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. o CHAPTER 'II COMPREHENSIVE PLAN o The minimum monthly discharge of White River in extreme drought years under present conditions of upstream development would be nearly twice the peak monthly diversion re~uirement of the irrigable land area under the Savannah Butte Canal, The only flows available for diversion from the White River to the Savannah Butte Canal, however, would be the residual flows of White River remaining at the canal diversion site after upstream development of the potential Yellow Jacket reclamation project and pos- sibly other potential ups~ream industrial developments. Although the available residual water supply is assumed to be ade~u~te for irrigation of the lands under the Savannah Butte Canal, a careful a~alysis of the ade- ~uacy of the supply under conditions of future comprehensive upstream development would be re~uired for feasibility investigations, " Return Flows , n Return flows from use of project w&ter on Deadman Bench are expected to accrue in Red Wash and be available for diversion by the Wonsits Canal. Return flows to Red Wash are expected to average approximately 60,000 acre- feet annually or about 40,000 acre-feet during the irrigation season. Estimated distribution of return flows over the irrigation season is shown belOW, . May June July August September Total Acre- feet 4,700 7.500 9,300 10,000 8.500 40,000 The estimaterlof return flow for the Juniper project were made by com- parison with actual measurements of return flow on Orchard Mesa near Grand Junction, Colo, , which has comparable climate and is at approximately the same elevation as Deadman Bench, Return flows. were estimated on the basis of 1,61 acre-feet per acre from 37,000 acres of land on Deadman Bench. This figure represents diversion re~uirements at the turnouts from main canals with allowances made for water that would be lost through consump- tive use on project lands and in incidental areas, Allowances also were made for return flows that would accrue as a result of canal seepage losses. . Some regulatory storage probably would be re~uired on Red Wash in order to assure that return flow would be available at the head of the Wonsits Canal at the beginning of each irrigation season. The need for this stor- age and the probable ~uantities and ~uality of the return flow from Dead- man Bench will be further studied in any future investigations undertaken of the comprehensive plan, Probably the development of return flow could best be deferred until actual measurements could be made of the pattern of occurrence and the ~uality of the water. 31