How is the Region Defined?

The specific geographic extent of the Bay Area IRWMP is based on the boundary of the San Francisco Bay Regional Water Quality Control Board (Region 2). This boundary was selected for two primary reasons: hydrology and jurisdictions. Hydrologically, the Region 2 boundary generally represents the watershed interfluve for Bay-draining surface flows and runoff. Although some coastal Marin, San Francisco, and San Mateo County lands are included within the Region 2 boundary, a majority of lands drain to the Bay. For the purposes of developing a plan to manage integrated water resources, using a physically based watershed boundary that drains (a majority of) lands to a common receiving water body (the Bay) is advantageous. Additionally, Region 2 is a historically defined jurisdictional boundary. Using a well-understood and existing jurisdictional boundary reduces confusion for participating agencies who are already familiar with its geography.