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 Thompson Project

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OI)'ffll",.Uam

St'cond at the start and prolV'e~!'iH"I~' d,.crNIS('s, "'{'ar the
lowf'r end of thf' canal. the Platte Vullf'}' Irrigation Co.
cOflslrllctl:"'d Coal Hidge Waste Lake lor storage. This
re"-t'r\-'oir was built under an agreement with the i\"orth-
ern Colorado Water Con,;er\-'ancy Di",trict. Undf'r the
agrl"ement. tht' lake pruvide", JUO cubic leet p.'r M'cond 01
South Plaue Supply' Canalllows.

Charlt'''' lIano_t'n F..I..dt'r Canal

Beginning at tht' outlt't of Flatiron Rt',;er\-'oir. the Chari.."
Hanst'n Fl't'der Canal {'xtend~ northward to Horsetooth

E.I<';O P"""rpl.nl

Re~rvoir. Tht' canal halO a capacity of 930 cubic fft't per
S('('ond to th{' Big Thompson Ri"er and 550 cubic f(>{'t
per IOt'cond to the re*r\-'oir. The canal cro,."f'~ the Big
Thomp~n Rh'er and U.S. Highway 34 in a 9.foot-diam-
eter st(>{'1 !'iphon. :\ eontrol "tructure ahead of the Big
Thomp.,on Riwr Siphon prO\'ides a means to release ir-
rigation water to th.. Big Thomp!;()U Rh'er to bypa~;;
8urplu.~ water. and to rel..aH' water to th.. Big Thompson
Powerplant. The Hor>oetooth Supply Conduit. an impor_
tant feature of Ihf' eanal. div'erts wat..r from tht' Big
Thomp~on Hh'er about I milt' up~trt'am from the control
struchue /Iud deliwrs it via a tunnel to Ihe Charles
HanS('n Feeder Canal above the control slructure.
Divertt'd watl"r i~ used for power g",oeration at the Big
Thomp"on I'owerplanl. or water 8UrprU~ to tht' net'ih of
tht' Big Thompson Valley can he storffi in Horsetooth
Heservoir. l\orth of thl' Big Thompson Rivf"r. the eanal
paSM"S through four concrete-lined tunnels; the oudd of
the la"t tunnel discharges tht" watt'r into the 1I0rSt'tooth
Beservoir.

Big ThoUlI.",on I'mot'rplant

Tht' Big Thompson Powerplant is on the Big Thompson
HivE't aboul 9 miles west 01 wveland and just down-
slrt'am lrom the ri\'er cro....~ing of tilt' Charles Han!<t'n
Fet"tll'r Canal. Thl" plant ojWrales under an l'lf('ctivt' head
01 180 ft't't and has a gt'n{'rating capacit~, of 4.500
kilowatt".

Hor!'it'tooth H.."wr\oir

HorSt'tooth Hf'sen'oir. with II tolal capacity of about
151.750 acrt'-ff't't. furnisllf'!1 the main supply for the
Poudrt' Valley'. whf're 50 fl('reent of tht' projt'('t water is
u~d. TIlt' re,;en'oir is 6.5 miles long. and is lormed L~'
four largt' earthlill dams. Hor>'f:'tooth Dam c1oSt'!:l the
northt'rn t'nd of th{' vall..y. and Soldi{'r Canyon. Dixon
Canyon. and Spring Can~'on Dams clo;;e natural outlets
eroded Ihroll~h the h()gback ridge. TheM" dam.'! hllv'e
heiA"hls of 155. 226. 240. and 220 feet. respt'Cti\"el~'.
1Ot' daUl~ contain more than 10 million eubic ~'ards 01
f"arthfill.

Charl!:'!'- Han..,.n and :\-orth Poudrt' Supply Canal!'

Outlets al Horst'tooth Dam di~hargf' into the Charl{'s
lIansen Canal. which i~ designt'd 10 car~' a maximum 01
1.500 cubic lft't per M>("Ond northward 5.1 miles to Ihe
Cache la Poudre Riv{'r. Projt'Ct waler relf'lI~ into Ihe
rher at this point is u,;ed to supplement tht' water suppl~'
01 irrigation ~yslt'ms st('mming from the rinr. It also
,;ervt's as rt'plt'ni~hnlt'nt for the water taken from the
riw'r a lew miles upstrt'am by the ::\'orth Poudrt' Supply
Canal. a 1~.5-milt'-long ('snal which carrit's suppl..menl/ll
watt'r 10 the ::\.orth Poudre Ditch, Tho" 0.5-milt'. 250-
cuhic-foot-per-,;eeond Windwr Extension Canallahs