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<br />1.101538 <br /> <br />Alternatives, Including Proposed Action <br /> <br />2- t8 <br /> <br />The purpose of the program would be to protect the existing riverbanks where increased <br />erosion would result in economic damages to property owners. Bank protection by the <br />Sponsors would reduce the need for private landowners and local governments to install <br />their own measures. Where significant economic effects are not expected, the river will <br />be allowed to adjust naturally to the flow regime, and reach its own equilibrium. In those <br />instances, offers will be made to acquire erosion and/or flowage easements from <br />landowners at market value. <br /> <br />2.4.3.1 Design of Bank Stabilization Measures <br /> <br />Final design would be completed after approval of the Department of the Army (Section <br />404) pennlt for the project is granted. Sponsors submitted an application for said permit <br />in 1995. That application was withdrawn pending conclusion ofthis SEIR. The <br />application will be re-activated once this supplemental NEPA process is at or nearing <br />completion. <br /> <br />Several stabilization alternatives were considered for the program. The measures selected <br />for the PElS were riprap revetment and streambank vegetation. According to the PElS, <br />"the rock riprap would be placed where erosive forces are the greatest and the risk of <br />losing cultivated fields or structures is the most significant. Streambank vegetation was <br />not judged reliable enough given the risks in these locations; instead, vegetation would be <br />used at other sites where its likelihood of success would be higher or economic risk of <br />failure is low" (FElS, 1990), <br /> <br />Since completion of the PElS, more study has taken place and the bank stabilization plan <br />has been refined. The Corps of Engineers (COE) requested additional information to <br />fully support a revised Department of the Army permit application for stabilization. The <br />results of the work efforts requested by the COE are summarized in the Uncompahgre <br />River Balik Stabilization Study, Final Report (Sigma Consultants,lnc" 1995). That report <br />includes a channel stability analysis of the study reach (approximately 30 miles between <br />Montrose and the Gunnison River confluence near Delta) to evaluate the potential effects <br />of increased flows associated with the proposed project. <br /> <br />From the channel stability analysis, it was concluded that the Uncompahgre River within <br />the study reach can be classified as a wandering gravel-bed river. The banks are much <br />more easily erodible than the bed pavement, which consists of coarse material. The river <br />is expected to have a greater tendency to widen than to degrade. Except in a few short <br />stretches, the existing flood plain provides room for widening without loss of productive <br />lands. (Sigma Consultants, Inc., 1995) <br /> <br />The Sponsors would focus their bank stabilization efforts so that the river is not narrowly <br />constrained on both sides, Bank stabilization efforts will be limited to the terrace margins <br />and that, to the extent possible, the river be allowed to adjust on its own in a meander belt <br />between these protected surfaces. This should minimize both the risk of channel <br />instability and the likelihood of economic losses from bank erosion. Several stabilization <br />methods were considered: <br /> <br />AS Latera/Hydropower Project <br /> <br />July 2000 <br /> <br />