WSP10329

• File Number: 8441.700
• Description: Colorado Big Thompson Project - Annual Operating Plans
• Basin: South Platte
• Water Division: 1
• Date: 1/1/1993
• Title: Annual Operating Plans - Colorado Big Thompson Project - Water Year 1993-1994
• Water Supply Pro - Doc Type: Report/Study

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SUMMARY OF 1993 OPERATIONS

Water year J993 runoff was above average throughout the Colorado-Big
Thompson Project (Project) varying from 112 percent of average for the
inflow into !lake Estes to 122 percent of average for the inflow into
lake Granby and Green Mountain Reservoir.

Peak inflows ~o reservoirs within the Project occurred in mid June with the
exception of:Willow Creek Reservoir which peaked on May 29 at \,031 ft3/s.
Inflow to Gre~n Mountain Reservoir peaked on Ju~e 17 at 3,254 ft Is. Inflow
to lake Gran~y peaked on Junf 18 at 2,968 ft Is. Inflow to lake Estes
peaked on June 18 at 1,028 ft Is.

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 664 ft3/s on June 18. Project water del iveries peaked on
July 6 at 912:ft3/s at Horsetooth Reservoir and 607 ft3/s on July 9 at ~arter
lake. The maximum release at Green Mountain Reservoir was 1,432 ft Is on
July 2, and the maximum project delivery of 430 ft3/s occurred on August 20
and 21 to the" Big Thompson River.

Water year 1 ~93 preci pi tat i on tot a 1 s for October-September vari ed from
, 101 percent of average for the Green Mountain watershed to 113 percent of
average for t~e lake Granby and Willow Creek watersheds.

Winter precipjtation (October-January) on the Project was slightly below
average at 9~ percent of average. Green Mountain Dam during October
received only; 0.27 inches of precipitation which was only 24 percent of
average. The ~ake Granby and Willow Creek watersheds received 1.13 inches
of precipitation which was 96 percent of average during October. The east
slope of the p,roject was very dry. The lake Estes watershed received only
0.35 inches 9f precipitation which was only 34 percent of average.
November precipitation was much above average over the Project with Project
weather stati,ons averaging 150 percent of the 1961-1990 average.
Fort Collins r;ecorded 1.72 inches of precipitation which was the fifth
wettest Novemb~r in 92 years. They also recorded 23.8 inches of snow which
was the fourthlsnowiest November in 104 years. December precipitation was
much below average Project weather stations averaged only 60 percent of the
1961-1990 aver~ge. . Temperatures were much below average for December over.
the Project.

January climate in perspective - cold east slope, wet west slope.
Precipitation ~as above average on the west slope and below average on the
east slope. ;Temperatures were below average over the Project during
January. Febr.uary was colder than average and Project weather stat ions
averaged 4 degrees below average. February precipitation was much above
average rangirig from 183 percent of average for the Green Mountain
watershed to 310 percent of average for the lake Este.s and St. Vrain
watersheds. T~e following individual precipitation stations within the
Project record~d some very high amounts for February.

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