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<br />LAKE POWELL
<br />(COLORADO RIVER)
<br />
<br />
<br />Water Year 1987
<br />
<br />Lake Powell, which is impounded by Glen Canyon Dam, was
<br />operated as part of the Colorado River Slorage Projecl
<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 1987. .
<br />
<br />At the start of water year 1987, Lake Powell had an active
<br />content of 23,362,000 acre-feet at elevation 3,689,6 feet (93
<br />percent full), The most probable operating plan based on the
<br />October forecast caUed for total water year releases of 11,2
<br />MAF based on an unregulated inflow of 12,4 MAP, The
<br />reasonable maximum (upper decile) water supply had
<br />scheduled water year releases of 15.5 MAP based on an
<br />unregulated inflow of 17,7 MAP,
<br />
<br />On January 1, 1987, Lake Powell was at elevation 3,684 with
<br />an active content of 22,534,000 acre-feet. The January 1
<br />forecast of April through July runofffor Lake Powell was 9.5
<br />MAF or 116 percent of average. Discharges from Glen
<br />Canyon powerplant averaged 27,300 cfs (82 percent of
<br />maximum capacity) for lhe month of January, The February
<br />runoff forecast was decreased to 8.5 MAP and subsequently
<br />
<br />ACIUAL RELEASES
<br />
<br />WY 1987
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<br />
<br />powerplant releases were decreased to an average 64 percent
<br />of capacity, In March, the forecast dropped to 7.5 MAP and
<br />was 7,0 MAP or 86 percent of average on May 1. To insure
<br />filing Lake Powell by the end of June, powerplant releases
<br />werc lowered to an average 40 percent of capacity during the
<br />months of March through May, The elevation of Lake Powell
<br />on June 1 was 3,694,7 feet (97 percent full) and the June
<br />forecast had increased slightly to 7,1 MAP, To contain this
<br />volume and completely fill Powell without spilling, releases
<br />were increased to average 50 percent of powerplant capacity
<br />for June, The Maximum lake elevation of 3,698.5 feet (99
<br />percent full) was reached on June 25, Lake PoweU recorded
<br />a peak regulated infiow of 52,800 cfs on May 21, with
<br />maximum releases from the powerplant of 20,000 cfs (60
<br />percent capacity) on June 17 through June 30,1987,
<br />
<br />The total 1987 water year unregulated inflow to Lake Powell
<br />was 13,625,000 acre-feet which is equivalent to a most
<br />probable water year supply, Total water year releases below
<br />Glen Canyon were 13,605,000 acre-feet all of which passed
<br />through the powerplant. The spillways at Glen Canyon were
<br />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 />ResefVoir 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 />Powerplani
<br />
<br />Number of Units
<br />Total Capacity
<br />
<br />8
<br />1,247,000 KW
<br />
<br />13
<br />
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