By Ken Jury, Senior Journalist Ret. (Marine & Aquatic Ecology), May 2009
There are concerns with a temporary regulator from Clayton to Hindmarsh Island! We are informed that the temporary infrastructure is to secure the Goolwa Channel from the effects of acid sulphate soils; to contain dry silt and to improve air quality for residents.
This extract is from a Submission. It was originally prepared as a result of various details and values described within the Draft Environmental Impact Statement (EIS) for the proposed Wellington Weir. The connection herein concerns the impact from downstream acidity near communities facing the much reduced waterway, with an emphasis on airborne silt and the means to contain it with a proposal to pump water from a receding Lake Alexandrina into the Goolwa Channel.
Key points:
Without delay, water levels in the Goolwa Channel must be returned to full width/depth.
The reason for the proposed temporary regulator is reluctantly understood. Option F is agreed although given that the barrages are also restricting nature, it would be more realistic not to have any barriers and let nature take its course throughout.
Insofar as for sourcing water from Lake Alexandrina to fill the channel, this is un-acceptable.
Most known scientific data on the subject of acid sulphate soils in Australia concur when dealing with the treatment of acid soils proliferation. That is to maintain a wet environment, to keep acid soils covered where possible with water. Simply, the acid problems of the lower lakes and within the eastern extremities of the streams to the western side of the system, are the results of a lack of water caused by several poorly managed factors of the past, and by drought.
Albeit, to use highly saline lake water to refill the Goolwa Channel would be retrograde, notwithstanding the costs involved with pumping of water from one side of the regulator to another. To cause further receding of water levels in Lake Alexandrina, from an already diminished supply, is not acceptable. To do so will exacerbate an already tenuous acid problem throughout the western side of the system. This should not, in any way be agreed upon. At the same time, silt dust (possibly acid bearing?) from the channel is fast becoming a real health issue for many residents. This must be checked as quickly as possible!
Alternatively, serious consideration should be given to a trial use of fresh, oxygenated seawater into the Goolwa Channel. Clearly, using seawater from the Goolwa Barrage to the Clayton Regulator could be an example of commonsense in what may well become the future of the system throughout the entire region, from the weir to the barrages.
After-all, a similar disaster was successfully countered in Western Australia’s largest inland waterway, Mandurah’s Peel-Harvey estuary. The huge Dawsville Channel was engineered to introduce huge volumes of fresh, oxygenated seawater from the Indian Ocean. Today, this region of WA is flourishing. Its fishery has doubled and its tourism has never been better.