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2.04.7 Hydrology Description <br />(2) Surface Water <br />(a and b) <br />The project area is located in the Colorado River Basin. This is the <br />second largest basin in Colorado encompassing more than 18,160 square <br />miles and 19,340 miles of streams. The quantity of flows through the <br />basin is greater than the combined flows of all the other basins in the <br />state. <br />There is a USGS Colorado River stream gage located 1.2 miles upstream <br />from the Colorado -Utah state line and 12 miles southwest of Mack. At this <br />location the Colorado River drains an area of 17,843 square miles. The <br />period of record for this water stage recorder (09163500) is 1951 though <br />2010. Annual run -off averages 4,446,000 acre feet. The annual mean <br />flow is 6,137 cfs. Maximum peak flow of 69,800 cfs occurred on May 27, <br />1984. <br />It is not anticipated the Colorado River floodplain will impact the Loadout <br />operations. According to Mesa County GIS, the mapped FEMA floodplain <br />is approximately 800 feet from the southern edge of the permit boundary <br />and is at an elevation of 4460 feet. The elevation of the Loadout at the <br />southern edge of the permit boundary (800' north of the mapped FEMA <br />floodplain) is approximately 4466 feet. The FEMA floodplains are based <br />on the 100 -year event. In addition, it is not likely the Loadout operations <br />will impact the Colorado River. Water from the sediment ponds will be <br />disposed of at an approved off site disposal facility, and the small amount <br />of water discharged from silt fences into Reed Wash is negligible. <br />As explained in 2.04.5, two small tributaries to the Colorado River cross <br />the permit and adjacent area. They are Reed Wash which bisects the <br />permit boundary and Loma Drain which is located on the west side of the <br />permit boundary. <br />Reed Wash has a large drainage area, approximately 30 square miles, <br />north of the proposed permit boundary. The Peck and Beede Wash, the <br />East Branch and Bulkley Wash all join Reed Wash prior to it flowing under <br />State Highway 6 & 50 and the Union Pacific rail line immediately north of <br />the proposed permit boundary. Reed Wash primarily handles return <br />irrigation flow, groundwater induced by irrigation and precipitation run -off. <br />Permit Application 2.04 -18 12/11 <br />