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<br />I'
<br />I
<br />
<br />IJ.SruOYAREA
<br />
<br />A.
<br />
<br />Location
<br />
<br />Precipitation
<br />The a~erage annua 1 prec i pi tat i on for the Montrose ~ici nit)' is
<br />approximately 9 inches (rain and snow). The hydrologic eovirOMent is
<br />moderated by the Uncompahgre Plateau to the southwest of Montros e. The
<br />effect of the Uncompahgre Plateau on the local weather pattern places
<br />Montrose and the Uncompahgre Valley in a precipitation "shadow" in the
<br />winter. This condition also limits the influx of lI~ist air 1I1asses lnto
<br />the valley during the summer. The ~S1Jlt is d relatively low surrmer
<br />and winter precipitatior1 tiithin the valley. Figure 11-1 shows the
<br />location of the geographic features affecting the weather patter ns;n
<br />the vicinity of ~ontrose.
<br />
<br />The City of Montrose is located on the Colorado west slope within
<br />the UnCOI.lpahgre River Basin, approxilMtely 25 miles upstream of the
<br />confl uence of the U ncor;~ldhgre Ri ~er wi th the Gunni son Ri ver. Mont rose
<br />dlso lies dpproxiJlldtely 60 mile:; south of Grand Junction dnd the
<br />confluence of the Gunnison and Colorado Rivers. Figure 11-1 shows
<br />~ontrose and vicinity.
<br />
<br />B. Major Basin Characteristics
<br />Study Streams
<br />The three study stredms: Cedar Cree~, Montrose Arroyo, and Dry
<br />Cedar Cree~ either flow through or near the City of Montrose, Colorado.
<br />Montrose Arroyo flows through the center of Montrose, and is tributary
<br />to Cedar Cree~. Both Cedar Cree~ and Cry Ceddr Creek are tributary to
<br />the Uncompahgre River. Ceddr Cree~ al so flows through the City, while
<br />Dry Cedar Creek circumvents the City near its southern boun<1ary (s ee
<br />Figure 11-2),
<br />
<br />Soils
<br />-
<br />
<br />Four general soil associations predominate in the study watershed.
<br />1nthe lowerba,in, the Billing,-Christidnburg association is Inadeup
<br />of deep, nearly level and gently sloping,finetomoderatelyfinetex-
<br />tured soils on alluvial fans, flood plains, and terrace,. TheChipeta
<br />Persayoilssociation is constituted of shallow, neilrlylevel tohl1ly
<br />fi ne to rnoderate ly fi ne ly textured soil s deri ~ed from ,ha 1 e or .
<br />lTIudstone.
<br />
<br />The headwaters of Cedar Creek originate in the Ci""'drronRidge
<br />aredatanelevationofdpproximately9,40Dfeet. The creek flows then
<br />inogenerdllywesterlydirection,throughthenortheasternportionof
<br />the City of Montrose to the Uncompahgre River, the downstrealn 1 imitQf
<br />this study (approxir.iately 3 miles northwest of Mont~ose). The dra inage
<br />a red encompassed is approx i,~ate ly 56 square ,~i1 es (see Fi gure I I -2 -
<br />"SilsinondRainfdll IsopluvialMap" "nd Table 11-1 for dralnage dred of
<br />suo-basins and n~jor basins).
<br />The upper reaches nf Montrose Arroyo lie apilroxi,nately 7 miles
<br />",~st "f MDntrose ~t an e1 evat inn of approxiblately 7,SOO feet. Tile
<br />stream flows ino northwesterly direction through ttleCity of Mon trose
<br />to its confluence with Cedar Creek, irmlediatelYllorthwestofthecity.
<br />The st ream's dra i nage area is dPpl"oximately 17,8 s<luare ,~i 1 es.
<br />The upper "edches of Dry Cedar Creek lie approximately 10 miles
<br />southeostofMontroseotanelevationofgpproximately9,400feet. The
<br />streal.l flows ill a generolly norUiwesterly direction to its confluence
<br />with the Uncompahgre ~i ver one mile south of the City. The stream
<br />dra1nsdndredcomprisingapproximately21.9sqoarerniles.
<br />
<br />The Bostwick-Cerro dssocidtion is found in the upper baSin areas.
<br />It is composed of deep, gently sloping, moderately fine textured soils
<br />on alluvial fans and valley side slopes. The rock outcrop-
<br />Trdvessillaassociation is composed of bare rock outcrop and shall ow,
<br />roll1ny to steepr.:Oderately COdrsotextured soils found on hills,
<br />ridges,andsidesoflll€sas.
<br />
<br />Vegetation
<br />
<br />Along I"-Ich of the rn~Jor drain~\les, the '!eget i ve cover consists of
<br />eJ(trel"oly dense, cedar, juni per forest ~nd sd~ebrush, WIth acca.npanylng
<br />hedvydebris. The land in the upper basin is covered with moderilte to
<br />dense growths of bru,hwith a native \lrass understory. Thcremaining
<br />areas in the 10wcrbasin arc primilrily tile "8ildlandS"ilreas of steeper
<br />s lop~s wi th Illinf"'dl ground cover. The vegetat io" tha~ docs exi,t is
<br />composed basically of various 'lathe grasses and forbs, with occa-
<br />sion~l sage. The vegetation in the urbanized ~reilS is composed mainly
<br />oftrecsilndldwns, (whiChtendtoreducerunoffduetotheusuallllini-
<br />In"l slopeond tht' water absorption).
<br />
<br />TABLE 11-1
<br />MAJOR DRAINAGE BASIN CHARACTERISTICS
<br />
<br />Land Use
<br />
<br />Strea,n
<br />
<br /> Basin
<br />El!'vation (Ft. MSL) Len\lth r,vera\le Are~
<br />Headwdters Confluence (t'!i) Slope (') 12.<.\. Mi.)
<br />9400 5700 24.8 2.H 56.3
<br />7500 575(: 1G.6 3,' l7.S
<br />'1400 5800 14.3 4.7 21.9
<br /> .10-
<br />
<br />In the non-urbanized arcas of the basins, land use is devoted to
<br />either irrigated crop land {i.e., alfalfa,corll,mdize, or barley) or
<br />graz i n9 1 and. or the 1 and j s not used ~t all.
<br />
<br />Cedar Creek
<br />"1olltroseJl.rrOjo
<br />Dry Cedar Cl.e~k
<br />
<br />'. i t h i n the urUdlli zed por~ i on of tile bas i ns, tile non.;e~etat~d
<br />d r~a, dre 910nera 11y covered by buil dings or pd~e<: dredS (wh i cr. f>f~.
<br />
<br />-11-
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