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Ie . . . . . . . . . . . . . . . . . . . . . I. . . . . . . ,. . . . I,. . . . I. . . ,. , '. . . (; . . . . . . . . . Drainage lOO-yr Flooding Source Drainage Area Description Area (mi2) Discharge (cfs) Section 35 Wood Gulch at mouth 18.11 Outside Bounds Yeager Gulch at mouth 1.38 Outside Bounds Taylor Park Reservoir does not provide flood control. Because it is likely that spillway facilities have been designed to evacuate flood flows in excess of the l00-year discharge, it has been assumed that reservoir will not affect downstream loo-year flood discharge. In actuality, there will be some flood flow attenuation due to surcharge capacity in the reservoir and travel times from the reservoir inflow points to the spillway. Storage in Blue Mesa Reservoir does not affect floodplains in Gunnison County. Peak flow records are available at several USGS streamflow gages within the county. USGS Bulletin 17B procedures were used to calculate peak discharges for specific return intervals at each of the gages containing adequate data for the estimation. The estimated l00-year discharge using these procedures for each of the sites is shown in Table 4, while more detailed calculations are shown in the Appendix. In general, the discharges shown in the table compare well to those calculated using the regional equations. Because the gage flows measure actual peak flows, where available, l00-year peak discharge as estimated from gage flows using Bulletin 17B procedures should be considered more accurate than the regional equations and used for analysis and design. T bl 4 P k 100 D' h t: S I d USGS G . Sta' a e . ea -year ISC arge or eecte agIng hODS USGS lOO-year Station Station Discharge ID Name (cfs) 09109000 Taylor River Below Taylor Park Reservoir, Co. 2,160 09110000 Taylor River At Almont, Co. 4,123 09 II 2500 East River At Almont Co. 5,830 09113500 Ohio Creek Near Baldwin, Co. 1,604 09118ooo Ouartz Creek Near Ohio City, Co. 820 09124500 Lake Fork At Gateview, Co. 3,208 09125000 Curecanti Creek Near Sapinero, Co. 568 09126000 Cimarron River Near Cimarron, Co. 2,053 09132500 North Fork Gunnison River Near Somerset, Co. 9,250 Communities should regulate the approximate floodplains on a case-by-case basis. FEMA requires that a detailed floodplain analysis must be performed by a professional engineer and submitted by the developer or development proponent for development projects involving more 5 acres or more than 50 units (whichever is more restrictive). Hvdraulic Analvsis Hydraulic methods used for the approximate floodplain delineations shown on the Gunnison County FIRM panels are not available or have not been documented by FEMA. For future 7