Since the California Gold Rush of 1849, sediment deposition, erosion, and the bathymetry of South San Francisco Bay have been altered by both natural processes and human activities. Historical hydrographic surveys can be used to assess how this system has evolved over the past 150 years. The National Ocean Service (NOS) (formerly the United States Coast and Geodetic Survey (USCGS), collected five hydrographic surveys of South San Francisco Bay from 1858 to 1983. Analysis of these surveys enables us to reconstruct the surface of the bay floor for each time period and quantify spatial and temporal changes in deposition, erosion, and bathymetry.

The goal of this research project was to examine the ecological and hydrological function of the Napa-Sonoma salt ponds and their importance for waterbirds, including integrated studies on primary productivity, macroinvertebrates, plants, and fishes. This progress report presents the preliminary research results from the first year of the fieldwork.

These web pages detail the change in sedimentation in Suisun Bay from 1867 to 1990 by using Geographic Information Systems for analyses. The change is based on historical hydrographic surveys made by the U.S. Coast and Geodetic Survey (USCGS) and the National Ocean Survey (NOS). The Suisun Bay survey timeline shows the occurrence of these hydrographic surveys in relation to activities such as hydraulic mining and flood control projects in central California. Tidal flat area change is studied where data was available.

Sedimentation in San Pablo Bay changed dramatically during the past 140 years. From 1856 (the earliest detailed hydrographic survey) until at least the late 1800's hydraulic mining debris filled San Pablo Bay. During the early 1900's sedimentation slowed and, in the late 1900's, San Pablo Bay was erosional as the supply of hydraulic mining debris decreased and Central Valley water projects diminished sediment supply to the Delta and Bay. These pages show change in sedimentation using computer analysis and display of historical hydrographic surveys made by the US Coast and Geodetic Survey (USCGS) and the National Ocean Survey (NOS).

To preserve a viable wetland habitat around the Bay, management agencies have begun to identify the threats to existing wetlands and to determine viable strategies for wetland restoration in areas that are now diked agricultural land or salt evaporating ponds. Those agencies, in coordination with other appropriate groups, have initiated the first major wetland restoration endeavor to use dredge spoils, the Sonoma Baylands Restoration Project. USGS is studying how the structure and form of the wetland changes over time to aid agencies in evaluating this important experiment.

San Francisco Bay has lost most of its freshwater wetlands and salt marshes through dikes, fill, and sedimentation. An ambitious project to restore some of those wetlands is taking place at Sonoma Baylands. USGS is supporting the effort by investigating the occurrence, fate, and accumulation of organic contaminants in sediments and biota. Some preliminary results and conclusions are now available.

These detailed maps integrate urban growth, wetland change, and major earthquake epicenters in the SF Bay Area over time, 1850-1990.