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The SCS method provides for consideration of a variety of surface <br /> conditions affecting runoff in each drainage sub-basin. These surface <br /> conditions include bare rock, sparsely covered alpine tundra, grass- <br /> land, shrub covered areas, disturbed areas, roads, cuts and fills, <br /> r <br /> forested areas and structures. <br /> i <br /> Rainfall estimates were obtained from National Oceanic and Atmos- <br /> pheric Administration (NOAA) data (5) . The May - October series <br /> was used in this study since precipitation falling during other <br /> months of the year occurs in the form of snow. Although snowmelt <br /> would be expected to produce a greater volume of runoff in this <br /> area, the maximum peak flows will result from summer rains and <br /> intense thunderstorms. The rainfall amounts for durations of 10 <br /> minutes to 24 hours from storms having recurrence intervals of 2 <br /> to 100 years are shown graphically on Figure 2. The 10-year/24-hour �^ <br /> precipitation event used for culvert sizing is 1.9 inches of total <br /> 1 <br /> depth as shown on Figure 2. <br /> The precipitation values obtained from the NOAA atlas were also com- <br /> pared with precipitation values derived from U. S. Weather Bureau j <br /> Technical Paper No. 40 (6). The comparison was favorable and the } <br /> NOAA atlas values were used for design since they are based on a i <br /> greater amount of more recent data. <br /> 37 <br />