WSP05072

• File Number: 8224.700
• Description: Missouri Basin - Pick Sloan Project - Annual Operating Plans and Reports
• State: CO
• Basin: South Platte
• Water Division: 1
• Date: 1/1/1987
• Author: DoI, BoR
• Title: Annual Operating Plan Western Division Water Year Operations 1987 Water year Outlook 1988
• Water Supply Pro - Doc Type: Annual Report

HIGHLIGHTS OF 1987 OPERATIONS

Water year 1987 runoff was below average throughout the System (Western
Division System) varying from 58 percent of average into the Seminoe
Reservoir to 83 percent of average for the river gain between Alcova and
G lendo Reservoi rs. For most watersheds in the System i nf 1 ow vo 1 umes
were the lowest since the dry' year of 1981.

Peak inflows to reservoirs within the System occurred early due to warm
temperatures and were much below normal. The inflow to Seminoe
Reservoir peaked on May 3 at 3,650 cubic feet per second. On May
17, inflows to Willow Creek Reservoir and Lake Granby peaked at
339 cubic feet per second and 1,705 cubic feet per second, respectively.
Green Mountai n Reservoi r and Lake Estes i nfl ows peaked on June 9 at
1,665 cubic feet per second and 730 cubic feet per second, respectively.

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 for the water year was 754 cubic feet per second
on May 11 to deliver noncharge water and bypass inflow. Project deli-
veries peaked on May 11 and 12 at 1,379 cubic feet per second at
Horsetooth Reservoir and 485 cubic feet per second at Carter Lake on July
25. The maximum release at Green Mountain Reservoir was 708 cubic feet
per second on September 29 to meet downstream prior rights.

Semi noe-Kortes releases were made on ly to meet power product i on as a
spi 11 condition did not occur. The maximum turbine release was 2,220
cubic feet per second on January 31. Irrigation demands were high in
July and early August on the North Platte Project. This resulted in
peak discharges of 3,442 cubic feet per second on July 21 at Pathfinder
Reservoir, 7,610 cubic feet per second on July 28 at Glendo Reservoir,
and 5,184 cubic feet per second on August 1 at Guernsey Reservoir.

Water year precipitation totals for October-September varied from 73
percent of average on the Seminoe watershed in Wyoming to 110 percent' of
average on the Lake Estes and St. Vrain watersheds in Colorado.

A major snowstorm occurred in the Guernsey Reservoir area on October 20,
with 0.63 inches of preci pitat i on recorded. October was a snowy month
as Lake Granby and Semi noe Reservoi r recei ved 0.91 inches and 0.63
inches of precipitation, respectively on October 22. The Lake Estes
area recorded 1.12 inches of precipitation due to snowfall on November
1. Heavy snowfall occurred for a few days in early spring at Guernsey
Reservoir, Glendo Reservoir, and Green Mountain Reservoir.
Precipitation amounts recorded were 0.52 inches on March 8 at Guernsey
Reservoir, 1.04 inches on March 20 at Glendo Reservoir, and 0.60 inches
on April 12 at Green Mountain Reservoir. The Seminoe Reservoir
watershed also received 0.52 inches of precipitation on April 20 due to
snowfall. The above precipitation amounts were the maximum recorded
precipitation due' to snowfall at the various Reservoirs and Lakes within
the System during water year 1987.

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