Water resources data for the 1984 water year for Idaho 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 discharge records for 178 gaging stations; stage only records for 2 gaging stations; stage only for 9 lakes and reservoirs; contents only for 17 lakes and reservoirs; water quality for 22 gaging stations and 66 wells; and water levels for 420 observation wells. Additional water data were collected at various sites, not involved 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 State and Federal agencies in Idaho, adjacent States, and Canada.