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<br />- .? <br />, <br /> <br />. <br /> <br />. <br /> <br />. <br /> <br />Staff recommendation: Staff recommends that the Board: 1) designate and approve the 1 DO-year detailed <br />floodplain information contained in said report within the City of Florence and unincorporated Fremont <br />County, and 2) authorize staff to prepare a floodplain resolution to be signed by the Director and <br />transmitted to the City of Florence, Fremont County and to FEMA. This action is recommended in order <br />to meet statutory requirements, <br /> <br />2) Consent Al!:enda Item 2b <br />Floodplain Resolution Number: FPR 03-569 <br />Affected Community: Mesa County <br />Name of study to be formally acted on: "Bosley Wash -Phase I Watershed Floodplain Delineation, <br />Mesa County, Colorado" dated July 2002, by HDR Engineering. <br />Studied Streams: Bosley Wash <br />Technical Issues: Bosley Wash flows from north to south and is a tributary to the Colorado River <br />within Mesa County. It is generally located in an area between Grand Junction and Palisade, <br />Numerous landowners within the watershed experienced flood damage during intense rain events <br />during July and August of 1999. Mesa County retained HDR Engineering to address the issues <br />identified by the landowners within the Bosley Wash watershed. A hydrologic model (HEC-HMS) <br />was developed to quantify stormwater hydrographs, volumes and flow rates within the subject <br />watershed assuming existing land use conditions, Hydraulic profiles for the IOO-year flood and other <br />recurrence intervals were then computed using HEC-RAS, Model geometry was developed using a <br />combination of aerial mapping, surveyed cross-sections, and USGS quadrangle maps, The focus of the <br />I DO-year floodplain delineation was along Bosley wash between Interstate 70 and the Colorado River. <br />This reach comprises approximately 3,7 lineal miles of the most downstream portion of the <br />drainageway, <br />Community response: Mesa County requested and received a non-reimbursable investment from the <br />CWCB construction fund for the purpose of completing a watershed study and new floodplain delineation <br />study for Bosley Wash. The CWCB Project Manager, Larry Lang, worked closely with Mesa County and <br />its consultant, HDR Engineering, during the scoping, planning, and implementation phases of this study. <br />The County was very appreciative of the CWCB's support and assistance, and is receptive to the <br />proposed designation action for the subject floodplain study. The County is very much in support of the <br />new floodplain information, and is transmitting a letter to the CWCB requesting formal Board action on <br />the subject floodplain information report, <br />Staff findings: The subject floodplain study contains the most current detailed 100-year floodplain <br />information for Bosley Wash within Mesa County. CWCB staff has determined that the subject <br />floodplain information for Mesa County is in conformance with the CWCB's rules and regulations for <br />designation and approval of approximate floodplain information. <br />Staff recommendation: Staff recommends that the Board: 1) designate and approve the 100-year <br />detailed floodplain information contained in said report for Mesa County, and 2) authorize staff to prepare <br />a floodplain resolution to be signed by the Director and transmitted to Mesa County and to FEMA, This <br />action is recommended in order to meet statutory requirements. <br /> <br />Flood Protection. Water Project Planning and Financing. Stream and Lake Protection <br />Water Supply Protection. Conservation Planning <br /> <br />3 <br />