New spillway experiment: pouring oxygen into the Murray

Experiment: The Hume Dam spillway, where Murray-Darling Basin Authority will try to switch up its release tactics and inject more oxygen-rich water into the Murray River. Photo by Murray-Darling Basin Authority

A new technique at the Hume Dam spillway gates will help inject more oxygen into the Murray River.

Traditionally, Murray-Darling Basin Authority (MDBA) releases water from Hume Dam through the power station and outlet values, which suck through oxygen-poor water from the bottom of the dam.

After fruitlessly trying to inject compressed air into the power station outlets, MDBA is switching it up and taking from the top.

Water will now be released from the spillway, putting far cleaner and oxygen-rich surface water into the river system.

MDBA river management acting executive director Andrew Kremor said dissolved oxygen levels remained low immediately downstream of Hume Dam for several kilometres, even when MDBA started injecting compressed air into the valves in early January.

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

Low oxygen levels in the water can lead to aquatic animals struggling to breathe and town water quality decreasing.

Hume Dam is effectively full, at 99 per cent capacity, but releases to meet downstream demand for water will overtake inflows in coming days and the storage level is starting to decline.