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<br />to LPATH was increased. The new spill discharge was used to adjust <br />discharges in the floodway models, both on the main channel and in the <br />LPATH spill. <br /> <br />Floodways were developed by adding encroachments to the cross <br />sections in the hydraulic models and increasing the encroachments <br />until the maximum allowable rise was attained. Encroachments were <br />based on an equal reduction in conveyance from both sides of the flood <br />plain. A single floodway model was used for the entire study reach. <br />The floodway models were HFTFL~Y for the one-half foot rise floodway <br />and lFTFL~Y for the one foot rise floodway. <br /> <br />Just east of Wastewater Treatment Plant Number Two, the main flow <br />of the Cache La RJudre leaves its channel during large flood events. <br />The hydraulic models used in this study follow this breakout. The <br />half foot and one foot floodways were delineated along the breakout <br />flow path. TO protect the low flow channel of the river from <br />encroachment, a floodway was delineated for this reach with boundaries <br />on the banks of the low flow channel. <br /> <br />Just below Taft Hill Road, a flow division was modeled by <br />subtracting the left overbank flow from the total discharge and <br />confining the remaining flow to the channel. For floodway delineation <br />it was assumed that the confining banks fail. The total discharge was <br />used in the floodway models. This condition results in lower base <br />flood elevations in this area for the floodway computations than were <br />computed for the flood profiles. <br /> <br />The floodway boundaries for the two floodways are shown on the <br />flood boundary and floodway map plates. In certain areas the floodway <br />boundaries crossed lakes for a considerable distance. At the request <br /> <br />12 <br />