The Murray-Darling Basin Plan has the vision that dredging in Murray Mouth would not be needed 95 per cent of the time.

SAND MOVED: One of the dredges operating at the Murray Mouth, which connects the river with the ocean. The operation has been ongoing for five years.
SAND MOVED: One of the dredges operating at the Murray Mouth, which connects the river with the ocean. The operation has been ongoing for five years.

Five years have now passed since dredges began operating at the Murray Mouth to keep the river connected to the sea.

Since January 9, 2015, more than 5.2 million cubic metres of sand has been removed from the mouth of the River Murray.

Two dredges are operating between the Goolwa and Tauwitchere channels 24 hours a day, 7 days a week.

In the 2018/19 financial year the cost of dredging was approximately $6 million.

The cost of Murray Mouth dredging is shared equally between the Commonwealth, New South Wales, Victoria and South Australian governments.

Murray Darling Basin Authority spokesperson said the cost of the dredging varied depending on a range of site conditions.

This included water flows through the Barrages and out to sea, sea conditions and sand deposition in the Murray Mouth, Goolwa and Tauwitchere channels.

"One or two dredges can operate for up to 24 hours a day each depending on the need. The dredges also have down time due to maintenance.

"Annual dredging costs for the past few years has varied between $3 million and $6 million. It's important to note that in drier years the cost of dredging is more," the spokesperson said.

Department of Environment and Water (DEW) spokesperson said mariners should continue to use caution when travelling through the area and a small section of the Coorong National Park remains closed.

The Murray-Darling Basin Plan, which became law in 2012, set the goal that the Murray Mouth should remain open without the need for dredging 95 per cent of the time.

However, that goal will only be pursued if an extra 450 gigalitres of water is recovered for the environment, an action contested by interstate governments.

"Barrage releases, combined with dredging, have helped to maintain connectivity of the Murray Mouth (exchange of water) between the Coorong and the Southern Ocean.

"There are no volume targets set for dredging. Rather, the dredges usually operate around the clock and an average of 5000-6000 cubic metres of sand is removed per day when two dredges are operating continuously," the spokesperson said.

"The plan is to continue with dredging throughout summer and autumn in preparation for the winter when sand ingress significantly increases.

"This is prudent given the need to protect the exchange of oxygenated water between the Coorong and Southern Ocean, particularly given the current low flows across the Murray-Darling Basin and minimal water releases over the barrages.

"Dredging plans for the Murray Mouth are assessed on a regular basis and adjustments updated as required."

Alexandrina councillor Melissa Rebbeck is chair of Murray Darling Basin Authority Region 6 said the Murray Mouth was "the canary in the coalmine for the entire Basin".

"Science and fact have shown us that rivers die from the mouth up.

"Keeping the mouth open is essential for protecting River Murray water quality, flushing salt and nutrients to the sea," Ms Rebbeck said.

"Connectivity between the river and Coorong is also needed for fish breeding.

"At risk, is a vulnerable ecosystem of wildlife that have depended upon the flow of the Murray Mouth, as well as, commercial fishing in the Lakes and Coorong which contributes around $20 million per year to the state's economy and the benefits local economies receive from boating and tourism.

"Dredging will continue to be important, particularly in times of low flow, to keep the mouth open, but so is further environmental water recovery and we maintain our call for Basin States to stay focused on achieving the full 450GL."

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