Committee working to identify actions managers should take based on HF183 fecal contamination measurements

SCCWRP and the Southern California Stormwater Monitoring Coalition have convened an 12-member advisory committee to develop recommendations for what management actions are appropriate to take upon measuring exceedances of a genetic indicator of human fecal contamination known as HF183 in runoff.

The management advisory committee’s deliberations, which began in January, follow publication of a 2025 SMC study that identified the numerical threshold, or inflection point, at which levels of HF183 in wet-weather runoff correspond to an elevated illness risk for people swimming and surfing in contaminated receiving waters.

Unlike with more established indicators of fecal contamination like Enterococcus bacteria, which have regulatory thresholds, stormwater managers lack guidance on if and how to act upon measuring HF183 in runoff or a water body. Consequently, they have struggled with how to use HF183 measurement data as a basis for taking actions to protect the health of beachgoers and others downstream who may be inadvertently exposed to fecal contamination.

The committee’s membership includes representation from both the stormwater and wastewater management sectors, along with water-quality regulators, an environmental nonprofit, and experts in microbiology and health risk modeling. The committee’s recommendations are expected to be finalized in summer 2027.