WSP12905

• File Number: 8441.700
• Description: Colorado Big Thompson
• State: CO
• Basin: South Platte
• Date: 1/1/1999
• Author: USDOI/BOR
• Title: Annual Operting Plans Colorado Big Thompson Project & Western Division Systems Power Operations, Water Year 1999 Summary of Actual Operations
• Water Supply Pro - Doc Type: Annual Report

than average for March. Pueblo had a new record high temperature of 81 of on March 21 which
broke the old record of 80 OF set in 1995.

For April, precipitation was 126 percent of average on the western slope of the CBT and well
above average at 397 percent of average on the eastern slope during April. The Willow Creek
and Lake Granby watersheds were the lowest at 72 percent of average. The Poudre watershed
was the highest at 402 percent of average. Fort Collins set a record on April 30 for most
precipitation for that day with 2.41 inches. April was also the second wettest April of record in
Fort Collins.

April weather usually produces significant storm systems that move through the Project area, and
this April was no exception. On the Western Slopes, precipitation was close to normal however
on the Eastern Slope, precipitation was abundant and caused local high flows in most lower
elevation streams and rivers. Snow-pack however was very close to average at 96 percent with
Green Mountain & Willow Creek at 105 percent to 81 percent for Lake Granby basin.

May was a dry month on the west slope and wet on the Eastern Slope. The Willow Creek and
Lake Granby watersheds were the lowest at 69 percent of average to the Green Mountain
watersheds at the highest at 145 percent of average. Temperatures for May were varied but
close to average.

June brought a varied amount of precipitation over the project. The Willow Creek and Lake
Granby watersheds were the lowest at 86 percent of average. The Lake Estes and St. Vrain
watersheds were the highest at 124 percent of average. Fort Collins had a record precipitation
amount for June 10 with 0.85 inches of rain falling, beating the old record of 0.84 inches of rain
on that date set in 1936. Precipitation over the project has been 124 percent of average to date
for water year 1999 (October-June). For July, precipitation was the lowest in the Poudre
watershed with 81 percent of average. However the Willow Creek and Lake Granby watersheds
were the highest at 190 percent of average. Precipitation for September was above average at
128 percent over the Project. The Poudre Basin did have the highest at 182 percent of average.
Fort Collins recorded a record amount of precipitation for September 1 with 0.94 inches of rain.
The old record for that date was 0.44 inches set in 1998.

The maximum temperature recorded at Green Mountain Reservoir was 87 OF on July 4. The
maximum temperature recorded at Lake Granby was 82 OF on July 5, and Lake Estes recorded a
maximum temperature of 84 OF on July 3. The minimum recorded temperature at Green
Mountain Reservoir was -250F on December 21. The minimum recorded temperature at Lake
Granby occurred on January 29 and was -20oP, and Lake Estes recorded a minimum temperature
of -17 OF on December 23.

2

Alva B. Adams (Adams Tunnel) diversions totaled 165,400 acre-feet (72 percent of average) for
the water year.

The Northern Colorado Water Conservancy District declared a quota of 80 percent (248,000
acre-feet) for the allocation of Project water to allotment contract holders for water year 1999.