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Sijou Irrigation District September 18-19, 2007 Agenda Item 18a Reservoir Storage 5/1 8/1905 1/15/1914 37,709 20226 Volumetric decree This decree is for additional Gage amounts to fill the reservoir to Reservoir Storage 5/18/1 905 1/13/1936 Height 26302.20226 GH 30.0 if the 30.0' volumetric decree does not fill the reservoir Reservoir Storage 12/31/1929 6/08/1965 37,709 31423.29219 Refill decree Proiect Description The purpose of this project is to undertake repairs to the District's irrigation diversion structure to ensure that it can continue to divert water from the South Platte River. Several repair alternatives were looked at, as follows: 1. No-action alternative 2. Perform temporary remedial work to return diversion to normal operation 3. Replace 100 feet of diversion structure with new spillway gate, using existing intake gates 4. Replace 200 feet of diversion structure with new spillway gate, using existing intake gates Alternative 1, No-action alternative - If a project is not pursued, the District will eventually be unable to fill Empire Reservoir, resulting in an annual loss of delivery of 15,900 acre feet of irrigation water. This is not acceptable to the District. Alternative 2, Perform temporary remedial work to return diversion to normal operation - This would involve an immediate fix to any current problem, but solutions could range in length from several months to several years. This level of repair leaves the ditch vulnerable to the ditch being taken out of service and the loss of water. Remedial activities of this nature are impossible to budget for and create a hardship that is no longer acceptable to the District. Alternative 3, Replace 100 feet of diversion structure with new spillway gate, using existing intake gates - This would include replacing part of the river diversion structure, a 100 foot length in the current board system, and constructing an Obermeyer Pneumatic Spillway Gate that uses an inflatable bladder to raise and lower the gate. Lowering the gate during times of high river flow would greatly reduce "wear and tear" on the entire intake system, reduce the sand accumulation that forms upstream and in the intake canal, and alleviate debris problems in the structure. The cost of this alternative is approximately $720,000. Alternative 4, Replace 200 feet of diversion structure with new spillway gate, using existing intake gates - This alternative is similar to Alternative 3, but would increase the gate length to 200 feet, instead of 100 feet. The increased length of the gate would completely alleviate the problems associated with the sand bar, and greatly reduce the sanding problem in the intake ditch. The cost of this alternative is approximately $1,368,000. Selected Alternative 3, Replace 100 feet of diversion structure with new spillway gate, using existing intake gates - The project will involve construction of a 100 foot long Obermeyer Pneumatic Spillway Gate (Bladder Gate) structure, 7 feet high, and located immediately adjacent to Page 3 of 5