NAWQA Program - The NAWQA Program studies status and trends in the waters of the United States.
USGS Water Resources of California - Contains realtime streamflow, current conditions in California, data, maps, features, and reports. Updated daily.
Water Quality of San Francisco Bay - The current and past water quality of the SF Bay-Estuary, including temperature, salinity, chlorophyll and other measurements
Government:US Agencies:Department of Interior:US Geological Survey:USGS Water Resources Division