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3.1 Hydrologic Analyses Hydrologic analyses were carried out to establish the peak discharge- frequency relationships for each flooding source studied in detail affecting the community. Regional 100- and 500-year peak flow values were determined from discharge frequency data compiled for representative stream gaging stations in earlier Colorado River Basin studies. The peak flow values were converted to discharge in cubic feet per second per square mile (CSM), and envelope curves were developed showing 100- and 500-yea. snowmelt flood events on a regional basis. The 100- and 500-year snowmelt floodflows for the Colorado River at Palisade were determined from the regional envelope curves. Peak discharge-drainage area relationships for the Colorado River are shown in Table 1. 3.2 Hydraulic Analyses Analyses of the hydraulic characteristics of flooding from the sources studied were carried out to provide estimates of the eleva- tions of floods of the selected recurrence intervals. Water-surface elevations of floods of the selected recurrence intervals were determined through use of the COE HEC-2 step-backwater computer program (Reference 3). Cross sections for the Colorado River were digitized from orthophoto- topographic maps provided by the u.s. Bureau of Reclamation (Refer- ence 4). Roughness factors (Manning's "n") used in the hydraulic computations were chosen by engineering judgment and based on field observations of the streams and flood plain areas. Starting water-surface elevations were obtained from a previous report published by the COE (Reference 5). All elevations are referenced to the National Geodetic Vertical Datum of 1929 (NGVD). 4.0 FLOOD PLAIN MANAGEMENT APPLICATIONS The NFIP encourages State and local governments to adopt sound flood plain management programs. Therefore, each Flood Insurance Study produces maps designed to assist communities in developing flood plain management measures. 6