The Thames River basin includes streams draining the Quinebaug River (141 square miles), French River (99.5 square miles), and Middle River (about 6 square miles) basins in south central Massachusetts. Drainage areas, using the latest available 1:24 ,000 scale topographic maps, were computed for the first time for streams draining more than 3 square miles and were recomputed for data-collection sites. Streamflow characteristics at seven sites, were calculated using a new data base with daily flow records through 1980. These characteristics include annual and monthly flow statistics, duration of daily flow values, and the annual 7-day mean low flow at the 2-year and 10 year recurrence intervals. Seven-day low-flow statistics are presented for 32 partial-record sites, and the procedures used to determine the hydrologic characteristics of the basin are summarized. Basin characteristics representing 14 commonly used indices to estimate various streamflows are provided for seven gaged streams. This gazetteer will aid in the planning and siting of water-resources related activities and will provide a common data base for governmental agencies and the engineering and planning communities.