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connnuni ties in this aspect of floodplain management. Under thi s concept, the area of the lOa-year floodplain is divided into a floodway and a floodway fringe. . The floodway is the channel of a stream, plus any adjacent floodpla~n areas, that must be kept free of encroachment so that the 100-y~ar flood can be carried wi thout substantial increases in flood hetghts. Minimum Federal standards limit such increases to 1.0 foot, provided 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. A floodway was not computed for Cherry Creek because the determination of a floodway was no~ within the scope of this study. Harvard Gulch, downstream of South; Logan Street, and Dakota Avenue Tributary are shallow flooding areas for which the floodway concept is not applicable. No floodway has been presented for Harvard Gulch between South Ogden and South Logan Streets and for Harvard Gulch Overflow due to the fully developed nature of this iarea. No floodways were delineated along: the South Platte River primarily due to split-flow conditions. ' The floodways presented in this study were computed on the basis of equal conveyance reduction from each side of the floodplain. The results of these computations are tabulated at selected cross sections for each stream segment for which a floodway is computed (Table 3). As shown on the Flood Insurance R.te Map (Exhibit 1), the floodway boundaries were computed at c~oss sections. Between cross sections, the boundaries were interpolated. In cases where the floodway and lOa-year floodplain boundaries are either close together or collinear, only the flQodway boundary has been shown. The area between the floodway and ,lOa-year floodplain boundaries is termed the floodway fringe. The: floodway fringe encompasses the portion of the floodplain that i could be completely obstructed without increasing the water-su~face elevation of the lOa-year flood by more than 1.0 foot at l(ny point. Typical relationships between the floodway and the floo~way fringe and their significance to floodplain development are shown in Figure 2. 28