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<br />74 Na\ional Water Summary 1984-Hydrologic Perspectives
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<br />"vapO'allon I ' "
<br />MunlC,pal
<br />E~po,,~' and Industr,al
<br />Figure 43. Source of dis.
<br />solved solids in the Colo-
<br />rado River bas,", ($ou.ce:
<br />ModifIed from Janel, 19&4.
<br />P.33B.1
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<br />Dissolved So/ids- Case Studies
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<br />DISSOLVED SOLIDS IN THE COLORADO RIVER BASIN
<br />72G-4070
<br />
<br />By James E. Kircher
<br />
<br />INTRODUCTION
<br />
<br />The Colorado River i~ an important ~Olln:c
<br />of water for more lhan 14!j~ million people,
<br />many indu~trial usen, and about 2.'1: million
<br />acres of irrigaled agrll.:u]lural land. :\.. (he
<br />Colorado River and ih tributarie.. nO" from
<br />their headwaters 10 lheir mouth... the concen-
<br />lralions of dissohed ~olid'i. increase 10 undesira-
<br />ble lelCb, which result in millions of dollars of
<br />damage annually !() agrkullural, industrial,
<br />and municiral "atCT users (U.S. Bureau of
<br />Reclamation, )9R3a). The co,", auributed (0
<br />e)icessive dissohed solid, in lhe Colorado Ri\'er
<br />~yMem was about $91 million in 19XJ (D. H.
<br />.\h:rritl. U.S. Bureau of Rectam:uion. "riUen
<br />commun., ]98-1).
<br />The effecls on munkipal and indll~trial
<br />users o..'cur primarily as increased ,"aler-
<br />lrealmenl cmls. accderaled pipe corro~ion and
<br />appliance ,"car, increased usage of ~()ap and
<br />detcrgelll. and decrea..ed water palatabililY. For
<br />irrigalOr~, lhe grealer di..M)ln"d.solld.. concen-
<br />tratiom cau..e decreased crop yicld~, altcred
<br />cror pall('rn~, increased soillea;;tJing and drain-
<br />age requiremenls. and increascd managemerll
<br />eO\ts. Depending on the ~oil wndiliom, Ihe
<br />composition of dis,solved ..olid.. in lhe ";l{cr,
<br />and the lype of crop, agricultura] [mse'i. occur
<br />when di~..olved-~olids l'on~'\.'ntration~ of applicd
<br />irrigation water reach 700 to S50 miJJigram~ per
<br />Iitcr(mg/LI.
<br />The 1,400-mile (mi)-Iong Colorado River
<br />originate.. in the Rlkky .\lounlains of ColoraJo
<br />and i~ joincd by it<; principal lributary. lhe
<br />Gr\.'cn River, which originate.. in Wyoming.
<br />Th\.' ColoraJo River and ils tributaries drain
<br />2-1:!.OOO square miles (mi:!), including rans of
<br />seven Stales-ArilOna. California, Colorado,
<br />Nevada, New .\k\ico, Utah, and Wyoming. (lr
<br />onc-lwelfth of lhe cOnlerminous United
<br />Slales-and 2,()O() mi'= in .\le,ieo.
<br />Precipilation in th;.' Colorado River basin
<br />range.. from as much as NJ inche.. per year
<br />lin./yr) in the m;.lullIains to as little as 2 in./yr
<br />in the desen.. adja.:enl to the middle and lower
<br />reaches. The range in prccipitation and natural
<br />,"ct- and dry...:limatic cycles h:l\c affected sig-
<br />nificantly the den.'lopmenl of the Colorado
<br />River reservoir comrle\. \lany dams and res\.'r,
<br />voirs (')iisl along the Colorado River in order 10
<br />~lore ..ufficient water !() maimain no,", of lhe
<br />ColoraJo Ri\cr 10 meCl down..tream needs
<br />during dry periods. In fact, Ihe many re":[\oir~
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<br />in the Colorado River ba..in can ..tore amounts
<br />of "'ater equivalent to the aq:rage now of the
<br />Colorado River for several year.. (U.S. Geologi-
<br />cal Survey. 198.J, p. 32).
<br />
<br />SOURCE OF DISSOLVED SOLIDS
<br />The di"olved.solids concentration of the
<br />Colorado Riv'('f at its headwaters in the moun-
<br />lains i.. about 50 mg/L. This amOUnl increa'i.es
<br />progressivdy downstream as a result of WOller
<br />use and dis~oh'ed-solid.. contribution'i. from a
<br />variety of source'> and r;.'a.:hes an 3v'erage con-
<br />celllralion of about 850 mg/I. 3tlmperial Dam.
<br />Ari7. About om'-half of the dissohed-so1ids
<br />con.:enlralion in the Colorado River ba..in is
<br />;lllributed 10 nalural ~ourt.'es (U.S. Bureau of
<br />Redamalion, IlJS3bl. The remaining one-half
<br />of the collc\.'nlration i~ cau..ed by irrigation.
<br />r\."ervoir e\":lporation, river-ba~in e)irons
<br />fmo..tly of headwater no,"'>), and municipal
<br />and industrial u'e(fig. -13).
<br />Incr\..as\.... in disso]ved-..olid.. concenlralions
<br />are the re..ult of two main proccs..es-addition
<br />of di..solvcd ..olids!() wat\.'r from surfa;.'c-water
<br />and ground-WOller tributary inllows and the
<br />concentration of dis'olwd solids through waler
<br />loss;.'s l;Iy evaporalion. The addition of dis-
<br />_..olvl'd ,olids to a given amount of water r;.'sults
<br />primarily from ..urface water percolating into
<br />the ground and div.oh ing mineral _subslances.
<br />includlllg ferli1i7er... from thc soil and sub..oil.
<br />When the water return, 10 the river sy..tem, the
<br />di....ol\'ed-..olid.. load i.. increa..ed. The concen-
<br />lralion of di\\ohcd solid~ in water involves the
<br />los.. of ....ater by rc..enoir ev-aporation, by ex-
<br />portation of fre..her "aler from the basin, and
<br />l1y e\'apolrampiration from irrigated crops. As
<br />"aler i~ \.'vaporaled and lranspired by plants,
<br />the rl'sidual di."ohed ~(llid\ concentrale in the
<br />soil and remaining ,"alt'r.
<br />
<br />DISSOLVED-SOLIDS ANALYSIS
<br />Walcr dc\dopmenl has led to changes in
<br />the qUanlit~. and quality of WOller nowing in thc
<br />Colorado River basin. .\fO"1 walcr-develop_
<br />mcnt projecl" in the ba..in '"cre complete by
<br />I %5. For thi.. reason. thc period from I %5 to
<br />]l)SJ "a" chchen for analnis of the variatiom
<br />in dissoh;.'d-~olid~ load,: and conl'cntration..
<br />....ithin lhe Colorado River ba..in. These ana.
<br />I~w~ "crc made at 26 site" ,"hich had concur.
<br />rent rel,'ord~ of "Oller discharllC and dissolsed-
<br />..l)lidsl'onl,'cntralions (lab!\" -Il.L '
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