Laserfiche WebLink
<br /> <br />- <br /> <br />BASIC S1UDIES <br /> <br />'--:; <br />:.." <br />~ Very li'tle increase in dissolved-solids pi~kup is expected ~h~n the ex- <br />r..: panded project goes 1nt_.o full operation. <br /> <br />The s~udies deS~ribed above afford some Suppor. for the assumptions <br />set forth earlier in 'he report that a pickup rsnge of from ~ero to 2 tons <br />per acre is indica1.~d fa:" i rrib'"ated acreages af:,er :he inltinl leaching. <br />The pickup on 'he Florlda Project is negligible and that on the Eden Proj- <br />ec' ....ill p!'Obably stabilize a litf-Ie above 2 t.ons per aCT'2. <br /> <br />Considerable v3.riation in '_he effects of irrigation ret.urn flo'", on <br />""ater quality is to be expecr~d. Differences arise due to the size of <br />'he irrigated area,:;,. the number of '_imes the ret.urn flow is rensed, prop- <br />0rties of the soils and drainage area.. nUJ:lber of year~; land has been irri- <br />~uted, nature of aquifers, rainfall, dilution. tempel~~ure. irrigation <br />me~,hods, st,orage r::-servoi r'.3, '/egetat.ion, and type 01. return 1'10'" channels. <br /> <br />Cons~~ptive use and return ~lo'" studies are now being ~~dertaken by <br />t~he Burea:, of Reclamation on existing proJeets in small, closely eon- <br />rolled areus, Wi <:,h a small addi tional expense~. it has been pos$ible to <br />obtain quali t-y data and thereby determine the effp.~+ of irriga~,ion on wa- <br />ter quali....y. The study areas are purposely beint'. held small to achieve <br />ber,ter control. bw r~hey '..'ill be as representat ive as pOGsible of exist- <br />ing prO,iects, Th.o> rA.sult.F pertaining .,0 the quanti ty of return flow will <br />be very helpful in ,~stirnn'_ing eff~c:ts on ....ater quali'y of ret'.lrn flo....s <br />from larger areas where measurement of inflow and ou~flow is nat al~ays <br />possible or pI"a2'tical. <br /> <br />Special s.:.udies in other areas in the basin wi 11 be undel"::.aken from <br />'.irne to time :'0 de:,el"llline watcr quality condit ions. and studies of proj- <br />':.~ such as Florida and .t:den ....ill be repeated or continued in order to <br />-ialuate r.:!l<'lnges WiLh ',.ime, The mor~ c:omplex al".~af ....ill be considered <br />for inveti~igation at a later dat.e ...hen sui'ficlen'_ funds are available <br />to carry OUt meaningful s~udles, Proje~~s in '.hi. -.::at_egory i!lclude 'he <br />Grnnd Valley and UI:compahgre Pro,iec:,; in Colorado 'lnd possiLly some di- <br />re"t diversiOIi prc,iec'_s along 'he Colorado Rive!' bel()',; Hoover Dam.. such <br />as Pnlo Verd"" Valley and t.he Colorado River Indian Reser-/a',ior... An im- <br />pOTran-<- .~onsiJeratlo!'! in quality studies is mea~l-lr'~ment 01' re' ,.1r!1 flo..... <br />If ~.he re' urn flow can b,- measured and i ;3 queli + y j~ +~er.:li!1ed. the ....a :.er <br />and 5a1-:: blJdge~s can 0,' c:ompu~.ed b,'cHlise '.he inflo.... ~" nearly ah;ays <br />gaged and i t-~ quali ty easily de'eI"_'lineLi. <br /> <br />'1\.10 ar'_,as no~ being manl ,ored for irrigation effe(~t5 are the Seed- <br />skad~e Developmenr ~arm and a block of aboue 700 3cre~ of land ..1:hin <br />~,he Grar:.d Valley Proje0t. The Grand Val:'e~,. area is part.iaL..:: isolated <br />by natural washes and drained sllfficien~,ly to pemi '_ $ampling ani meas- <br />uring of return 1'10..5, Sa:nplinF began during t!i,f: 1966 irrigation season, <br />bu~ the resu11.s are no' sig:1ifi..~a.n;. enoUf;h ',0 indica'.e a trend. <br /> <br />30 <br />