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<br /> <br />. the River Oaks subdivision and the adjacent industrial park in the new floodplain (in contradiction <br />to its omission in previous floodplain delineations). <br /> <br />. <br /> <br /> <br />. <br /> <br />The new study made use of more current and complete topographic information developed by 111e <br />town and the counties, detailed two-dimensional hydraulic modeling of flows in the South Side to <br />better analyze the complex flow pattern there prior to a revised one-dimensional fmal analysis, and <br />a detailed analysis of return flows from the South Side across the Highway 82 Bypass back to the <br />main river floodplain. During the technical analyses the town's consultants found that through <br />much of the Basalt study reach current floodplain elevations were already 1 foot or more above the <br />previous lOO-year elevations, due primarily to encroachment from various development and <br />infrastructure activities. The Town of Basalt chose to pursue delineation and adoption of a zero- <br />rise floodway, since much of the standard FEMA I-foot rise had already been "used up". Both <br />Basalt and Pitkin County have adopted the new, more restrictive floodway. Eagle County is in the <br />process of considering its adoption for the Roaring Fork portion of the county. CWCB staff <br />supports the technical findings of this new study and the preparation and adoption of a zero-rise <br />floodway to deal with the specific floodplain problems in 111e Basalt area. <br /> <br />Community response: The floodplain information report was initiated by the Town of Basalt, in <br />cooperation with Pitkin and Eagle Counties. Throughout the technical study process the town and <br />its consultants coordinated its efforts with CWCB staff. On October 18, 2001111e Town of Basalt <br />sent a letter to the CWCB formally requesting designation and approval of the study, for 1110se <br />portions ofthe study area within the corporate limits of Basalt. On October 23, 2001 Pitkin County <br />sent a similar letter regarding portions of the study area within unincorporated Pitkin County. Eagle <br />County is supportive of the floodplain delineations contained in 111e new report. However, Eagle <br />County wished to examine the implications of the zero-rise floodwav delineation contained in the <br />report and chose to delay submission of a formal request for designation and approval of Eagle <br />County portions of the study area until that examination had been completed and approved by the <br />County Commissioners. <br /> <br />Staff findings: CWCB staff has determined that the subject detailed floodplain information is in <br />conformance with the CWCB's rules and regulations for floodplain designation and approval. The <br />revised 100-year flood profile and floodplain delineation are reasonable and appear to accurately <br />describe flood hazards in the affected communities, Staff will urge the Town of Basalt, Eagle <br />County, and Pitkin County to incorporate said study into the FEMA Flood Insurance Study to be <br />used for floodplain management, regulation, and flood insurance purposes, The most current <br />regulatory floodplain mapping published for the Roaring Fork River in the vicinity of Basalt was <br />studied by detailed methods, however a number of updates and revisions have taken place in the <br />October 2001 Floodplain Information Report CWCB finds that the previously published floodplain <br />delineations for the subject study reach contained in the June 1987 Flood Insurance Study for the <br />T6Wi1ofl3ilSalt, and--nle :)eptember 1988 l'lood .In$urance Study for Pitkin County shouldbe <br />replaced by the current inforni.ation in the October 2001 Floodplain Information Report presented <br />here for designation and approval.. <br /> <br />Flood Protection. Water Project Planning a;nd Financing. Stream and Lake Protection <br />Water Supply Protection. Conservation Planning <br /> <br />3 <br />