Upper Santa Ana Valley – San Timoteo
Statistics
- Basin Name
- Upper Santa Ana Valley – San Timoteo
- Basin Number
- 8-002.08
- SGMA Basin Priority
- Very Low
- Critically Overdrafted
- No
- Hydrologic Region Name
- South Coast Hydrologic Region
- Counties
- Riverside, San Bernardino
- Adjacent Basins
At-A-Glance
Located in California’s hydrologic region, the Upper Santa Ana Valley – San Timoteo is 158,534.44 acres in size. This Very Low priority basin is home to an estimated 50,453 people (2010 value), which have been at a rate of 60.73.
Upper Santa Ana Valley – San Timoteo is a(n) basin with approximately 390 wells, of which approximately 38 are water supply wells. Groundwater accounts for approximately 98 percent of the basin’s water supply.

Basin Notes
2004: Bulletin 118 basin description
Incomplete basin boundary modification request pending with DWR
Santa Ana Watershed Project Authority
2019: Basin boundary modification. Per DWR: It “removes areas of low permeability, well- consolidated bedrock from the basin. The revised basin boundary follows geologic contacts of alluvium and bedrock using a qualified geologic map.” Phase 2 draft priority: very low.