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<br />July 31, 1956; July 26, 1965; and, May 5 and 6, 1973. On Big Dry <br />Creek, flooding has occurred on September 10, 1973; July 26, 1965; <br />and, May 5 and 6, 1973. Historical data on flood damages for the <br />other streams are scarce. <br /> <br />2.4 Flood Protection Measures <br /> <br />In the Little Dry Creek Basin, upstream of Greenwood Village, the <br />Englewood Dam, which was completed in 1936, controls 9,5 square <br />miles of the total 25 square miles in the basin. The reservoir has <br />a maximum capacity at the crest of the dam of 1760 acre-feet. This <br />is sufficient to prevent overto~ping of the dam by the lOa-year <br />flood. <br /> <br />The City of Greenwood Village restricts development within 75 feet <br />of each bank of streams within the corporate limits. The city also <br />restricts development near flood plains to a minimum elevation of <br />1.0 foot above the lOa-year flood elevation, as determined by the <br />Urban Drainage and Flood control District flood plain studies <br />(References 1, 2, 3, and 4). These restrictions have helped to <br />reduce the potential for damage from floods. <br /> <br />3.0 ENGINEERING METHODS <br /> <br />For flooding sources studied in detail in the community, standard hydro- <br />logic and hydraulic study methods were used to determine the flood hazard <br />data required for this study. Floods having recurrence intervals of 10, <br />50, 100, and 500 years have been selected as having special significance <br />for flood plain ma~agement and for flood insurance premium rates. The <br />analyses reported here reflect current conditions in the watersheds of <br />the 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 in the community, <br /> <br />The discharges for Big Dry Creek, as adopted for this study, were <br />developed for the Flood Insuran~e Studies for the City of Littleton <br />and Arapahoe County (References,5 and 6) utilizing the HEC-I hydro- <br />logic computer model. The portion of Big Dry Creek within Greenwood <br />Village is comprised of a 0.5-mile reach of channel connecting the <br />reaches studied in the Littleton and Arapahoe County Flood Insurance <br />Studies. <br /> <br />The lOa-year frequency flood discharges on Little Dry creek, Greenwood <br />Gulch, and Prentice Gulch were taken directly from a report prepared <br />for the Urban Drainage and Flood Control District (Reference 1), <br /> <br />4 <br />