Water resources data for the 1991 water year for Indiana consist of records of discharge, stage, and water quality of streams and wells; reservoir stage and contents; and water levels in lakes and wells. This report contains records of discharge for 183 stream-gaging stations, stage for 7 stream stations, stage and contents for 1 reservoir, water quality for 3 streams, and water levels for 80 lakes and 95 observation wells. These data represent that part of the National Water Data System operated by the U.S. Geological Survey in Indiana in cooperation with State and Federal Agencies.