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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Reasonable Maximum Inflow Fo...ecast

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Colo...ado-Big Thompson Project

Green Mountain Reservoi...

With a ...easonable maximum inflow forecast. releases from G...een Mountain
Rese...voir for bypass of inflow, replacement, power. and ...ive... and
...eservoi... ...egulation will ave...age 170 ft3/s in Februa...y and Ma...ch and
will be increased in April to nea... 475 ft3/s afte... ice conditions permit
to ...educe the storage content to 55,000 ac...e-feet by Ap...il 30. Releases
fo... power will be increased, as required, from May through July to allow
the reservoi... to fill without spilling in ea...ly July. June and July
releases a...e expected to average nea... 1,425 ft3/s. The reservoi... wi 11
remain nearly full throughout the remainde... of the water yea.... With
reasonable maximum runoff, it is estimated that the cities of Colorado
Sp...ings and Denver would not deplete the Blue River du...ing
April-September. which would not cause any power inte...fe...ence at Green
Mountain Powerplant.

Willow Creek Rese...voir

Willow Creek Rese...voir storage would reach the maximum reservoi... capacity
of 10.200 acre-feet by the end of June. With above-ave...age storage
in G...anby and a reasonable maximum fo...ecast, 67,500 acre-feet of wate...
would be pumped to Granby during the April-July ...unoff period.
App...oximately 6.700 acre-feet of water fo... required irrigation
...equirements and fishery augmentation flows would be bypassed to the
...iver during Ap...il-July. Reservoi... sto...age would be near g.OOO ac...e-feet
at the end of the wate... year.

Lake G...anby

Sto...age in Lake G...anby will d...op to a minimum of about 134.100 acre-feet
by the end of March. Thereafter. Lake Granby sto...age wi 11 fi 11 to
417,900 acre-feet by the end of July which is 121.900 acre-feet below
the maximum reservoir capacity of 539.800 ac...e-feet. Reservoi... sto...age
of 409,700 acre-feet at the end of the wate... yea... would be near the
30-year ave...age of 419.500 acre-feet.

East Slope/Colorado-Big Thompson P...oject

With reasonable maximum runoff forecast on February 1. below-ave...age
supplemental i......igation demands equal to 162,800 acre-feet will be
expected on the P...oject du...i ng water year 1990. Di ve...s ions through
Adams Tunnel wi 11 be at capacity of 550 ft3/s from Februa...y 1 th...ough
March 20. Adams Tunnel and Olympus Tunnel diversions will be minimized
from Ma...ch 21 th...ough Ap...il 28 to accommodate the Pole Hill Canal,
Afterbay. and Powe...plant maintenance scheduled during this period. For
May th...ough Septembe.... Adams Tunnel diversions wi 11 be scheduled to
maximize the dive...sion of available "skim" water and meet irr-igation
demands on the east slope. Approximately 7.500 ac...e-feet of available
skim wate... would be bypassed du...ing June because Olympus Tunnel is at
capacity of 550 ft3/s.

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