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<br />- ~. <br /> <br />floodplain where development and structures can be located at <br />levels relatively safe from flooding, Within the floodway, man's <br />activities must consider the impact on the hydraulics of the <br />stream. When locating deflector dikes or irrigation structures, <br />the top elevation of the embankments should not be sited above <br />the 10-year flood elevation, Within the s~udy reach, a jetty <br />configuration is required to stabilize the channel and provide <br />erosion protection to the development within the flood fringe <br />areas. <br /> <br />Flooded Areas <br /> <br />The 100-year floodplain adjacent to Colorado Highway No. 55 <br />is approximately 2 miles in width, The right-side laO-year <br />floodplain (South) is one-half mile in width and the left-side <br />100-year floodplain (North) is one and one-half miles in width, <br />as delineated by the Corps of Engineers, Right-side floodplain <br />development includes the wildlife refuge within the overbank <br />area. It consists of heavy vegatative cover with a roughness <br />coeffient of n = 0.1. Left-side floodplain development consists <br />of intense irrigated agricultural, union Pacific R,R" Highway <br />No. 138 and the corporate area of Crook, Colorado. It has an <br />average roughness coeffient of n = .045. During times of flood, <br />floodwaters will flow to the lower floodplain friction value <br />because it provides less resistance to flow. The overbank areas <br />were inundated during the 1965 and 1973 flood events. The Town <br />of Crook is shown completely within FEMA's Special Flood Hazard <br />zone (See Exhibit 1). Therefore, new federally-backed mortgages <br />require the purchase of flood insurance for every property within <br />the community. <br /> <br />Erosion Of Streambanks And Dikes <br /> <br />'. <br /> <br />Following the,1973 flood, the State of Colorado constructed <br />two deflector dikes within the right overbank areas, These dikes <br />provided protection to certain features within the game refuge <br />and were also constructed to maintain the channel alignment in <br />its' northeasterly direction. To mitigate the impacts to the <br />left-streambank, the State of Colorado through the Division of <br />Wildlife assisted landowners in the construction of three <br />deflector dikes. These dikes are accountable for the present <br />channel alignment. <br /> <br />-6- <br />