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<br />LAKE POWELL
<br />(COLORADO RIVER)
<br />
<br />
<br />Water Year 1991
<br />
<br />Lake Powell, which is impounded by Glen Canyon Dam, is
<br />operated as part of the Colorado River Storage. Project
<br />(CRSP) in accordance with governing compacts and laws to
<br />provide conservation storage, river regulation. power
<br />generation. recreation, and fish and wildlife enhancement.
<br />
<br />Lake Powell began water year 1991 at elevation 3637.6 fect
<br />with a live content of 15,720,000 acre,fect (65 percent full).
<br />April through Ju]y unregulated inflow to Lake Powell was
<br />5,286,OOOacre,feet (65 percent of average), Total unregulated
<br />inflow into Lake Powell in water year 1991 was 8,385,000
<br />acre,feet, only 70 percent of the 11,900,000 acrc,feet
<br />unregulated average. Actual regulated inflow for wolter year
<br />1991 was 7,5l0,OOOacre,fect. Regulated inflow to Lake Powell
<br />peaked at 38,000 cubic feet per second on June 17, 1991.
<br />
<br />Beginning on August 7, 1991, test interim minimum and
<br />maximum releases and controlled fluctuations were
<br />established below Glen Canyon Dam, pending development
<br />
<br />ACTUAL RELEASES 1991
<br />
<br />THOUSo\ND "CRE-FEEl
<br />1200
<br />
<br /> / ......... '"
<br /> V
<br /> / i"-o... /
<br /> /" .......
<br />...-'
<br /> , , I
<br />
<br />1000
<br />
<br />800
<br />
<br />800
<br />
<br />400
<br />
<br />200
<br />
<br />o
<br />ONDJFMAMJJAS
<br />
<br />and implementation of the interim criteria on November I,
<br />1991. The interim criteria acc intended to reduce the effects
<br />of power operations on downstream natural resources until
<br />the Glen Canyon Environmental Impact Statement is
<br />completed. Lake Powell has a minimum objective annual
<br />release of 8.23 million acre. feet. as set forth in the Operating
<br />Criteria. The delivery of the 8.23 million acre.feet, coupled
<br />with continued below normal inflow, reduced li..oe storage at
<br />the'end o[wateryear 1991 to 14,699,OOOacre,fect (60pcrccnt
<br />full). The reservoir elewtion on September 30, ]99] was
<br />3628.6 feet, over 70 feet below the maximum pool elevation of
<br />3700 feet.
<br />
<br />Maintaining a nUn1mum release of 8,230,000 acre-feet
<br />annually from Lake Powell combined with the lowest
<br />consecutive 5 years of inflow on record (1987 through 1991),
<br />and a refilling of the upstream reservoirs has reduced the
<br />storage of the reservoir below its capacity by approximately
<br />9,500,000 acre-feel.
<br />
<br />LAKE POWELL
<br />
<br />Reservoir
<br />
<br />Acre-feet
<br />
<br />Elevation, feet
<br />
<br />Storage Capacity
<br />Rated Head
<br />Minimum Power
<br />Surface Area. full
<br />Reser""ir Length, full
<br />
<br />24,322,000
<br />9,428,000
<br />4, ]26,000
<br />
<br />3700
<br />3570
<br />3490
<br />16l,390Acres
<br />186 Miles
<br />
<br />Powert>lant
<br />
<br />Number of Units
<br />Total Capacity
<br />
<br />8
<br />1,247,000 KW
<br />
<br />13
<br />
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