Laserfiche WebLink
<br />. <br /> <br />l\J <br />l\J <br /><::; <br />o <br /> <br />Water-bearing formations in the Picea~ce Creek Basin appear <br />to be substantial, in part because the bowl-shaped basin inhibits <br />ground water outflow from the region (Brown et al., 1977). Prin- <br />cipal regions of recharge are the Cathedral Bluffs, the Grand Hog- <br />back, and the divide between the White and Colorado rivers. From <br />these areas, moisture travels coward the center of the Piceance <br />Basin (Andrews, 1975). Annual recharge is approximately 24,100 AF <br />(Brown et al., 1977) to 29,000 AF (U.S. Dept. of the Interior, 1974), <br />primarily from spring snowmelt. Discharge from the Piceance Basin <br />is primarily by evaporation and stream seepage--little water is <br />removed by well taps. Eighty percent of the ground water seepage <br />in the Piceance Basin flows toward Piceance Creek and 20 percent <br />flows into Yellow Creek. About four-fifths of the annual stream <br />flow in the Piceance Basin is derived from ground water (\leeks, 1976). <br /> <br />Estimates of total water supply in the Piceance Basin vary from <br />2.5 maf (Coffin et al., 1971) to 25 maf (U.S. Dept. of the Interior, <br />1973). Not all of this supply would be economically recoverable, <br />of course. It is the opinion of one investigator that no more <br />than one-half of the ground water supply could be mined and produc- <br />tively used (,~ittlesey, 1977). <br /> <br />. <br /> <br />Structurally, the Piceance Basin consists of the Uinta and <br />Green River formations. The latter formation is divided by the <br />Mahogany Zone (the oil-rich fraction) which forms a relatively <br />impermeable boundar/ between the upper and lower aquifers. The <br />upper aquifer consists of the Uinta Formation and part of the <br />Parachute Creek Ne:1lber of the Green River FO!'tilation. The higher <br />yielding, lower aquifer contains the Evacuation and Parachute <br />Creek members. Generally, the Uinta Fo~ation can be reached at <br />a depth of about 200 feet. The lower aquifer is as little as <br />500 feet below the land surface, though the rich water-bearing zone <br />is closer to 1,000 feet in depth (U.S. Bureau of Land Hgmt., 1976?). <br /> <br />There is no continuous water table in the Piceance Creek <br />Basinj rather, due to complex fractures in the basin, there is a <br />series of perched.water tables. These perched water tables result <br />in potentiometric (pressure) conditions (Brown et al., 1977). <br /> <br />Well yields vary according to their surface locations and the <br />geologic units tapped. Water supplies at Anvil Points and at the <br />Colony oil shale operations are relatively meager compared to the <br />more geologically favored northern parts of the Piceance Creek Basin <br />(Andrews, 5975). Oil shale lease Tract C-b yields less water than <br />Tract G-a. Production from the latter location could yield 1,500 <br /> <br />5. See Figure C.l in Appendix C for locations of oil shale tracts <br />C-a and C-b. <br /> <br />. <br /> <br />D-13 <br />