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of the City. The Riverside Park area has experienced repeated flood danger as the erosion and undermining of protective levees has necessitated extensive flood fighting and levee repair. Several streets in that area, as well as along Rosevale Road west of the river, have been flooded and traffic has been disrupted. On farmland and ranges south and southwest of the ci ty, crops have been lost and irrigation facilities have been seriously damaged. Between Grand Junction and the northern county boundary near DeBeque, Colorado River overflow has inundated ranches and farmland; isolated people and cattle; damaged or destroyed irrigation facilities; damaged orchards by uprooting trees, eroding soil, and depositing debris; inundated roads; and disrupted traffics. Gunnison River floods have caused damage mainly in the reach just above its mouth, where ranches and farms have been inundated, buildings and cattle have been slated, and people have been stranded for varying periods of time. The abutments of the bridge south of Grand Junction and a portion of the south bank upstream from the bridge have been seriously eroded. Dolores River floods has isolated people and livestock, damaged or destroyed growing crops, and damaged crop and pastureland with deposits of silt and debris. Flood fighting has been required to prevent traffic disruption. Flooding is known to have occurred on many of the lesser streams in the county, but data on contributing precipitations, peak flows, and damage are not available. Historical and descriptive data on floods and flooding in Mesa County were based on Floodplain Information and Flood Hazard Information reports prepared by the COE in 1973 and 1976 (Reference 4, 5, 6, and 7). Expected level s of flooding on the Colorado River, Leach Creek, and West Creek are shown in Figures 2, 3, and 4, respectively. The principal cause of flooding on Plateau Creek and Buzzard Creek is a rapidly melting heavy snowpack during May, June, and July. Rainfall on melting snow may hasten the melting process and increase floodflows. A major f load had occurred on Plateau Creek in 1922. Based on the record from a stream gage on Plateau Creek located approximately 6 miles east of Collbran, this flood had an estimated discharge of 3,080 cfs which corresponds to a frequency 1n excess of 100 years. On Grove Creek, thunderstorms are the principal cause of flooding. Beaver dams have been built on Grove Creek, and these may aggravate flood problems by blocking culverts or creating backwater. Major flooding along Roan Creek is caused by rapid melting of the mountain snowpack during late May to early July, as well as summer rainstorms. There is also the potential for flooding as a result of rainfall occurring on melting snow. The most recent damaging 13