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Geohydrologic framework of the Roswell ground-water basin, Chaves and Eddy Counties, New Mexico

Technical Report ·
OSTI ID:5775335
This report describes the geohydrology of the Roswell ground-water basin and shows the long-term hydrostatic-head changes in the aquifers. The Roswell ground-water basin consists of a carbonate artesian aquifer overlain by a leaky confining bed, which, in turn is overlain by an alluvial water-table aquifer. The water-table aquifer is hydraulically connected to the Pecos River. Ground-water pumpage from about 1500 wells in the basin was about 378,000 acre-feet in 1978. Irrigation use on about 122,000 acres accounted for 95% of that pumpage. Permeable zones in the artesian aquifer are generally controlled by lithologic changes in the Permian San Andres Limestone and Grayburg Formation and by fractures in the carbonate rock. The thickness of the artesian aquifer in the more heavily pumped part of the basin ranges from 260 to 460 feet. The confining bed is composed of slightly to moderately permeable rocks of the Permian Grayburg, Queen, and Seven Rivers Formations. The shallow aquifer is composed of permeable beds of sand and gravel in the valley-fill alluvium, which is Pliocene, Pleistocene, and Holocene in age. In 1975, the maximum saturated thickness of the valley fill was about 250 feet in depressions northeast of Roswell, south of Dexter, and at Artesia. Hydrostatic heads in the artesian aquifer declined 230 feet in the south part of the basin from 1905 to 1975. The maximum decline in the head of the shallow aquifer from 1938 to 1975 was 120 feet. The chloride concentration of ground-water samples collected in 1978 ranged from 15 to 7000 milligrams per liter for the artesian aquifer and from 20 to 3700 milligrams per liter for the shallow aquifer. The chloride content has gradually increased through the years in the eastern parts of both aquifers. 31 refs., 28 figs., 1 tab.
Research Organization:
Geological Survey, Roswell, NM (USA)
OSTI ID:
5775335
Report Number(s):
USGS-TR-42; ON: TI85901214
Country of Publication:
United States
Language:
English