“How G-MW manages its storages depends on many things,” he said.
“The key factors are the size of the storage, where the storage is located in the broader river catchment, and the actual infrastructure at the dam itself.”
Most G-MW storages have fixed crest spillways, meaning once they reach full supply level, they simply begin to spill.
Lake Eildon, Cairn Curran and Lake Buffalo all have gated spillways, meaning there is a greater ability to control outflows from these storages.
However, Dr Bailey noted that fixed crest spillways, such as the one at Lake Eppalock, have a role to play during times of flood.
“Even at storages with fixed crest spillways, being full does not stop a storage from providing flood mitigation,” he said.
“The spillways cause the water to back up and rise, and slow the rate that water moves downstream.”
Recent years have seen considerable rainfall fill storages across the state. June 2023 was also a wetter than usual month, with inflows to Lake Eildon being recorded at three times the monthly average.
However, the Bureau of Meteorology’s long-range forecast predicts a drier than average August to October, including a likely El Niño development.
“We know that drought and flood are both an inevitable part of our climate,” Dr Bailey said.
“Our storages cannot prevent either event, but they do lessen the impact of both.
“We therefore need to manage against both situations, which is a significant balancing act.”
You can listen to Dr Bailey discussing how water storages are managed via the G-MW website: www.g-mwater.com.au/podcast
The G-MW website also contains further information on how storages are managed: www.g-mwater.com.au/managing-storages
