Lake Sinclair is a multi-purpose impoundment on the Oconee River in central Georgia. The reservoir serves as a source of cooling water for Plant Branch, a four-unit coal-fired steam electric generating station located on a peninsula between the Little River arm and Beaverdam Creek, a smaller tributary of the lake. Cooling water for Plant Branch is drawn from the Little River arm and discharged into Beaverdam Creek, raising ambient water temperatures.
The purpose of this study was to assess the response of fish to the thermal discharge of Plant Branch during summer and winter periods, and to compare the fish abundance in and near the thermal plume to the lake-wide abundance and distribution pattern. We helped our client (GeoSyntec Consultants) conduct mobile surveys with an acoustic system that multiplexes between two split-beam transducers. One of the transducers was mounted in a side-looking configuration to sample from near-surface to about 2 m depth; the second transducer was mounted in a down-looking configuration to sample from 2 m below the surface to the bottom. To estimate fish density, the acoustic data were echo integrated and scaled by the acoustic size of single fish as determined from data from resolved, individual fish. As part of the thermal plume study, we also collected bathymetry information to be used in conjunction with fish density and temperature data for the assessment of the zone of passage available to fish in the Beaverdam Creek embayment.