The Murray–Darling Basin Authority (MDBA) is trialling a different method of water releases from Hume Dam. 

Water quality issues have prompted the MDBA to trial Hume Dam releases through gates and valves in a bid to improve downstream flows. 

Dissolved oxygen levels remain low immediately downstream of the dam for several kilometres, even though the MDBA has been releasing water through the valves to increase aeration. Additionally, compressed air has been added to water releases through the power station since earlier this month.

“The very high levels of bushfire residue which entered the lake over the past few years has led to complex processes that use up a lot of the available oxygen in the lower layers of the lake,” says MDBA acting Executive Director River Management Dr Andrew Kremor.

“A drop in oxygen can make it difficult for fish and other aquatic animals to breathe, so we have tried valve releases to create a spray which aerates the water as it hits the river, and air has been added to releases through the power station.”

The MDBA will trial releasing a small volume of water through the spillway gates for a few days before stopping to assess the effectiveness of the method.

“This trial is being considered as recent water quality monitoring has shown that dissolved oxygen levels are much better in the upper layers of the lake, compared with the lower levels where water is released through the power station and outlet valves,” Dr Kremor said.

“These spillway releases will only be during the day and the valves will be used overnight which we hope will optimise an improvement in dissolved oxygen levels.

“If successful, the MDBA may consider continuing to use the spillway to assist with improving dissolved oxygen levels.”