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I I I I I I I I I I I I I I I I I I I all of Slate River. Due to lack of data, no additional flood frequency analysis is performed for the reach of the Slate River above Crested Butte and the results for the downstream reach are utilized to represent the entire reach. 5.1.3 Results for Reach 2 Before any analysis was completed, the data record for both the Slate River and East River gages were filtered for rain on snow events, using the 0.5 inch criteria discussed in Section 4.1.1. One rain on snow event was found in the record of the Slate River gage. The East River at Almont results are described in Section 5.4. The REGFREO and HEC-FFA programs were used to perform the analysis on the flow record in Table A.1. Prior to using the REGFREO program HEC-FFA was used on both the East River at Almont and Slate River near Crested Butte data to test for low and high outliers based on a methodology described in Bulletin 17B. Any outliers were manually removed from the REGFREO data set. The 1977 flow for the East River gage was determined to be a low outlier. The results from the analysis are presented in Figure 5.1.3.1. Additionally, the adopted statistics and the 10, 2, 1, and 0.2 percent chance exceedence flows are presented in Table 5.1.3.1. Table 5.1.3.1 Flood Frequency Analysis Results for Reach 2 Slate River above Confluence with the East River Std. Flow (C18) Mean Dev. Skew Chance Exceedence 10% 2% 1% 0.2% Peak 3.017 0.090 0.000 1,356 1,592 1,684 1,888 1-Dav 2.986 0.090 0.000 1,263 1 ,482 1,568 1,758 3-Dav 2.975 0.090 0.000 1,231 1,445 1,529 1,714 5-Day 2.963 0.090 0,000 1,198 1,406 1,487 1,667 7-Day 2.952 0,090 0.000 1,168 1,370 1 ,450 1,626 15-Dav 2.901 0.090 0.000 1,038 1,219 1,289 1,446 30-Dav 2.852 0.090 0.000 928 1,089 1,152 1,291 60-Day 2.763 0.090 0.000 756 887 938 1,052 15