Laserfiche WebLink
<br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />J <br />I <br />t <br /> <br />Description of Dry Creek Floodplain <br /> <br />Dry Creek is a left bank tributary of the Cache La Poudre River. Dry Creek flows south through <br />the northeast portion of Fort Collins before joining the Cache La Poudre River south of Fort <br />Collins Airpark (Figure 1, Vicinity Map). The basin is about 23 miles long and 3 to 3.5 miles <br />wide and has a drainage area of about 65 square miles. Basin elevations range from 6960 feet, <br />m.s.!. near its headwaters to 4910 feet, m.s.!. near its mouth. The Dry Creek floodway has an <br />approximate width from 600 to 1,200 feet within the urbanized area of the City. <br /> <br />In the upper portion of the basin, the stream is steep, narrow, and deeply incised with active <br />headcutting. Lower in the basin, the Dry Creek channel is relatively stable with wide, shallow <br />floodplains except below the Larimer and Weld Canal in Fort Collins, where the channel does <br />not exist in several areas. Upstream from the Alta Vista Community, the Dry Creek channel is <br />undefined except for a small drainage ditch just downstream from College Avenue. <br /> <br />Extensive commercial and residential development is located within the Dry Creek floodplain <br />from College Avenue to the Larimer and Weld Canal within the City limits. Downstream from <br />the Larimer and Weld Canal, the Dry Creek channel has been obliterated from Willox Lane to <br />downstream from the trailer court at College Avenue. In the Fort Collins Airpark, the disposal of <br />building material and other fill in the Dry Creek channel has reduced the capacity of Dry Creek. <br />The filling and regrading of the Dry Creek channel took place prior to the City and County <br />entering the National Flood Insurance Program and prior to the enactment of floodplain <br />management regulations which now prohibit such activities. <br /> <br />Presently, the impact of new development in the lower basin of Dry Creek is already increasing <br />the magnitude and frequency of drainage flows. In the past, much of the excess drainage from <br />irrigated farmland was intercepted by irrigation canals. Today, these canals no longer have the <br />capacity to intercept larger flood flows and increased drainage flows. The irrigation canals <br />should be bypassed with proper conveyance provided in the drainageway. <br /> <br />Figure 2, Dry Creek Existing Floodplain, shows the delineation of the floodplain and floodway <br />from just above Willox to Mulberry Street (Highway 14). The delineation includes some area <br />located within the jurisdiction of Larimer County, however, depicts the most developed portions <br />of the floodplain. <br /> <br />Photographs I and 2 show aerial views of the North College Avenue corridor portion of Dry <br />Creek. The approximate floodplain is delineated by red and the approximate channel by black <br />dashed lines on both photos. Photograph 1 is looking northeast from downtown and photograph <br />2 is looking south from Terry Lake. The channel, delineated by dashed black lines, has been <br />obliterated throughout most of the reach by pre-Firm development and grading. The remaining <br />portion ofthe "native" channel, visible as a line of trees, has been identified as a natural resource <br />area and is observed in the upper left (northwest) portion of photo I. The Cache La Poudre River <br />is visible in the foreground of photo 1 and the background of photo 2. <br /> <br />3 <br /> <br />