The purpose of this report is to present the results of a flood-profile study made for Hoosier Creek and its tributary, South Hoosier Creek. The reaches studied extend from near the south Linn County line upstream to U.S. Highway 218 on Hoosier Creek, and from the mouth to U.S. Highway 218 on South Hoosier Creek. A total of about 11 miles of stream is included in the two reaches. The profiles shown in the report are computed for a very large flood under existing valley conditions and for a smaller flood under two assumed conditions of encroachment. This information can be used to supplement the existing county zoning ordinances for flood plains and to aid in future flood-plain management when part or all of the area is urbanized. This report is the result of a cooperative agreement between Linn County, Iowa, and the U.S. Geological Survey that provides for the collection and analysis of hydrologic data in Linn County.