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<br /> <br />WATERSHED MANAGEMENT <br /> <br />ISSUE: <br /> <br />WM-l Lack of current and accurate floodplain mapping in Colorado <br />communities, especially rural unincorporated areas and in areas experiencing <br />development. <br /> <br />BACKGROUND: <br /> <br />Much of the flood damage suffered in this disaster period occurred in areas not <br />shown on FEMA maps as 1 OO-yeor floodplain oreas. Areas subiect to "storm <br />drainage" problems (as opposed to riverine flooding problems, if such a distinc- <br />tion can be drawn), areas downstream of irrigation ditches, areas subject to <br />ponding without satisfactory outlet paths, areas beyond the limits of the 100- <br />year (and even 500-year) flooding, and areos where debris accumulation and/ <br />or human emergency intervention altered flow patterns were all witnessed in <br />1997. Floodplain managers, emergency responders and citizens can all ask, <br />"Can we rely on these floodplain maps during an actual flood emergency?" <br /> <br />RECOMMENDATIONS: <br /> <br />- Seek funding (local, State, Federal & private) to sponsor an all-day <br />workshop on floodplain mapping issues <br />-In view of the 1997 experience, compare current FEMA and other <br />floodplain maps to the outlines of the areas of inundation during <br />flooding in 1997; identify specific technical issues of concern to <br />hydraulic engineers who prepare floodplain maps <br />- Develop specific recommendations for each of the pertinent <br />technical issues <br />-Implement recommendations on a pilot basis by conducting <br />floodplain studies in Colorado communities where a particular <br />floodplain-mapping problem was experienced <br />- Examine pilot studies with independent outside reviewers and <br />make adjustments, as necessary <br />- Access information from EPA's Index of Watershed Integrity that uses <br />15 data layers to characterize individual watersheds <br /> <br />LEAD AGENCIES: <br /> <br />CWCB, Urban Drainage and Flood Control District, CU, CSU, Colo. School of <br />Mines, irrigation companies, private consulting engineers, FEMA, COE (includ- <br />ing HEC in Davis, CA), NRCS <br /> <br />FUNDING: <br />Agency and program funding <br /> <br />SCHEDULE: <br />One to five years <br />