Field and laboratory studies were carried out on 20 streams in Coles County, Illinois from 1967 through 1970. A large reservoir (Lincoln Lake) is planned by the Army Corps of Engineers and, if completed, will have considerable impact on Coles County. A record of existing conditions was desired in order to help determine the effects of the reservoir in the area. Studies were made of the bottom fauna, plankton, and fishes in the streams. Physical and chemical characteristics such as pH, hardness, dissolved oxygen, turbidity, nitrites, nitrates, phosphates, sulfates, and carbon dioxide were also measured. (Author)