The Colorado River hydrologic region of California is one of the 10 major hydrologic regions of the state as identified by the California Department of Water Resources.
The Colorado River hydrologic region has a surface area of about 20,000 sq mi (52,000 km2), and includes all of Imperial County, and portions of Riverside, San Bernardino, and San Diego. With an average of 5.5 in (140 mm) rain annually, this is the most arid hydrologic region of the state. The Colorado River drainage basin is the major watershed of this region. The Colorado River hydrologic region has 71 state-recognized alluvial groundwater basins and subbasins.[1]
- ^ "California GROUNDWATER Bulletin 118" (PDF). water.ca.gov.