Water-resources data for the 1998 water year for Kansas consist of records of stage, discharge, and water quality of streams; elevation and contents of lakes and reservoirs; and water levels of ground-water wells. This report contains records for water discharge at 149 gaging stations; elevation and contents at 19 watershed lakes and reservoirs; and water-level data at 19 wells. Also included are data for 27 high-flow and 2 low-flow partial-record stations; and 2 chemical quality of precipitation stations. Miscellaneous onsite water-quality data were collected at 138 stations. These data represent that part of the National Water Information System collected by the U.S. Geological Survey in cooperation with State, local, and Federal agencies in Kansas.