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additional costs for restocking after winter fish kills. The no-action altemative was considered unacceptable. Alternative No. 2, purchase senior water rights, or a lease of a dependab/e augmentation water supply to allow the lake to remarn full in all years, was rejected because firm-yield senior water rights are not available in the quantity required to offset evaporative depletions in a dry year. This alternative also involved the enquiry of purchasing or leasing senior water rights from Denver Water delivered via the Roberts Tunnel to the North Fork. This alternative is not feasible since the Robert Tunnel water must be used in the Denver Metro Area as mandated by Denver's Blue River decree for that water. Alternafive No. 3, regulate reservoir levels and purchase water riQhts. This alternative may be feasible depending on the seniority of the augmentation water rights actually purchased and their location in the river basin. The more senior the augmentation water, and/or the closer the augmentation source is to the North Fork confluence with the South Platte, results in less fluctuation of lake levels. The concept of this alternative is to allow the KTC to continue to divert water from Beaver Creek. When the ditch is out of priority in normal hydrologic type years reservoir evaporation depletions would be offset with augmentation water purchased that is available in average type years but not in dry years. In order to continue diversions in dry years when augmentation credits are not available, a low level outlet would be installed to allow releases from storage to make up for evaporation losses. In other words, during times of a senior call with no augmentation water available, lake inflows need to equal lake outflows. Our preliminary opinion on cost to implement this alternative is $20,000 to 50,000 to modify the outlet works. A conceptual drawing of the outlet is provided in Appendix F. The outlet is designed to be located at the emergency spillway rather than the dam, to possibly avoid the more detailed approval process for dam modifications. The cost to purchase water rights is estimated at $250,000 to $550,000, which costs depend on the amount, seniority and location of the augmenting water rights. Operationally the lake levels may still experience severe draw downs in a series of dry years if marginal senior water rights are purchased for augmentation as seen in Alternative 1. The difference is that fresh water could be run through the lake more often to benefit the fishery and water quality, and the augmentation water supply would allow the lake to stay full longer for recreational purposes. Selected Alternative No. 4 is Alternative 3 plus raising the existing dam approximately one foot. This allows the lake level to be returned to historic levels prior to the State Engineer lowering the level to maintain three feet of free board for dam safety. In addition, senior water rights would be purchased and converted to augmentation water to offset evaporation during most circumstances. The increased capacity from the dam crest raising would allow storage to offset evaporation when the augmentation water is out of prioriry. In severe dry years, the lowered outlet would allow diversion to the lake to continue, because evaporation losses would be made up with releases of storage water down to elevations lower than physically possible at this time. This combination appears to best meet the needs identified by KTC to maintain high water levels for recreational purposes, provide a constant source of inflow and sufficient depth to maintain the fishery. Kenosha Trout Club Page 5 of 9 Feasibility Study - Augmentation Water Purchase 1038KTCO2 March 2001