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<br />. <br /> <br /> <br />. <br /> <br />CHAPTER 4 <br />FLOODPLAIN <br />ADMINISTRATION <br />AND <br />DELINEATION <br /> <br />.ECTION 1.0 <br />LOODPLAIN <br />MANAGEMENT <br /> <br />COLORADO STATEWIDE <br />DRAINAGE AND FLOODPLAIN MANAGEMENT CRITERIA MANUAL <br /> <br />Local communities are encouraged to develop future (built-out) conditions <br />floodplain information, especially when the area plan indicates a substantial <br />amount of future development. Once developed, communities may request <br />FEMA to show future conditions floodplains on the FIRM maps in addition to <br />the existing conditions floodplains. <br /> <br />Communities should regulate and guide their proposed floodplain <br />developments based on the floodplain management guidelines provided in <br />this section and the available existing conditions 100-year floodplain <br />information. If future (built-out) conditions floodplain information is available <br />to local communities, then, the proposed floodplain developments should be <br />regulated based on the future conditions floodplain information. <br /> <br />1.4 LEVEL OF PROTECTION <br /> <br />The standard of practice, as required by FEMA, is to implement the floodplain <br />management regulations based on a 100-year flood event. The 100-year peak <br />discharge at a given point is the estimated peak discharge that has a 1 % probability <br />of'occurrence in any given year. Flow rates in excess of the 100-year estimate can <br />and will occur, but with lower probability. In those instances, typically the depth of <br />flow and floodplain widths will be greater than indicated on the 100-year floodplain <br />maps provided by FEMA. <br /> <br />Therefore, the guidelines described in this chapter will not necessarily protect a <br />property owner against flood events that exceed the 100-year peak flow estimate. A <br />property owner may choose to provide a greater level of protection than what is <br />required by the floodplain management guidelines, especially in the case of critical <br />facilities, buildings that store hazardous materials, and where building content <br />damage could be significant. <br /> <br />1.5 <br /> <br />SOURCES OF FLOOD HAZARD AREA INFORMATION <br /> <br />Many watercourses in the State of Colorado have been analyzed by various <br />engineering studies sponsored by local, state, or federal agencies. The 100-year <br />floodplain information generated and/or published by FEMA can be found on the <br />Flood Insurance Rate Maps (FIRM) and Flood Insurance Studies (FIS). All floodplain <br />data generated by FEMA and other engineering studies should be available at the <br />local Floodplain Administrators office, the CWCB, or FEMA. The existing floodplain <br />studies and delineations should be evaluated to determine if the information is still <br />valid. When determined appropriate, the existing studies should be used to minimize <br />duplication of work and to maintain continuity of the analysis. <br /> <br />Please note, floodplain data is periodically updated to reflect changes due to <br />floodplain modifications or the use of better technical data. Users of the floodplain <br />information should check with the local Floodplain Administrator to ensure that the <br />information is current. Readers are referred to Sections 2 and 3 of this chapter for <br />detailed discussions on the floodplain delineation and revision methods. <br /> <br />AUGUST 2002 <br /> <br />FLOODPLAIN <br />MANAGEMENT <br /> <br />CH4-105 <br />