WSP03460

• File Number: 8441.700
• Description: Colorado Big Thompson Project - Annual Operating Plans
• Basin: South Platte
• Water Division: 1
• Date: 1/1/1989
• Title: Annual Operating Plans - Colorado Big Thompson Project - Water Year 1989-1990
• Water Supply Pro - Doc Type: Report/Study

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HIGHLIGHTS OF 1989 OPERATIONS

Wate... year 1989 runoff was be 1 ow average throu9hout the Co 1 orado-Bi 9
Thompson Project (Project) va...yin9 f...om 55 percent of average for the
inflow into Willow C...eek Rese...voir to 81 percent of ave...age into Green
Mountain Reservoi....

Peak inflows to reservoi...s within the P...oject occu...red in late May and
mid-June and were much below no...mal. On May 12, inflow to Willow Creek
Rese...voir peaked at 290 ft3/s. The inflow to G...een Mountain peaked on
May 24 at 1,910 ft3/s. Inflow to Lake G...anby peaked at 1,485 ft3/s on
May 30 and the Lake Estes inflow peaked on June 17 at 440 ft3/s.

River ...e1eases f...om Willow Creek Reservoi... and Lake Granby were made to
meet only minimum required ...e1eases fo... fish habitat. The maximum
release at Lake Estes for the water year was 305 ft3/s on August 3 to
bypass inflow. Project delive...ies peaked on August 17 at 769 ft3/s at
Ho...setooth Reservoir, and 581 ft3/s at Ca...te... Lake on July 9. The maximum
release at Green Mountain Rese...voir was 953 ft3/s on September 5 and the
maximum release of 500 ft3/s to the Big Thompson River occu......ed on
July 20.

Wate... year p...ecipitation totals for October-September va...ied f...om
80 percent of average on the Willow C...eek and Lake G...anby wate",sheds to
87 pe...cent of ave...age on the Lake Estes and St. Vrain wate...sheds.

Winte... p...ecipitation (Octobe"'-January) was below average on the Project,
at 73 percent of ave...age. The Lake Granby and Wi 110w C...eek watersheds
recei ved the fi ...st sign ifi cant ...ai n mi xed with snowfall of the water
yea... on Novembe... 3, 4, and 5 with 0.44 inches of prec i pitat i on bei ng
...ecorded. On Novembe... 3, the Green Mountain Dam station recorded
0.29 inches of precipitation due to ...ain mixed with snowfall. Snow and
rain occurred at Estes Park on Novembe... 15 and 0.40 inches of precipitation
was recorded. No significant dai ly snowfall above 0.50 inches was
...eco...ded on the P...oject in Decembe... and Janua...y. The Lake Estes
wate",shed was the on 1y a...ea to ...eco...d above normal preci p i tat ion fo...
January at 120 pe...cent of ave...age. Februa...y was a snowy month on the
Lake G...anby and Will ow C...eek wate",sheds with 164 percent of average
...eco...ded. The Green Mountain wate...shed was also above average for
F eb...uary averagi ng 160 percent of norma 1 preci pitat i on. A tot a 1 of
2.54 inches of p...ecipitation was ...ecorded fo... the Lake Estes watershed in
Feb...ua...y which was much above no...ma1 at 488 pe...cent of ave...age.

A major snowstorm hit the Project area f...om Feb...ua...y 2 through February
5, with 1.48 inches of precipitation recorded at G...een Mountain, 0.79
inches of p...ecipitation reco...ded at Lake Granby, and 2.08 inches of
precipitation ...ecorded at Lake Estes.

Ma...ch snowfall was below normal on all watersheds within the P...oject with
Lake Estes precipitation at only 15 percent of average. Precipitation
due to snowfall was much below no...ma1 on all watersheds on the P...oject
in April, except for G...een Mountain at 123 percent of average.

The maximum snow-water accumulations fo... all watersheds on the P...oject
occu...red on March 1 and Ap...i 1 1. On the P...oject, Green Mountain

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