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4-29 <br />• In September 1972, before the period of record, a discharge <br />of 2,160 cfs was estimated by the U.S.G.S slope-area method, <br />based on a measured flood depth of 8.9 feet (Ugland, 1980). <br />Annual maximum mean daily discharges and the months in which <br />they occurred are presented in Table 4.5-3. The peak dis- <br />charge of 2,630 cfs was measured on a day in which the <br />maximum mean daily discharge was only 115 cfs, whereas, in <br />1979, the maximum mean daily discharge was 180 cfs but <br />the instantaneous peak discharge was only 198 cfs. Further- <br />more, the total annual flow during 1974 was only 32 percent <br />of the long-term mean annual flow, while the flow was 279 <br />percent of the mean. This comparison shows that the instanta- <br />neous peak flow for Munger Creek will not necessarily occur <br />• during a "wet" year. <br />4.5.3.2.2 Estimated Floods <br />Runoff rates were calculated according to the methods <br />described in the "Manual for Estimating Flood Characteristics <br />of Natural-Flow Streams in Colorado" (McCain and Jarrett, <br />1976). The manual was developed to provide a simplified <br />method for calculating approximate limits of flood-prone <br />areas along streams in Colorado. The manual contains methods <br />for calculating 10-, 50-, 100-, and 500-year peak discharges <br />and flood depths for natural-flow streams. The peak discharge <br />information is applicable to a wide variety of studies ranging <br />from rapid approximation of flood-prone areas to detailed <br />• floodplain studies based on precise hydraulic field measurements. <br />