Influence of a Thermal Electric Generating Station on Water Chemistry and Distribution of Plankton

Thirty-one locations within a 3- by 6-km area, bordering Lennox Generating Station (Bay of Qunite, Lake Ontario), were sampled during the summer thermal stratification period. Distributions of crustacean zooplankton, rotifers, phytoplankton, and selected chemical parameters in near-surface waters were determined prior to, during, and following capacity pumping of the station, over a 2-week period. Effects of station operation on species composition or abundance of plankton occurred primarily in the immediate discharge area, affecting a region of approximately 1 km². Similarly, reduced levels of turbidity and pH, and an increase in concentration of dissolved silica, occurred in the discharge area. These changes were attributed to relocation of cooling water, which was drawn from the hypolimnion and returned to the lake surface.