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<br />LYONS COLORADO FLOOD HAZARD MITIGA TJON PUN <br /> <br />Flood Risk and Vulnerability <br /> <br />LYONS FLOOD HISTORY <br /> <br />Lyons' residents have experienced floods <br />since the area was first settled in the early <br />1860s. Floodplains were undefmed at that <br />time, so many settlers unknowingly <br />located themselves in floodplains for quick <br />and easy access to water supplies. <br /> <br />One contributing factor to historical and <br />current flooding in Lyons is the location <br />and development of buildings surrounding <br />the North and South St. Vrain creeks. A <br />majority of the town is situated in the <br />FEMA 100-year floodplain, meaning this <br />area has a one percent chance of a flood <br />equaling or exceeding any historical flood <br />in any given year. This means those <br />houses located in close proximity to water <br />are at risk for encountering flood. The <br />floods that threaten Lyons occur in a 10 - <br />25 year cycle ranging from quick onset to <br />prolonged water accumulation. <br /> <br />Lyons geographical location also <br />contributes to flooding in this area. Lyons <br />lies in a valley with steep sloping foothills <br />which is a prime location for severe runoff <br />conditions. These foothills act as cloud <br />collection pockets for storm systems <br />trapping and holding storms in the valley. <br />In addition, the semi-arid climate, which <br />combines sparse vegetation with intense <br />rainstorms and prolonged snowmelt, <br />contribute to flood risk in this area. <br /> <br />Information taken from the United States <br />Army Corps of Engineers indicates a <br />number of significant floods occurred in <br /> <br />1864,1876,1894,1919,1941, 1949, 1951, <br />1957, and in 1969. The most intense flood <br />experienced by Lyons was May 31, 1894, <br />which, at an estimated peak discharge of <br />9,800 cubic feet per second, washed away <br />20 homes. <br /> <br /> <br />1957 Flood - Railroad washout near Lyons. <br /> <br /> <br />Lyon., Colorado - May 7,1969. <br /> <br />Also, Lyons' rise in population has led to <br />an increase in land pressures (more people <br />and structures per sq. mile), and floodplain <br />encroachment (more structures being built <br />in floodplain areas). People continue to <br />build structures close to water supplies for <br />esthetic beauty, convenience and crop <br /> <br />3 <br />