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intake pipe to a culvert located under the detention pond and Hampden Avenue (State Highway 30). Peak discharges for Sanderson Gulch a~d Weir Gulch were determined as part of the 1972 UDFCD Major 1 Drainageway Planning report (Reference 41). The 10-, 50-, and 100-year discharges were calculated using the Colorado Urban Hydrograph Procedure (Reference 40) for fully developed basin conditions. The SOD-year discharge was extrapolated from the data. Peak discharges on Weir Gulch downstream of Barnum Lake were revised to reflect channel improvements at Barnum Lake and incre~sed culvert capacity at West 6th Avenue (U.S. Highway 6). . Peak discharges for First Avenue ~ributary and Dakota Avenue Tributary were determined as part of, the 1977 UDFCD Flood Hazard Area Delineation report (Reference 20). Those discharges were calculated in accordance with the Colorado Urban Hydrograph Procedure (Reference 40) assuming fully developed basin conditions. The subbasin hydrographs were routed ,downstream. The Puls Method was used to calculate discharges at tocations where storage had a significant effect. ' Peak discharges for Sand Creek were d~termined as part of .the 1977 UDFCD Flood Hazard Area Delineation, report (Reference 42). The hydrologic analysis was based on tile development of a surface- runoff model of the Sand Creek basin using the runoff block of the IlPA Storm Water Management Model. (Reference 37). Discharge hydrographs developed from the mode11 were then routed along the main stem of Sand Creek by use bf an unsteady flow-routing I . . .... .. procedure developed by James A. Harde~ and modified by the MiSSOUri River Division of the COil. Discharge probability relationships were developed by inserting pre~ipitation-frequency values (Reference 43). The discharges were qalculated for fully developed basin conditions. Peak discharges for the South Platte River were determined as part of the September 1985 UDFCD Flood HlIzard Area Delineation report (Reference 44). Peak-frequency value:s for the South Platte River were taken from the May 1983 Hydrolo~ic Study report prepared by Merrick and Company under contract to rhe UDFCD (Reference 45). Peak discharge-drainage area relation$hips for all streams studied by detailed methods are shown in Table' 2. 3.2 Hydraulic Analyses Analyses of the hydraulic characteristics of flooding from the sources studied were carried out to pr;ovide estimates of the eleva- tions of floods of the selected recurr~nce intervals. , , Locations of selected cross sections dsed in the hydraulic analyses are shown on the Flood Profiles (Ilxh~bit 1). For stream segments where a floodway was computed (Section 4.2), selected cross section locations are also shown on the' Flood Insurance Rate Map 18