Temecula Basin is a

sedimentary basin Sedimentary basins are region-scale depressions of the Earth's crust where subsidence has occurred and a thick sequence of sediments have accumulated to form a large three-dimensional body of sedimentary rock They form when long-term subsidence ...

, which, along with the Aguanga Basin, is part of the Elsinore Fault Zone, in southwestern

Riverside County, California Riverside County is a County (United States), county located in the Southern California, southern portion of the U.S. state of California. As of the 2020 United States Census, 2020 census, its population was 2,418,185, making it the fourth-most ...

. The Temecula Basin is a basin of down faulted Mesozoic basement rock, overlain by late Cenozoic continental sediments.

Aquifer

The Temecula Basin is also a local ground water basin and

aquifer An aquifer is an underground layer of water-bearing material, consisting of permeability (Earth sciences), permeable or fractured rock, or of unconsolidated materials (gravel, sand, or silt). Aquifers vary greatly in their characteristics. The s ...

in southwestern Riverside County. It is the largest groundwater basin in the San Diego water region.San Diego Region - The Basin Plan
from waterboards.ca.gov accessed April 26, 2015 This aquifer is recharged by precipitation in the valley, underflow and by surface flow from the creeks draining the surrounding mountains and the southern Perris Block in the watershed of Murrieta Creek and

Temecula Creek Temecula Creek, formerly known as the Temecula River, runs U.S. Geological Survey. National Hydrography Dataset high-resolution flowline dataThe National Map accessed March 16, 2011 through southern Riverside County, California, United States, pa ...

, tributaries of the

Santa Margarita River The Santa Margarita River which with the addition of what is now Temecula Creek, was formerly known as the Temecula River, is a short intermittent river on the Pacific coast of Southern California in the United States, approximately U.S. Geolog ...

.Gerald A. Waring, UNITED STATES GEOLOGICAL SURVEY Water-Supply Paper 429, Ground Water In The San Jacinto And Temecula Basins, California, Government Printing Office, Washington, 1919
/ref> Experiment Station Record, Volume 41, United States. Office of Experiment Stations, United States Agricultural Research Service, U.S. Government Printing Office, 1920., p.785
/ref>

History

In 1919, a USGS Water Supply Paper described the Temecula Basin: :"Throughout the lowland of Murrieta Valley the ground-water level is within 20 ft. of the surface, and beneath the greater part the depth to water is less than 10 ft. . . . The sampled well waters from Murrieta Valley range in quality from fair to good for domestic uses and for irrigation. ... In the lowland along Murrieta Creek for two or three miles above Temecula, the ground-water level is within 6 or 8 ft. of the surface, and the continual evaporation from this moist area has caused the concentration of alkali. Chemical examination of the waters tested indicates that in most of them sodium is the predominant base. . . . Throughout the lowland of Temecula Valley proper ground water is found within 20 ft. of the surface, and in the wide sandy flats of its upper portion is less than 10 ft. below the surface. ... In the minor valleys In the upper part of the Temecula Basin, water is generally found relatively near the surface in the alluvial and residual materials."

References

Geology of Riverside County, California Peninsular Ranges Sedimentary basins of North America Structural basins of the United States {{RiversideCountyCA-geo-stub