Calls to remove Lower Lakes barrages 'put to bed' by new report

Many irrigators, along with the NSW and Victorian governments, have called for the barrages to be lowered, claiming it would return the lakes to their natural salt water environment and allow for more upstream extraction.

However, the CSIRO-led study found the Coorong and Lower Lakes at the mouth of the Murray River were "largely fresh" prior to European settlement, and removing the barrages would have significant ecological and socio-economic impacts, while not producing any water savings.

The panel behind the report looked at more than 100 studies in make its determination.

MDBA chief executive Phillip Glyde said the report confirmed his organisation's management of the Lowe Lakes was based on good science.

"The lakes were fresh, the lakes are fresh and removal of the barrages will make the those lakes salty - and that is contrary to the existing international commitments we've made to protect the environment, economic, social and cultural values," Mr Glyde said.

If the barrages were removed, Mr Glyde said more water would need to move down the system to keep the lakes fresh.

"If we need more water to keep those lakes fresh because we've let salt water in from the sea, then we need to take more water back from industry and that would be a disaster," he said.

"The barrages were, and are, an investment in keeping irrigation industries upstream going."

Mr Glyde acknowledged there would always be different views and scientific opinions when dealing with such a complex natural system, however he hoped the study would put an end to the debate.

"I'd like to think we can leave behind this debate about the history of the lakes and move on," he said.

However, that's unlikely to be the case, with both NSW and Victoria both questioning whether it would be sustainable to maintain the lakes' fresh water environment.

NSW Water Minister Melinda Pavey said the management of the Lower Lakes had to "reflect the reality of the world we live in", and called for trigger points to open and close the barrages.

"The report highlights that under current management during periods of extreme drought the barrages ensure there is no water in the Lower Lakes and they dry up, creating acidification issues like what occurred during the millennium drought," Ms Pavey said.

"This is why we have been calling for the barrages to be opened during times of extreme drought.

"If the barrages are opened, we have the ability to again mimic nature and allow the sea water back into the Lower Lakes during extreme drought."

The report noted under climate change, the management of the Lower Lakes and Murray Mouth would become increasingly challenging, as sea level rise would cause more seawater to flow into the lakes and evaporation would be higher.

That part of the report drew the attention of Victorian Water Minister Lisa Neville.

"This report raises issues around whether enough fresh water can be supplied to overcome the impacts of climate change and keep the Lakes fresh," Ms Neville said.

However, South Australian Water Minister David Speirs said the report finally put the conspiracy theories about the Lower Lakes to bed.

"The science review reinforces the need for fresh water to maintain the environmental health of the region and shows there would be devastating outcomes if seawater was allowed to flow unimpeded," Mr Speirs said.

"The report also shows that removing the barrages would not result in water savings.

"The Coorong and Lower Lakes are internationally recognised wetlands which are an important environmental, social and economic asset for our state and country."

Mr Glyde said the focus should now be on how to "meet and beat" the challenges of climate change across the basin, which the plan was already doing to some degree.

"By returning about 20 per cent of the water from consumption to the river, we have better protected the system, even through this dry period over the last few years," he said.

"[The basin] is more resilient and if the ecosystem is more resilient, so are the industries that rely on it and so are the communities that depend on those industries."