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• Structural Controls. The Nucla Mine lies in the Colorado Plateau Physiog ra ph is Province <br />within the Canyon Lands Section (Price and Arnow, 1974). This section is an upwarped <br />plateau containing several large folds, laccolithic mountains that rise above the plateau <br />surface, deeply incised drainage and an intricate set of deep canyons (Lohman, 1965; <br />lorns et al., 1965). <br />Structural control on the shallow ground water in the area, i.e., upper Dakota sandstone <br />and alluvium, appears to be insignificant. This is principally due to the large extent of <br />sandstone outcrops. This allows recharge to occur along topographic highs rather than <br />structural highs with water table conditions predominating. However, an artesian head may <br />be developed if a lesser coal bed or sandstone aquifer is confined by impermeable strata. <br />Piezometric surfaces in deeper formations such as the loner Dakota, Burro Canyon, <br />Morrison and Entrada Formations whose ground water is under artesian pressure closely <br />conforms to structural influence lLohman, 1965). In these formations, recharge occurs <br />along structural highs, i.e „ an outcrop which corresponds to the limb of a syncline or <br />the fractured crest of an anticline. Movement of water within these formations is down <br />• dip with faults acting as boundary conditions or conduits for flaw. These artesian waters <br />are the principal suppliers of water to areas near Grand Junction which is northwest of <br />Pea body's Nucla mining operation. <br />Re~c Tonal Ground Water Recharge, Movement and Discharge. The principal areas of ground <br />water recharge are in the plateaus and mountains, which receive the greater amounts of <br />annual precipitation, Ground water movement is from areas of recharge to areas of natural <br />discharge, which include springs, gaining reaches of springs and areas of ph reatophy to <br />growth, Ground water consumption by phreatophytes and hydrophytes in the Colorado and <br />Utah parts of the upper Colorado Region has been estimated by Robinson (1958) to be more <br />than 2 million acre-feet per year. Ground water occurs under both water table and <br />artesian conditions. Water table conditions commonly exist in shallow alluvial aquifers <br />along the larger streams, in principal recharge areas, and in the relatively flat lying <br />rocks that predominate certain sections of the region. Artesian conditions occur locally <br />throughout the region but are prevalent in the bedrock aquifers of the major structural <br />basin. <br />Regional Ground Water Quality. In the upper Colorado Region, fresh water is generally <br />• available from shallow aquifers in most consolidated units in areas above 7,000 feet in <br />7-3 Revised 04/11/88 <br />