Napa-Sonoma Valley – Napa Valley

Source: CA DWR

Napa-Sonoma Valley – Napa Valley


  • Basin Name
  • Napa-Sonoma Valley – Napa Valley
  • Basin Number
  • 2-002.01
  • SGMA Basin Priority
  • High
  • Critically Overdrafted
  • No
  • Hydrologic Region Name
  • San Francisco Bay
  • Counties
  • Napa
  • Adjacent Basins
  • Napa-Sonoma Valley - Lowlands 2-002.03, Napa-Sonoma Valley - Sonoma Valley 2-002.02,


Located in California’s San Francisco Bay hydrologic region, the Napa-Sonoma Valley – Napa Valley is 44,660 acres in size. This High priority basin is home to an estimated 31,275 people (2010 value), which have been at a rate of 10.14.

Napa-Sonoma Valley – Napa Valley is a(n) basin with approximately 1321 wells, of which approximately 42 are water supply wells. Groundwater accounts for approximately 75.73 percent of the basin’s water supply.

Source: CA DWR
Source: CA DWR

Basin Notes

As an alternative to a GSP, Napa County an analysis of basin conditions that it argues demonstrates that the basin has operated within its sustainable yield over a period of at least 10 years.  Click here to view the details.

Napa County groundwater information: Napa County Watershed Information and Conservation Council: Groundwater page

Bulletin 118 2003 basin description

Bulletin 118 1980 basin description

2014 Basin Prioritization comments:
Two isolated areas in the Sonoma Valley indicate substantial declines in GW elevations and RWQCB report that 43 underground fuel tank leaks have occurred in the basin (unpublished B-118 data) (Ludhorff & Scalmanini Consulting Engineers, 1999).

2018 Final Basin Prioritization changed the priority from medium to high.

GSA Information

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