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Ground-water conditions in the Anza-Terwilliger area, with emphasis on the Cahuilla Indian Reservation, Riverside County, California, 1973-86

Water-Resources Investigations Report 88-4029
By:  and 
https://doi.org/10.3133/wri884029

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Abstract

Demand for groundwater in the 96-sq mi Anza Terwilliger area of California has increased in recent years because of population growth and agricultural development. In order to evaluate the potential effects of continued growth and development on the water resources of Cahuilla Indian Reservation, water level, land use, and water quality data were collected and analyzed. Water level measurements indicate that, as in previous years, groundwater normally moves toward streams in Anza and Terwilliger Valleys. However, during the summer, when pumping is at a maximum, groundwater moves toward two areas of groundwater withdrawal in Anza Valley. One area where groundwater levels were lowered extends to the northern boundary of Cahuilla Indian Reservation. Groundwater use during 1986 is estimated at 10,000 acre-ft, 6,000 acre-ft more than in 1973. The water table, however, generally has risen since 1973 due to the wet climatic conditions that generally have prevailed since 1976. Dissolved-solids concentrations during 1984-86 ranged from 184 to 1,320 mg/L. Water from two wells on Cahuilla Indian Reservation had dissolved-solids concentrations higher than the U.S. Environmental Protection Agency recommended limit for drinking water of 500 mg/L. No wells sampled on the reservation contained water with nitrate concentrations above the U.S. Environmental Protection Agency recommended limit of 10 mg/L. The observation-well network was found to be generally adequate, but the addition of one water level and two water quality observation wells would enhance its effectiveness. (USGS)

Suggested Citation

Woolfenden, L.R., Bright, D., 1988, Ground-water conditions in the Anza-Terwilliger area, with emphasis on the Cahuilla Indian Reservation, Riverside County, California, 1973-86: U.S. Geological Survey Water-Resources Investigations Report 88-4029, iv, 79 p. :ill., maps ;28 cm., https://doi.org/10.3133/wri884029.

Publication type Report
Publication Subtype USGS Numbered Series
Title Ground-water conditions in the Anza-Terwilliger area, with emphasis on the Cahuilla Indian Reservation, Riverside County, California, 1973-86
Series title Water-Resources Investigations Report
Series number 88-4029
DOI 10.3133/wri884029
Year Published 1988
Language ENGLISH
Publisher U.S. Geological Survey,
Description iv, 79 p. :ill., maps ;28 cm.
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