Information on the sources of climatologic, hydrologic, and hydraulic data for the Illinois River basin is compiled in 20 tables. The study was conducted in cooperation with the U.S. Army Corps of Engineers, Rock Island District, to provide information for their master regulation manual of the llliniois Waterway. Eighteen governmental agencies were queried and a literature search was conducted to identify the source and availability of information on precipitation, major storms, streamflow, water quality and sediment, major floods, water-surface profiles, bridges and other structures, stream geometry, aerial photography, flood damages, Illinois River access facilities, Federal lands, and data ratings. A selected bibliography of published reports was developed.