Cold water pollution occurs below large dams when hypolimnetic water is released during periods of thermal stratification, with water temperatures being up to 16°C below predicted natural temperatures. Hypolimnetic releases can impact the thermal regimes of downstream river systems for up to 300 km. These temperature changes can affect the health of aquatic biota such as algae, macroinvertebrates and fish. An innovative thermal curtain, being a large polymer structure suspended within the water column, was installed on a large dam on the Macquarie River, Australia in 2014 as an economical solution to mitigate cold water pollution by drawing epilimnetic water to the low-level fixed valve. Following implementation of the curtain, temperature improvements of 2.5°C were observed during summer whilst the dam was at low capacity. In 2016, the dam filled to full capacity and a cyanobacterial bloom occurred, leading to a mixture of curtain, spillway and bottom releases. The varied releases from the dam will be discussed in terms of their impact on downstream thermal regimes and algal concentration, assemblages and potentially toxic cyanobacteria.