Water resources data for the 1978 water year for Michigan 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 temperature of ground water. This report contains discharge records for 187 gaging stations; stage only records for 1 gaging station; stage and contents for 5 lakes and reservoirs; water quality for 65 continuous-record stations and 6 lakes; and water levels for 45 observation wells. Also included are 93 crest-stage partial-record stations and 18 low-flow partial-record stations. Additional water data were collected at various sites, not part of the systematic data-collection program, and are published as miscella- neous 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 Michigan.