| OCR Text |
Show FILLING OF UPPER BASIN STORAGE UNITS In order to accomplish an initial filling of Lake Powell to the water surface elevation at which the Glen Canyon powerplant could be put in operation, releases of water from Lake Powell were curtailed during late 1964 and early 1965. This curtailment caused a draft of Lake Mead storage water to a point below the rated power head at Lake Mead that is regarded as necessary to maintain power generation at Hoover powerplant. With a favorable 1965 spring runoff, initial power generation at Glen Canyon Dam was maintained, and Lake Mead was restored to rated head (elevation 1122.8) in June 1965. Thereafter the level of Lake Mead remained above rated head and Lake Powell was held constant due to a remarkable fall and early winter runoff. The spring runoff of 1966 was extremely disappointing. It was possible only to achieve a maximum level at Lake Powell of elevation 3545.68 in June 1966, and a content of 9,536,000 acre-feet. Thereafter there was a draft on Lake Powell storage to maintain rated head at Lake Mead and power generation at Glen Canyon powerplant. By the end of water year 1965-1966, the water surface of Lake Powell had receded over 16 feet to elevation 3529.46 and a content of 8,421,000 acre-feet representing a net storage loss of 43,000 acre-feet. Lake Mead at the end of water year 1965-1966 contained 15,011,000 acre-feet of available storage at elevation 1127.66 with a net gain of 296,000 acre-feet. It should be noted that in excess of % million acre-feet were retained in Lake Mead in the 4.9 feet of depth above its rated head. The gates were closed at Blue Mesa reservoir on October 26, 1965, and commercial power generation is expected to commence in March 1967. The results of the filling procedures adopted by the Secretary of the Interior at Lake Powell, Flaming Gorge, Navajo and Blue Mesa Reservoir in the Upper Colorado River Basin and at Lake Mead in the Lower Basin are illustrated in the graphs on the following pages. For reference purposes, the graph for Lake Mead has been extended back to 1935 when water was first stored behind Hoover Dam. 27 |
