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<br />LAKE POWELL
<br />(COLORADO RIVER)
<br />
<br />
<br />Water Year 1986
<br />
<br />Lake Powell, which is impounded by Glen Canyon Dam, was
<br />operated a, part of the Colorado River Storage Project
<br />(CRSP) in accordance with governing contracts and laws to
<br />provide conservation storage, river regulation, power
<br />generation, recreation, and fish and wildlife enhancement
<br />during water year 1986.
<br />
<br />At the start of water year 1986, Lake Powell had an active
<br />content of22.8 MAF at elevation 3,685.6 feet (91 percent full).
<br />The most probable operating plan based on the October
<br />forecast called for total water year releases of 12.2 MAF based
<br />on an unregulated inflow of 13.5 MAF.
<br />
<br />On January 1, 1986, Lake Powell was at elevation 3,687 with
<br />an active content of 23.0 MAF. The January 1, 1986, forecast
<br />of April through July runoff for Lake Powell was 10.6 MAF,
<br />or 130 percent of average. Discharges from Glen Canyon
<br />powerplant averaged 20,000 cIs for January and February. In
<br />March the forecast increased to 135 percent and was 132
<br />percent of average on April 1. To reduce the risk of bypassing
<br />the powerplant, releases were increased to 90 percent of
<br />capacity during March and 100 percent of capacity during
<br />April.
<br />
<br />ACfUAL RELEASES
<br />
<br />WY 1986
<br />
<br />1000 CFS
<br />00
<br />
<br />
<br />40
<br />
<br />.0
<br />
<br />.,
<br />
<br />NDJ FMAMJ JASO
<br />
<br />The April through July runoff forecast made on May 1, 1986,
<br />had increased to 12.6 MAF or 154 percent of average. To
<br />contain this volume of runoff the river outlet works at Glen
<br />Canyon were opened on May 8, 1986, to bypass a discharge of
<br />17,000 cIs. This bypass release was maintained together with
<br />'maximum powerplant releases of31,5oo cIs for the remainder
<br />of the month of May. The June 1, 1986, runoff forecast
<br />increased to 13.0 MAF or 159 percent of average, and the river
<br />outlet works remained open at 8,000 cIs for the first week of
<br />June. On June 10, 1986, Lake Powell recorded its peak
<br />regulated inflow of 79,000 cIs. At this time the river outlet
<br />works were shut off and maximum powerplant releases were
<br />sustained for the rest of June. Powerplant releases were
<br />reduced during the month of July to allow Lake Powell to
<br />gradually fill. The maximum lake elevation of3,7oo.02 feet was
<br />reached on July 27-28, 1986.
<br />
<br />The total 1986 water year unregulated inflow to Lake Powell
<br />was 18.2 MAF which is equivalent to a reasonable maximum
<br />(upper decile) water supply. Total water year releases below
<br />Glen Canyon were 16.6 MAF of which 1.02 MAF bypassed
<br />the powerplant. The spillways at Glen Canyon were not used.
<br />
<br />LAKE POWELL
<br />
<br />Reservoir
<br />
<br />Acre-feet
<br />
<br />Elevation, feet
<br />
<br />Maximum Storage
<br />Rated Head
<br />Minimum Power
<br />Surface Area, full
<br />Reservoir Length, full
<br />
<br />25,002,000
<br />9,428,000
<br />4,126,000
<br />
<br />3,700
<br />3,570
<br />3,490
<br />161,390 Acres
<br />186 Miles
<br />
<br />Powerplant
<br />
<br />Number of Units
<br />Total Capacity
<br />
<br />8
<br />1,247,000 KW
<br />
<br />13
<br />
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