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• groundwater also enters the alluvium from the talus deposits on <br />the valley sides during snowmelt and rainstorms. Flow from the <br />bedrock beneath the talus may also contribute to the groundwater <br />in the alluvium. Some of the groundwater in the alluvial valley <br />fill probably moves downward into the Garden Gulch member. <br />BEDROCR AQUIFERS <br />There are three bedrock, water-bearing units of significance <br />occuring on the site listed below from oldest to youngest in <br />geologic age: <br />Green River Formation (Bedrock) <br />Garden Gulch member <br />Parachute Creek member <br />Evacuation Creek member <br />• <br />Garden Gulch Member: This member is composed almost entirely <br />of shale in the site area and apparently is not significantly <br />fractured. The permeability of this member is, therefore, <br />probably low throughout the property. This stratigraphic unit <br />functions chiefly as a groundwater drain for the overlying <br />Parachute Creek member and the alluvial fill in Lower Middle <br />Fork Valley, and transmits subsurface outflow beneath the southern <br />boundary of the Dow West Property. The low-yield (less than <br />30 gpm) characteristcs and poor water quality from the member. <br />preclude its development as a construction or domestic water <br />supply source. Recharge to the Garden Gulch member is from <br />the overlying Parachute Creek member, the talus and alluvium, <br />and by direct infiltration by precipitation where the member <br />is exposed (Metcalf b Eddy, 1975). <br />• <br />X21 <br />