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<br />
<br />ACKNOWLEDGEMENTS
<br />Till' S~cr~mento District, Corps of
<br />I-:r.~i"rcr.;. l':ratefully acknowledges the
<br />"",,,;l""C<' and cooperation of the "Grand
<br />,I,,,,,,ti,,n Daily Sentinel." the "Grand Valley
<br />,;",_t'llt....theCityofGrandJunction,theMesa
<br />
<br />County Planning Commission alld ,'arious
<br />other Mesa County al<endes, the Colorado
<br />Department of Highways. variol's Federal
<br />ageneies, and otherswhodirectlyor inclirectl,-
<br />aided in the preparation of this report. .
<br />
<br />BACKGROUND INFORMATION
<br />
<br />DESCRIPTION OF THE STUDY
<br />AREA
<br />
<br />l;rand Junction. theeounty seat and the
<br />l,,,,~,.;t cit,.. between Denver and Salt Lake
<br />('ity. i; located at the confluence of the
<br />(',,1<,..,,<!()<\nd Gunnison Rivers about 25 miles
<br />f''''HlhcUtahborder.ltlie:salanelevationof
<br />"1",,,( 4GOO feet between thc Uncompahgre
<br />I 'lal":\\L on th~~outh lInd the Book Cliff~ on the
<br />"""111, bolh of which rise about 2700 feet
<br />"I."'t, the city. George Cr..wford... former
<br />~"n'l""'r of K..n,as, established the townsite
<br />ill \SSl.ByspringofJ8i:l2,thefirstirriK"ation
<br />b.'JI,I,e; were complete..nd..griculture and
<br />I!\"""l,,~k raising had begun. A narrow-g..ge
<br />I",~ of the Denver and Rio Grand Western
<br />i,,,iin~.u from GunnLson was completed to
<br />
<br />DRAINAGE AREA
<br />The~oloradoRiverriseshighintheRoeky
<br />l>.lountalll~ ~n the western slope of the Con.
<br />tmcntal O"'lde. Th~ river flows southwesterly
<br />from Its headwater r~gions to the vicinity of
<br />Grand Junction. we~lerly and northwesterly
<br />through thestudY..rea, theneenorthwesterly
<br />through most of its remaining course in
<br />Colorado_ Thn Gunnison Rivpr,the principal
<br />trobular.' to 'h^ C' d . .
<br />~ < oora 0 R1ver 1n Colorado
<br />also' h' .
<br />. rosesat ,ghelcvationsonthewests!ope
<br />
<br />Grand Junction in 1882 and the main linc
<br />from Denver was completed through thc city
<br />in 1891. The area is extensively irriK"ated and
<br />mueh of the rur..l land is developed for
<br />farming. livestock r..ising, and orch"rd~,
<br />However, the economic base of Grand Junc.
<br />tion is verr diversified. In addition to
<br />all"riculture, it involves. among other thin!':".
<br />various industri..land commercial endeavors.
<br />and activities related to recreation and
<br />tQurism. Grand Junction is a major rail and
<br />highwaycenter..nd the principal urbana,'ea
<br />in Western Color:ado. The eit}, ha.~a"re5ent
<br />populatiOllofabout22.000.
<br />
<br />of the Continental Divide. Its main st~m
<br />follows a southwesterly course from
<br />headwaterareastoGunnisonwhereitturn~to
<br />flow west for about 40 miles,thencegPTlerally
<br />northwesterly tQthe Color..do River at Graod
<br />Junction. Leach Creek. Hori~on Drive
<br />Channel. and Lewis Wash originate in the
<br />Rook Cliff" arN.. The dr..inage arcas oflhc
<br />streams under "tudy and the elevations of
<br />their hcadll'atcrareas:areshown in Table 2,
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<br />TABLE 2
<br />
<br />DRAINAGE AREAS AND
<br />HEADWATER ELEVATIONS
<br />
<br />Stream
<br />
<br /> ApproxImate
<br /> Approxlmale ElevaUonof
<br />Location Draln,geArea HeadwalerArea
<br /> sq.ml. It. (msl)
<br />GagingSt..tion 17.100 12,000
<br />near Fruit..
<br />Gaging Station 7.930 14,000
<br />near Grand Junction
<br />At mouth 2; 5.500
<br />At"F" Road 2 5.500
<br />At mouth 5 5.500
<br />
<br />Colorado River
<br />
<br />Gunnison River
<br />
<br />Leach Creek
<br />Hori~on Drive
<br />Channel
<br />uwisWash
<br />
<br />The climate of the area is arid towmiarid
<br />with yearly precipit..tion aver..ging aboutS
<br />inches..t Gr..nd Junction, from about 10 to 15
<br />inches in headwater areas of the Book Cliffs
<br />and ..bout 40 inches in the headwater region~
<br />ufthcCoioradoandGunni>;unRiver~. Mostuf
<br />thc annual preeip;tation in the higher
<br />elevations occuro as snow and a deep snow.
<br />pack"cwmul..tcs. Tcmper..tures are "ften in
<br />theninetiesinthesummerandbelowfree~ing
<br />in the winter. OCl'f1Sionall)', summertime
<br />temper..ture may e.(eecd 100" and winter
<br />
<br />temperature may drop as low as.20Q. Natural
<br />vegetation in valley areasprim..rilyconsists
<br />ofcottQnwood a)ld willow, desertshrub,and
<br />an understQry of ha,d)' grasses. Prominent
<br />between SOOOand 80(l() leet arejuniper, pmon
<br />pine. oak, big sagebrush, and Douglas Fir.
<br />From 8000 feet tQ timberline. vegetation
<br />consists mainly of :l-"pen. ~pruce, sub.alpine
<br />fir.lodgcpolepine,;;.ndnati'{cgrassc5;;.nd
<br />shrubs. Vegetation issparse..bovetimberline
<br />but includes grass''5, sedges, and alpine
<br />willow.
<br />
<br />NATURE OF FLOOD PROBLEMS
<br />As noted,mostoftheannual precipit.a.tion
<br />in the highcr regions of the basins of the
<br />Colorado lInd Gunnison Rivers occurs lIS snow
<br />and II d~ep snowpack accumullllffl, General
<br />r..instQrms coverinl\" larl\"e areas for extended
<br />
<br />periods can occur in the region during spring
<br />and summer. Conveetive type cloudburst
<br />storms of small areal extent. which aCC<lunt
<br />for about half of the normal annual precipita.
<br />tion in the Grand Junction a......, can be
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