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<br />Upper Colorado River Basin Hydrology <br /> <br />The Upper Colorado River Basin experienced 5 consecutive years of extreme drought from <br />September 1999 through September 2004. In the summer of 1999, Lake Powell was essentially full <br />with reservoir storage at 97 percent of capacity. Inflow volumes for 5 consecutive water years were <br />significantly below average. Total unregulated inflow in water years 2000, 2001, 2002, 2003, and <br />2004 was 62, 59, 25, 51, and 51 percent of average, respectively. Inflow in water year 2002 was the <br />lowest ever observed since the completion of Glen Canyon Dam in 1963. <br /> <br />Hydrologic conditions improved in water year 2005 (October 2004 through September 2005) in the <br />Upper Colorado River Basin. The elevation of Lake Powell increased by 31 feet during water year <br />2005, and water storage in Lake Powell increased by 2.77 million acre-feet. Unregulated inflow to <br />Lake Powell in water year 2005 was 105 percent of average. While hydrologic conditions have <br />improved, and the severity of drought conditions has eased, it is premature to declare that the <br />drought in the Upper Colorado River Basin is over at this time. <br /> <br />During 2005, Lake Powell reached a low elevation on April 8, 2005, at 3,555 feet (145 feet from full <br />pool). Reservoir storage had declined to 33 percent of live capacity. The last time Lake Powell had <br />been this low was in May 1969. The water surface elevation increased through the spring and early <br />summer of 2005, reaching a peak elevation of 3,608.4 feet on July 14, 2005. The current elevation <br />of Lake Powell is 3,602.0 feet (98.0 feet from full pool). Current storage is 11.9 million acre-feet <br />(49 percent of live capacity). <br /> <br />While inflow to Lake Powell was above average during most of2005, inflow has been below <br />average since July. Unregulated inflow to Lake Powell in July, August and September of2005 was <br />91, 77, and 68 percent of average, respectively. <br /> <br />The water surface elevation of Lake Powell will likely continue to decrease through the fall and <br />winter until April 2006, when anticipated snowmelt runoff will cause the water surface level to <br />increase once more. The projected elevation of Lake Powell on January 1, 2006 is about 3,598 feet. <br /> <br />