For flood protection and stream stewardship purposes, the Santa Clara Valley Water District divides the county into five major watersheds:
All of which drain northward to San Francisco Bay, and the
which drains southward to Monterey Bay.
Each watershed or subwatershed is slightly different in terms of its vegetation, soils, hydrology, human uses, and development.
In the next phase of the One Water Plan effort, each of the following watersheds will have its own detailed plan.