Innovations in Bacteria Compliance: Upper Los Angeles River Watershed Human Health Risk-Based Special Study

Bacteria impairments remain one of the most challenging water quality issues in Southern California, resulting in beach closures and unsafe conditions for recreators. The Upper Los Angeles River (ULAR) Watershed Management Group (WMG) is pursuing an innovative method to address the Los Angeles River Bacteria Total Maximum Daily Load requirements. Following years of implementation challenges and evolving understanding of human health impacts and risks related to bacteria impaired recreational beneficial uses, the ULAR WMG adapted their approach with an innovative, data-driven, reprioritization of efforts. Specifically, the ULAR WMG refocused efforts to the highest risk source of illness-causing pathogens (i.e., human waste) and the highest risk areas of the watershed, where it is more likely illness-causing pathogens are present and is applying greater emphasis on targeted source control in their management strategies.

Human waste typically contains a higher concentration of pathogens, thereby increasing the risk of gastrointestinal illness through recreational exposure. Recent studies demonstrate human waste source control is a more cost-effective long-term approach to reducing pathogens relative to the current focus on structural BMPs. Further, advancements in human marker tools—such as HF183—can better identify conditions under which pathogens are contributing to downstream impaired receiving waters. The ULAR WMG’s adapted approach leverages an innovative risk-based prioritization approach, advancements in source investigation tools, robust data collection, and a newly developed human waste source identification and tracking toolbox to conduct human waste source investigations to reduce public health risks and help restore the beneficial uses of the iconic LA River.