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Det.a il ed infonnati on on fl oods before the turn of the century is vpry 1imit.ed, Infonnation on past flooding is based on newspaper accounts and interviews with 10ngt.ime residents of the area. Largp floods occurred at Canon City in 1909, 1921. 1933. 1941, 1957, 1965 amI 1974. Peak discharges for these historic flood event.s were all less than the 10-year flood peak discharge, as predicted by the hydrologic analysis used for this flood insurance study. These floods have caused maj or damage, di srupti ng hi ghway and ra i 1 road tra Hic and communication services, drowned livestock, destroyed agricultural lands, roads, bridges, and buildings. Several lives have been lost and numerous others injured. The flood of August 1921, which registered the highest flood flows ever at Canon City caused the most damage downstream of Canon City. The river reached a discharge of 19,000 cubic feet per second (cfs) (Reference 2), flooding many streets and also washing out many bridges, The railroad through the Royal Gorge and Canon City has been washed out or damaged in the floods of 1909, 1933, 1941, 1947, and 1965. In all of the mentioned floods many bridges were lost and large amounts of acreage were inundated as in the flood of 1957 when 150 to 200 ac res of 1 and between Canon City and Florence were under wa ter , 2,4 Flood Protection Measures Along t.he lower reaches of Forked Gulch, SOO feet above t.he confl u- ence with Arkansas River, the city has construct.ed a concrete 1 ined channel to stabil ize the banks to prevent. further destruct.ion of the Griffin Avenue bridge. The city has also adopted an ordinance regulating development in the flood plain (Reference 3). 3.0 ENGINEERING METHODS The flood plains in Canon City were estimated using standard hydrologic and hydrau1 ic study methods to detennine the flood hazard data required for this study. Flood events of the magnitude which are expected to be equalled or exceeded once on the average during any 10-, 50-, 100-, and 500-year period (recurrence interval) have been sel ected as having special significance for flood plain management and for flood insurance premium rate. These events, commonly tenned the 10-,50-,100-, and 500-year floods, have a 10, 2, 1, and 0.2 percent chance, respectively, of being equalled or exceeded during anyone year. Although the recurrence inter- val represents the long tenn average period between floods of a specific magnitude, rare fl oods coul d occur at short interval s or even withi n the same year. The risk of experiencing a rare flood increases when periods greater than 1 year are considered. For example, the risk of having a flood which equal s or exceeds the 100-year flood (1 percent chance of annual occurrence) in any 50-year period is approximately 40 percent (4 in 10), and, for any 90-year period, the risk increases to approximately 60 percent (6 in 10). The analyses reported here reflect flooding potentials based on conditions existing in the county at the time of completion of this study. Maps and flood elevations will be amended periOdically to reflect future changes. 6