SA must contribute fair share to Murray Darling Basin Plan

More particularly, they see it as failure by upstream states to give them everything they feel they deserve from the water resources of those states to maintain their riverine environment as they choose.

They constructed 7.6 kilometres of barrages (sea dykes) across the five outlets of the terminal lower lakes and Murray River to stop sea water from entering these formerly estuarine lakes - the only estuary in Australia that needs "protection" from sea water.

In reality it's more convenient for local communities that the lakes are permanently fresh without having to put up with the tiresome twice daily tidal influences which would have left boats from the large tourism developments stranded on their sides.

Another furphy is that the barrages are needed to keep the lakes fresh to safeguard Adelaide's water supply.

A lock on the Murray on the upstream side of the lakes could easily achieve the same outcome.

The consequence of turning formerly estuarine lakes into man-made freshwater lakes is that annually 900 gigalitres of precious fresh water evaporates from the lakes, instead of sea water.

This is fully one third of the water being saved by the basin plan - and painfully extracted from upstream communities.

This is almost equal to the volume of two Sydney Harbours.

Notwithstanding that, Adelaide is not even in the basin.

In fact, only a tiny six per cent of the basin is in SA, and this portion of the basin has a negligible contribution to the water resources of the basin.

SA is effectively adopting an attitude of sponging when it comes to water.

Without denying that it is only fair for SA river communities, and even Adelaide, to have a fair share of Murray River water, South Australians need to put their shoulder to the water wheel and lift their game to contribute a fair share to water management.

The South East Drainage Scheme drains a large area of SA turning unusable swampy land into productive farmland.

It does this by diverting thousands of gigalitres of fresh water that used to drain into the Coorong out to sea.

Now SA stridently demands upstream states give up more water because 'their water extraction is killing the Coorong.'

The evaporation of fresh water from the Murray's lower lakes, and the diversion of water from the Coorong, is likely to exceed the total amount of water that will be recovered for the environment under the basin plan.

Both actions are the work of the SA government.

The same government made sure that when the plan was drafted the lower lakes, Coorong and South East Drainage Scheme area were deliberately excluded from management under the plan, even though all are located in the basin.

During the Millennium drought SA was given $300 million for a desalination plant to reduce usage of Murray River water.

SA says it is very concerned about the environmental health of the Murray, but it won't run the desal plant at capacity because river water is cheaper.

SA insists the Murray mouth is kept open nine years out of 10 through increased flows down the Murray.

In 2016, due to floods in Victoria, the Murray ran at very high levels for five weeks, much higher than is possible under increased Basin Plan flows and yet several weeks after the flow subsided the SA government started dredging the mouth again to keep it open.

The Murray mouth was closed in 1830 when discovered by Charles Sturt and will continue to close while the barrages are in place because they restrict tidal scouring.

Dredging has cost $50 million in the past decade, more than the cost of a new lock upstream at Wellington and to remove or modify the barrages.

Of all the water recovered through buybacks under the plan, SA has only contributed about 10 per cent.

Upstream states continue to provide the majority of water returned to the environment at great economic cost, only to send it down the Murray to man-made fresh water lakes and then pour it into the sea to offset the environmental damage being caused by the actions of SA governments.

The Murray Darling Basin Plan has some major flaws, which can be remedied, but it is better than having no plan.

Upstream states are willing to work with SA to produce better outcomes from the plan, but it is time for SA to realise the free ride is over.