Water resources data for the 2003 water year for Louisiana consist of records of stage, discharge, and water quality of streams; stage, contents, and water quality of lakes and reservoirs; and water levels and water quality of ground water. This report contains records for water discharge at 76 gaging stations; stage only for 86 gaging stations and 7 lakes; water quality for 56 surface-water stations (including 44 gaging stations) and 142 wells; and water levels for 313 observation wells. Also included are data for 158 crest-stage and flood-profile partial-record stations. Additional water data were collected at various sites not included in the systematic data-collection program, and are published as miscellaneous measurements. These data represent that part of the National Water Data System operated by the U.S. Geological Survey and cooperating Federal and State agencies in Louisiana.