Water resources data for the 1977 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, in three volumes, contains discharge records for 72 gaging stations; stage records for 66 of these gaging stations; stage only for 30 gaging stations; contents for 1 reservoir; stage only for 10 lakes; water quality for 148 stations; 27 of these at gaging stations; 215 areal stations, 10 lakes, and 174 wells; and water levels for 696 observation wells. Also included are 199 crest-stage partial-record stations and flood-profile partial-record stations. Additional water data were collected at various sites, not involved in the systematic data-collection program, and are published as miscellaneous measurements. Records for a few pertinent stations in bordering States are also included in this report. These data represent that part of the National Water Data System operated by the U.S. Geological Survey and cooperating State and Federal agencies in Louisiana.