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Creek Center Tributary, Sand Creek East Fork Subtributary, Spring Creek, and Templeton Gap Floodway using topographic maps at a scale of 1:6,000, with a contour interval of 2 feet (Reference 26). Flood boundaries for Monument Creek Tributary were determined from aerial photographs at a scale of 1:4,800 (Reference 27). Dry Creek flood boundaries were determined using topographic maps at a scale of 1:1,200 with a contour interval of 2 feet (Reference 2). Some flood plain boundaries for reaches studied by approximate methods were delineated using the existing Flood Hazard Bou~dary Maps for the City of Colorado Springs and El Paso County (Refer- ences 28 and 29). The 100- and SOD-year flood plain boundaries are shown on t3e Flood Insurance Rate ~~p (Exhibit 2). On this ma~, the 100-year flood plain boundary corresponds to the boundary cf the areas of special flood hazards (Zones A and AE); and the SOO-jear flood plain bound- ary corresponds to the boundary of areas of moderate flood hazards. In cases where the 100- and SOD-year flood plain boundaries are close together, only the 100-year flood plain boundary has been shown. Small areas within the flood plain boundaries may lie above the flood elevations but cannot be shown due to limitations of the map scale and/or lack of detailed topographic data. 4.2 Floodways Encroachment on flood plains, such as structures and fill, reduces flood-carrying capacity, increases flood heights and velocities, and increases flood hazards in areas beyond the encroachment itsel:. One aspect of'flood plain management involves balancing the econo- mic gain from flood plain development against the resulting increase in :lood hazard. For purposes of the NFIP, a floodway is used as a ~ool ~o assist local communities in this aspect of flood ?lain pa~agement. Under this concept, ~he area of the 100-year flood plain is divided into a floodway and a floodway fringe. The flood- way is the channel of a stream, pl~s any adjacent flood 91ain a~eas, that ~ust be kept free of encroac3ment so that t~e lOO-year flood ~an be carried witho~t substa~tial increases i~ flood heig~ts. Minimu~ Federal standards li~it such increases to 1.0 foet, pro- vided that hazardous velocities are not prod~ced. The floodways in this study are presentee to local agencies as minimun standards that can be adopted directly or that can be used as a basis for additional floodway studies. Hazardous velocities wou~d occur during flooding on the ~pper reaches of Monument Creek near t~e Town of Pal~er Lake and on Mc~~ment Cree~ Tri~~tary under existing channel conditio~s (Reference 3). Encroac~ments, islands, and f:ood bo~ndaries are s~bject to extre~e erosion when velocities are so high. Therefore, t~e I~O-year ::ood boundary was des:gnated as the =loodway as shown on t~e ?lood :ns~r- 2~C~ ~3te ~ap (Ex~ibi~ 2). 20