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optimal reservoir capaciry under current administrative practices. Their analysis is presented in a report titled "Evaluation of Yield from Cucharas Reservoir No. 5" and dated December 2005. A supplement to this report was completed in November of 2006 and is titled "Yield / Exchange Evaluation of Cucharas Reservoir and Huerfano Valley Diteh". The report details the exchange potential and timing for exchanges to other reaches of the Arkansas River basin and is presented in Appendix F for reference. Based on the results of their hydrologic analyses and the reservoir operation model study, Lytle Water Solutions offered the following conclusions and recommendations: 1. The average annual inflow to Cucharas Reservoir is estimated at 8, 460 ac-ft/yr with a range from 160 ac-ft/yr to 35, 500 ac-ft/yr for the period of record 1980 to 2003. 2. In priority flows from strict administration of the main stem of the Arkansas River is estimated to average 2, 565 ac-ft/yr and range from 25 ac-ft/yr to 27,300 ac-ft/yr for the period of record 1980-2003. 3. The yield of the reservoir is relatively insensitive to the alternate elevation-area- capacity tables that have been developed for Cucharas Reservoir. 4. Because the Cucharas River's runoff happens earlier than the Arkansas River's runoff, the calls placed on the Arkansas River now affect the Cucharas River such that there is a large amount of runoff in the Cucharas Rive that must be passed through the reservoir and cannot be stored. When the Arkansas River begins its runoff and in priority water may be available in the in the Cucharas River at the reservoir, there is very little flow in the Cucharas River, so additional storage availability is minimal. This creates a relatively low average annual yield when compared to the maximum storage capability. 5. ° The Huerfano Valley Ditch can provide significant water supplies if the HCIC temporarily retires the consumptive use associated with historic use of the ditch. The yield could be on the order of 3,100 ac-ft/yr. 6. While the average annual reservoir yield was 1, 319 ac-ft, the distribution of these yields was more sporadic. No firm annual yield could be developed from the reservoir due to the sporadic yields. However, by using Cucharas Reservoir as a supplemental source to the Huerfano Valley Ditch, the target demand was met in 11 of the 24 years simulated. 7. Based on the results of the hydrologic analyses, the capacity after rehabilitation of the existing dam or building a new dam should be similar to the current storage capacity of approximately 28,000 ac-ft at the spillway crest. Water rights held by the Huerfano - Cucharas Irrigation Company are tabulated as follows: Huerfano-Cucharas Irrigation Company Water Rights Name Huerfano Valley Ditch Huerfano Lake Huerfano Valley Ditch Cucharas Reservoir Adjudication Date 02/23/1898 02/23/1898 10/03/1921 10/03/1921 Priority Date 02/02/1888 02/02/1888 2,101 ac-ft 02/23/1898 18 cfs 03/14/1906 Absolute 31,958 AF Amount 42 cfs Cucharas Reservoir 10/03/1921 03/14/1906 Conditiona135,404 AF Cucharas Feasibility Study ~ Project Background and Need