Radio telemetry was used to determine the seasonal distribution and thermal preferences of 30 muskellunge in Melton Hill Lake, a mainstem reservoir in east Tennessee. Unlike many reservoirs, Melton Hill Lake offers a thermally heterogeneous environment year-round resulting from cold hypolimnetic discharges from an upstream dam and warmwater discharged from a coal-fired electric generation plant. Due to the wide range of water temperatures with suitable dissolved oxygen throughout much of the year, Melton Hill Lake differs from other systems in which muskellunge have been studied using biotelemetry. Fish in summer and early fall were widely distributed between the steam plant and Melton Hill Dam. In the spring, late fall, and winter they tended to occupy a small reach downstream of the stream plant. When the greatest range in water temperatures was available (summer 2010; 7 -33 C), tagged fish selected water between 20 to 25°C. During winter, they aggregated in the warmest water available at the thermal plume discharged from the steam plant.