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<br />6.0 OTHER STUDIES <br /> <br />Flood boundaries have been reconciled with previous studies on Big Dry <br />Creek (Reference 4), Little Dry Creek (Reference 20), Clear Creek <br />(Reference 19), and the South Platte River (References 2, 3, 10, and <br />23). <br /> <br />There are past published reports on flooding throughout Adams County <br />except on Box Elder Creek and Comanche Cr~ek. The 1963 U.S. Army Corps <br />of Engineers' Denver Metropolitan Region iFlood Plain Information (FPI) <br />report, Volume I, (Reference 10) was a~opted by the Colorado Water <br />Conservation Board (CWCB) in 1967 as the official flood plain study for <br />the South Platte River. Following the 1965 flood and other mOre recent <br />flood experiences, as well as the consttuction of Chatfield Dam, the <br />U.S. Army Corps of Engineers considers, the 1963 FPI for the South <br />Platte River to be outdated. In September of 1977, the Urban Drainage <br />and Flood Control District published a Flood Hazard Area Delineation of <br />the South Platte River. This study has ~een revised to agree with the <br />UDFCD study, which is based on more detjailed topographic mapping and <br />many more surveyed cross sections. The delineation shown of the South <br />Platte River is based on a lOa-year discharge assuming projected 1990 <br />basic conditions. Minor differences between the Adams County study and <br />the flood insurance studies for the Cities of Brighton, Thornton, and <br />Commerce City can be attributed to the use of a projected lOa-year <br />discharge in the county study, as opposed to present conditions <br />analysis in the city studies. <br /> <br /> <br /> <br />A Flood Plain Information report (Reference 20) was prepared in 1968 by <br />the U.S. Army Corps of Engineers, Omaha Oistrict, which included Little <br />Dry Creek in Adams County. Minor discfepancies' occurred because the <br />U.S. Army Corps of Engineers assumed blockage at culverts and bridges <br />during flood stages, and the present study is based on unobstructed <br />flow. <br /> <br />The Urban Drainage and Flood Control, District (UDFCD) published a <br />report on Big Dry Creek (Reference 4) ; in March 1973. The lOa-year <br />flood profile in this report was in suqh close agreement that it was <br />decided to use ihe Urban Drainage and Flood Control District's profile <br />except for the area around Interstate: 25, which was adju~ted upon <br />approval of UDFCD to reflect our analysis. <br /> <br />A Flood Plain Information report was published in January 1966 by the <br />U.S. Army Corps of Engineers, Omaha District, regarding flooding along <br />Clear Creek (Reference 19). Comp&rison of reports reflected <br />discrepancies throughout the entire str~am length because the present <br />study was based on considerably higher discharges. Other discrepancies <br />may be attributed to recent improvements', such as the Broadway crossing <br />and the Interstate 270 interchange, which were not present in 'the U.S. <br />Army Corps of Engineers report. Upon contact, the U.S. Army, Corps of <br />Engineers stated that their report was no longer valid. Peak <br />discharges for Clear Creek are being, recomputed, and results of a <br />revised detailed study of this stream ~ill eventually be added to the <br />Flood Insurance Rate Map. The lOa-year flood boundary originally <br /> <br />32 <br />