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Reminder of Gunbower Creek lowering

Construction of a fishway next to Gunbower Creek. Vertical concrete slots
19 May 2021

Communities along Gunbower Creek are being reminded of the lowering of a large section of the waterway over the irrigation off-season to allow for the construction of fishways at the Cohuna and Koondrook weirs. 

Water for the environment and irrigation water won’t flow down the creek until the start of the new irrigation season on August 15.

As a result, the water level has already started to drop. The lowering will be more noticeable in some sections of the creek than others, with only deep pools remaining in stretches.

At the Cohuna Weir pool, the water level will be lowered about one metre below the full supply level.

The town supply will not be impacted by the lowering, and Goulburn-Murray Water has communicated with relevant stock and domestic customers.

“Up until 2013-14, Gunbower Creek dropped from May to August as part of the annual irrigation shutdown period,” Goulburn-Murray Water General Manager Infrastructure Delivery Services Warren Jose said.

“Since then, water for the environment has kept the creek flowing to help native fish such as the Murray cod survive and thrive.

“This is a one-off lowering to allow us to complete a key section of the Cohuna and Koondrook fishway works.

“We are lowering the creek now to ensure we don’t impact irrigation delivery. Once irrigation season begins, the flows will recommence.”

North Central Catchment Management Authority (CMA) Major Projects Executive Manager Tim Shanahan said the fishways would be a boon for the creek.

“Both weirs are the last barriers to fish passage along Gunbower Creek,” he said.

“The fishways will allow fish, including the Vulnerable Murray cod which are breeding in Gunbower Creek, to safely move downstream into the Murray River, and to move upstream and recolonise sections the upper reaches of the creek.

“The Koondrook fishway will provide year-round passage to native fish such as golden perch, Murray cod and Threatened silver perch from the river into the creek for the first time in more than a century.”

Conditions in the creek will be monitored during the drawdown.

“Construction of the fishways is an economic boost to the local region, and in partnership, Goulburn Murray Water and the North Central CMA are ensuring irrigation supplies aren’t being affected by doing the works during the irrigation off season”, Mr Shanahan said.

The Cohuna fishway is fully funded by GMW and will comprise of a 23-slot vertical slot fishway attached to the existing Cohuna Weir.

Improvements in public access and fencing for safety will also be completed to further enhance and complement the recent Gannawarra Shire Cohuna CBD waterfront development.

The Koondrook Weir fishway is co-funded by the Victorian Environmental Water Holder and the Victorian Government, and is part funded from the sale of water for the environment to irrigators. 

It will comprise of a double-entrance and double exit vertical slot fishway, with sheet pile walls to create a stilling pool to dissipate energy. 

The undershot gates will be replaced with overshot gates to allow for improved flow conditions and safe downstream fish passage.