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I I I I I I I I I I I I I I I I I I I TABLE 1 100 YEAR FLOOD ELEVATIONS Cross Cross Existing 100 Year Section Section Stream Bed Snow Melt Flow Number Station Min. Elevation Flood Elev. (cfs) 35 51 +27 8901.20 8907.26 676.5 36 51 +32 8901.25 8907.52 676.5 37 51 +50 8901.60 8907.65 719.2 38 51 +89 8902.20 8907.85 719.2 39 52 + 54 8903.80 8909.24 791.0 40 52+88 8904.70 8909.08 799.3 41 52+94 8904.70 8909.83 799.3 42 53+94 8905.90 8911.17 805.0 43 55+04 8908.00 8913.77 805.0 44 55+54 8908.40 8914.52 805.0 45 57+19 8911.60 8916.49 805.0 46 58+ 11 8914.00 8918.14 805.0 47 60+05 8918.10 8923.06 805.0 48 60+43 8919.30 8923.53 805.0 49 60+83 8920.10 8925.03 805.0 50 61 +30 8921.30 8925.20 805.0 * Permission to survey cross section number 5 across private property was not granted by the property owner. FLOODWAY DELINEATION The hydraulic analysis included computation of the water surface profile of Coal Creek through the Town of Crested Butte. Water surface profiles were determined using the 49 channel cross sections and the Corps of Engineers HEC-2 computer program. The floodway computations were completed using a maximum of a one foot rise in the water surface elevation as established by the State of Colorado regulations. The floodway analysis was completed with 805 cfs of flow in Coal Creek assuming that Coal Creek is improved to convey this flow through the Town of Crested Butte. A floodway is defined as an improved and narrowed channel capable of conveying the 100 year occurrence flows while creating a rise of not more than one foot in the water surface elevation of the unimproved channel. The f100dway analysis was completed for only the unimproved portion of Coal Creek between station 29+ 75 (section 9) and station 39+90 (section 14). Results of the 100 year floodway computations from HEC-2 are shown in Table 2. The floodway 7