Urban runoff has been identified in water quality policy documents for San Francisco Bay as a large and potentially controllable source of pollutants. In response, concentrations of suspended sediments and a range of trace organic pollutants were intensively measured in dry weather and storm flow runoff from a 100% urban watershed. Flow in this highly urban watershed responded very quickly to rainfall and varied widely resulting in rapid changes of turbidity, suspended sediments and pollutant concentrations. Concentrations of each organic pollutant class were within similar ranges reported in other studies of urban runoff, however comparison was limited for several of the pollutants given information scarcity. Consistently among PCBs, PBDEs, and PAHs, the more hydrophobic congeners were transported in larger proportions during storm flows relative to low flows. Loads for Water Years 2007-2010 were estimated using regression with turbidity during the monitored months and a flow weighted mean concentration for unmonitored dry season months. More than 91% of the loads for every pollutant measured were transported during storm events, along with 87% of the total discharge. While this dataset fills an important local data gap for highly urban watersheds of San Francisco Bay, the methods, the uniqueness of the analyte list, and the resulting interpretations have applicability for managing pollutant loads in urban watersheds in other parts of the world.
A Bay RMP study employed a cutting edge analytical technique to detect low levels of five unmonitored compounds in wildlife of San Francisco Bay. San Francisco Bay wildlife were tested for previously unmonitored contaminants using a non-targeted analysis that screens mainly for long-lived, fat-soluble, chlorine- and bromine-rich chemicals. Bay mussel and harbor seal samples contained five contaminants not previously identified in Bay wildlife, and for which toxicity is largely unknown.
San Francisco Bay wildlife were tested for previously unmonitored contaminants using a non-targeted analysis that screens mainly for long-lived, fat-soluble, chlorine and bromine-rich chemicals. Bay mussel and harbor seal samples contained five contaminants not previously identified in Bay wildlife, and for which toxicity is largely unknown. Most of the Bay chemical contamination was from high priority contaminants that the RMP already monitors, or closely related compounds. Future non-targeted analysis could include techniques that examine water-soluble compounds.
Preliminary measurements of microplastic pollution in San Francisco Bay are featured in a recent San Jose Mercury News article on AB 888, a bill to ban microbeads in personal care products. San Francisco Estuary Institute is conducting a study on microplastics on behalf of the Regional Monitoring Program for Water Quality in San Francisco Bay, in partnership with San Francisco Baykeeper. Findings to date suggest Bay water has similar levels of contamination as the Great Lakes, despite substantial dilution from the Pacific Ocean.
