ESTIMATED STREAM FLOW REQUIREMENTS FOR FISHES OF THE WASHITA RIVER BELOW FOSS RESERVOIR,WESTERN OKLAHOMA1

Velocity and depth preference curves for juvenile and adult red shiners (Notropis lutrensis) were developed for each season of the year. The incremental methodology, developed by the U.S. Fish and Wildlife Service for quantifying the amount of physical habitat available for fish, was applied as a basis for recommending minimum stream flows for life stages of red shiners and channel catfish (Ictalurus punctatus) in the Washita River below Foss Reservoir. The minimum stream flow required to support populations of red shiners and channel catfish was estimated to be 0.60 m³/s during all months except April and May, during which flushing flows of 3.0 m³/s were recommended. Under drought conditions a contingency flow of 0.18 m³/s was recommended for August through March, a flushing flow of 2.4 m³/s for April and May, and a flow of 0.30 m³/s for channel catfish spawning in June and July. Standing crop of adult red shiners per weighted usable area averaged 2.73 g/m² (27 kg/ha) for two sites on the Washita River. A positive relation between standing crop and weighted usable area was suggested. Use of the incremental methodology on the study reach below Foss Reservoir required 96 person-hours of labor, excluding training, travel, and developing preference curves, and a total cost of $1,762, of which $1,200 was for the purchase of equipment.