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002030 Tudor/State Alternative 8 Preliminary Alternative 8 would have only one major feature, a 196,000 acre-foot capacity Elkhorn Reservoir (See Map 3). This reservoir would store flows from the South Fork and upper mainstem for eventual release to the River to serve conservation uses in the lower basin. A 14.0-megawatt Elkhorn Dam Power Plant would generate power using these flows. These flows would occur mainly during the irrigation season and would produce some intermittent dependable capacity. An average of 47,300,000 kilowatt- hours of energy would be produced annually be this alternative. Elkhorn Reservoir would supply 64,800 acre-feet of water per year for municipal and industrial uses and 216,700 acre-feet of water per year for agricultural uses. It would produce a yield of 14,400 acre-feet of water per year of new water. It should be noted that there are only two competitive "sets" of alterna- tive projects. The first set would be Grey Mountain Reservoir standing alone (Alternative I), with a possible major peaking power addition con- sisting of Idylwilde Reservoir plus major power works, which produces Alter- native 2; and the second set being Elkhorn standing alone (Alternative 8), with a major peaking power addition consisting of New Seaman Reservoir plus major power works, which produces Alternative 7. The two major sets are mutually exclusive, as the selection of one set forecloses on the develop- ment of the other. Within each set, however, the conservation reservoir cmlld be developed independently with or without the peaking power elements. Thus, it is probably most meaningful to compare the single reservoir alter- natives, Alternative 1, with Grey Mountain Reservoir" versus Alternative 8, with Elkhorn Reservoir, separately and then the peaking power increments consisting of Idylwilde plus associated features (Alternative 2 minus Alter- native 1) and New Seaman plus associated features (Alternative 7 minus Alternative 8). Because of the high heads and flows available, run-of-the- river power is a logical increment for all alternative projects. Thus, it would be most enlightening to view the single-reservoir alternative projects as multipurpose conservation storage structures encompassing run-of-the-river hydropower. It is not appropriate to attempt to compare Idylwilde and New Seaman separately, as they were not formulated to stand alone. Summary Evaluation From an engineering standpoint, no apparent reasons are found to preclude construction of any of the four altetnatives studied. No serious geologic problems were found. .",,further optimization of facil ities' designs would be necessary, according to the report, to develop more refined cost estimates and better project output data. 4