Global warming will affect river flows. We'll have more rain and less snow. Snow remains will melt earlier in the year.
California's major rivers will flow higher during winter and lower during spring and summer.
This is all assuming CO2 doubles (likely) and El Niño will remain the same (probably).
Read about the new research by Lawrence Livermore:
New Climate Research Reveals Growing Risk of Water Shortages and Flooding in California
Large-scale Ecosystem Restoration Initiatives
Protecting and Restoring the San Francisco Bay-Delta
CDEC - California Data Exchange Center
Installs, maintains, operates hydrologic data collection network.
Snow gages, precipitation and river stage sensors.
Lots of forecasts reports, charts, satellite images.
CA State Water Board
Protects and enforces many water uses:
industry, agriculture, municipal, environmental