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1910 to 1976. Separation of the gaged data into snowmelt and rainfall categories was not considered. Several forms of regional comparisons were made as an aid 1n evaluating and interpreting the statistical flood frequency analysis. These include flood discharges calculated from regional multiple regression equations (TM-1, Reference 3), the index flood method (WSP 1683, Reference 4), and comparisons wi th runoff (CSM) ratios for adopted laO-year frequency flood discharges in northwest Colorado. The hydrologic analysis for the White River near Rangely was based on annual peak flow data for snowmelt and rainfall floods. Annual peak flows for rainfall and snowmelt floods have been published by the USGS (Reference 5). Additional annual peak flows, for rainfall and snowmelt floods were obtained from inspection of the USGS strip charts. Frequency analyses were made on both peak flow data sets. The two frequency curves were assumed to represent independent events and a composite flow-frequency curve was developed for each gaging station. A regional regression analysis was then made to determine peak flow as a function of drainage area and return period (Reference 6). Flow data on the Whi te River were based on the following USGS stream gages: Gage Gage Number Years of Record White River near Watson, Utah White River near Rangely, Colorado White River near Meeker, Colorado 09306500 09306300 09304800 51 8 70 For the ungaged streams, Coal Mine Draw and College Canyon Draw, peak flows were adopted from the hydrology analyses previously conducted in the development of a storm-drainage master plan for the Town of Rangely (Reference 7). College Canyon Draw and Coal Mine Draw have drainage areas of 1.8 and 2.9 square miles, respectively, and are below 6,000 feet. Rainfall events generate flood peaks for small basins below elevation 6,000 feet. The U.S. Soil Conservation Service method (Reference 8) was used to generate hydrographs based on regional parameters. Peak discharge-drainage area relationships for the streams studied in detail are shown in Table 1. 3.2 Hydraulic Analyses Analyses of the hydraulic characteristics of flooding sources studied were carried out to provide estimates elevations of floods of the selected recurrence intervals. from of the the The water-surface through use of (Reference 9). elevations for the streams studied were computed the COE HEC-2 step-backwater computer program 8