The Cedar River begins near Hayfield in southwestern Minnesota and flows from northwest to southeast across Black Hawk County in north-central Iowa. Major tributaries to the Cedar River in the county include Black Hawk Creek, Elk Run Creek, Beaver Creek, Crane Creek, and Wolf Creek. This reconnaissance study, initiated in July 1990, identified communities within Black Hawk County that experience flooding problems. Flood damage reduction measures were considered for the communities of Janesville; Finchford; Dewar; Gilbertville; Hudson; Evansdale; North Cedar and Cedar City (city of Cedar Falls); and Dunkerton. Also, sedimentation of the Cedar River and the Cedar Valley Lakes Conservation/Recreation Master Plan are discussed in the report. The report summarizes the hydraulic, hydrologic, economic, environmental, and cultural resources investigations undertaken for the study area. Alternatives considered for flood damage reduction included snagging and clearing; channel modifications; levees and/or floodwalls; and nonstructural alternatives. A flood damage reduction plan is economically justified at Dunkerton, Iowa. The plan involves a channel modification to Crane Creek and a levee to protect Dunkerton from flooding.