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<br />. . <br /> <br />~ could restrict flows crossing 287, and cause a higher water surface west of 287 <br />in the vicinity of Isabelle. In effect, 287 from the Leyner Cottonwood Ditch north <br />to the Lafayette Reservoir acts as a long weir. If 287 is raised, water surfaces <br />west of 287 could potentially be higher from Isabelle north to the Lafayette <br />Reservoir. <br /> <br />The FHAO shows Lafayette's Reservoir to be out of the 100 year floodplain. TEA <br />requires more information from Lafayette (embankment topo and materials) to <br />determine if the embankment should be classified as a "levee", and to determine <br />whether or not the reservoir becomes inundated during the 100 year flood. <br />However, Lafayette has indicated that the City is not concerned about the <br />reservoir being inundated by floods. <br /> <br />COOT should provide Lafayette, Erie, and Boulder County analysis of the impact <br />of the 287 changes on the floodplain. <br /> <br />( <br /> <br />In summary, a cursory review of the proposed 287 cross sections and FHAO <br />HEC-2 indicates that the new 287 could cause higher water surfaces at the <br />287/1sabelle intersection, but that impacts upstream and downstream should be <br />minimal. Parties potentially affected by the higher water surfaces should be <br />provided with a more detailed analysis to better determine the effects of the new <br />highway. The communities are responsible to FEMA to report changes in <br />floodplains and therefore should have COOT provide such information that will <br />document the effects. <br /> <br />As FEMA directed at our November, 1996 meeting, TEA will not modify theJ4 <br />FHAO HEC-2 for the new construction in this area. <br /> <br />( <br />