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<br />LYONS COLORADO FLOOD HAZARD MITIGATION PIAN <br /> <br />The August 10, 1994 Lyons Flood <br /> <br />THE EVENT <br /> <br />On the night of Aug. 10, 1994, a storm cell <br />hovered over Lyons. At approximately <br />10: 15 p.m., the town was inundated with <br />rainfall accompanied by high winds of <br />close to 100 miles an hour. An estimated <br />three inches of rain fell in the Lyons <br />vicinity within 30 minutes. The town's <br />drainage system, unable to manage such <br />large quantities of water, backed-up <br />spilling over its banks, causing an urban <br />flash flood. <br /> <br />The flood waters originated from the <br />foothills located to the north, east and west <br />of town. Water flowed in a steady stream <br />on most north - south streets. High winds <br />brought down tree limbs damaging cars, <br />yards and homes. A newly framed house <br />located in Eagle Canyon, just west of town, <br />collapsed as a result of the strong winds. <br />Lightning struck a service line at a home <br />knocking out electricity at about 10:13 <br />p.m.; it was three hours before power was <br />restored. Fortunately there were no deaths <br />or injuries. <br /> <br />The hardest hit area of town was between <br />Evans Street and north of Reese Street. The <br />towns drainage system, the ditch, runs <br />through this vicinity canying runoff water <br />from the northern foothills south through a <br />residential area and then flows into the <br />North St. Vrain Creek. This manmade <br />ditch is built of red sandstone found in the <br />surrounding foothills. It is roughly four <br />and a half feet in width and about three to <br /> <br />r <br /> <br />- -- <br /> <br />three and a half feet deep and is generally <br />empty from October to May. During peak <br />runoff and snowmelt months (May - <br />September), there is usually a steady flow <br />of about six inches of water in the ditch. <br /> <br /> <br />Lyon', drabtage ditch: photo taken at property on <br />Reeu Street. <br /> <br />Factors that Contributed to the Flood <br /> <br />Over the years, parts of the ditch have been <br />re-routed or covered for landscaping or to <br />build roads while some parts remain above <br />ground and visible. The ditch was not <br />designed for flood and is capable of <br />carrying only minimal amounts of water. <br />Most of the underground pipes, being <br />smaller than the upstream water channels, <br />are unable to transport water as fast as the <br />upstream channels themselves. This causes <br />water to back-up and spill over the banks <br />during rainstorms or high runoff. <br /> <br />7 <br />