Water-quality data were collected during 1979-87 at selected locations In the central part of the James River basin, North and South Dakota, by the U.S. Geological Survey and the U.S. Bureau of Reclamation to document baseline conditions In three wildlife refuges. These data are needed to determine potential impacts on water quality of augmented flows in the James River from proposed operation of the Garrison Diversion Unit. This report contains statistical summaries of 190 water-quality characteristics and constituents determined from samples collected at 10 main-stem gaging stations and 94 sampling sites in the study area. Characteristics and constituents are compared to State water-quality standards and the number of measurements exceeding each standard is noted. Seasonal or bimonthly means were calculated for selected characteristics and constituents and the amount of data available for each gaging station and pool is included.