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<br />Records show that the Eagle River flooded significantly in 1912;
<br />1947; 1957; 1959; and, most recently, on June 26, 1969, with a 2-
<br />year recurrence interval. All of these floods occurred during June
<br />RererenCCe 7). 1'l,e RlaximUlll flood-oL-X:e_c9rd occurred in 1912,
<br />however, no recurrence interval is available for this flood. Two
<br />floods, August 1956 and September 1967, were recorded for Sweetwater
<br />Creek (Reference 7).
<br />
<br />No flood history was available for Taylor Creek, Downey Creek,
<br />Seven Castles Creek, Otto Creek, Frenchman Creek, Beaver Creek,
<br />West Lake Creek, East Lake Creek, Two Elk Creek, Deep Creek,
<br />Squaw Creek, McCoy Creek, Cross Creek, Stone Creek, and Whiskey
<br />Creek.
<br />
<br />2.4 Flood Protection Measures
<br />
<br />Ruedi Reservoir, located on the Fryingpan River east of the Town of
<br />Basalt and completed in July 1968, with a storage capacity of
<br />102,300 acre-feet (Reference 8), will afford some protection from
<br />floods caused by rainfall. The total probable maximum discharge
<br />from the outlet structure and spillway is 73S0 cubic feet per
<br />second, approximating the SOO-year flood in the Town of Basalt
<br />(Reference 8). Prior to this study, Eagle County had not practiced
<br />any form of flood plain mangement. There are no other known flood
<br />protection measures in the areas studied in Eagle County.
<br />
<br />3.0 ENGINEERING METHODS
<br />
<br />For the flooding sources studied in detail in the county, standard
<br />hydrologic and hydraulic study methods were used to determine the flood
<br />hazard data required for this study. Flood events of a magnitude which
<br />are expected to be equalled or exceeded once on the average during any
<br />10-, 50-, 100-, or SOO-year period (recurrence interval) have been
<br />selected as having special significance for flood plain management and
<br />for flood insurance premium rates. These events, commonly termed the
<br />HUH :LO.:OO.... SO-, 100-, and SOO-year floods, have a 10, 2, 1, and 0.2 percent
<br />chance, rE,spec,EiveJ.'l ,of being.equailed or exceeded...during .anyy-,"a",.,
<br />Although the recurrence interval represents the long term average period
<br />between floods of a specific magnitude, rare floods could occur at short
<br />intervals or even within the same year. The risk of experiencing a rare
<br />flood increases when periods greater than 1 year are considered. For
<br />example, the risk of having a flood which equals or exceeds the lOO-year
<br />flood (1 percent chance of annual occurrence) in any SO-year period is
<br />approximately 40 percent (4 in 10), and, for any 90-year period, the
<br />risk increases to approximately 60 percent (6 in 10). The analyses
<br />reported here reflect flooding potentials based on conditions existing
<br />in the county at the time of completion of this study. Maps and flood
<br />elevations will be amended periodically to reflect future changes.
<br />
<br />8
<br />
<br />REVISED: 1/25/83
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