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<br />SUMMARY
<br />
<br />Aquifers occur within bedrock formations and unconsolidated Quaternary
<br />sands and gravels in the study area. Water from the Mancos Shale seldom is
<br />used because of generally inadequate yields or undesirable quality. Specific-
<br />conductance values for water from the Mesaverde Formation ranged between 325
<br />to 5,390 ~S/cm and reported well yields from 0.7 to 24 gal/min.
<br />
<br />The Dakota Sandstone, Morrison Formation, and Entrada Sandstone may be
<br />potential aquifers. Wells in the Dakota Sandstone yield 5 to 14 gal/min in
<br />the study area and two wells had specific-conductance values of 629 and 1,900
<br />~S/cm.
<br />
<br />Unconsolidated alluvial deposits found in stream valleys contain the best
<br />producing aquifers. Water in these deposits had specific-conductance values
<br />that ranged from 80 to 32,200 ~S/cm. Wells completed in alluvial deposits
<br />were reported to yield from 1 to 750 gal/min.
<br />
<br />Ground water issuing from springs generally is less saline
<br />water, especially for those springs with shorter flow systems.
<br />as much as 200 gal/min were reported. Spring water commonly is
<br />sulfate bicarbonate water.
<br />
<br />than we 11
<br />Discharges
<br />a calcium
<br />
<br />of
<br />
<br />REFERENCES
<br />
<br />Brogden, R.E., and Giles, T.F., 1976a, Availability and chemical charac-
<br />teristics of ground water in central La Plata County, Colorado: U.S.
<br />Geological Survey Water-Resources Investigations Report 76-69, map scale
<br />1:125,000, 1 sheet.
<br />_____1976b, Availability and chemical quality of ground water in the Crystal
<br />River and Cattle Creek drainage basin near Glenwood Springs, west-central
<br />Colorado: U.S. Geological Survey Water-Resources Investigations Report
<br />76-70, map scale 1:125,000, 1 sheet.
<br />Brogden, R.E., and Giles, T.F., 1977, Reconnaissance of ground-water resources
<br />in a part of the Yampa River basin between Craig and Steamboat Springs,
<br />Moffat and Routt Counties, Colorado: U.S. Geological Survey Water-
<br />Resources Investigations Report 77-4, map, scale 1:125,000, I sheet.
<br />Brooks, Tom, 1983, Hydrology and subsidence potential of proposed coal-lease
<br />tracts in Delta County, Colorado: U.S. Geological Survey Water-Resources
<br />Investigations Report 83-4069, 27 p.
<br />Cashion, W.B., 1973, Geologic and structure map of the Grand Junction quad-
<br />rangle, Colorado and Utah: U.S. Geological Survey Miscellaneous Investi-
<br />gations Map 1-736, scale 1:250,000.
<br />Fenneman, N. M., 1946, Physical divisions of the United Station: U.S.
<br />Geological Survey map prepared in cooperation with Physiography
<br />Committee, U.S. Geological Survey, scale 1:7,000,000 (reprinted 1964).
<br />Giles, T.F., 1980, Reconnaissance of ground-water resources in the vicinity of
<br />Gunnison and Crested Butte, west-central Colorado, U.S. Geological Survey
<br />Water-Resources Investigations/Open-File Report 76-812, map scale
<br />1:125,000, 1 sheet.
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