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<br />of 10, 50, 100, and 500 years have been selected as having special ~ig- <br />nificance for flood plain ~a~agement and for flood insurance premium <br />rates. The analyses reported here reflect current conditions ~n the <br />watersheds of t~e streams. <br /> <br />3.1 Hydrologic Analyses <br /> <br />Hydrologic analyses were carried out to establish the peak discharge- <br />frequency relationships for floods of the selected recurrence inter- <br />vals for each stream studied in detail. <br /> <br />A gaging station on the Yampa River, located approximately 8 miles <br />upstream from Hayden, was the principal source'of data for defining <br />discharge-frequency relationships for the Yampa River. The gage has <br />been operating since 1966, providing 10 years of data. The record <br />of annual maximum peak discharges at this station wus correlated <br />against the same years of data for the Yampa River at the Steamboat <br />Springs gaging station. A correlation equation was determined and <br />used to generate an additional S9 years of data for the Hayden <br />station. Values of the 10-, SO-, 100-, and SOD-year peak discharges <br />were obtained from a log-Pearson Type III distribution of the <br />combined 69 years of annual peak flow data (References 3 and 4). <br /> <br />To define discharge-frequency data for Dry Cre8k, several methods of <br />analysis were used. A u~it hydrograph involving rainfall-runoff <br />relationsjips yielded the adopted results (Reference 5). Other <br />methods included a regional analysis procedure, as i~cicated i~ a <br />report by the U.S. Geological Survey (Reference 6), and a regional <br />procedure relating peak discharges and drainage area for nearby <br />gaging stations having similar hydrologic characteristics (Refer- <br />ence 5). <br /> <br />Peak disc~arges for the 10-, 50-, 100-, and 500-year floods of <br />streams in the study area and maximum known peak discharges for <br />nearby streams having similar hydrologic characteristics are shown <br />on Table 1. <br /> <br />J.e. Temple Reservoir was analyzed by routing the lOO-year peak dis- <br />charge developed from a regional relationship of peak discharges and <br />drainage areas of nearby gaging stations. With this information and <br />informa~ion from field inspection by geologists and engineers from <br />the u.S. Bureau of Reclamation, Grand Junction Office, it appears <br />that the dam is now functionally sound and capable of safely passing <br />a lOO-year flood discharge. <br /> <br />3,2 Hydraulic Analyses <br /> <br />Analysis of t~e hydraulic c~aracte~istics of streams i~ the cornnunity <br />were carried out to provide estimates or the elevations of floods of <br />the selected recu~re~ce intervals along each stream studied in detail. <br /> <br />5 <br />