2023-2024 Executive Summary
SCCWRP’s microbial water quality research is focused on developing tools that allow managers to understand and minimize risk of human exposure to waterborne pathogens. Whether swimming and surfing at the beach, or consuming shellfish harvested from coastal waters, the public depends on rigorous, fully vetted science to rapidly detect aquatic microbial contamination and to inform remediation strategies. Advances in molecular microbiology are enabling the water-quality management community to develop incrementally stronger, more effective solutions for protecting public health. SCCWRP’s goal is not only to improve the speed at which microbial contamination can be detected, but also to develop molecular methods for tracing contamination back to a specific source and upstream origin point. SCCWRP also is focused on helping water-quality managers better understand how field measures of microbial contamination correspond to specific levels of health risk.
SCCWRP’s microbial water quality research is focused around three major areas: (1) Microbial source tracking, which involves using molecular methods to identify whether humans vs. various individual animal species are responsible for observed contamination – and to identify where in a watershed the contamination is coming from and potentially which specific type of stormwater or wastewater infrastructure is responsible; and (2) microbial risk assessment, which involves quantifying health risk for Southern California’s beachgoing population through epidemiological studies, as well as through health risk modeling approaches such as Quantitative Microbial Risk Assessment (QMRA) that estimate illness risk based on site-specific considerations; and (3) advancing molecular methods for microbial contamination detection, which involves validating the accuracy and applicability of DNA-based methods for measuring microbial contamination and expanding the range of pathogens for which those techniques are applied. SCCWRP’s focus for 2023-2024 will be on:
- Identifying human sources of fecal contamination: SCCWRP is working to identify specific sources of human fecal contamination in Southern California waterways by tracking and quantifying the relative contributions of public sewers, private laterals, septic systems, illicit connections and illegal discharges, and individuals experiencing homelessness. This work, which includes quantifying both relative contributions and the factors that control these contributions, is a reflection of the fact that human fecal sources appear to be widespread in Southern California waterways, particularly during wet weather. During the region’s short but dynamic storm events, source tracking is incredibly difficult because so many possible human sources are mixed together in stormwater runoff. SCCWRP’s source-tracking investigations build off previous SCCWRP research that has found that the risk of gastrointestinal illness from body contact recreation during wet weather is greater than the risk illness during dry weather, and that genetic markers of human fecal contamination (i.e., HF183) and human pathogens are commonly found in wet-weather discharges. SCCWRP also is working to establish relationships between HF183 and human pathogens, utilizing QMRA to establish health risk thresholds for wet-weather discharges. Especially as management questions shift from “Are human fecal sources found in wet weather?” to “Which specific human source(s) are found in wet weather?” SCCWRP’s overarching goal is to help managers optimally remediate human fecal sources during storm events to protect beachgoer health.
- Evaluating the SHEL water-quality standard: SCCWRP and its partners are continuing to investigate whether a State water-quality standard known as SHEL that is designed to protect the health of people who consume shellfish from Newport Bay in Orange County has been appropriately set. With a preliminary study finding that there is no relationship between water-quality indicators and pathogens found in Newport Bay shellfish during dry weather, SCCWRP will continue to support managers in determining if there is a scientific basis for pursuing development of a site-specific standard for Newport Bay. The findings of the Newport Bay work could have broad implications for other water-quality managers statewide that are managing discharges that exceed the SHEL standard.
- Enhancements to PCR-based measurement methods: SCCWRP has been at the forefront of developing molecular measurement methods such as qPCR and then later ddPCR for application to beach water quality monitoring. This technology continues to evolve with development of more sophisticated instrumentation that can measure more channels simultaneously and target more endpoints. SCCWRP will continue to develop this technology and work to transition it into application in partnership with its member agencies. SCCWRP will also this year focus on developing new approaches to distinguish genetic material associated with viable bacteria from that which represents remnant material associated with disinfected discharge or other natural degradation processes – the latter of which could lead to overestimation of infective particles in the environment.