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<br />FLOOD POTENTIAL - PRESENT CONDITIONS <br /> <br />FLOOD HISTORY <br /> <br />Hazards of large Floods <br /> <br />Flooding in the study area can result from snowmelt runoff, general <br /> <br /> <br />rains, and cloudburst storms. The runoff from snowmelt occurs during <br /> <br /> <br />the period from late May to early July. This is the time of the year <br /> <br /> <br />that the study area is vulnerable to flooding, especially if there is <br /> <br /> <br />warmer than usual temperatures and the snowmelt is augmented with rain. <br /> <br /> <br />Runoff from snowmelt is characterized by moderate peak flows, long <br /> <br /> <br />duration, and large volumes of water. Buena Vista receives most of its <br /> <br /> <br />annual rainfall during the months of July through October. The inten- <br /> <br /> <br />sity of rainfall from cloudburst storms is usually high and the runoff <br /> <br /> <br />is characterized by high peak flows of short duration with relatively <br />small volumes of water. <br /> <br />Amount of damages and hazardous conditions caused by any flood are <br /> <br /> <br />dependent upon: developments in the flood plain, topography of the <br /> <br /> <br />flooded area, obstructions and debris, depths and velocities of flow, <br /> <br /> <br />and rates of rise and duration of flooding. <br /> <br />Documentation in regard to flood problems in the Buena Vista area is <br /> <br /> <br />meager. A search through newspaper accounts revealed little in respect <br /> <br /> <br />to a history of flooding. According to the July 5, 1957 issue of the <br /> <br /> <br />"Chaffee County Republ ican," the mo.st notable flood occurred on July J, <br /> <br /> <br />1957. This flood was described by many long-time residents as the worst <br /> <br /> <br />in history. Damage to streets and bridge crossings was extensive. <br /> <br /> <br />Numerous residences' received .lawn and garden damage and a few homes. and <br /> <br /> <br />buildings had water on the first floor. The 1957 flood had a frequency <br /> <br /> <br />occurrence of greater than once in 100 years, as estimated from the <br /> <br /> <br />Cottonwood Creek streamgage data. <br /> <br />Under present conditions, potential floods of the 100- and500-year <br /> <br /> <br />frequency magnitude would inundate portions of the residential and <br /> <br /> <br />commercial developments in Buena Vista and the urban area west of town. <br /> <br /> <br />In the low lying areas, floods of lesser magnitude could cause similar <br /> <br /> <br />problems on a smaller scale. The approximate area of the 100-year flood <br /> <br /> <br />is shown on the Flood Hazard Area Index Map, Detailed outlines showing <br /> <br /> <br />the approximate limits.of 100- and 500-year floods are located on the <br /> <br /> <br />Flood Hazard Area Maps, Sheets 1 through 8, There is only a minute area <br /> <br /> <br />of possible flooding from Cottonwood Creek shown on Sheet 2 (extreme <br /> <br /> <br />southwest corner); however, this sheet is included to maintain mapping <br /> <br /> <br />consistency in the study area. Floodwaters from Cottonwood Creek could <br /> <br /> <br />cause damages to buildings, lawns, gardens, temporary loss of business, <br /> <br />inventory replacement, cleanup costs and repair. Streets, road and <br /> <br /> <br />bridge crossings, communication and power lines are also subject to <br /> <br /> <br />damage. Some 160 existing buildings, including residential and commer- <br /> <br /> <br />cial structures, are partially or totally located in the 100-year flood <br /> <br />plain. <br /> <br />8 <br /> <br />7 <br />