South Australia’s water problem

We all know the Murray Darling Basin Plan (MDBP) was implemented primarily for environmental reasons. But does the environment benefit from all the water that ends up in South Australia?

The answer is no. In fact the environment would be better off if a lot of that water was retained in Queensland, NSW and Victoria.  Indeed, much of it could be used for agriculture in those states, at no cost to the environment but with multiple benefits for regional Australia.

The MDBP calls for the ‘return’ of 2,750 GL of water to the environment, via water rights purchased from farmers and efficiency measures. A further 450 GL is to be returned subject to certain conditions.

Under the Plan, SA is guaranteed a minimum of 1,850 GL a year. However, according to the SA EPA, SA’s total water consumption is just 1,000 GL per year, of which agriculture consumes three-quarters. Households, manufacturing and mining account for the remainder.

Adelaide also has a desalination plant capable of producing half its household and industry requirements. The plant must only use renewable energy though, which means it is expensive and rarely operates.

Unlike in southern Queensland, NSW and Victoria, where the loss of irrigation has devastated many regional communities, the purchase of water rights in SA has had little impact. Of the almost 1,500 GL of rights bought by the government, less than 10% has come from SA.

Despite this, many South Australians believe they live a precarious life due to a lack of water. So significant is this perception that it is said to determine the outcome of marginal SA seats.

To be fair, most South Australians are probably pretty ignorant about why they have this perception. Most would not realise, for example, that Lake Alexandrina and Lake Albert (the lower lakes) are kept artificially fresh by five barrages erected in the 1930s to prevent the entry of the sea. As a consequence, tidal flows are unable to keep the Murray mouth open, which is now quite silted and requires constant dredging.

They also will not know that the South East drainage scheme, which converted huge areas of wetlands into productive farmland, diverts large amounts of water and salt out to sea instead of into the Coorong, where it once flowed. This has had a very deleterious effect on the Coorong.

And they will believe, because it’s what they have been told, that sending more and more water down the Murray will somehow keep the Murray mouth open and restore health to the Coorong, despite neither being true.

What actually happens is that around 900 GL of fresh water simply evaporates in the lower lakes. That’s 900 GL, taken from the other states, which has zero environmental benefits. Evaporation will always occur, but if the Murray mouth was open and the sea was free to enter, it could be seawater that evaporates (or at least a mixture of fresh and seawater). An artificial environment is being maintained at the expense of Australian farming and rural communities.

What ought to happen is for the SA government to demolish the barrages and remove Bird Island, a sand island that has formed in the mouth of the Murray as a result of the effect of the barrages. This would allow the Murray to run free.