U.S. Geological Survey ground-water studies in Colorado
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Geology topics
Publications and source records attributed to J.B. Weeks.
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The relation between pumpage and change in storage was evaluated for most of a three-county area in southwestern Nebraska from 1975 through 1983. Initial comparison of the 1975-83 pumpage with change in storage in the study area indicated that the 1 ,042,300 acre-ft of change in storage was only about 30% of the 3,425,000 acre-ft of pumpage. An evaluation of the data used to calculate pumpage and change in storage indicated that there was a relatively large potential for error in estimates of specific yield. As a result, minimum and maximum values of specific yield were estimated and used to recalculate change in storage. Estimates also were derived for the minimum and maximum amounts of recharge that could occur as a result of cultivation practices. The minimum and maximum estimates for specific yield and for recharge from cultivation practices were used to compute a range of values for the potential amount of additional recharge that occurred as a result of irrigation. The minimum and maximum amounts of recharge that could be caused by irrigation in the study area were 953,200 acre-ft (28% of pumpage) and 2,611,200 acre-ft (76% of pumpage), respectively. These values indicate that a substantial percentage of the water pumped from the aquifer is resupplied to storage in the aquifer as a result of a combination of irrigation return flow and enhanced recharge from precipitation that results from cultivation and irrigation practices. (Author 's abstract)
The Regional Aquifer-System Analysis Program of the U.S. Geological Survey was initiated in 1978. The purpose of this program is to define the regional geohydrology and establish a framework of background information on geology, hydrology, and geochemistry of the Nation 's important aquifer systems. This information is needed to develop an understanding of the Nation 's major groundwater flow systems and to support better groundwater resources management. As of 1986, investigations of 28 regional aquifer systems were planned, investigations of 9 regional aquifer systems were completed, and 11 regional aquifer systems were being studied. This report is a bibliography of reports completed under the Regional Aquifer-System Analysis Program from 1978 through 1986. The reports resulting from each regional aquifer-system study are listed after an introduction to the study. During 1978-86, 488 reports were completed under the Regional Aquifer-System Analysis Program, and 168 reports which were partially funded by the Regional Aquifer-System Analysis Program were completed under the National Research Program. (Author 's abstract)
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The U.S. Geological Survey is cooperating with the U.S. Bureau of Mines in the selection of a site for a shaft and experimental mine to be constructed in the Piceance Creek basin, Rio Blanco County, Colo. The Piceance Creek basin, an asymmetric, northwest-trending large structural downwarp, is located approximately 40 km (25 mi) west of the town of Meeker in Rio Blanco County, Colo. The oil-shale, dawsonite, nahcolite, and halite deposits of the Piceance Creek basin occur in the lacustrine Green River Formation of Eocene age. In the basin the Green River Formation comprises three members. In ascending order, they are the Douglas Creek, the Garden Gulch, and the Parachute Creek Members, Four sites are presented for consideration and evaluated on geology and hydrology with respect to shale-oil economics. Evaluated criteria include: (1) stratigraphy, (2) size of site, (3) oil-shale yield, (4) representative quantities of the saline minerals dawsonite and nahcolite, which must be present with a minimum amount of halite, (5) thickness of a 'leached' saline zone, (6) geologic structure, (7) engineering characteristics of rock, (8) representative surface and ground-water conditions, with emphasis on waste disposal and dewatering, and (9) environmental considerations. Serious construction and support problems are anticipated in sinking a deep shaft in the Piceance Creek basin. The two major concerns will be dealing with incompetent rock and large inflow of saline ground water, particularly in the leached zone. Engineering support problems will include stabilizing and hardening the rock from which a certain amount of ground water has been removed. The relative suitability of the four potential oil-shale experimental shaft sites in the Piceance Creek basin has been considered on the basis of all available geologic, hydrologic, and engineering data; site 2 is preferred to sites 1, 3, and 4, The units in this report are presented in the form: metric (English). Both units of measurement are necessary as measurements were taken in English units, and most of the contracting agencies involved are using predominantly English units.
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