10 November 2009
by Trevor Harden
That the water resource of the Murray Darling basin has been over allocated to the detriment of the whole riverine environment – there is no question that it needs to be fixed for the long term health of the river.
Right now, this extreme and continuing drought has reduced the available water to less than one third of the allocation – well below even that which might be aspired to in a restructured and better managed future resource.
Irrigators and their communities are suffering throughout the basin.
While the drought continues, (with this large shortfall in available water – caused by drought), the environmental flows of fresh water needed to restore the Lower Lakes even to sea level, are just not there – the required fresh water does not exist.
Lake and lower river levels will continue to fall with; - increasing salinity, - risk of irreversible acidification, - windblown storms of corrosive dust, and - physical impacts upon lake shorelines and river banks.
Sea water is allowed through the barrages to mix with the limited freshwater flows from the river to raise water levels to cover exposed lakebeds and reduce threats of acidification – ie an estuarine environment is created.
With an estuarine mix of salinities across the lakes, there is an urgent need for a barrier at or near Wellington, to protect the quality of water extracted from the river for human uses from saline contamination.
And with increasing lake salinity from summer evaporation, water quality above Wellington is under threat with or without the seawater option.
The only logical conclusion?
An estuarine/seawater solution to the Lower Lakes crisis
- so much to gain - so little left to lose
And yet the SA Government is irrationally committed to a freshwater ‘solution’, which is clearly impossible right now, (and may well be impossible in the future), and will not even consider the use of seawater to create the estuarine sea level mix which so clearly is needed.