As part of a maturing science strategy, the Regional Monitoring Program for Water Quality in San Francisco Bay (RMP) focuses on monitoring and modeling of emerging contaminants in major pathways in an effort to track Bay contaminants back to their sources and better inform management. Both in the Bay Area and globally, the wastewater pathway has received significant attention for its role in transporting emerging contaminants to receiving waters. In contrast, few studies have examined emerging contaminants in urban stormwater runoff.

To fill this data gap, the RMP conducted a major multi-year study to provide screening-level data (occurrence and concentration) and evaluate the role of stormwater as a transport pathway for a suite of contaminants identified as important for the Bay. This monitoring effort spanned four wet seasons (water years 2019-2022), sampled both urban and reference (minimally developed) sites during storm events, and analyzed five broad classes of contaminants: per- and polyfluoroalkyl substances (PFAS), organophosphate esters, bisphenols, ethoxylated surfactants, and tire- and vehicle-derived compounds. The majority of study findings were published in a peer-reviewed journal article; this document serves as an accompaniment to the article, with additional data and interpretation useful to local water quality managers.