The objectives of this study were to define (1) the average 3-day natural low-flow with a 20-year recurrence interval for five low-flow partial-record sites and one continuous record station, (2) losing and gaining reaches of the main stem of the Sulphur Fork Red River and major tributaries, and (3) the quality of water during low-flow. An additional objective was the collection of continuous streamflow and temperature data at selected sites for development of a thermal model for use as a guide in design and management of a small reservoir. The quantity of surface water during low-flow varies considerably throughout the basin. Streamflow during periods of drought is groundwater discharging through numerous springs and seeps. The average 3-day, 20-year low-flow of the six study sites range from 0.1 to 2.2 cubic feet per second. Seepage investigations in October 1976 show that as much as 4.4 cubic feet per second are lost from the Sulphur Fork Red River within a reach of 1.7 miles between river mile 30.8 and 29.1. Seepage investigations in July 1977 show that as much as 3.7 cubic feet per second are gained in the Sulphur Fork Red River within a reach of 0.8 miles between river mile 42.6 and 41.8. Measured discharges from the 12 major springs in the basin ranged from less than 1 to 1660 gallons per minute during low-flow. Water quality of streams varies in time and space. Specific conductance ranged from 200 to 1,800 micromhos per centimeter at 25O centigrade during the 1976 seepage investigation on the Sulphur Fork Red River. During the two-year study the specific conductance of water from the springs ranged from 230 to 675 micromhos per centimeter at 25O centigrade.