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<br />PREFACE <br /> <br />This hydrology addendum is part of a program by the Colorado Water Conservation Board <br />(CWCB) to make approximate floodplain maps prepared by the Federal Emergency Management <br />Agency (FEMA) easier for local governments to use. This CWCB report provides limited <br />engineering information to support the approximate delineations on the maps. and it provides <br />floodplain management information to guide the local governments in the use of the maps. <br /> <br />The official floodplain information for Fremont County is the Flood Insurance Study (PIS) with its <br />associated Flood Insurance Rate Maps (FIRMs), dated September 29,1989. The PIS was prepared <br />by FEMA, and includes engineering information for those streams that were studied in detail. <br />However it does not include any engineering information to describe basis of the approximate <br />floodplain mapping. The initial purpose of this report, therefore, is to provide the County with <br />limited supporting information for the approximate floodplain delineations. This addendum <br />includes a description of a hydrologic analysis that was performed for the County as part of the <br />CWCB's technical assistance program. The hydrologic analysis is consistent with the FEMA <br />mapping. In addition, the addendum gives the County some basic information about floodplain <br />management and it gives some alternatives that could be considered in formulating and <br />implementing its floodplain management objectives. <br /> <br />A second function of this report is to assure that the PIS meets the basic technical requirements for <br />designation and approval by the CWCR Without a hydrologic analysis, the approximate floodplain <br />information in the Fremont County PIS cannot qualify for CWCB designation. Colorado statutes <br />require that local governments obtain from the CWCB the designation and approval of floodplain <br />information for its use in regulatory purposes. This addendum provides a means for the PIS to meet <br />that statutory objective. <br /> <br />The PIS was prepared prior to the completion of a CWCB document entitled Guidelines for <br />Determining IOo..year Flood Flows for Approximate Fwodplains (Guidelines). The Guidelines <br />provide the necessary hydrologic information in support of the approximate lOO-year floodplain <br />boundaries identified on the Flood Insurance Rate Map (FIRM) panels. The hydrologic information <br />contained in the Guidelines was used in preparing this addendum and it supports the subsequent <br />designation of the Fremont County PIS. <br />