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INTERPRETATION AND USE OF REPORT DATA Flood Fr""JL.lencyanc Discharge The l~-, 50-, 10~-, and 5~~-ycar flood events were used as the flood frequencies for this floodplain analysis. Thus the data developed in this report will be compatible not only for re<;Julation purposes and H. B. 1~41 designations, but al so fo r Federal Insur ance Administration flood insurance rate studies. These various flood events have an average occurrence of once in the number of years "s indicated. For example, the 101il-year flood 1 , I I I occurs, on the average, once in a 100 year period, and has a one percent chance of being equaled or exceeded in any given year. The particular uses for the various flood events in addition to those stated above are as follows: 10-year "nd 50-Year Flood Events :nfarmation regarding these luwer frequt!ncy floods " especially useful for future cnginlilcring studies and land use plaf'lning purpos..s relat..d to minor road systems, minor channel irn?roVenH!nt", th.. loc'lti"n ^' p" r~" oW, U~cP'dth'nal facilities, ilgricultlHal lands, and appurtenant structures. The use of the lower frequency floods may be considered for structures and uses of this type on the smaller tributaries and in areas where the high risk of 3tructural failure is ecow..'1'1icall:.' fe",.':i~lc ::!::d tr;c !':J:~~d ~: life :l:1d property ~~ nonexistent. l0~-Year Flood Event Th~ lZ~-year flood event m~y also be used for engine"ring design purposes where a lower riSk of failure than the 10~ or 50-year floud is desired. However, the most important use of H the l~~-year flood event lies in floodplain designation and laf'ld use regulation as set forth in state statutes. The State of Colorado considers the 102'-year frequency flood as the flood event to be used in designing and protecting structures and dwellings for humaf'l occupation. Therefore, all floodplain re9ulations are based upon the 10'J-year flood. Also, the area which would be inundated by the HHl-year flood may be delineated as an area of state interest as set forth in H.B. 1041, the state's land use bill. 500-Year Flood Event The 500_year flood event is useful in making the public aware that floods larger than the 100~year flood can and do occur. Just because a person is living above the lll0-year flood boundary does not mean that he is completely safe from flooding. The 5110-year flood event Can also be used for regulilting high risk developments Ylithin the floodplain such as nuclear power plants, or the storage or manufacture of toxic or explosive materials. T<:tblc J li.3ts the j)eJK ~'.3ch::rge::: <:tr.d ;.;.J.::er :;"rtJcc clcv.:<:<.on:> for the l~~, 50-, 100-, and 500-year tload events at selected reference points. "