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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Emerging from Alva o. Adams Tunnel into the East Portal Reservoir, the
wate... flows ac...oss Aspen C...eek Valley in a siphon and then unde... Rams
Ho...n Mountain through a tunnel. At this point, it enters a steel
penstocK and falls 205 feet to Marys Lake Powe...plant. This powerplant
is located on the west shore of Ma...ys Lake, which p...ovides afterbay and
forebay capac ity fo... re-...egu 1 at i ng the fl ow. Between Marys Lake and
Estes Powe"'plant, on the sho...e of Lake Estes, the wate... is conveyed by
P...ospect Mountain Conduit and Prospect Mountain Tunnel.

Lake Estes, below Estes Powerplant, is fo...med by Olympus Dam constructed
across the Big Thompson River. The afterbay storage in Lake Estes and
the fo...ebay storage in Marys Lake enable the Estes Powe...plant to meet
daily variations in energy demand.

Wate... f...om Lake Estes and some Big Thompson Rive... floodwaters are
conveyed by Olympus Siphon and Tunnel and Pole Hill Tunnel and Canal to a
penstock through which the wate... d...ops 815 feet to Pole Hill Powe...plant.
It is then ...outed th...ough Pole Hill Powerplant Afterbay, Rattlesnake
Tunnel, Pinewood Lake, and Bald Mountain Pressu...e Tunnel, and dropped
1,055 feet th...ough two penstocks to Flati...on Powerplant. This
powe...p 1 ant charges into Flat iron Reservoi..., wh i ch regu 1 ates the wate...
for release to the foothills sto...age and dist...ibution system. The
afte...bay sto...age in Flatiron Reservoir and the fo...ebay sto...age in
Pinewood Lake enable Flati...on Powerplant to meet daily power loads.

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Southward, the Flatiron ...eversible pump lifts wate... f...om Flatiron
Rese...voir, a maximum of 297 feet, and delivers it th...ough Ca...te... Lake
P...essure Conduit and Tunnel to Ca...te... Lake. When the flow is ...eve...sed,
the unit acts as a turbine-gene...ato... and p...oduces electric energy.

The St. Vrain Supply Canal delivers water from Ca...ter Lake to the Little
Thompson Rive..., St. V...ain C...eek, and Boulder C...eek Supply Canal. The
latter delivers wate... to Boulder C...eek and Boulder Reservoir. The South
Platte Supply Canal, diverting f...om Boulde... Creek, delivers water to the
South Platte Kive....

Northward, the Cha...les Hansen Feede... Canal transports water from
Flat iron Reservo i... to the Bi g Thompson River and Ho...setooth Reservoi r.
The canal crosses the Big Thompson River in a siphon above the river and
highway. Wate... f...om the Big Thompson Rive... can be diverted into the
canal by Dille Dive...sion Dam and utilized fo... powe... gene...ation at Big
Thompson Powe...plant.

Project wate... del iveries and Big Thompson River wate... to be returned
to the rive... a...e d...opped through a chute from the feeder canal ahead of
the siphon c...ossing, or a...e passed through the Big Thompson Powerplant
to convert the available head to elect...ic ene...gy.

Horsetooth Reservoi... is west of Fo...t Collins between two hogback ridges,
where Horsetooth Dam closes the gap at one end. So 1 die..., Di xon, and
Spring Canyon Dams and Satanka Dike close the ...emaining gaps.

An outlet at Soldier Canyon Dam supplies wate... to Fort Collins, ...ural
wate... districts, Colorado State Unive...sity, and the Dixon Feeder Canal
fo... the i...rigated a...ea cut off from its wate... supply by the rese...voir.

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