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Ie . . I. i. . . . . . . . . . . . . . . . . . . . . . . . . . . '. . '. . . . . . . . . . . . . I. . . . . . . . a e " ummary 0 cua lSC ar2es Drainage tOO-year Flooding Source Drainage Area Description Area (mi) Discharge (cfs) Alkali Creek at mouth 63.49 1,600 Beaver Creek at mouth 17.33 600 Buffeur Creek Upstream of Gore Creek 3.99 200 Cross Creek at mouth 35.56 1,100 Deep Creek at mouth 48.41 1,300 Downey Creek at mouth 6.54 300 East Coutter Creek Upstream of Van Springs Res. 9.74 400 East Lake Creek at mouth 30.92 1,000 Fall Creek Upstream of Notch Mountain 10.28 400 Creek Frenchman Creek at mouth 16.28 600 Grousse Creek at mouth 11.93 500 Gypsum Creek at mouth 102.35 2,300 Homestead Creek at mouth 63.08 1,600 Lake Creek at mouth 51.74 1 ,400 McCoy Creek at mouth 6.33 300 Otto Creek at mouth 3.05 200 Seven Castles Creek at mouth 1.60 100 Squaw Creek at mouth 17.23 600 Stone Creek at mouth 4.78 200 Sweetwater Creek at mouth 111.45 2,400 Two Elk Creek at mouth 15.85 600 Van Springs Reservoir Upstream of Eagle County Line 7.67 300 West Lake Creek at mouth 14.21 500 Tbl3S f Cal I ted D" h 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 gages containing adequate data for the estimation and which have approximate floodplains shown on the FIRMs. The estimated 100-year discharge using these procedures for each of the sites is shown in Table 4, while more detailed calculations are shown in the Appendix. The Cross Creek discharges agree fairly well - there is slightly more drainage basin area at the mouth of the creek than at the gage. The Beaver Creek discharges differ more significantly. Although the drainage basin areas are essentially identical, the amount of land development within the basin likely has an impact on peak flows and makes the regional regression calculations less accurate. Because the gage flows measure actual peak flows, where available, loo-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. 8