WSP00880

• File Number: 8441.100
• Description: Colorado Big Thompson Project - Project Description
• State: CO
• Basin: South Platte
• Water Division: 1
• Date: 12/1/1982
• Title: Colorado - Big Thompson Project
• Water Supply Pro - Doc Type: Project Overview

Colorado-Big Thomp.wn Project

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EII.t Pona!. AI.-a 8. Adam~ Tunn../

Granh}' Dam and Lake Grallhy

Granby Dam is locatf'd on the Colorado Riv('r about .';.5
milf'l; northt>llst of Granby. It collt~('ts and ~tores mosl of
the projt'ct water supply. including Ihe now of Iht' Col-
orado Hiver and water pumpt"(1 from U'ilJow Crt'{'k. The
dam is consll"llcled of compacted earthCiIJ. 298 fft,t hi~h.
wilh a crt'i11length of 861 feet. There are 12.722 ft'l'l (If
auxiliary dikes. TIlt' re~n'oir has a capacity of 539.800
aCre-ff'el. Total '-olunw of Ihe dam is 2.974.000 cubic
}'aT<k The dihs hut' a Iota I volume of 1.739.000 cubic
yards.

U'iIIo\o' Cr_k Ham. Hl"sen-oir. alltl Pumpill~ Plant

Willow Cret'k Dam is 127 feet high. 1.100 ft't'tlong. and
conslructf'd of earthCill. There are 3.4 miles of canals
with a capacity of 400 cubic feet pt'r ~nd and a pump-
ing plallt with Iwo 200-cubic-foot'per.~nd pump", Ihat
lift water 175 ft'(<t into Lake Granby. The dam din.rts an
a\"f'rage of 40.000 acre-ft't't of wat('r each }'l;"ar from
Willow Crl;"ek into Lake Granb}'. The rt''''t''rvoir capadt},
is 10.600 acre.ff'el.

GranLy Pumpin~ Plant and Pump Canal
Water is pumrffi from Lake Granby into Shadow .:\-Ioun-
tain Lah by Granby Pumping Plan I and Canal. The
pumping plant contains thrt't' centrifugal pump~ with a
lotal capacity of 600 cubic feet per R"cond at ISO.foot
head. -The pumping lift ranges from 85 to 186 feet ac.
cording to the water ",urfac(" elevation in Lake Granb}'.
The water is di;,chargPd into a canal which halO a capac.
it~, uf 1.100 cubic feel per -"t"Cond. and conveyl'd 1.8 miles
to Shadow .\lountain Lake.

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Shadow ~Iountain Dam and Ht"i;t"T\-oir

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Shadow :\lowlIain Dam. located on the Colorado HiHr
below its confluence with the Grand Lake outlet. is an
earlhCiIl slrUclure 63 feet high and 3.077 feel long. The
re!<l"r\"oir forml'd by the dam has a lolal capacity of
IB.4'()() acre-feet alld is linked to Grand Lake through a
connecling channel. Shadow .\Iountain Lake receives the
water pumpt-'(l from Lake Granby and also intercepts
:\'orth Fork flows of the Colorado Rin'r. Project water is
releaR"d from Grand Lakt" directly into tilt> Alva B.
Adams Tunnt'!. through which il flows to the eastern
slope of tJw Continental Divide.

Aha B. Adams Tunnd

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This 9.i5.fuol.diallleh:-r. 13-milt"l{)n~ tunn." t":l.lt'nds from
Grand Lal..l' through thl" Continental Ilhidl' to ,( poin!
t5 Illil.~s ,;Qutll"'t":'t of E~k" ParI... It has a ("apac'it.~, of
5.')0 l"ubi.> f""t'! per """'OIl1/.

Eafil Slopt" Pow""r Sp;tl:"I1I-LTpper

The struclurt>s of thi!; s}'slem conH}' water 4.3 miles from
the l"ast portal of Alva D. Adams Tunnel to Ihe Big
111Ompson Hiwr.

Eme,,~'ing from Ihl;" tunnel into thl" Easl Portal ReM"rvoir.
the water flows across A"pen Crt"ek \' alley in a siphon
and then under Ram!'! Horn .:\-Iountain in a tunnel. AI
this poinl. tlU" water I'nters a slt"el penstock and falls 205
feet 10 :'\laT}'s Lak!> Powerplant. whkh has an inslalled
capacit~. of 8.100 kilowatts. This plant is locatr-d on the
west shor(" of .\tarys Lake. which has been enlarged by
dikin,;:- Ihe small natural basin 10 provide afterbay and
forellay capacit}. lor rt."regulating Ihl;" flow. From :\Iaf}'s
Lake to Estes Powt>rplant. the water is droppt'd 482 feet
in a preJO.SUTe syslem consi"ting of Prospect Mountain
Conduit and Prospect .:\-tountain Tunnel.

ESles Powerplant contains three genera ling units ""rved
by three 78-inch-diameter penstocks about 0.75 mile
long. TI1(' inslalled plant capacit}, is 45.000 kilowatt!>
when operating und('r an nerage net head of 482 feel.

Ol~mpus nam. d lOIWd t"arthfill s'rlll'lUfI' ...ith II t'Oll<"rete
u'l'rflo... ~jJill"'ay. i, 70 ft"et high and ha" a l'r..,.t It'ngth of
1.951 fed. It impounds I.ake Est'-'!' on lilt' Rig Thomp,;on
HiH'r and pro\-if!el; regulatinj!" fapat'it~ for en!:'r!!":, pur.
po"",-",, The lal..l' has a totall'apadt) of ahout 3.100
,HT("-fn.'1 and I'ontrol~ the di"rhllrg""s from E~th 1'0"''''1''
plant, ri\er inflo... alld outflo.... and relt"a~(.,. of projeet
\oatl'r to Ihe Lo\o('r Ea,t :-:-Iope Po"'''''r :-;~-st("m.

Ea"t 5lol.e Po...!:"r Systt:"m.Lo....t>r

This sptem conveys project water from Lakt' Esles in a
..uulheasterly direclion to the F(X)thills storage and supply