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<br />. <br /> <br />I'\) <br />t- <br />CJ:J <br />... <br /> <br />The vater quality of the Wasatch Formation varies from fair to <br />excellent. In the northern two-thirds of Sublette County, Wyoming, <br />about one-half of the vater samples show TDS to be less than 500 ppm. <br />Le~els of dissolved solids increase southward aloQg the general direc- <br />tion of ground water transport in the Upper Green River Basin. In <br />addition, mineralization increases with aquifer depth, again corre- <br />sponding to the duration of contact with mineralized rocks. In the <br />southern portions of the basin, the Wasatch Formation has scattered, <br />high sodium (near Farson and Eden, WyomiQg) and fluorine levels. <br />Water quality decreases, and becomes moderately saline, as TDS rise <br />to levels as high as 3,700 ppm (Welder, 1968). Water hardness, indi- <br />cated by the content of calcium carbonate, is as high as 570 ppm. <br /> <br />The Fort Union Formation, along ",ith the I,asatch Formation, <br />underlies most of the Upper Green River Basin, though the former sur- <br />faces only in limited areas. East of the Rock Springs uplift, the <br />Fort Union Formation forms a narrow quarter-moon boundary around the <br />anticlinal arch of the uplift and then, again, it appears as a narrow <br />corridor east of the Washakie Basin. Yields greater than 500 gpm <br />are possible in ",ells 2,000 to 5,000 feet dee;> located in the thicker <br />portions of the formation. Spe.cific yields are largely unknown and <br />the waters are rather highly mineralized. Total dissolved solids <br />from the Fort Union Formation ranges from 800 to 3,300 ppm; the <br />average is about 2,000 ppm (Welder and McGreevy, 1966). <br /> <br />. <br /> <br />Two of the most promising artesian sources of ground water are <br />the Tipton and Laney Shale members of the GreeQ River Formation. <br />Both members crop out together in a broad north-south corridor just <br />west of the Rock Springs uplift and then dip westward. The Tipton <br />Shale ~ember is found at depths of 580 to 1,900 feet. Wells yield <br />from 10 to 170 gpm in the Tipton nember. Water is found between 20 <br />and 265 feet below the surface in the Laney Shale Me~ber and, because <br />of its shallower location, well yields are somewhat lower--from 1 to <br />75 gpm. Dissolved solids are between 500 and 3,000 ppm for the Tip- <br />ton Shale Member, but hardness is lov (only 18 ppm). The Laney Shale <br />Member contains water with a concentration of 650 to 4,200 ppm of <br />IDS, while the water hardness is as high as 1,620 ppm (Welder, 1968). <br /> <br />Most of the unconfined aquifers in the Upper Green River Basin <br />are Quaternary age alluvial, terrace, and eolian deposits. Alluvia <br />yield the best quantities of water, from less than 10 gpm to more <br />than 500 gpm along the thicker deposits of perennial streams. Allu- <br />vial deposits along several major streams are up to 40 feet thick <br />(Robinove, 1963). Dissolved solids range from 250 to 2,800 ppm <br />(Welder, 1968). Well depths are generally less than 50 feet. <br /> <br />In summary, the most promising aquifers are the main body of <br />the Wasatch Formation, especially in the northern part of the Upper <br />Green River Basin (where the rate of recharge is greatest), the Laney <br /> <br />. <br /> <br />D-7 <br />