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<br />u.o 1 3 2 <br /> <br />\ <br />I <br />\ <br />I <br />I <br /> <br />-9- <br /> <br />extent. Colorado says that dnta for drouth oonditions _ and sub-normnl cy- <br />cles such as 1951-1940, Ilre important, but. says thnt such d"ta should ap- <br />pellI' sepl\ro,tely from virgin flow estimations. Duo to the unoertainties as <br />to \'lhen nnotrer such cycle of years may bo encountered, and as to I'Ihnt then <br />mny be the status of development, Colorado snys that so-callod virGin 1'101'lS <br />for ouch Iln assumed drouth oycle will be misleading, and will not indicate <br />tho strellmfloYlG o.'/a11ablo for irriGation, power, and other purposes, unless <br />Ilccompllnied by reservoir operation studies to shol'l the offects of stream- <br />Clow regulation nnd the additional supplies of wnter thereby made avnilable <br />durinG such a period of yeo.rs. Colorndo suggesto the inc lusiDn in 10 he Ro- <br />port of suoh reservoir operation studies on virgin flow oonditions to shol'l <br />tho regulating effect at Lee Ferry and the Internntiono.l Boundary of mass <br />opcro.t ions of reservoirs above those points. <br /> <br />20. Virgin flow quontities "hown in the Heport are the sum Df. (a) <br />the average annual streamflows reoorded at (Dr oaloulated for) the desig- <br />nated gaGing station) plus (b) the allowanoes for upstrealn "depletions" <br />in the avernge yellr of the same periOd, - sllid "depletions" beinr, the 'luan~ <br />tities of wntor estimated to have boon vdthheld from the stream by the di- <br />version, use and storllge of wnter from and in the nlltural drainage basin <br />upstream from the designnted station. Neither the reoorded stronr.1floVlB nor <br />the "depletion" alloMlnoBs of the historio period, are shom in the Heport. <br />Colorado suggests that, for two key stations _ the lteport should contain <br />detailed information cOllcerninr, both items; nnd thr,t the lcoy stations should <br />bel Colorado River at Lee Ferry and IZlternntionnl Boundary_ <br /> <br />21. Colorado points out that sinoe "deplotions" are II part of tho es. <br />timnted "virgin flows," nn undorstanding of whnt is monnt by "virgin flows" <br />depends in part on the menninr, of "depletions," whioh nre defined in <br />c;enernl ns the differences between diversions nnd returns) and that evapo- <br />ration losses from oxlsting and potentinl mtlin-stem rosorvoirs uro entered <br />0." depletions, but a.re IIOt mensurab Ie by the differenoe between divorsions <br />and returns. A proper dofinition of "depletions" would inolude both the <br />manner of ealculation, or the L'Mtors employed in the estimations, and the <br />pl(\ce of evaluation, ,''''ether at tln plnces where such "depleticno." occur, <br />or in terms of thoir rosultin::; effocts at pcints downstream. The dnta <br />pr03cnto<1 nl'e inconsiotont in thi C ronpoct, nnd therefore are not diroct- <br />ly cOl,'pfIl"'hlc. lip pOl' \)f\3ill doplotions tlpp"nr to hf\ve boon ovnluatod ao. of <br />the I'l..lcllo whOI'll they ocour, whereas in tho Bouldor and Gila divisicns of <br />tho Lov,er Basin, the upstroo.m "deplet;ions" appear to have been croditod <br />with the estimated salvnc;e of water or reduotions in natural oonveyanoe <br />losses attributable to the diminished volumes and regulnted ohnrncter of <br />'~ho floYlG resulting from upstronm devolopmon'~. Colortldo urGes that both <br />lli\r;ins bo ~roated aliko. <br /> <br />22. The recorded "treal1lflows nt desi(7lntod Gac;ing stations nro the <br />unconnumod outflow" from l;ho upstrenm drainnCo basin, '~hnt vel'e not with- <br />held from the stream ei'~hor by rnnn-mo.do "deplotions" or b,y- natural 10sges <br />of wator. In calculatinr; the "virr,in I'lows" of the Report, the rnnn-made <br />"doplotions" v;Ore added to the rocorded outflows, and '~he naturnl 109ses <br />1'I0re ic;norod. Thus "virr;in nows" moy bo said to indioato tho stror,mflows <br />tho.t mic;ht havo been recorded durin,; the aVert\r;e :,;""1' of a similar climntic <br />