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^' , . , '. .'. - . ,(}lJ19'2::l i::'~,:':k;:'(;.t>< ' .......-... :..:". -7- or greater assumed releases from storage, will he,ve the effect of reducing losses of water from the reservoir by evaporation and spill (a result which is evident and admitted), and will thereby increase the "amounts of usable water," - a conclusion questioned by Colorado depending on whe.t is meant by "usable water." On the other hand, the !';raphs and other tabulations s'lbmit- ted by Kansas tend to show that greater assumed relee,ses from stor!\ge are also aocompanied by smaller average volumes of water in storage, and by per- iods of greater frequency and longer duration when the reservoir will be empty. This means that the assumed greater releases. from storage must be made during shorter periods of time, and that any release in exoess of essen- tial irrigation requirements at the time, even though such excess release be at divertible rates, may in fact be wnsted and lost through non.use. Ele~ ments of time as well as volume are neoessarily involved in suoh water supply and irrigation requirment considerations, and estim~tes of losses of water 'should inolude totals from both river and reservoir. 18. As shown by available streamflow reoords at the State line and Garden City, relatively large volumes of divertible streamflows (and of so-called "usable water" as here calculated by Kansas) were wasted and lost through non. use for the reason that, at the intermittent times of their oocurrence, their volumes were in exoess of essential irrigation requirements at the, time. Plans for operating the irrigation pool in Caddo a Reservoir should not be;based on arbitrarily assumed releases from storage, but should recognize, among other things, that water supplies at and belaw Caddoa are related to eaoh other, are parts of the waters of the interstate stream, and are not unlimited in amount; and that reservoir operations, to regulate Caddoa flows heretofore di- verted and used in Colorado and Kansas, and to conserve Caddoa flows hereto- fore unused and wasted by Garden City, should oontemplate releases from stor- age to supplement the supplies diverted from unregulated streamflows and re- ceived from natural preoipitation. 19. From river and reservoir operBtion studies previously made by Colo- rado it appears that "demands on the reservoir" assumed by l\ansas in Studies 3 and 4 were arbitrary and exoessive, with the result that the c~lculated greater "ll.lIlounts of usable water," and of so-o!\lled "new water" estimated therefrom, are misleading. The reported results of Study 2, after oorrection for "Caddoa flows heretofore used in Kansas," indioate an 'tVElrage annual quan- tity of so-oalled "new water" that appears to be consistent with the quantity of so-called "surplus" calculs.ted by Colorado for the same period used by Kansas, when the two results are adjusted to the srone basis for the ll.lIlounts of water heretofore used in Vlater District 67 and in Kansas. 20. Both the "new water" and "surplus" quantities above mentioned were caloulated; and reported o,S '.verages, for a study period representing what may be termed the first-,half of the useful life of Caddoa Reservoir irrigation pool, during which the effective storage capaoity, progressively diminished by siltation, averaged about 300,000 ecre feet. Similar studies covering the second.half of the useful life of the irrigation pool, if made, would involve an effective storage capacity averaging about 100,000 acre feet, or one-third that assumed for the studies under discuss~on, and probably would disclose correspondingly smaller quantities of "new" or "surplus" water. Hhen the