WSP00886

• File Number: 8407
• Description: Platte River Basin - River Basin General Publications
• State: CO
• Basin: South Platte
• Water Division: 1
• Date: 4/16/1990
• Author: BOR
• Title: Annual Operating Plans - North Platte Project Water Years 1989-1990
• Water Supply Pro - Doc Type: Report/Study

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ANNUAL OPERATING PLAN AFTER FEBRUARY 1

Most Probable Inflow Forecast

Colorado-8ig Thompson Project
Green Mountain Reservoir

Turbine releases for replacement, bypass of inflow, power, and reservoir
regulation wi 11 approximate 150 ft3/s during February and March. If
most probable runoff conditions develop, releases will be increased to
340 ft3/s during April to achieve the desired storage target of
65,000 acre-feet at the end of April.

As the reservoir fills during the May-July runoff period, releases will
be adjusted to achi eve a fi 11 without spill duri ng the early part of
July. With normal inflow and near-average releases for downstream water
users duri ng August and September, storage is projected to be about
135,000 acre-feet by the end of September.

With most probable runoff conditions, Denver and Colorado Springs'
Blue River depletions are projected to be about 52,200 acre-feet during
the February-September period. These depletions would cause about
12 gigawatt-hours of power interference at Green Mountain Powerplant.

Willow Creek Reservoir

Under the most probable conditions, Willow Creek Reservoir will fill to
about 10~OOO acre-feet by the end of June. The minimum required releases
of 7 ftJ/s to the river during February, March, and April, 24 ft3/s
during May, and 44 ft3/s during June will be maintained. During April
through September, approximate ly 43,900 acre-feet wi 11 be pumped to
Lake Granby. While maintaining the required river release for downstream
water rights, Willow Creek storage will be near 9,000 acre-feet at the
end of the water year.

Lake Granby

Lake Granby storage will be lowered to 130,800 acre-feet by the end of
March. With most probable inflow, storage is expected to reach
287,400 acre-feet by the end of July. This is 252,400 acre-feet below
maximum reservoir storage, only 65 percent of average and the lowest end
of July storage since 1977. Granby Reservoir content of about
258,500 acre-feet at the end of the water year will be only 62 percent of
average.

East Slope/Colorado-Big Thompson Project

If climatic conditions produce most probable inflow, a near normal
supplemental irrigation demand equal to 264,900 acre-feet would be
expected on the Project. Adams Tunnel diversions will be at capacity
from February 1 through March 20, averaging 550 ft3/s due to below normal