The Merrimack River basin in northeastern Massachusetts includes streams draining the Nashua (507 square miles), Concord (400 square miles), Shawsheen (78.0 square miles), and lower Merrimack (275 square miles) River basins. 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 12 gaging stations were calculated using a new data base with daily flow records through 1981. 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 79 partial-record sites and procedures used to determine the hydrologic characteristics of a basin are summarized. Basin characteristics representing 14 commonly used indices to estimate various streamflows are presented for 12 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.
