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this concept, the area of the lOO-year flood is divided into a floodway and a floodway fringe. The floodway' is the channel of a stream plus any adjacent flood plain areas that must be kept free of encroachment in order that the lOO-year flood may be carried without substantial increases in flood heights. Minimum standards of the Federal Emergency Management Agency li.mit such increases in flood heights to 1.0 foot, provided that hazardous velocities are not produced. The floodways in this report are presenteo to local agencies as minimum standards that can be adopted or that can be used as a basis for additional studies. . v Because of high-velocity conditions, the floodways were developed for Fountain Creek, Ruxton Creek, Sutherland Creek, and Williams Canyon by applying the allowable rise to the energy gradeline instead of the water-surface elevation. Floodways were also identi- fied by the criteria that allow a maximum ha;~ardous velocity of 3 feet per second at the edge of the floodway fringe. These hazar- dous velocity criteria proved to be determinant in the floodway delineation. For Williams Canyon and Ruxton Creek, the floodway boundary is the same as the 100-year flood boundary. A floodway fringe has been computed for some areas alonq Fountain and Sutherland Creeks wihout reaching the allowed l-foot rise in energy gradeline or water-surface elevation. The data presented in the Floodway Data Table represents the computed water-surface elevations. ~ 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 were tabulated at selected cross sections for each stream segment for which a floodway was computed (Table 2). . As shown on the Flood Boundary and Floodway I~ap (Exhibit 2), the floodway widths were determined at cross sections; between cross sections, the boundaries were interpolated. In cases where the boundaries of the floodway and the lOO-year flood are either close together or collinear, only the floodway boundary has been shown. The area between the floodway and the boundary of the 100-year flood is termed the floodway fringe. The floodway fringe thus encompasses the portion of the flood plain that could be completely obstructed without increasing the water-surface elevation of the 100-year flood more than 1.0 foot at any point. Typical relation- ships between the floodway and the floodway fringe and their signif- icance to flood plain development are shown in Figure 4. . l4