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<br />whole-foot water-surface elevations of the base (lOa-year) <br />flood. This map is developed in accordance with the <br />latest flood insurance map preparation guidelines publish- <br />ed by the Federal Insurance Administration. <br /> <br />6.0 OTHER STUDIES <br /> <br />A Flood Plain Information Report was prepared in October 1968 <br />by the U. S. Army Corps of Engineers, Omaha District, which <br />included Big Dry Creek in Littleton (Reference 15). In this <br />report, the lOa-year flood profile for Big Dry Creek is <br />2 feet to 10 feet lower than the flood elevations used <br />in this study. The difference in the flood profiles is <br />attributed to modified flood plain conditions, as well as <br />. increased development in the basin since the 1968 study. <br />The lOa-year flood magnitude used in this study is more than <br />twice the flood peak calculated by the U. S. Army Corps of <br />Engineers in the earlier study. Another study on Big Dry <br />Creek has been completed for the Urban Drainage and Flood <br />Control District (Reference 4). An interim report was <br />published in March 1974, which reflects current conditions. <br />No flood profile data for existing channel conditions were <br />available in this report; however, an approximate flood <br />plain limit was published which compared well with the flood <br />plain limits determined in this study. The flood hydrology <br />of the Urban Drainage District study also agrees with <br />the discharges used in this report. <br /> <br />On Slaughterhouse Gulch, a study report was completed for the <br />City of Littleton in r1ay 1974 (Reference 13). No variation <br />in flood profile data was found between this study and the <br />original report. As a result, the flood data in this report <br />are authoritative for the National Flood Insurance Program <br />and the flood plain management program of the city. <br /> <br />No official flood profile data were available for the South <br />Platte River through Littleton. However, a flood plain map <br />of this reach of the river, prepared by the U. S. Geological <br />Survey in 1968, was available from the Colorado Water <br />Conservation Board (Reference 16). The flood plain limits <br />delineated in this study compared very closely with the <br />original limits designated by the U. S. Army Corps of <br />Engineers. Discussions were held with the U. S. Army Corps <br />of Engineers to resolve differences and verify the flood <br />plain limits of this study. The flood information provided <br />in this report reflects current conditions (1974) on the <br />Platte River, including the existence of 'Chatfield Dam. <br /> <br />. <br /> <br />This study is authoritative for the purposes of the National <br />Flood Insurance Program; data presented herein either super- <br />sede or are compatible with all previous determinations. <br /> <br />30 <br />