Intensive Survey of the Trinity River Segment 0805

Intensive water quality surveys were conducted on the Trinity River (Segment 0805) September 13-15 and October 25-28, 1982. Twenty-nine mainstream stations, eight tributary stations, and seven dischargers were sampled. In September, stream widths ranged from 39-112 feet, discharge increased from 16 cfs at the upstream end to 905 cfs at the lower end, and stream velocities ranged from 0.49-1.45 fps. In October, stream width varied from 39-101 feet, discharged increased from 36 cfs at the upstream end to 800 cfs at the lower end, and stream velocities ranged from 0.44-1.15 fps. Atmospheric reaeration coefficients (K2 at 20 degrees C) were relatively low, ranging from 0.2116-2.0887 per day. Background water quality at Station 1 was high. The stream became effluent dominated below Station 2 and water quality was impacted through the remainder of the segment, with depressed dissolved oxygen and elevated levels of nutrient compounds. Due to high flow events that preceded each survey, worst-case water quality conditions were not existent except in the reach upstream from the Elm Fork Trinity confluence in September, where dissolved oxygen levels were < 2.3 mg/l for 10 miles with levels less than the segment criterion (1.0 mg/l) at Station 3. In both surveys, water quality recovery was incomplete at the lower end of the segment.