The Building Block of the Bay

Sediment like sand, silt, and mud is critical to the health of the San Francisco Bay ecosystem. It is the physical foundation for tidal marshes, which must grow vertically to keep pace with sea level rise and continue functioning as natural filters for nutrients and pollutants from urban, agricultural, and industrial runoff. Sediment on the Bay floor can store contaminants within water trapped between the mud or sand particles, and suspended sediment can transport contaminants throughout the Bay.

Sediment is dredged from Bay shipping channels, harbors, and ports. Some dredgers remove sediment from the Bay completely, which helps remove contaminants from the system, and some is reused in wetland restoration projects. In addition, suspended sediment is a key factor limiting algal blooms. Researchers and decision makers are focusing more on sediment processes in the Bay, driven by the need for better information on water and sediment quality, as well as the impacts of climate change and sea level rise on the Bay’s tidal wetlands.