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<br />Recommendations <br />Based on the findings summarized above, the CWCB staff recommends the following mitigation <br />measures: <br /> <br />Short-Term Mitigation Measures <br />. Design and replace the existing drainage system commencing at the intersection of County <br />Road 44 and Highway 40, downstream to the West Fork of the Elk River to address problem <br />no. 2 listed above. The undersized 24 inches culvert should be added to or replaced with a <br />larger culvert. (The staff estimated 250 cfs weir flow passed over CR 44 with additional 25 <br />cfs through the CR 44 24" culvert, and an additional 50-100 cfs detained by ponding storage <br />and passed through the Hwy 40 culvert to the east of CR 44.) The new drainage <br />system/culvert should be designed to pass at least 250 to 350 cfs without overtopping the <br />highway or the county road. <br /> <br />. Replace the existing undersized culvert with a new culvert to address problem no. 3 listed <br />above. The new culvert should be designed to pass flows between 250 and 350 cfs. The <br />existing swale on the north side of the highway can remain as,is. <br /> <br />. Replace the existing culvert with a properly sloped 24" diameter culvert to address problem <br />no. 4 listed above; however, this action will require the south side borrow ditch (between <br />highway and railroad) to be properly designed and constructed to provide adequate slope to <br />the West Fork of the Elk River. <br /> <br />. Improve the capacity of the existing ditch to address problem no. 5 listed above. In addition, <br />install a 48" diameter culvert under the existing driveway to allow water to flow from east to <br />west along the ditch. <br /> <br />Long-Term Mitigation Measures <br />The Lower Elk River Rood Association and Routt County should make a formal request to the <br />Colorado Water Conservation Board to seek funding to perform a multi-objective drainage <br />master plan study for the Lower Elk River basin. The master plan could identify strategies for <br />solutions to flooding problems, erosion problems, channel stability problems, and address habitat <br />and environmental concerns/issues for the study reach. This request is for an Elk River <br />Floodplain Management Planning and Improvement Study. <br /> <br />IV. SUPPORTING INFORMATION <br /> <br />Attached are several sheets that contain pertinent photographs and other supporting information <br />for this report. <br /> <br />3 <br />