Reservoirs in warmer climates often have thermal stratification occurring over the hotter periods of the year resulting in bottom (hypolimnial) waters significantly colder and less oxygenated than surface waters. When this cold bottom hypolimnial water is released downstream via bottom release valves on dams, cold-water thermal pollution can occur where river temperatures are much lower than would occur naturally. The dam releases can also impact the quality of the water with changes in downstream nutrient regimes and phytoplankton communities. We present data investigating the dynamics of thermal pollution in the Severn River, Australia, downstream of Pindari Dam. Cold water pollution occurred in the river from Spring through to Autumn, closely following the formation and breakdown of thermal stratification within the reservoir and was detectable up to approximately 150 km downstream of the dam. Thermal pollution was most severe during summer, with temperatures up to 13°C colder in the river downstream of the dam compared to reference sites. Changes in nutrients and phytoplankton downstream were also observed as a result of the hypolimnial dam releases. We will discuss plans for amelioration of thermal pollution in the river through reservoir management and the monitoring being done to test its effectiveness and measure improvements in ecosystem health.