18 May 2009
Quoted remarks are taken directly from the Murray Futures "Directions for a healthy future" report with our analysis directly below.
"The goal is to secure a future for the Coorong, Lower Lakes and Murray Mouth as a healthy, productive and resilient wetland system that maintains its international importance. Achieving this will also support the local economy and communities."
The report equates wetlands with freshwater, which is misleading. Estuarine wetlands are also valuable. Scientific studies have shown that the Coorong has always been primarily a marine (seawater) system, not a riverine (freshwater) system. Further, the Lower Lakes have been partly salty for at least 6000 years before the barrages were built in 1940.
"Over the next 20 years, the long-term plan for the region will work towards keeping freshwater in the Coorong, Lower Lakes and Murray Mouth system."
The time frames are excessively long. Artificially keeping freshwater in the Lakes is also at odds with climate change predictions for decreasing Murray Darling Basin flows and rising sea levels. The report also glosses over the adverse socio-economic impacts of not restoring water to the Lakes. Communities are hurting now and cannot afford to wait decades.
"The secondary management techniques [for bio-remediation of acid sulphate soils] are still the subject of experimentation to establish their effectiveness on the scale required."
There is no time to experiment. Saturating acid sulphate soils with water is the only proven management option. Freshwater is unavailable, which only leaves seawater.
"Seawater is seen as a last resort option."
Seawater has always been a natural part of the Lower Lakes.
"An immediate transition to a permanent marine environment is not considered to be environmentally responsible. "
The report does not explain why a marine environment is "not responsible".
"The likely tidal flow and means of flushing the system are not considered sufficient to support a healthy, functioning marine ecosystem in the short to medium term. It is anticipated that any increase in the tidal influence on the Coorong, Lower Lakes and Murray Mouth will result in increased sand loading at the Murray Mouth, which in turn will exacerbate issues associated with a blocked Murray Mouth."
This warrants scientific scrutiny. Where are the models and data that support these claims? It is equally feasible that barrages and channels could be modified to maximize tidal flows and minimize sand loading. Other shallow estuarine lakes, such as the Gippsland Lakes, are healthy marine ecosystems with extensive seagrass beds.
"Current predictions are for a rise of at least 0.3 m by 2050 and 1.0 m by 2100. At some point, it is likely that the site will assume a more estuarine character."
It will become increasingly difficult (and costly) to maintain freshwater lakes.
"The CSIRO Sustainable Yields report is optimistic that under the extreme dry climate change scenario, the Lower Lakes will remain predominantly freshwater, but that there would be occasional periods where the levels would fall below sea level. The timing and severity of these events remains uncertain. However, it is acknowledged that the modelling contains significant uncertainties about the rate and extent of climate change."
Optimistic views are just that, optimistic. In the face of these "significant uncertainties", the prudent action is to conserve freshwater for the benefit of the entire Murray Darling Basin, not just the Lower Lakes.