From abstract: 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.