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:2'; 1e~timates. The previous and present pondage capacities are as follows, Forebay capacity--Princeton Pow~rplant Forebay capacity--Pancho powerp1.anb Salida Forebay Salida Afterbay Previous (acre-feet) 500 200 250 200 Pre sent (acre-feet) 500 250 300 300 The hourly operation studies took advantage of the additienal check structures now provided in the power canals which will permi.t change in power releases as may be necessary to. meet load requirements. Power releases from Salida Afterbay were held to plUS or mi.nus 25 per cent of average releases to avoid a wide fluctuation of river flow below Salida. Irrigation and municipal water supplies Previous water supply studies for irrigation were based on a service area figure of 322,000 acres and the 1911-1944 period. With the organization of the conservancy district, the total irrigation service area was reduced to 280,600 acres. About 267,800 acres are situated in the Arkansas River Valley and will receive direct service by the project. The Fountain River Valley lands of about 12,800 acres can be served only b.y return flows from municipal water used b.y Colorado Springs. Reduction of the project acreage and extension of the water supply data necessitated revision of the original reservoir operation study. Because revised transmountain importations varied only slightly from the original estimates, it was considered necessary to revise only the operation of the terminal Pueblo. Reservoir. Thus imported water, plus storable Arkansas River flood flows, plus past winter diversions, was regulated in the Pueblo. Reservoir so that irrigation supplies and benefits under the revised acreage could be determined. With respect to irrigation, this operation study gives the same results as would a combined power and irrigation operation except fer the effect of evaporation from upstream reservoirs. SUch evaporation would reduce the project yield and introduce mi.nor errors in the spills. These factors, however, were accounted for by analysis and their effects are reflected in the irrigation benefits. The Pueblo Reservoir study was made for the period 1911-1957. The preproject headgate shortage for the 267,800 acres of Arkansas Valley lands in the service area is 317,200 acre-feet annually for the 47 years of study. The post-project headgate shortage for these lands for the same period would be 154,100 acre- feet annually. Thus, the project would alleviate J.63,100 acre,.feet 12