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A number of irrigation ditches; such as the Treasure Pass, Rober-Lohr and Fachs ditches convey water across natural drainage boundaries from the Colorado River Basin. A number of reservoirs also regulate flow in the basin. The Rio Grande is affected by the Beaver Creek, Santa Maria, Rio Grande and Continental reservoirs. 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 spa rse vegeta ti on of the foothills and pasture land at the lower elevations. Consequently, the majority of the flood problems in the study area are caused by rapid snowmelt. This type of flooding has a long duration runoff which results 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 storms. These types of floods are characteri zed by hi gh peaks, small vol umes and short duration. The potential for the most severe flooding is created by the combination of rapid snowmelt with long duration rain- fall . Information on past flooding is based on newspaper accounts and inter- views with longtime residents of the area. Large floods occurred at Monte Vi sta in 1884, 1905, 1911, 1927, 1949, 1957 and 1970. These floods have caused major damage, disrupting highway and railroad traffic and communication services, drowned livestock, destroyed agricultural lands, roads, bridges and buildings. The fl ood of 1884 is consi dered the most severe fl ood known in Monte Vista, with an estimated peak discharge of 20,000 cubic feet per second (cfs) at Al amosa, Colorado. The Colorado State Engineers Annual Report of 1911, proposed melting snow and rainfall as the cause of the flood in 1911. This flood has an estimated peak discharge of 14,000 cfs. In June of 1927, a peak flow of 18,500 cfs was recorded in Monte Vista. Flooding was due to four days of cloudbursts and incessant rains. Floods in the Monte Vista Area generally ranged from 4,000 to 7,000 cfs between 1926 and 1967. 2.4 Flood Protection Measures The City of Monte Vista has no existing regulations or ordinances concerning floodplain management or protection measures other than those of the Uniform Building Code, 1976 edition. 3.0 ENGINEERING METHODS For fl oodi ng sources studi ed in deta il in the community, standard hydro- logic and hydraul ic study methods were used to determine the flood hazard data required for this study. " Flood events of the magnitude which are 5