Intensive survey of East Fork Trinity River segment 0819.




Twidwell, S.R.

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An intensive survey of the East Fork Trinity River (Segment 0819) was conducted April 25-28, 1983, by the Texas Department of Water Resources. The study area on the East Fork consisted of the reach between the dam on Lake Ray Hubbard to the river's confluence with the Trinity River. The East Fork drains portions of Dallas, Rockwall, and Kaufman Counties. Water quality and hydraulic data were collected from 13 mainstream stations, five tributaries, and five municipal dischargers. A release of 1.3 m3/s of water from Lake Ray Hubbard was made a week prior to and during the study so that water quality and hydraulic characteristics of the East Fork Trinity River were evaluated under a moderate flow, steady state regime. Stream width was widest (x 29.1 m) and velocity slowest (0.11 m/s) for the portion of the East Fork Trinity River that communicated with the discharge canal from Lake Ray Hubbard. For the rest of the East Fork Trinity River, stream widths ranged from 8.8 to 25.7 m, and discharge increased from 0.77 m3/s in the upper portion to 2.6 m3/s in the lower portion of the segment. Stream velocities varied over the segment but were highest (> 0.3 m/s) in the lower portions that have been straightened and dredged. The poor quality effluent from the City of Garland's Duck Creek Sewage Treatment Plant (BOD5 98 mg/l, TSS 27 mg/l, NH3-N 15.9 mg/l) appeared to completely dominate the quality of the East Fork Trinity River. Despite the moderate flow from upstream, a dissolved oxygen sag zone developed in the East Fork Trinity River downstream of Garland's outfall for 25 river kilometers. The effluent from the City of Mesquite's Sewage Treatment Plant, which had a high level of ammonia nitrogen (15.3 mg/l) apparently contributed to extension of the dissolved oxygen sag. The middle portion of the East Fork was anoxic in the early morning hours and mean levels for six of ten mainstream stations were less than the segment criterion (4 mg/l). Levels of ammonia nitrogen (> 4 mg/l) and fecal coliform bacteria (> 400/100 ml) were elevated throughout most of the East Fork Trinity River.


26 p.


water quality, rivers, hydrology, water chemistry, water analysis, wastewater, sewage treatment, dissolved oxygen (DO)