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Feasibility Study for the Plaza Project — Phase 2: McDonald Ditch Implementation Project Section 6 - Alternatives Evaluated During the development of the Plaza Plan, alternatives for the Phase 2 Project Elements were analyzed by the Plaza Stakeholders. The Plaza Stakeholders, a diverse group of 34 individuals, represent interests within the Sevenmile Plaza and the greater community of the San Luis Valley. The Plaza Stakeholders' role was to advise the Partnership, review and discuss Project deliverables, and make strategic planning decisions with a specific focus on agriculture needs, wetlands, wildlife habitat, and nonconsumptive uses of the Rio Grande. 6.1 Streambank Alternatives The stakeholders examined the condition of each streambank and developed desired mitigation measures including: no action needed, bioengineering needed, stream access point development, and extensive streambank stabilization recommended. The streambank recommendations coincide with the recommendations for other elements. Because the streambanks in the project reach are all privately owned, the implementation of the stakeholders' recommendations will be dependent on landowner preference. In addition to improvements to the streambanks, the landowners can also take action to improve the riparian and aquatic habitat. As described in the 2001 study, the following actions will lead to habitat improvements: • Protecting the riparian zone (reducing cattle grazing, provide development buffer, etc.); • Creating various runs and riffles, thereby decreasing the existing large expanses of slow - moving water (which is lacking in habitat); • Instigating special regulations on the taking of trout and provide more stocking; • Preventing erosion and flooding. 6.2 Wetland Alternatives The Stakeholders worked closely with Rio Grande County officials and a representative from the US Army Corps of Engineers (USACE) to ensure all requirements for reclaiming the wetland were addressed. The following objectives were critical in narrowing options and formulating a design: • Develop a plan to reclaim the damaged wetland that meets the requirements of USACE; • Ensure acreage after Project completion is equal to acreage before damage; • Ensure topography maximizes edge effects and opportunity for riparian species colonization; • Ensure proper functioning hydrology is intact; • Coordinate wetland improvements with the efforts at the nearby streambanks and McDonald Ditch. 6.3 Diversion Alternatives Pulling from personal accounts and field trips to sites on the Rio Grande, Arkansas, Poudre, and Big Thompson Rivers, the Stakeholders identified types of diversions they were interested in examining for potential application at the McDD. The NRCS performed preliminary surveys of the project elements and developed initial designs and cost estimates for each of the alternatives. Costs were derived by the NRCS from "The Means Heavy Construction Cost Data." The four alternatives were: • Diversion Alternative #1: Concrete Diversion • Diversion Alternative #2: Steel and Grouted Rock Diversion • Diversion Alternative #3: Hybrid Rock and Concrete Diversion • Diversion Alternative #4: Pipeline 6.3.1 Diversion Alternative #1: Concrete Diversion A concrete diversion dam would span the entire width of the river, checking the water behind it. The concrete structure would have the highest installation costs, but the lowest maintenance costs of all of the proposed diversion alternatives. The structure would not be passable to fish or 14