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<br />of Lincoln Avenue. Above average rainfall occurred throughout July and August of ] 961 causing <br />localized flooding in various parts of town. Discharge estimates were not available. <br /> <br />In 1983, the Cache La Poudre threatened flooding from rapid snowmdt in the mountains. <br />Although severe flooding did not occur, the river remained above flood stage for 45 days and the <br />Governor declared a state of emergency. The flood peak occurred on June 21, at 6,660 cfs. <br />Damage did occur in a number of areas from ch3l1Ilel bmu< erosion and meander migration <br />including a gravel pit capture near the Environmental Learning Center. The bike u:ai1, a dike <br />along Mulberry Street, Countryside Mobile Home Park, the Cache La Poudre Elementary School <br />and Junior High School, and the Fort Collins W<lSte Water treatment Plant No.2 were all <br />threatened by the snowmelt runoff flooding. <br /> <br />The spring of 1995 was also a year for high runoff associated with snowmelt. Although the <br />Cache La Poudre remained for the most part witbin its banks in town, except for bike trail <br />flooding and some bank erosion, three teenagers had to be rescued from the river and crop <br />damages east of Fort Collins was in the millions of dollars. In addition, the Burlington Northern <br />Railroad embankment failed near the 1-25 crossing as a result of gravd pit capture of the <br />floodwaters. The flood peak occurred on June 1 S at 4,690 cfs. <br /> <br />The flood hydrology of the Cache La Poudre River is primarily controlled by spring snowmelt <br />runoff, which produces annual flood peaks with magnitudes generally less than the 10'year event <br />(about 6000 cfs). Larger floods are generally associated with runoff from sununer <br />thunderstorms. Rainfall on snow can produce the largest floods. The river contains a nwnber of <br />flood hazard areas, from the narrow canyons in the mountainous west to the wide floodplain in <br />the east. Due to the rapidly growing population, the flood hazard is constantly changing. <br /> <br />The Colorado State University Earth ResOluces Pepartrnent is currently gathering data on the <br />paleoflood history of the Cache La Poudre River Canyon. Flood slackwater deposits, which are <br />fine'grained sediments which settle from suspension in areas of reduced flow during floods, have <br />been found high above the current stream level in the Poudre Canyon. Flood sediments indicate <br />multiple peak discharges during the last 6,500 years. Some of these discharge values are <br />significantly larger than the highest gaged disch;:trges at the canyon mouth gaging station, which <br />has been in operation since 1882. The peak discharge during this time period of record was <br />21,000 cfs, in June 1891. <br /> <br />Spring Creek <br /> <br />Spring Creek, which is a right bank tributary to the Cache La Poudre River, flows from west to <br />east through Fort Collins. Beginning at Spring Canyon Dam and Horsetooth Reservoir, Spring <br />Creek flows easterly until it joins the Cache La Poudre River near the intersection of Timberline <br />Road and Prospect Road. The Spring Creek basin has a drainage area of 30 square miles. The <br />upper 18 square miles of the basin is controlled by Spring and Dixon Canyon Dams and <br />Horsetooth Reservoir, which were constructed by the Bureau of Reclamation in 1954. Below the <br /> <br />II <br />