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<br />CWCB for Buena Vista and Chaffee County, The detailed floodplain information within that <br />report was adopted for use in the Buena Vista Flood Insurance Study, <br /> <br />Community Resoonse to the CWeR Desil!Jllltion and Approval Process <br /> <br />A letter from the CWCB was transmitted to the Town of Buena Vista regarding the Board's <br />proposed action for designation and approval of the Buena Vista FrS. The Town was receptive to <br />the Board's proposed actions, and requested that the CWCB designate and approve the floodplain <br />information currently available to the community, A meeting was held between Town officials and <br />CWCB staff to discuss hydrology issues, floodplain regulations, and the designation and approval <br />of the FIS, <br /> <br />ENGINEERING METHODS <br /> <br />HvdrolO2ic Analvsis <br /> <br />Hydrology information used for the Cottonwood Creek floodplain delineation in Buena Vista's FrS <br />is discussed in Section 3,1 of the FrS, The 100-year peak flow for Cottonwood Creek at its <br />confluence with the Arkansas River is reported to be 1,300 cfs, and the drainage area is 105 square <br />miles, The hydrology information for the Arkansas River upstream of its confluence with <br />Cottonwood Creek was estimated by performing a flood frequency analysis (in accordance with <br />Bulletin 17B) utilizing available gage data on the Arkansas River at the Buena Vista gage, The <br />computed peak flow value for this study is 4,540 cfs, This value supersedes the value of 3,930 that <br />is published in the Buena Vista Flood Insurance Study (March 30, 1982), <br /> <br />The 100-yr peak flow on the Arkansas River downstream of its confluence with Cottonwood Creek <br />was estimated using a procedure outlined in "Manual for Estimating Flood Characteristics of <br />Natural Flow Streams in Colorado" (CWCB and USGS, 1976), The procedure, entitled "flood <br />information near gaged sites on the same stream," utilizes the computed loo-yr flow for the Buena <br />Vista gage in conjunction with a weighted ratio of the drainage areas at the ungaged and gaged <br />sites, Table I presents a summary of discharges for the studied streams in Buena Vista <br /> <br />Table 1- Summary of Discharges <br /> <br /> <br />Arlumsas River upstream of its confluence with <br />Cottonwood Creek at the <br />Arkansas River just downstream of its confluence with <br />Cottonwood Creek <br />Cottonwood Creek at its confluence with the Arkansas <br />River <br />Cottonwood Creek upstream of its confluence with the <br />Arkansas River at the <br /> <br />.w~: <br /> <br />4,540 <br /> <br />720 <br /> <br />5,170 <br /> <br />105 <br /> <br />1,300 <br /> <br />65 <br /> <br />936 <br /> <br />3 <br />