WSP06804

• File Number: 8441.700
• Description: Colorado Big Thompson Project - Annual Operating Plans
• Basin: South Platte
• Water Division: 1
• Date: 1/1/1992
• Title: Annual Operating Plans - Colorado Big Thompson Project - Water Year 1992-1993
• Water Supply Pro - Doc Type: Report/Study

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SUMMARY OF 1992 OPERATIONS

Water year. 1992 runoff was below average throughout the Colorado-Big
Thompson Ptoject (Project) varying from 59 percent of average for the
inflow intp Willow Creek Reservoir to 83 percent of average into
lake Granby.

Peak inflow~ to reservoirs within the Project occurred in late May with the
exception of the Big Thompson River above lake Estes which peaked on
June 26 at ~49 ft3/s. Inflow to Green Mountain Reservoir peaked on May 21
at 1,753 fti/s. Inflow to lake Granby peaked at 1,954 ft3/s on May 27.
Inflow to W1110w Creek Reservoir peaked at 250 ft3/s on May 28.

River releases from Willow Creek Reservoir and lake Granby were made to meet
only minimum required releases for fish habitat. The maximum release at
lake Estes Was the minimum fish release of 125 ft3/s be~inning on May 16.
Project water del iveries peaked on May 6 at 638 ft /s at Horsetooth
Reservoir anp 510 ft3/s at Carter ~ake on July 14. The maximum release at
Green Mounta~n Reservoir was 792 ft /s on August 22, and the maximum project,
del iveryof 1400 ft /s to the Big Thompson River occurred on November 14,
1991. '

Water year pr,eci pi tat i on totals for October-September vari ed from 88 percent
of average o~ the Green Mountain, lake Granby, and Willow creek watersheds
to 122 percent of average on the PoUdre watershed.

Winter precipitation (October-January) on the Project was much below
average at ~6 percent of average. Green Mountain Dam during October
received 0.531 inches of rain mixed with some snowfall, which was 48 percent
of average.' The lake Granby and Willow Creek watersheds received
2.06 inches of rain mixed with snowfall during October, which was
84 percent Of average. The lake Estes watershed received 0.57 inches of
rain mixed with snowfall, which was 64 percent of average. November
precipitationl was much above average over the Project with Project
precipitationistations reporting 136 percent of average. December was very
dry over the Project with some Project stations reporting zero
preCipitation: for December. The following individual precipitation
stations within the Project recorded very low amounts in December.

Individual PreciDitation Stations Within Project:

Station Amount Recorded. December 1991 (Inches) Rank in Yrs of Record

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All ens park
Breckenridge
Climax
Dillon
Estes Park
Flatrion
Gl6SSW
GllNW

.19
.08
.43
.25
.00
.00
.31
.40

3rd lowest in 47 years
lowest in 44 yrs
3td lowest in 42 yrs
4th lowest in 58 yrs
Tied for lowest in 83 yrs
Tied for lowest in 34 yrs
6th lowest in 44 yrs
4th lowest in 52 yrs

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