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CWCB Loan Narrative Overview 10 <br />PROJECT ALTERNATIVES <br /> HCIC has evaluated several different alternatives regarding the Cucharas Dam and the use of its existing storage rights. <br /> 1. Repair the Existing Dam to Allow Storage at a Reduced Storage Level. - This envisions repairing the existing dam and refashioning a spillway up to a standard that meets dam safety regulations, lowering the face of the dam and installing new gates. <br /> 2. Rehabilitate the existing Dam to Allow Full Reservoir Storage. - URS addressed this alternative in their 2006 feasibility report and determined that the costs associated with this alternative were greater than construction of a new RCC dam downstream of the existing dam. GEI also considered this alternate in their 2010 study and arrived at the same conclusion. Additional evaluations would be warranted to confirm if this conclusion is true. The core of the rock fill dam is stable and the foundation appears to be sound. 3. Rebuild a New RCC Dam to Allow Full Reservoir Storage. - This was the recommended alternative of both the 2006 URS and the 2010 GEI feasibility report and remains a viable long-term goal of HCIC. The estimated 27 to 30 million dollar cost would have to be phased in. SELECTED ALTERNATIVE Based on the potential increased amount of irrigation water to soon become available to HCIC and the resultant ability to re-introduce water back on the formerly irrigated farmland along with the recommendations of URS and GEI, HCIC has decided to develop a two phased approach to rehabilitating the Cucharas Dam. The new approach would be to initially and further develop engineering plans and analyses (Phase I) and then rebuild (Phase II) the Cucharas Dam. One of the major problems with the existing dam, which has been previously identified, was a significantly inadequate spillway. Under the previous SEO Rules and Regulations for Dam Safety and Dam Construction, the spillway was required to safely route the runoff generated by 75% of the probable maximum storm as defined by the National Weather Service. URS in their 2006 feasibility report estimated that the current spillway has a capacity of 42,000 cfs, but the routed reservoir outflow from the 75% PMP event was over 100,000 cfs and would overtop the dam by approximately 8 feet. Since that report, the SEO has promulgated new Rules and Regulations for Dam Safety and Dam Construction that allow reductions in the NWS PMP values for altitude and the use of a site specific weather model developed by the SEO for high altitude precipitation referred to as the Extreme Precipitation Analysis Tool (EPAT). Reductions of 40% of the Probable Maximum Precipitation (PMP) values have been observed in some basins with the use of this tool. Over 90% of the 640 square mile drainage basin flowing into the reservoir is above 6,000 ft. MSL, the lower limit for use