Time series of suspended-solids concentration in Honker Bay during water year 1997

Suspended-solids concentration (SSC) responds differently to seasonal variations, such as Delta outflow and wind in shallow water areas than in deep-water channels. Although San Francisco Bay includes extensive areas of shallow water, with about one-half of the surface area of the Bay being less than 2 meters deep (Conomos and Peterson, 1977), deep-water channels along the spine of San Francisco Bay, not shallow waters, are generally sampled by the Regional Monitoring Program (RMP; SFEI, 1997) and the U.S. Geological Survey (USGS; Buchanan and Schoellhamer, 1996; Edmunds et al., 1997; Freeman et al., 1997).

The purpose of this article is to provide an example of how SSC varies in shallow water. Time series of SSC were measured at several sites in Honker Bay. Measurements were made from December 1996 to March 1997 to observe the first wintertime freshwater flood pulse pushing salinity out of Honker Bay and delivering the first flush of sediment from the Central Valley watershed to the Bay. Instruments also were deployed from April to August 1997 to measure the return of salinity to Honker Bay as freshwater flow diminished, and to measure resuspension of sediment by wind-waves. Honker Bay was chosen because of its ecological significance to many estuarine plants and animals that depend on shallow waters for shelter and nourishment (Atwater et al., 1979; Cloern et al., 1983).

Total concentrations of seven trace elements measured by the RMP are well correlated with SSC (Schoellhamer, 1997a, 1997b). Thus, the spatial and temporal variability of some trace elements of concern to the RMP is analogous to the SSC variability discussed in this article.