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<br />-4- <br /> <br />The summary of river trend and fluvial processes does not adequately take into account the <br />natural variability of the system, Sufficient data is not presented to support hypothesis and <br />conclusions. For example, there is no description of the presence and configuration of "sand <br />bar habitat". No data is presented describing historic versus current trends in the frequency, <br />distribution, size, and elevation of sand bars. A more qualitative analysis is appropriate <br />where there are uncertainties, lack of quantitative data, and system variability. <br /> <br />8. The DEIS analysis of impacts and environmental consequences relies too heavily on the <br />Sediment Vegetation model. There are significant unknowns regarding the use of this <br />promising but unproven tool. The states of Colorado, Nebraska, and Wyoming had an <br />independent review of the data and model developed by DOl (see Platte River Channel <br />Dynamics Investigation, Parsons, May 2003). The Parson's review cast serious doubt <br />regarding the definitive conclusions reached by DOL Significant issues concerning process <br />relationships (geomorphic, plant physiology and the linkage of the two) and calibration and <br />verification issues persist. This "tool" forms the foundation upon which all assumptions and <br />projections of impacts are formed. <br /> <br />The National Academy of Science (NAS) review of Endangered and Threatened Species on <br />the Platte River, April 2004 had the following remarks regarding Sed Veg: "The study <br />committee did not evaluated three items.. ..an advanced computer model, SEDVEG, to <br />evaluate interactions among hydrology, river hydraulics, sediment transport, and vegetation <br />being developed, but not yet competed or tested (emphasis added), by the USBR for <br />application on the Platte River, and ",. . the committee did not access the newer models <br />because they have not been completed or tested, but recommend that they be explored for <br />their ability to improve decision making. (emphasis added). The NAS further states: "The <br />committee also recognizes that there has been no substantial testing of the predictions <br />resulting from the DOl's previous model work, and it recommends that calibration ofthe <br />models be improved". <br /> <br />Notwithstanding these limitations, the DEIS establishes "performance criteria" for fluvial <br />processes which are analyzed using the Sed Veg Model. PeaklPulse flows are linked to <br />habitat forming processes and channel width; sediment transport and grain size are linked to <br />channel degregadation, incision, and channel narrowing. The DEIS team relates these <br />processes to habitat hypotheses for the species to come up with their results, <br /> <br />The DEIS contains no summary of the accuracy and precision of Sed Veg both in terms of <br />it's model processes and the raw data that is used for model runs. For example is the <br />precision of the flow and sediment data and vegetation germination and mortality data <br />greater than the predicted trends? The DEIS team clearly had concerns in this regard as <br />they inappropriately modeled trends for 61 years even though the length of the action <br />alternatives is only 13 years, Any analysis done on the action alternatives should be directly <br />linked to the period of the federal action. In addition, there is no quantitative discussion of <br />the required river stage change and the number of days needed to create sand bars and how <br />that information is accounted for in the model or whether it historically occurred. The DEIS <br />analysis appears simplistic with a one to one relationship between river stage and sand bar <br />formation. <br /> <br />Flood Protection. Water Project Planning and Finance. Stream and Lake Protection <br />Water Supply Protection. Conservation Planning <br />