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hazard a For purposes of the Flood Insurance Program, the concept of a floodway is used as a tool to assist local communities with this aspect of flood plain management. Under this concept, the area of the IOO-year flood is divided into a floodway and a floodway fringe. The floodway is the channel of the stream, plus any adjacent flood plain areas, that must be kept free of encroachment in order that the lOO-year flood be carried without substantial increases in flood heights, Criteria adopted by the Federal Emergency Management Agency limit such increases to 1.0 foot, provided that hazardous velocities are not produced. The floodways in this report are presented to the city as minimum standards that can be adopted or that can be used as a basis for further studies. Floodways are not established for sheetflow areas or for streams studied by approximate methods. Also, floodways are not applicable where the 100-year flood is confined to the stream channel. Floodways for this study were computed on the basis of equal con- veyance reduction from each side of the flood plain. However, under no circumstance is the floodway encroached into the stream channel itself. Floodway boundaries were determined at cross sections used in the analysisa Between cross sections, the boundaries were inter- polated. The results of floodway computations are shown in Table 1. The area between the floodway and the boundary of the lOO-year flood is termed the floodway fringe. The floadway fringe thus encompasses the portion of the flood plain that could be completely obstructed without increasing the water-surface elevation of the IOO-year flood 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 23". 25