Per- and polyfluoroalkyl substances (PFAS) are a broad class of fluorine-rich specialty chemicals with many uses across consumer, commercial, and industrial applications and products. The carbon-fluorine bonds that define this class afford PFAS stability during use and extreme persistence, resulting in widespread occurrence in the environment, wildlife, and humans. The EPA has identified PFAS as an urgent public health and environmental issue. To understand the scope of PFAS contamination in California, the State Water Resources Control Board (SWRCB) developed a statewide assessment requiring testing of drinking water systems and site investigations of locations likely to contain PFAS, including publicly-owned treatment works (POTWs) as a part of the July 2020 State Water Board Investigative Order. POTWs that are a part of the San Francisco Bay Regional Water Quality Control Board (Region 2) were exempted from the investigative order to conduct a two-phase regional study in conjunction with the Regional Monitoring Program for Water Quality in San Francisco Bay (RMP), led by the San Francisco Estuary Institute (SFEI), to address the monitoring needs of the SWRCB efficiently as well as to inform the monitoring strategy, management actions, and program decisions of the RMP. Insights gained from the regional approach would be shared with SWRCB, Region 2, and other POTWs across California.