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A 3-year study was conducted by the U.S. Army Corps of Engineers assessing water quality related impacts of aquaculture of 250,000 channel catfish (Ictalurus punctatus) in floating net pens in the Rock Creek Arm of Lake Texoma, Oklahoma/Texas. Five large nylon nets suspended from a floating framework of galvanized metal anchored in open water 100 m offshore made up the net pens with fish stocking densities varying from 88 to 219 fish/m3. Water quality sampling was conducted biweekly from April to September and monthly from October to March at three locations. On all sampling dates field measurements of water temperature, pH, dissolved oxygen, and conductivity were recorded at 1 m depth intervals and water samples were collected at a depth of 0.6 m and near the bottom of the water column at each site. Sample analyses included: total alkalinity, total hardness, turbidity, chloride, sulfate, orthophosphate, total phosphorus, nitrate-N, nitrite-N, total Kjeldahl nitrogen, total organic carbon, dissolved organic carbon, biochemical oxygen demand, and chlorophyll a. The results showed statistically significant decreases in water temperature and dissolved oxygen and significant increases in field conductivity in surface waters near the net pens relative to other sampling sites. The most dramatic water quality effect observed during the study was decrease in dissolved oxygen levels near the net pens following lake turnover in the second year.

Nephelometric turbidity and Secchi disc were measured at 16 sampling stations at Lake Carl Blackwell, Oklahoma on 54 dates from 12 February 1982 to 24 January 1983. Measurements of precipitation, wind velocity, effective fetch, water depth, and sediment particle size were also recorded. Turbidity values ranged from 16 to 1 140 NTU and Secchi disc transparency from 2 to 110 cm. Turbidity was generally highest at shallow water sampling stations in the western end and upper arms of Lake Carl Blackwell and decreased with increasing depth. Increases in turbidity during the spring of 1982 were attributed to sediment resuspension and drastic turbidity increases were observed following heavy May rains. Two multiple regression models were developed to predict nephelometric turbidity levels for a given set of climatological and morphometric parameters. One model was based on data for the entire sampling period and is useful in predicting turbidity under high inflow conditions. A second model was derived from data collected prior to periods of heavy rains and is useful in predicting turbidity under more common conditions of moderate winds and rain.

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