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can be carried without substantial increases in flood heights. Minimum Federal standards limit such increases to 1.0 foot, pro- vided that hazardous velocities are not produced. The floodways in this study are presented to local agencies as minimum standards that can be adopted directly or that can be used as a basis for additional floodway studies. The floodways presented in this study were computed for certain stream segments on the basis of equal conveyance reduction from each side of the flood plain. Floodway widths were computed at cross sections. Between cross sections, the floodway boundaries were interpolated. The results of the floodway computations are tabulated for selected cross sections (Table 2). The computed floodways are shown on the Flood Insurance Rate Map (Exhibit 2). In cases where the floodway and lOa-year flood plain boundaries are either close together or collinear, only the floodway boundary is shown. The area between the flood way and lOa-year flood plain boundaries is termed the floodway fringe. The floodway fringe encompasses the portion of the flood plain that could be completely obstructed without increasing the water-surface elevation of the lOa-year flood by more than 1.0 foot at any point. Typical relationships between the floodway and the floodway fringe and their significance to flood plain development are shown in Figure 7. I- 100.YEAR FLOOD PLAIN -I F LOODWA Y FRINGE FLOOQWA Y FLOODWAY FRINGE STREAM CHANNEL FLOOD ELEVATION WHEN CONFINED WITHIN FLOOOWAY AREA OF FLOOD PLAIN THAT COULD BE USED FOR DEVELOPMENT BY RAISING GROUND o FLOOD ELEVATION BEfOREENCAOACHMENT ON FLOOD PLAIN LINE AB IS THE FLOOD ELEVATION BEFORE ENCROACHMENT. LINE CD IS THE FLOOD ELEVATION AFTER ENCROACHMENT. .SURCHARGE IS NOTTO ExceeD 1.0 FOOT IFEMA REQUIREMENT) OR LESSER AMOUNT IF SPECIFIED BY STATE. Figure 7. Floodway Schematic 12