WSP09032

• File Number: 8407
• Description: Platte River Basin - River Basin General Publications
• State: CO
• Basin: South Platte
• Water Division: 1
• Date: 2/27/1991
• Author: BOR
• Title: Annual Operating Plans - North Platte Project Water Years 1990-1991
• Water Supply Pro - Doc Type: Report/Study

2

I
:1
I
I
I,
I
I
I
I
,I
I
I
I
I
I
"
t
I
I

and 4,17 inches of precipitation recorded at Horsetooth. The March 1990
precipitation amounts resulted in the following record and near records
being set.

Station Amount Recorded. March 1990 (Inches) Rank in Yrs. of Record

Ft. Coll ins 5.63 Highest March in 90 years
of record
Flatiron 4.03 Second highest March in
33 years of record
GL6SSW (Granby 1.88 Second highest March in
Pumping Plant) 43 years of record
GLINW (National Park 2.97 Second highest March in
Service headquarters 51 years of record
near Grand Lake)
Estes Park 2.21 Sixth highest March in
82 years of record

March snowfall was much above normal on all watersheds within the Project
with the Poudre watershed precipitation at 377 percent of average.
Precipitation due to snowfall continued above normal in April on all
watersheds on the Project except the Poudre watershed. The Lake Estes and
St, Vrain watersheds recorded 134 percent of average April precipitation.
Significant snowfall occurred on AprilS on the east slope with 0.73 inches
of precipitation recorded at Flatiron, From April 24 through April 29, a
steady snowfall on the west and east slopes resulted in 0,84 inches of
preci pitat i on recorded at Green Mountai n, 1. 32 inches of preci pitat ion
recorded at Lake Granby, and 0.88 inches of precipitation recorded at Lake
Estes.

The maximum snow-water accumulations for all watersheds on the Project
occurred on March 1 and April 1. Green Mountain recorded 13,4 inches on
May 1, Willow Creek recorded 8.6 inches on April 1, Granbyrecorded
11.1 inches on April 1, and Lake Estes recorded 12.4 inches on April 1.
Percent of average ranged from 87 percent at the Willow Creek watershed to
115 percent at the Lake Estes watershed.

Snow courses for watersheds within the Project averaged 89 percent of normal
snowpack water content on May 1. The Wi 11 ow Creek watershed recorded a
snow-water accumul ation on May 1 of only 51 percent of normal. The May 1
snow-water content for the Green Mountain and Lake Granby watersheds were
92 percent of normal and 90 percent of normal, respectively. The Lake Estes
watershed snow-water content was 93 percent of average on May 1. The
St. Vrain and Poudre watersheds May 1 snow-water content were above average
at 102 percent of average and 103 percent of average, respectively.

Steady rainfall occurred in the Lake Estes area on May 8 with 0.71 inches
of precipitation recorded and again from May 28 through May 30 with
0,75 inches recorded over the 3 days. Significant rainfall occurred from
May 28 through May 30 on the east slope with 2.57 inches of precipitation
recorded at Pole Hill, 2.71 inches of precipitation recorded at Flatiron,
and 2.16 inches of precipitation recorded at Horsetooth. Precipitation was
varied over the Project and averaged 101 percent of average. Precipitation
was much below normal over the Project area in June, with Willow Creek and