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2.04.5 General Description of Geology and Hydrology <br />Geology <br />The surface geology of the permit and adjacent area is influenced by the Mancos shale <br />formation which is extensive in western Colorado. To the north the Mancos shale is <br />capped by the Book Cliffs, which stand out in bold relief above the valley. The soils in <br />the permit and adjacent area have developed in place of the Mancos shale. <br />Surface Water <br />The permit and adjacent area lies west of the Fruita refinery on areas of relatively level <br />ground with an overall gradient to the southwest. The area is drained by two drainage <br />areas, Reed Wash in the central portion of the permit area and Loma Drain to the west. <br />Reed Wash and Loma Drain flow generally southwest to the Colorado River, a distance <br />of only about 0.25 miles. <br />Loma Drain as the name implies drains the area surrounding the town of Loma. The <br />Loma Drain primarily handles return irrigation flow, groundwater induced by irrigation <br />and precipitation run -off. Flows are high during the peak of the irrigation season and <br />are low during the winter. High flows would also occur as a response to intense <br />precipitation events. <br />Reed Wash drains a large area north of the proposed permit boundary. The Peck and <br />Beede Wash, the East Branch and Bulkley Wash all join Reed Wash prior to it flowing <br />under State Highway 6 & 50 and the Union Pacific rail line immediately north of the <br />proposed permit boundary. Reed Wash primarily handles return irrigation flow, <br />groundwater induced by irrigation and precipitation run -off. Flows are high during the <br />peak of the irrigation season and are low during the winter. High flows would also occur <br />as a response to intense precipitation events. <br />There is a USGS Colorado River stream gage located 1.2 miles upstream from the <br />Colorado -Utah state line and 12 miles southwest of Mack. At this location the Colorado <br />River drains an area of 17,843 square miles. The period of record for this water stage <br />recorder (09163500) is 1951 though 2010. Annual run -off averages 4,446,000 acre <br />feet. The annual mean flow is 6,137 cfs. Maximum peak flow of 69,800 cfs occurred on <br />May 27, 1984. <br />Permit Application 2.04 -7 04/11 <br />