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<br />6,'\'
<br />
<br />\.
<br />
<br />...""
<br />
<br />14
<br />
<br />Gnytnrtl V. Skogl',/t",
<br />
<br />conlinue all Ihe way across. Movemenl of bolh types of airma!Ses Is obslrucled and
<br />dCnccled by Ihe encircling mounlains so Ihal lheir inleraclions and eWeels wilhin Ihe
<br />ba~in are weaker and more erralic Ihan airma5Ses in mo~1 other parIs of lhe United
<br />Stales.
<br />The Pacific Ocean and Ihe Gulf of Me~ieo, whose nearesl eoasllines are 600 and 1000
<br />miles, respeelively, from Ihe cenler of Ihe basin, provide mosl of Ihe moislure for prccipi-
<br />lalion. Air masses moving in {rom Ihese souree~ are Pushed up 10 high altilude~ and lose
<br />much of Iheir moislure before Ihey enler Ihe basin (Iorns 1.'/ ",., 19(5).
<br />Averalle annllal preeipilalion rangcs from Icss Ihan 6 inehcs in Ihe 10wesI valleys 10
<br />more Ihan 50 inches in Ihe higher mOllnlains while Ihal in mosl vlllleys nnd nllrkllJrllral
<br />areus varies from 10 In 20 Inches A yeAr. rreclpltlllion from IlIle OClober through mid.
<br />Arril consisls primarily of snow, parlicularly al higher elevalions. Snow accumulalions
<br />occasionally e~ceed 100 inches al Ihe higher elevalions and do nOI complelely melt unlil
<br />lale summer.
<br />Temperalures vary widely wilh exlremes being recorded from _' fiO"F al Taylor Park,
<br />Colorado, 10 IIS'F al Lecs Fcrry, Ari?onn. Mcan monlh/y lempcmlure~ nre
<br />lowcsl in January and highesl in July and generally show aboul 50"F seasonal dilTerence.
<br />The average frosl-free period or ConsecUlive period with temperatures above 32"F varies
<br />from 20 days or less al elevalions above 8500 feel 10 more Ihan 180 days al elevations
<br />below 5000 feet. The growing season is slighlly longer than the frosl-free period for the
<br />grnss and alfalfa crops which predominate. on the higher elevolion lands. Annual evopor.
<br />alion from lakes and reservoirs is estimated.lo range from less Ihan 30 inChes at higher
<br />elevalions 10 aboul 60 inches in Ihe lower valleys (Upper Colorado Region State-Federal
<br />Inter.Agency Group, 1971).
<br />
<br />m,/." r/',vourcl'S
<br />
<br />An nvcrnge of IIholll 95 mn{ of wnler a yenr is provided hy precipilnlion in Ihe Upper
<br />Colorado Region. Ahoul 80 maf of Ihi~ is relurned 10 Ihe nlmosphere by evapolranspirn_
<br />lion. The rcmuinillg 15 maf i~ Ihe slre:llnlJow ,lI1d ground wafer rcchargc. ^pproximalely
<br />75 per CClll of .he rllnolf in Ihe region is produced from oll/y I) rer cent of the region.
<br />The aormal now~ eonlribllled hy all tribularies in the Vrper Colonldo River nll~in
<br />have umoun'ed to II low of 69011 million cuhic melers (5.fi maf in 1934) and a high of
<br />29,607 million cubic meters (24.0 mal) in 1917. The aClual nows available in any year are
<br />seen to be quite variable, while the average annual nalural now has been computed to be
<br />18.504 million cuhic melers (15.0 man for Ihe 1906-197) period (Ilun~en. 19751. Flow
<br />duraliOll 'uhles und eurVe~ nnd du.n dcscribing seusonnl nnd annuul disehllrge varinhili'y
<br />are rresenlcd by lorns .'/ "/,, (1965).
<br />Tahlc 1 prescnls perlinenl ~Ire:lfnnow, ~nlini'y, prcci'lilnlion. nnd Innd IIrea dalt' for
<br />ench of Ihe 21 suh-ha.sins used in Ihe slully hy !'lug .'1 III. (1'177). Suh-hllsins I 12 consli.
<br />tllle Ihe Ureell divisioll, ~uh.bllsins 13--17 the Grand diVision, and sub-bosins 18-21 the,
<br />San Juan division. Most of the data was adapled from Ihe work of Hyatt 1'1 at. (I970~
<br />which updates much of Ihe data contained in previous reporls. A map ShOWing the
<br />'percentages of stream volume and salt load passing Ihrough the downstream node of
<br />'each sub.bosin is presented in Fig. 2. Stream volume .nd sail load are referenced 10 Ihe
<br />long term averages al Lee Ferry, Arizona.
<br />
<br />.~
<br />
<br />...------ '''-"1~ ...........':"""'......"""l"'I' . ,....._.J"",.
<br />
<br />~
<br />
<br />.~ "R[ .~..,.,.. "',"~ _,,~.~.. .. ~....,.,....~, _
<br />~'" . """" n'r...._, -"r "'_' ~~~~""",_r.""II'!" '
<br />
<br />.. ......... ..~,r......",",.__. '".~..._.~ ._._.....,....~" L_:.
<br />, ..
