Water resources data for Iowa for the 2003 water year consists of records of stage, discharge, and water quality of streams; stage, and/or contents of lakes and reservoirs; ground-water levels and water quality of ground-water wells. This report volume contains discharge records for 134 gaging stations; stage or contents for 9 lakes and reservoirs and 3 streams; water quality for 4 stream-gaging stations; sediment records for 11 stream-gaging stations; and precipitation record for 7 precipitation stations. Also included are data for 90 crest-stage partial-record stations.