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Records show that the Eagle River flooded significantly in 1912; 1947i 1957; 1959; and, most recently, on June 26, 1969, with a 2- year recurrence interval. All of these floods occurred during June (Reference 7). The maximum flood of record occurred in 1912i however, no recurrence interval is available for this flood. Two floods, August 1956 and September 1967, were recorded for Sweetwater Creek (Reference 7). No flood history was available for Taylor Creek, Downey Creek, Seven Castles Creek, Otto Creek, Frenchman Creek, Beaver Creek, West Lake Creek, East Lake Creek, Two Elk Creek, Deep Creek, Squaw Creek, McCoy Creek, Cross Creek, Stone Creek, and Whiskey Creek. 2.4 Flood Protection Measures Ruedi Reservoir, located on the Fryingpan River east of tlle Town of Basalt and completed in July 1968, with a storage capacity of 102,300 acre-feet (Reference 8), will afford some protection from floods caused by rainfall. The total probable maximum discharge from the outlet structure and spillway is 7350 cubic feet per second, approximatlng the 500-year flood in the Town of Basalt (Reference 8). Prior to this study, Eagle County had not practiced any form of flood plain mangement. There are no other known flood protection measures in the areas studied in Eagle County. 3.0 ENGINEERING METHODS For the flooding sources studied in detail in the county, standard hydrologic and hydraulic study methods were used to determine the flood hazard data required for this study. Flood events of a magnitude which are expected to be equalled or exceeded once on the average during any 10-, SO-, 100-, or SOO-year period (recurrence interval) have been selected as having special significance for flood plain management and for flood insurance premium rates. These events, commonly termed the 10-, SO-, 100-, and SOD-year floods, have a 10, 2, 1, and 0.2 percent chance, respectively, of being equalled or exceeded during any year. Although the recurrence interval represents the long t~rm average period between floods of a specific magnitude, rare floods could occur at short intervals or even within the same year. The risk of experiencing a rare flood increases when periods greater than 1 year are considered. For example, the risk of having a flood which equals or exceeds the 100-year flood (1 percent chance of annual occurrence) in any 50-year period is approximately 40 percent (4 in 10), and, for any gO-year period, the risk increases to approximately 60 percent (6 in 10). The analyses reported here reflect flooding potentials based on conditions existing in the county at the time of completion of this study. Maps and flood elevations will be amended periodically to reflect future changes. 8