In October 1993, the U.S. Geological Survey, in cooperation with the U.S. Environmental Protection Agency, began a study of the fill deposits in the Calumet region of northwestern Indiana and northeastern Illinois. Fill in this area is a mixture of steel-industry wastes, other industrial waste, municipal solid waste, dredging spoil, construction debris, ash, cinders, natural materials, and biological sludge. Fill deposits are concentrated along Lake Michigan; from the Lake Calumet area to the east of the Indiana Harbor Canal; along the Calumet, Little Calumet, and Grand Calumet Rivers; and along the Calumet Sag Channel. Industrial wastes and municipal solid wastes are used as fill near Lake Calumet. Steel-industry wastes, primarily slag, are used as fill along Lake Michigan, Wolf Lake, Lake George, parts of Lake Calumet, and parts of the Calumet and Little Calumet Rivers. Dredging spoil is located along the rivers, and in abandoned river channels, landfills, and tailing ponds. Cinders, ash, construction debris, and natural materials are scattered throughout the area.
Currently (1996), fill covers about 60.2 square miles of the study area. A total volume of about 2.1 x 1010 cubic feet of fill was calculated to be present in the Calumet region. Most of this fill is steel-industry waste.
Fill deposition in the study area has been essentially continuous from about 1870 to the present (1996). Fill deposited before 1964 was used as foundation for streets and railroad tracks, to create land for industrial expansion, and to dispose of waste material. Much of the fill deposited after 1964 was disposed of in landfills designed to minimize environmental effects.
Industrial wastes, municipal solid wastes, steel-industry wastes, and, perhaps, dredging spoil can be associated with increased concentrations of volatile and semivolatile organic compounds, pesticides, cyanide, metals, or major ions in ground water in this area. Construction debris, ash, cinders, and natural fill may be associated with increased concentrations of major ions in ground water.