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- I " , iJJ'c Summary of Evaluation of Alternatives Three of the alternatives considered in the analysis, Alternatives III-A, l\I-E, and l\I-F. could develop more water than any of Ihe olher alterna- tives. Nternative III-A was estimated to yield 102,000 acre-feet per year for release from storage, with34,000 acre-feet being delivered for use after conveyance losses, AlternativellI-E waS eslimated to develop approxi- mately 200,000 acre-feet per year for release from storage, with 160,000 acre-feet delivered to the Republican River Basin, Alternative III-F would develop 191.000 acre-feet per year, and recharge 63.200 acre-feet into Ihe South Plalle River alluvial sys- tem: of that, an estimated 42,200 acre-feet would be recovered. The expansion of an existing down- stream mainstem storage facility [Alternative III-D) or the conslruction of a new storage facility on a plains tributary (Alternative IV-A) would result in the smallest amount of water being developed and delivered for use. Potential water development in the upper mainstem part of the basin or on mountain tributaries would, in general. require a much greater fi- nancial commitment in terms of construction costs and interest during construction, This is indicated by the estimated investment costs shown for Allernatives loB and !I-A, Alter- native I-B. as described for purposes of this study. would require an in- vestment of over $1 billion. Alter- native I-C. managemenl changes of existing facilities, was assumed to require no initial investment to pro- vide a municipal watersupply. Pres- enl storage allocaled to water con- servation or flood control would be converted to municipal water supply storage, Alternative II-A includes a hyrdoelectric power component re- sulting in some of the larger initial , investment costs. 12 In all cases except Alternative I-C, the net economic benefit is estimated to be negative: Le., Ihe presenl value of project cosls exceeds the present value of project benefits, Alternative loB would involve the construction of new off-channel storage facilities to store upstream mainstem flows and has the lowest net economic benefit, Alternative I-C is the only alternative with a positive net eco- nomic benefit ($6.3 million). because it was assumed to require no initial investment, The analyses presenled in this study showed eslimated costs exceeding benefits; Le., the benefit-cost ratio was less than 1,0 for every project except Alternative I-C, (No benefit- cost ratio could be estimated for Alternative I-C because no costs were associated with this project.) The one project which contains a hydro- electric power component. Alterna- tive !I-A. has the highest benefit- cost ratio, Projects which involve an expansion of existing facilities. Al- ternative I-D and II-D, would require a much smaller initial investment and demonstrate a relatively larger benefit-cost ratio than the other alternatives, Most of the alternatives were esti- mated to provide small positive changes from present water quality conditions. The only exception is for Alternative !l1-E, which may cause a large negative change in water quality conditions in the downstream mainstem South Plalle River, because a large volume of water would be diverted from the South Platte River Basin and exported into Ihe Repub- lican River Basin. Allernative I-A may cause a large negative change from present fishery conditions within a reach of the upslreaID mainstem South PIalle River, The construction of an up- stream main stem reservoir would eliminate part of the cold water river- ine fishery and replace it with a stocked reservoir, Development fa- cilities outlined for Alternative U-A also may cause a large negative change from existing conditions. In contrast, the expansion of existing faciliJies(Aiternatives I-D. II-D. and III-D,) would cause small to moderate posilive changes in existing condi- tions. The expansion of these reser- voirs may resull'in higher lake levels for longer periods, which would contribute to more productive fish- eries, Terrestrial wildlife also might benefit from these conditions.