Keeping South Australia's Lower Lakes filled with fresh water is becoming increasingly difficult, according to an independent review released on May 12.
The CSIRO-led review — recommended by the Murray-Darling Basin Authority’s Advisory Committee on Social, Economic and Environmental Sciences — examined hundreds of scientific studies on the Coorong, Lower Lakes and Murray Mouth.
The independent review panel chair Dr Francis Chiew, from the CSIRO, said due to climate change the ability to manage the lakes would become more difficult.
“Under climate change, sea level rise would alter the hydrodynamics of the Coorong and Murray Mouth, and cause more seawater to flow into the Lower Lakes,” Dr Chiew said.
“Evaporation from the lakes would be higher (but) catchment runoff in the southern Murray-Darling Basin, and therefore inflow into the Lower Lakes, is projected to decline.
“Adaptation options are needed, not just for the CLLMM (Coorong, Lower Lakes and Murray Mouth), but as part of the whole Murray-Darling Basin system.”
The review also found that the main body of the Lower Lakes was largely fresh prior to European settlement, with moderate tidal influence and incursion of seawater during periods of low Murray River inflow.
It also revealed that upstream development has reduced the river inflow by about half, resulting in more frequent incursion of seawater into the Lower Lakes, and the barrages were built in 1940 in response to these changes.
“Removing the barrages would have a significant ecological and socio-economic impact,” Dr Chiew said.
VFF Water Council chair Richard Anderson said the review provided a clear choice between producing food and maintaining the freshwater nature of the Lower Lakes.
“More evaporation and less inflows — that’s what the report found and that means the government coming back to irrigators asking for more water and be damned if that is going to happen,” he said.
“It is about time that the MDBA’s planning for the Lower Lakes and South Australia’s water supplies considered the future, rather than grimly hanging on to the past.
“The VFF has long argued for Lock Zero.
“We now even have the scientists demonstrating the need for it.
“It’s time to build Lock Zero and choose food over the futile efforts to keep the Lower Lakes fresh.”
Murray Regional Strategy Group chairman Alan Mathers said the review was "another case of the MDBA marking their own homework".
“MRSG and most other groups support the retention and automation of the barrages, not their removal,” Mr Mathers said.
“There is no doubt the review terms of reference set by the MDBA were agenda-driven to ensure there was only one possible outcome.”
In response, Murray-Darling Basin Authority chief executive Phillip Glyde said the findings showed that river managers were on the right track in managing this integral part of the Murray-Darling Basin.
“The way the Lower Lakes are managed had in the past been contested, with some communities questioning whether the lakes were fresh prior to construction of the barrages and whether removing the barrages would result in an increase in water available for consumptive use,” Mr Glyde said.
“This comprehensive review of the science confirms it’s time to put history to bed and focus on the future.”