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<br />Chapter 2.0 Description of Alternatives 25 <br /> <br /> <br />01200' <br /> <br />of both the Service and the Navajo Nation. <br /> <br />2.4 ALTERNATIVES CONSIDERED BUT ELIMINATED FROM <br />DETAilED ANALYSIS <br /> <br />Because the Proposed Action was developed by utilizing the best available scientific <br />information developed through the GCDAMP process, no unique alternatives were <br />considered but eliminated during the development of the Proposed Action. There were, <br />however, modifications to the components of the Proposed Action that were considered <br />and rejected. They are considered here. <br /> <br />In the deliberations of the various work groups and committees of the GCDAMP, <br />many broad discussions were held and alternatives suggested that might meet the <br />management objectives. Some of the alternatives considered, but rejected for various <br />reasons are as follows. <br /> <br />Maximum releases greater than 45,000 cfs and durations longer than three days were <br />considered for the sediment conservation portion of the Proposed Action, but were <br />rejected for the following reasons: <br /> <br />. The current and projected near-term future elevations of Lake Powell would not <br />allow the use of the spillways, which are required for releases greater than <br />45,000 cfs. <br /> <br />. There is greater scientific strength in an experiment with a peak discharge that <br />can be more directly compared to the results of the 1996 beach/habitat building <br />flow test, which also utilized maximum flows of 45,000 cfs. <br /> <br />. Durations longer than 3 days of peak release would likely cause depletion of the <br />tributary sediment inputs and result in greater erosion and downstream <br />transport of sediment to Lake Mead. <br /> <br />Winter non-native fish suppression releases with a greater range of fluctuation and <br />greater and lesser ramp rates were considered for this portion of the Proposed Action <br />Alternative but rejected for the following reasons: <br /> <br />. Fluctuations with a peak of 25,000 cfs were considered for the winter non-native <br />fish suppression flows, but concerns were raised by the sediment researchers <br />that such flows would likely quickly erode the sandbar deposits newly created <br />by the sediment conservation portion of the tests. <br /> <br />. Unlimited up and downramp rates for the fluctuating flows were rejected <br />because of concerns related to beach stability, sediment transport rates, and <br />safety of canyon visitors. <br /> <br />. Use of ramp rates specified in the ROD was rejected because these rates would <br />not allow sufficient hours at the maximum or minimum releases to sufficiently <br />impact non-native fish. The hypothesis is that a hydrograph mimicking pre-ROD <br />