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within the San Isabel National Forest. Land use includes recreation, grazing, and a small amount of lumbering. Development within the National Forest boundaries is under contl'olled conditions and will have minor effects on potential flooding in the downstream areas. 2.3 Principal Flood Problems While slopes are steeper in the upper drainage basins, the dense vegetation in these areas serves to reduce rainfall runoff. A greater percentage of runoff is permitted by the sparse vegetation of the foothills and pasture land at the lower elevations. Consequently, the maj ori ty of the fl ood probl ems in the study area are caused by rapi d snowmelt. This type of flooding has a long duration runoff which l'esults in a continuous rise in water level thus producing a high runoff vol ume. Flood potential al so exists from long and short duration rain stonns. These types of floods are characteri zed by high peaks, small vol urnes and short durati on. The potenti a 1 for the most severe fl oodi ng is created by the combination of rapid snowmelt with long duration rain- fall , Documentation in regard to flood problems in the Buena Vista area is meager. A search through newpaper accounts revealed little in respect to a history of flooding. According to the July 5, 1957, issue of the "Chaffee County Republican," the most notable flood occurred on July 1, 1957. This flood was described by many long-time residents as the worst in history. Damage to streets and bridge crossings was exten- sive. Numerous residences received lawn and garden damage and a few hcmes and buildings had water on the first floor. The 1957 flood had a frequency occurrence of greater than once in 100 years, as estimated frcm the Cottonwood Creek stream gage data. Flooding problems within the Town of Buena Vista are aggravated by the restriction of drainage channels due to vegetation growth and accumu- lated debris. 2.4 Flood Protection Measures The Town of Buena Vi sta has adopted the Federal Emergency Management Agency's regulations concerning Federal Flood Insurance in special flood haza rd area s. The upper porti on of Cottonwood Creek ha s been dredged out since the 1957 flood to permit more flow to stay in the mai n channel. 3.0 ENGINEERING METHODS For flooding sources studied in detail in the community, standard hydro- logic and hydraulic study methods were used to determine the flood hazard data required for this study. Flood events of the magnitude which are 5