JO NOVA has posted on the Murray and Media Watch with comment:
“She [Jennifer Marohasy] wants to restore the estuary to its estuarine (salty) form. The end of Australia’s biggest river (the Murray) has barrages across it, to stop the salt water entering. The farmers near the end now depend on the freshwater, just as the farmers in the middle of the long river depend on the highly variable water there too. This is a big policy dog-fight I’m not in on. But I suspect if someone were suggesting putting barrages across the Yarra, the Swan or the Brisbane, the Greens and the ABC would not be attacking people who opposed the barrages. There is no higher principle or policy sense at work here.”
Read more here:
Charles Bourbaki made comment in the thread:
“Australia is one of those rare countries where the twice daily tidal influx has no influence on our estuarine rivers. Saltwater crocodiles are never seen in them and people are safe swimming many miles inland. The scientists at Media Watch know this and are quite rightly asking questions.”
I’m so used to having to defend my position and explain that there would be tidal inflows without the barrages that I didn’t get the sarcasm and left comment suggesting I have absolutely no sense of humour.
Thanks Jo and Charles for helping to get some much-needed perspective back into this issue – at least for me.
And the following letter sent into the Victor Harbour Times (a newspaper read by Lake Alexandrina residents) last autumn provides a very local perspective:
Sky High Salinity & SA Water
Tuesday, 31 May 2011
Re the statements by SA [South Australia] Water spokesperson published last week in the Times.
He started absolutely spot on with “The barrages are designed to protect water quality in the River Murray & Lower Lakes by providing a physical barrier between the fresh water in the Lower lakes & the saline water in the Coorong.”
This is exactly what SA Water is failing to do. They are maintaining too low a level upstream of the barrages. Currently levels US Goolwa barrage are fluctuating on the tide (Tuesday 31st between .28 metre & .54m). When a high tide and southerly wind arrive, like the .77m of the 24th May we have massive entry of saltwater. This is not a minor “some salt water entry”. Neat salt water reached as far as midway between Point McLeay and Point Sturt. There is large loss of freshwater dependent aquatic life along with loss of water by irrigators who receive no warning. Hope everyones auto watering systems for stock & irrigation were off.
It is not all flushed out in the following days. A week later we have salinity from 2,8000 at Clayton to 2,000 at Goolwa. Currency Creek went to almost 10,000 at the peak and will probably take months to come back down with the regulator limiting the flow.
There should no longer be a large number of gates open, flows are now down to 24,00Ml/day from some 80.000 at the end of February this year.
Two thirds of the gates should be closed with a level maintained around .5 – .6m.
Lets hope when they do eventually close the gates they have fixed the barrages, to prevent the saltwater leakage experienced last year. Have any capital works been done? Perhaps it’s not too late for maybe rubber strips between the joints in the logs.
The barrages needs to be managed to do what they were built for so as to benefit the Lakes community rather minimise SA Water’s costs & manpower requirement.
Ideally the level should be raised as much as possible to maxmise the flow into Lake Albert, Currency Creek and other salty wetlands. When all full level should be lowered to a safe level depending on sea tides and wind forecast. This cycle is then repeated in order to get maximum freshwater exchange into these areas.
PS Sunday evening looks a fair chance for another good dose of saltwater.
Thanks to CJ for finding the newspaper clipping for me… again.