The purpose of this study is determine the existence and extent of thermal pollution of Victorian Rivers arising from Goulburn-Murray Water storages
What is ‘Thermal Pollution’?
It is widely recognised that dams situated on natural waterways can have significant ecological impacts downstream. The presence of a dammed water body can result in a variety of environmental changes. These changes can include changes to the temperature regimes of streams below the dam wall.
Alteration to the temperature regime of natural waters has been termed ‘thermal pollution’ and can include both increases and decreases in the natural thermal regime. Releases made from dams, with no surface water release strategies, commonly cause a decrease in summer temperatures and an increase in winter temperatures downstream of dams. If water is released from the deeper, colder water of a dam or reservoir, downstream temperatures will decrease.
Biological effects of thermal pollution
In Australia, the most widely recognised effect of thermal pollution is that of depressed summer temperatures on native fish populations. Most native species breed over the warmer months and require relatively warm temperatures to induce spawning. More subtle impacts of cold water releases may not be directly obvious and may take longer for the symptoms to become obvious.
The Department of Sustainability and Environment (DSE) has initiated a cold water monitoring project in response to findings that suggested the frequency and location of existing monitoring sites and schedules were insufficient to determine an impact on the thermal regime downstream of Victorian dams.
In November and December of 2002, temperature loggers were placed within the Loddon, Campaspe, Goulburn and King River catchments above and below a number of dams and reservoirs. These loggers have been programmed to log the temperature of the water hourly and can store data for between two and three months. The cold water monitoring project was suspended in June 2009 due to the current low water levels in a number of the monitored storages. The data collected will be analysed by Natural Resources staff, for determining internal management options, DSE have also created a statewide report which includes data collected as part of this program.
For further information please contact Lydia Mattner.