Urban runoff is a large and potentially controllable source of pollutants to San Francisco Bay and many other urban aquatic ecosystems around the world. In a RMP study conducted in water years 2007-2010, SFEI scientists made intensive measurements for suspended sediments and a range of trace organic pollutants (PCBs, dioxins, PAHs, PBDEs, pyrethroids and OC pesticides) in dry weather and storm flow runoff from a fully urban watershed in Hayward.
Published in the journal Science of the Total Environment, results of this study showed flows from this watershed responded quickly to rainfall and varied widely, resulting in rapid changes in water clarity, suspended sediments, and pollutant concentrations. Concentrations of each organic pollutant class were within ranges reported in other studies of urban runoff, where available. Comparison was limited for several of the pollutants given information scarcity.
More than 91% of the loads for every pollutant measured were transported during storm events, along with 87% of the total water discharge. This dataset filled an important local data gap for highly urban watersheds of San Francisco Bay. In addition, the methods, the extended analyte list, and the resulting interpretations are useful for informing management of pollutant loads in urban watersheds in other parts of the world.
The journal article is freely available until July 17.
A SFEI technical report on this study is also available.