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c.) ~ additional diversions can be made upstream under tl'e same conditions in the .., ~ future, regardless of the status of storage in Caddoa Reservoir. Similar- """ ly, during winter months when irrigation needs are small or absent, the up- ~ stream flows have largely been diverted into storage; at times of major floods the upstream priorities and needs thereunder were fully satisfied; and at times when needs in Water District 67 were satisfied by local rain- fall, the upstream di tches heretofore have diverted all the streamflows whioh their oapacities permitted or their needs dictated, and hence, under the same conditions in tl'e future, no increased diversions can be made up- stream regardless of the status of storage in Caddoa Reservoir. 9. Waters impounded in the irrigation pool, representing flcms of the Arkansas and purgatoire Rivers that are undivertible or unusable upstream from Caddoa, will consist in part of supplies appropriated do~stre8l1l. or flows which if not withheld would or might have been diverted and used by ditches downstream in Colorado and Kansas; and in part of unappropriated wa- ters, or flows which if not impounded would or might have been unused and wasted. Segregations of the waters impounded in the irrigation pool. as be- tween appropriated and unappropriated volumes, if attempted, v.ould require arbitrary assumptions and large measures of estimation, and v.ould themselves be the source of continuing local Rnd interstate controversy, and of possible future litigation, The accounting with l'espect to the nature cf the im- pounded supplies, if attempted, would be further complicated by uncertain- ties as to prcper allcwances fer both siltation and evaporation. 10. The initial water storage capacity of the irrigation pool, as it is now constructed and as it may hereafter be enlarged by the installation of flood control gates, will diminish progressively or intermittently by reason of siltation, at rates whioh are widely variable and oar~ot be fore- oast with accuracy. being dependent on the frequency and magnitude of major floods, neither of which are prediotable. Ultimately, by reason of siltation, the effective storage capaoity of the irrigation pool will be destroyed. Its useful life may be extended only by the construction of storage faoilities upstream, to replace the capaoi ty in Caddoa Reservoir lost by siltation. While the extent of such depositions of sediment may be ascertained from time to time, after they have QOcurred, by periodic surveys from which pre- viously applicable capacity tables can be corrected, the quantity of water impounded at all other times. during intervals between such surveys, is neo- essarily unoertain, end the impounded quantities are subject to ohange, due to unavoidable losses by evaporation. at rates varying from day to day, and by months. seasons and years, with clirnatio and weather conditions, thus further complioating the aocounting and further multiplying the uncertain- ties and sources of dispute, if such segregations and determinations be at- tempted. 11. llhen the irrigation pool is empty, Caddoa dam will not interfere with usually prevailing streamflow conditions, nor with the delivery to senior priorities downstream in Water District 67 of waters claimed away fran junior priorities upstre!l11l in Water Districts 14 and 17. nor with the Stateline flows oommonly entering Kansas, - it being reoalled that appro- priators in Colorado have never been required, in the past, to refrain from diverting water, or to reduce the !l11l0W1ts diverted by them, in order to supplement or increase the Stateline flows entering Kansas. At times when (4)