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increases to approximately 60 percent (6 in 10). The analyses reported herein reflect flooding potentials based on conditions existing in the community at the time of completion of this study. Maps and flood elevations will be amended periodically to reflect future changes. 3.1 Hydrologic Analyses Hydrologic analyses were carried out to establish peak discharge- frequency relationships for each flooding source studied in detail affecting the community. Peak discharge-drainage area relationships for each flooding source studied in detail affecting Westminster, Colorado are shown in Table 1. Because no stream gage data were available for the streams studied, a rainfall-runoff analysis was conducted on the watersheds to determine the flood discharges. This was accomplished by using the Colorado UD&FCD Colorado Urban Hydrograph Procedure (CURP) rainfall-runoff computer program to develop the storm hydrographs (Reference 6) and the U.S. Army Corps of Engineers HEC-l flood hydrograph package computer program for the stream and reservoir routing. (Reference 7). For this analysi.. basin characteristics that define the size, shape, and runoff characteristics of the watershed, as well as rainfall amounts based on the selected recurrence intervals (obtained from the National Oceanic and Atmospheric Administration atlas of precipitation (Reference 8)) were used to compute flood hydrographs for various design points in the basin. All stream and- reservoir routings were accomplished using the Modified Puls Method. Since there was a lack of SOO~year precipitation data, the SOO-year frequency storm runoff values at each design point were calculated. The logarithmic values of the 10-, SO-, and IOO-year peak discharges were fit to a regression line by method of least squares. The SOO-year discharges were analytically extrapolated from the regression line based upon a log-normal probability relationship. For more detailed information see the final hydrologic analysis report for Big Dry Creek and Tributaries prepared by Greiner Engineering, January 1984. 3.2 Hydraulic Analyses Analyses of the hydraulic characteristics of flooding from the sources studied were carried out to provide estimates of the elevations of floods of the selected recurrence intervals. The analyses in this report reflect flooding potential based on existing land use conditions in the community as of December 1983. Map and flood elevations will be amended periodically to reflect future changes. For all streams studied, the water-surface elevations for floods of the selected recurrence intervals were computed using the U.S. Army Corps of Engineers HEC-2 Step-backwater computer program (Reference 9) . 6