Water resources data for the 1973 water year for Montana include records of data for the chemical and physical characteristics of surface water. Data on the quality of surface water (chemical, temperature, and sediment) were collected from designated sampling sites at predetermined intervals such as once weekly, monthly or less frequently. Records are given for 79 sampling stations of which 69 are continuous record stations, 2 are partial-record stations, and 8 are miscellaneous sites. Locations of surface water-quality stations are shown in figure 1. A few pertinent stations (not included above) in bordering States are also included. The records were collected by the Water Resources Division of the U.S. Geological Survey under the direction of George M. Pike, 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 Montana.