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<br />, THE PROBLEM
<br />
<br />The Colorado River Basin encompasses portions of
<br />seven states. The river fIaMt over 1.400 miles from its
<br />_ In Wyoming and CoIoIado, joins with
<br />tributaries In Utah and. New Mexico. flows through the
<br />Gmnd Canyon, provides state boundaries for Newd8.
<br />A~na, and California; and terminates In the ~ulf of
<br />California In the Republic of Mexico,
<br />Use of the river's water now and in futureyears has been
<br />81_ through along histol)/ of appropriations and
<br />~ that Include com_litigation, Ieglolation,
<br />and an In1Bmationaltnlaty,
<br />About half of the pre9(:Vlt salinity. conoentration in the
<br />Colorado Riwr at Hoover Dam near Las Vegas is
<br />atbibuted to natural sourtes. The remaining half Is man-
<br />induced as indicated in the chart.
<br />
<br />
<br />47% Natural Sources
<br />
<br />37% Irrigation
<br />12% Reservoir Evaporation
<br />3%exportll
<br />1%M&1
<br />
<br />~__~..<t--..,..,._
<br />
<br />For Irrfgators, theh~her Salinity conOentrations cause
<br />--....ad crop yields, aJtered Crop patterns, Increased .
<br />leaching and dr81naga requiremanlll, and In_ ,
<br />management costs Agricultural Josses (either through
<br />lOwer yields or increased pn)ductlon!~costs)
<br />begin when salinity leveia of applied Irrigation water"""'"
<br />700 to 850 mgIL, depending upon.soil conditio!ls and
<br />typeof'crop grown, A summal)/ of the effacts isplOllElllted
<br />~ ' ,
<br />
<br />mgIL
<br />
<br />Eflecl
<br />
<br />Below 500 .
<br />Above 500
<br />7llO-85O and
<br />above
<br />
<br />Good drinking water
<br />Municlpal and industrial losses
<br />Agricultural losses
<br />
<br />The Colorado River, at Its headwaters in the mountains
<br />of north-central Colorado, has a salinity (dissolved
<br />minerals) concentration of only about 50 mglL The
<br />salinity concentrations progressively increase d0wn-
<br />stream as a result of water diversions and salt
<br />contributions from avarietyofsources.ln 1981, thesalinity
<br />concantnotlonawmgedabout816 mglLatlmperialDam,
<br />the last major diversion point on the Colorado River in the
<br />Unl1ed States, Without control measures, the
<br />concentration ia projected to inc....., possibly """"'ing a
<br />level of 1009 mgIL' a'lmperiaJ Dam by about 3)10,
<br />
<br />, salinity CQ(iCenbation increases result from two
<br />prDCassos: saIlloedlng and saIlcoo.;,.,b_ Salt
<br />Ioeding il1Cl8llll8S the amount of sail for a gi'len amount of
<br />Walar, and sail conoentraIlon __ the am<>unt of
<br />diluting wafllr for a gi'len am<>unt ofl!all ..
<br />,'SaIlloeding is the add_ tothe_systamofmlnera/
<br />saIl$ fiom _ra1 and manmacle sour"es/SaIl
<br />cOOcentratIon _lis fiom the rlsa In salinity through
<br />~ depIQtions which COI~ .baltl the salt burden
<br />Intoa Jessarvolumoofwa1Orlnthe_systam, Generally;
<br />, the ai>pJ1Qltion of irrigation waIar....,1Is in Increased sail ,
<br />~becauseofsattloadlJ1g and 001 IIC6.lbClUng
<br />effects 01 consumpllvo use. The,loIaI saIlloed In the_
<br />fluctuates annually with the oVerall BasIn wa10r supply,
<br />As tho fpIlow1ng graph 11/_ since 1949, the'
<br />genenoIlnlnd Insalinlty coo";","dlIons at Imperial Dam
<br />has beeo upwanl, and the proJei;tad _ through the
<br />year 2010 (without waIar quality Im_ program)
<br />8leexpected to follow the oVerall rising lnlnd.
<br />The Josses _ with munldpal and Industrial use
<br />oCCur primarily from Increased waIar treatment costs,
<br />acoeIetated pipe corrosion and appliance wear, Increased
<br />soap and -.gem Illlllds. and --....ad water
<br />pa/alabillty, The EnvIronmon1aI _ ~
<br />recommends drinking water contain no more than
<br />500 mgIL ofTDS (loIaI d_ solids),
<br />
<br />
<br />TOTAL LOSSES
<br />$513,300 per mg/L (1982 dollars)
<br />
<br />~68f
<br />
<br />
<br />---
<br />
<br />-
<br />,
<br />-
<br />-
<br />,
<br />
<br />-~
<br />------
<br />
<br />-
<br />,- ,...,
<br />
<br />-,
<br />
<br />JI_w_-..._......
<br />-..."...inI.....1_...~o.n._........-....,."",...,2D1(I.
<br />
<br />The h~h saIlloed of about 9 mil/ion tons annually
<br />en1srIng Lake Mead in the Lower CoIonldo River BasIn
<br />advaISe;y effacts """"_12mll/lon people and 1 mil/ion
<br />IlCI89 of Irrigated lannland In the United SIatas.~
<br />In the am<>unt of $513,300 8Ie projected to occurforaoch
<br />inaeese of'l mgIL at Imperial Dam when salInity
<br />COlII,,~"llbcdlons l1lIICh the 875 to 1225 mgIL range, In
<br />1982, damagas were approximataly $113 mil/ion, Unless
<br />controia8le Implemanted, thedamagas could rlsato$267
<br />mil/ion annually by tho year 2010,
<br />In the lata 196O'sandear1y197O's, _aitheragional
<br />and national level began to recognize the _ and
<br />-. solutions,
<br />.Current projection from Quality olWater, Colorado River
<br />Bas'n. Progress ReportNo. 11, January1983. Department
<br />of the Interior.
<br />
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