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293u xviii ., only be reduced by use of a storage reservoir. Under ultimate operating conditions, a major portion of the shortage would be met by direct use of return flows from developmen t of other transmountain diversion projects in addition to return flows from the Colorado-Big Thompson Project. Under ultimate conditions. based on assumed return flows from upst:-eam develoj:lllent, there would be sufficient water provided through regulation of the South flatte River by Narrows Reservoir to irrigate 30,000 acres of currently dry-farm land or land partia.lly supplied by pump irrigation. Disposal of Water As stated previously, ultimate operation of the Colorado-Big Thompson Project, increased transmountain diversions by the city of Denver, and upstream irrigation and stora~e development by other potential transmountain diversion projects will. in the near future, significantly increaEe the water supply in the South Platte River. During the interim period, when only the oolorado-Big Thompson Project has been developed, the water supply available from Narrows will be used to provide a supplemental irrigation water supply for ~bout 230,000 acres of land lying along the South Platte River between Kersey and the Colorado-Nebraska State Line. Because of changes in the flow of the river, it is not believed desirable to set final pay- ment arrangments nt this time. In all fairness to water users. they should experi- ence the effect of the changed flow induced by tra;Jsmountain diversions before final repayment arraagements are made. In t11at belief i it :',"-s been proposed to the Com- missioner of ;:eclanation that for the interim perioe, yeater service contracts be- tween the United ~tates and individual water users or com[.anies shoYUQ be negotiated on an annual basis. The {rice at vrhich nateI' HOul" be sold each ,'ear nould be based on the anticipated supply and demand and the economic factors for that year. Under ultimate conditions, the water supply studies indicate that approximately .30,000 acres of new land can be furnished a full 'water supply. After full effect of the transmountain diversion has been demonstrated,a peI'manent repayment unit could be organized to contract for use of the water made available by the Narrows Reser- voir. As the adequacy of the supply is demonstrated, the distribution system to servr, the new lands would be built. A suitable allocation of reservoir Bpace would be made between water users needing only a supplemental supply and those requiring a full supply to insure equitable distribution. Summary o Negative benefits occasioned by the project: take out of production over 6,000 acres of productive irrigated land; remove ~rom the tax rolls, 26,150 acres of land that would be flooded by the reservoir; remove human habitation from 2,150 acres on which flood easements would be acquired but on 1Jhich farming could still take place. " Positive benefits would result: in the form of flood control along the South Platte River below the dan; in increased crop !,roduction by providing supplemental water for 2.30,000 acres during an interim period plus a full supply for 30.000 acres under the ultimate plan; by providing sediment control by retaini."-g harmful sedi- ments from Bijou Creek in the reservoir; by providing incidental fish and wildlife and recreation benefits. In the short term, increased t~ade would occur in the Fort l';"rgan area. The Narrows would be ofel'ated in accordance nit:, ";tate >:ater laws. In con- clusion, benefits in proportion to costs no,~d be at a ratio of 1.27:1 during the interim period and 1.52:3. during the ultimate period.