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Prairie Ditch Company Agenda Item 3 1 b <br /> May 9,2014(Updated May 23,2014) <br /> Page 3 of 5 <br /> Water Rights <br /> The Prairie Ditch is comprised of 18 water rights decreed between 5/1/1896 and 4/9/1903 with <br /> appropriation dates ranging from 1872 to 1901. These rights combine for a total decreed flow of <br /> 367.02 AF, and have an average total annual diversion of 16,000 AF (62.25 AF per share). <br /> Project Description <br /> The objective of this Project is to replace the deteriorating and inefficient Prairie Ditch diversion <br /> structure and headgate as a part of Phase 3 of the Plaza Project. The NRCS performed preliminary <br /> surveys of the project elements and developed initial design and cost estimates for a variety of <br /> alternatives. The following alternatives were analyzed by Plaza Stakeholders, a diverse group of 34 <br /> individuals with an interest within the Sevenmile Plaza and the greater community of the San Luis <br /> Valley. <br /> Alternative 1 —Concrete Diversion: This alternative would include building a concrete structure <br /> that spans the entire width of the river. This would have the highest initial cost but the lowest <br /> maintenance cost. The structure would not be passable to fish or boaters unless a side fish passage <br /> was included at additional cost. <br /> Alternative 2—Steel and Grouted Rock Diversion: This alternative would include building a steel <br /> and grouted rock dam that spans the entire width of the river. This would offer a lower initial cost <br /> than Alternative 1 but would have higher maintenance cost. This alternative would also be more <br /> natural looking than Alternative 1 but would also not be fish and boat passable unless a side fish <br /> passage was included at additional cost. <br /> Alternative 3—Abandon Diversion, use McDonald Ditch Diversion: This alternative would <br /> include removing the diversion dam and moving the headgate 2,000 feet upstream to the location of <br /> the McDonald Ditch headgate (subject diversion of Plaza Project Phase 2). As well as construction <br /> requirements to modify the McDonald headgates and increase the capacity of the McDonald ditch, <br /> the Company would also have to file for a change in water right moving its decreed location. These <br /> costs could easily eliminate any cost savings seen by combining with McDonald Ditch. <br /> Selected Alternative 4—Rock Diversion: This alternative will include a rock dam spanning the <br /> entire width of the river. The dam will be composed of very large rocks stacked tight enough to stay <br /> in place without being grouted. The rocks will create a series of drop structures allowing for fish <br /> and boat passage, improving habitat and recreation. This will have less initial cost than Alternatives <br /> 2 and 3 but will also have higher maintenance cost than Alternatives 2 and 3. This alternative will <br /> include a sluice to move sediment and debris past the headgate. <br /> In addition to the dam, the Project will also install four headgates consisting of three manual gates <br /> and one solar-powered automated gate to regulate ditch flows, improving diversion accuracy and <br /> accounting. The manual gates can also be used to regulate ditch flows if the automated gate <br /> malfunctions. <br /> Table 1 provides a summary of the cost related to the entire Project. The Company will be <br /> responsible for a cost share of only the diversion and headgate (Task 2 & 3). <br />