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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 on the basis of equal-conveyance reduction from each side of the flood plain. The results of these computations are tabulated at selected cross sections for each stream segment for which a floodway is computed (Table 2). . As shown on the Flood Boundary and Floodway Map (Exhibit 2), the floodway boundaries were computed at cross sections. Between cross sections, the boundaries were interpolated. In cases where the floodway and lOa-year flood plain boundaries are either close together or collinear, only the floodway boundary has been shown. The area between the floodway 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-sutface elevation of the lOa-year flood by more than 1.0 foot at any point. Typical relationships between the floodway and the fl60dway fringe and their signifi- cance to flood plain development are shown in Figure 2. I- iDa.YEAR FLOOD PLAIN -I FLQODWAY F A I NO E FLQODWAY FLOOOWAY FRINGE !STAEAM CHANNEL FLOOD ELEVATION WHEN CONFINED WITHIN FLOODWAY AREA OF FLOOD PLAIN THAT COULD BE USED FOR OEVELOPMENT BY AAISING GROUND LINE AS IS THE FLOOD ELEVATION BEFORE ENCAOACHMEN1. LINE CD IS THE FLOOD ELEVATION AFTER ENCROACHMENT.! .SURCHARGE ISNQTTOEXCEED 1.0 FOOT (FEMA REQUIREMENT) OR LESSER AMOUNT IF SPECIFIED BY STATE. Figure 2. Floodway Schematic ] 2