRP also is examining the utility of source-associated markers to identify microbial water pollution, and assessing the health effects of contaminated ocean water on swimmers. SCCWRP’s focus for 2018-19 will be on:
- 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.
- Assessing health effects on swimmers: SCCWRP and collaborators are continuing to work toward determining the appropriateness of setting site-specific objectives for water-quality criteria at Southern California beaches via Quantitative Microbial Risk Assessment (QMRA). A QMRA analysis is ongoing at Inner Cabrillo Beach, a popular swimming spot in the Los Angeles Harbor area where fecal indicator bacteria concentrations frequently exceed water-quality guidelines. As part of this effort, SCCWRP will be advancing the use of genetic methods to more accurately and rapidly measure the viral pathogens that are the illness vectors.