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<br />LAKE POWELL
<br />(COWRADO RIVER)
<br />
<br />
<br />Water Year 1990
<br />
<br />Lake Powell, "",ich is iropounded by Glen Canyon Dam, is
<br />operated as part of the Colorado Ri"'r Storage Project
<br />(CRSP) in accordance with go",rning compacts and la\\5 to
<br />provide conservation storage, river regulation, power'
<br />generation, recreation. and fish and wildlife enhancement.
<br />
<br />Lake Powell began water year 1990 at elevation 3665.2 feet
<br />with a li", content of 19,805,000 acre-feet (79 percent full).
<br />April through July unregulated inflow into Lake Powell was
<br />3,2 II ,000 acre-feet (40 percent ofa",rage). Total unregulated
<br />inflow into Lake Powell in water year 1990 was 5,477,000
<br />acre-feet, only 46 percent of the 11,900,000 acre-feet
<br />unregulated average. Actual regulated inflow for water year
<br />1990 was 5,135,000 acre-feet. Regulated inflow into Lake
<br />Powell peaked at 26,QOC) cubic feet per second on June IS,
<br />1990. Lake Powell has a minimum annual release of 8.23
<br />million acre-feet, as set forth in the Operating Criteria. The
<br />
<br />Water Year 1991
<br />
<br />The reser",ir is projected to continue to drop through the fall
<br />and winter, reaching its seasonal low point in March 1991,
<br />about 75 feet from full with a Ii", storage of 14,600,000
<br />acre-feet. During water year 1991, the minimum release of
<br />8.23 million acre-feet will be made in an effort to preser'"
<br />reservoir storage at Lake Powell. The operation plan for Glen
<br />
<br />ACTUAL RELEASES 1990
<br />
<br />THOUSAND ....cRE-FEET
<br />1200
<br />
<br /> V \
<br />/
<br />
<br />1000
<br />
<br />800
<br />
<br />800
<br />
<br />.00
<br />
<br />200
<br />
<br />o
<br />ONDJFMAMJJAS
<br />
<br />deli"'ryofthc 8.23 million acre-feet, coupled with continued
<br />beJownormal inflow, reduced li\e storage at the end of water
<br />year 1990 to 16,252,000 acre-feet (65 percent full). The
<br />reser",ir elewtion on September 30, 1990 was 3637.6 feet,
<br />over 60 feet below the maximum pool elevation of 3700 feet.
<br />
<br />Special releases for the research efforts of Glen Canyon
<br />Environmental Studies began in June of 1990. A constant
<br />release of 5.()(x) cubic feet per second was released the fIrst
<br />four days of June. Subsequent research releases consisted of
<br />several days of fluctuating releases followed byseveral days of
<br />5,000 cubic feet per second constant releases. There were a
<br />total of 52 days on which research releases took place in water
<br />year 1990. These research releases were performed to
<br />evaluate the effects of fluctuating flows on riverine and
<br />riparian zones downstream of the dam.
<br />
<br />Canyon releases will be the same for probable minimum, most
<br />probable and probable maximum inflow conditions (except
<br />September of 1991) due to dry upper basin conditions and
<br />reduced reservoir levels. Total water year releases of 8.23
<br />million acre-feet would allow Lake Powell to fill to about 82
<br />percent of full, 62 percent full, and 54 percent full; for the
<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 />Reser",ir Length, full
<br />
<br />25,002,000
<br />9,428,000
<br />4,126,000
<br />
<br />3700
<br />3570
<br />3490
<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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