Water resources data for the 1972 and 1973 water years for Michigan include records of data for the chemical and physical characteristics of surface and ground waters. Data on the quality of surface water (chemical, temperature, and sediment) were collected from designated sampling sites at predetermined intervals such as once-daily, weekly, monthly or less frequently, and at some sites data were recorded on punched paper tape at 60-minute intervals. Records are given for 394 sampling stations, of which 75 are continuous-records stations, 234 are partial-record stations, and 85 are miscellaneous sites. Records of chemical analyses also are given for 22 groundwater sites. Locations of surface water quality stations are shown in Figure 1 and 2. The records were collected by the Water Resources Division of the U.S. Geological Survey under the direction of T. R. Cummings, district chief. These data represent that portion of the National Water Data System collected by the U.S. Geological Survey and cooperating State and Federal agencies in Michigan.