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Thus, it appears that cloudburst floods are possible in the Steamboat Springs area. Cloudburst storm criteria were developed from NWS data (Reference 18). A 40-percent value of the probable maximum precipitation point rainfall for Steamboat Springs, plotted at about the 500-year frequency on a 3-hour rainfall frequency curve for Craig, Colorado (the nearest recorded), was selected for use as a cloudburst standard project storm. Loss rates were identical to those used for general rainfall. The ratio of 1oo-year cloudburst precipitation to the standard project storm precipitation was developed from this frequency curve. The 10- and 50-year floods were determined to be basically snowmelt events and were modeled after major snowmelt flows that occurred in June 1952, adjusting the 50- and 10-day volumes for their corresponding frequencies. The 1-, 5-, and lO-day flows for the tributary creeks were taken from their corresponding frequency curves. This was considered an adequate procedure in that the snowmelt frequency curves appear well defmed below 50-year events, and the results that would be obtained by more complex procedures would not differ appreciably. Flows for streams without frequency curves were derived from frequency curves with streams with characteristics similar to those under study. Computed standard project floods were used in conjunction with the log-Pearson Type III method statistical analysis (Reference 10) of available streamflow data to develop flow-frequency curves for the four streams. Average stream gradients in the study area, together with approximate drainage areas, are shown in the following table: Stream Location Approximate Gradient Drainage Area (Feet/Miles) (Square Miles) 20 70 4 90 8 140 Soda Creek Corporate Limit Butcherknife Creek Corporate Limit Spring Creek Corporate Limit Fish Creek Gaging Station 25 160 (Upper Station Near Steamboat Springs) Ratios of the computed standard project flood developed from the flow-frequency curves were used to determine the 10-, 50-, 100-, and 500-year flood events in areas where stream gage data were not available. The 1oo-year peak flows for streams studied by approximate methods were based on a Frequency-Discharge, Drainage Area Curve prepared from computed standard project floods. Standard project floods from the curve were reduced by approximate percentages to estimate the loo-year flood event. Peak discharge-drainage area relationships for Butcherknife, Fish, Soda, and Spring Creeks are shown in Table 1. 29