<br />
<br /> Th~ Ph.v,dcnl Envlron",,,nl ollhl' Colorado RII'I" Ba.dn U
<br /> / !II M' ..I. ""'" pr~'pI'ft/ltIIl and 10"" o>ro.' ft.. ,h, h.rdrnl"lllr ,u,,"""dn.' al ,h,
<br />Tabl, /. A_Gj/' a"""a ....0... " . . UPPn Colarado 11./,." Bu,'n
<br /> Wiler. Sllinil'. A.e.... InnUlI Suh-hltin
<br /> Averl.e InnuII A \'trl.e IIlinil, A nra.. annul'
<br /> Anrage .." '"od precipitation .rtl
<br />Sub-bl.in .Ireomnow "olume concentrltion (metric tonl) lmm). lkm',
<br />numher (m'l,eel (m' . 10.' Im.m
<br /> 311 448.000 2mJ 19.4~R
<br />I 4'.77 144136 2494 8019
<br /> 8.29 26U' '66 14H.mO IIMI
<br />2 ftlJ400U 21H
<br />3 l614 1770.28 ]92 4~4 I 'I,I}4
<br /> 114 )}},IHKI
<br />4 40.49 1216 N2 1.911.t.mO 2'IO.R 11,B.t
<br />, II lH4 .IWI.91 .11101 10.412
<br /> 280.000 36U
<br /> 18.93 '91.08 468 10.ll]
<br />6 103 348.000 2169
<br />7 1'-69 49469 1.861.000 199.9 B94
<br />8 UO.68 4"2.00 392 l.R8'
<br /> 202.000 2Jl9
<br /> 2.66 83.89 2402 9,)24
<br />9 2.1 H ].000 1~0.6
<br /> U4.32 4866.7) 449 ....12~
<br />10 I Y4.000 212 J
<br /> 4.11 129.'3 1500 6.1>41
<br />II 2.4w.,"") I~K.O
<br />12 Ihl44 50'1 US 481 BI..I I ~.~11
<br /> 262 8.l1,I"lO
<br />Il 100.65 ]147.11 1.44~.IUl 1279 6.910
<br /> 117.16 3694.77 390 2O.l.\4
<br />14 1.4.1.1.000 30'1.9
<br />U 6'-91 2078.69 694 2223 4.0.\3
<br /> 173.69 "'77J8 647 3,l47.OlX) '~..174
<br />16 ].9~H.r"1O 300.7
<br />17 '97.16 6211.51 6H 192.000 ZO~.l 11.979
<br /> 88.82 2U9
<br />18 2.R2 617.mO 2962 lH11
<br /> 20Ho2 Jill
<br />19 65.1 J 917.1"") .llKU 26.1 ~9
<br /> 7412 2.\56.26' JK9 21 ~.9 JJ.O~K
<br />20 7.1KO.lU)
<br />21 42561 . J.4~~ ()/) ~KO
<br />. Wafer and ~8'illil)' fi(l:ure~ rdtr 1('1 ,he node ....'nci;lIed wilh tach lIuh-hllo;in U ..hn,," in hit 2
<br />
<br />j
<br />I
<br />f
<br />I
<br />I
<br />i
<br />
<br />M t f the walcr comcs fmm the mountai'ns and high plalcaus. .bul mosl of the sail
<br />I d os 0 flower elc\.ations whcre prccipilahon is low and IIl1le water IS conln-
<br />oa comcs <('m , fit
<br />' I ' TI\e Gnnd Division wilh Ihe smallcsl Innd arca (l I Ie I )ree
<br />bull'd 10 I Ie Slre,lIns. . . . . (F' 2)
<br />. . . I 'h I S n"'re w'lIer 'Ind more sail load Ihan Ihe olher dIVISIOns 'Ig. .
<br />dIVISions; con n u e" . , . . l F
<br />. I 4L ""r ccnt of the W'llcr and 51 per ce,lI of Ihe sail lo,1l1.11 .ce erry,
<br />ApprnKlmale y ",., , . . I D' .' .
<br />^ . Ie' frOllllhc 6' 422 "I"arc kilomelers (24.101 slIuarc mIles) (,ran, I"SIC1n
<br />rll"lla COli s ~.. 'I' r !lasin
<br />which aecounlS for approximately 22 per l'enl of Ihe 101." land area of the ppe '. .
<br />Nole Ihnl Ihe dissolved solids concenlralion of 5XO mg/l at Lec "crry, AnlOna resu"~ tn
<br />7,7MO.OOO melric ton~ of salt leaving Ihe UpJlCr nas~n annually. .
<br />EXlensive ground waler reservoirs arc located m consohda~ed rocks and allUVium
<br />throughoul the region. The ground water i~ inlerrelated wlI.h surface runoff. DU,rtng
<br />periods of high runolT waler moves from the stream chann.els tnlO Ihe adJaeenl aqulfcrs
<br />as ground waler recharge, Conversely, during low now penods. grOl~nd water returns to
<br />slream channels and augmenl, the streamnow. ^"hollgh larl(c quanlllles of gn'"nd waler
<br />lie beneath the region, developmenl haH been Iimiled 10 n"oll' 1.1.1.0(_1 af a ).("a; .''';der
<br />19(,5 conditions, MOH' of Ihe grollnd waler Wilhdrllwn is IIsed for ml~nll'lplll "I" mlll~-
<br />triol purposes (Upper Colorado Region Slale-Federal Inler-Agency Group. 1971).
<br />
<br />Land use
<br />The upper Colorado Region (Upper Colorado Region Slale-Federal Inter-Agency
<br />Group, 1971) includes 405,000 acres thaI are waler bodies o{ more Ihan 40 acres, af!-
<br />
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