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<br />3. SUMMARY OF RESERVOIR LEVELS AND CONTENTS <br /> <br />RunofF during the year ending September 30, 1991 ranged from 44.2 <br />percent of the 78-year (1914-1991) mean at the San Juan station near San <br />Juan, Utah to 66.9 percent of the 78-year mean at the Colorado River <br />station near Cisco, Utah. The volumes of runoff at these stations were <br />1,308,600 acre-feet and 3,630,400 acre-feet respectively. Runoff ofthe <br />Green River station at Green River, Utah totaled 2,778,800 acre-feet, <br />which was 61.5 percent of the 78-year mean. <br /> <br />Lake Powell's lowest elevation of the 1991 water year occurred on <br />April 12, 1991 when the lake level was at elevation 3,627.12 feet (live <br />content 14,533,200 acre-feet). Lake Powell was at its highest point on <br />June 30,1991 at elevation of3,639.02 feet with a contentofl5,887,900 <br />acre-feet. Note that beginning in April 1991, the reported contents at <br />Lake Powell reflect an updated reservoir sediment survey which resulted <br />in a reservoir capacity of 24,332,200 acre-feet at elevation 3700.0 feet. <br />The previous survey indicated a content of 25,002,000 acre-feet at <br />elevation 3700.0 feet. In this report, the September 30, 1990 contents <br />of Lake Powell have been adjusted according to the updated survey. This <br />procedure ensures a more accurate estimate of change of reservoir content <br />and virgin flow for water year 1991. A total of 8,230,000 acre-feet was <br />released to the river below Glen Canyon Dam during 1991 water year. <br />The 1982-1991 (10-year) delivery to the Lower Basin (measured at Lee <br />Ferry) was 128,075,000 acre-feet. <br /> <br />Lake Mead, on September 30, 1991, contained 19,232,300 acre-feetB <br />of available storage water at elevation 1,173.01 feet. On September 30, <br />1991, the live storage of Lake Mead was 4,533,200 acre-feet more than <br />the storage in Lake Powell. <br /> <br />Table 1 on page 11 shows the Statistical Data for Principal Reservoirs <br />in the Upper Colorado River Basin. Table 2 on page 12provides the same <br />information for the Lower Colorado River Basin reservoirs. <br /> <br />The results of the long-range reservoir operation procedures adopted <br />by the Secretary of the Interior for Lake Powell, Flaming Gorge, Fontenelle, <br />Navajo, and Blue Mesa reservoirs in the Upper Colorado River Basin and <br />for Lake Mead in the Lower Basin are illustrated on pages 14-21 for the <br />1991 water year. <br /> <br />There was no equalization of storage as dictated by Section 602( a) of <br />Public Law 90-537. The drawdown of Lake Powell was governed by <br />factors other than the equalization criteria. <br /> <br />7 Adjusted for the change in storage in Colorado River Storage Project Reservoirs. <br />8Based on April 1, 1967 Capacity Table revised according to Sedimentation Survey <br />1963-1964. <br /> <br />10 <br />