I have been reading with increasing despair about the fate of this river system, the only major river system of inland Australia. Over the past century humans have basically destroyed it. The problems started early in the 20th century when irrigation began to open up land in the river basin to agriculture and horticulture for which it was entirely unsuited. Two of the biggest culprits have been cotton and rice, both very thirsty crops and in the latter case leading to accelerated evaporation as surface water is spread out over a large area during the growing season. But as far back as I can remember there have also being problems caused by the rising water table in irrigated areas pushing salt to the surface. Large parts of the formerly irrigated land area are now deserts, the salinity level of the lower river as a whole has risen, about a decade ago the mouth of the river closed up and it now has to be kept open by dredging. And still people take more water out of the system - the Victorian government, for example, is building a pipeline from the Murray to provide extra water for Melbourne. Adelaide has had a pipeline for decades.

In 1941, due to the reduced flow of the river caused by expanding upstream irrigation, the South Australian government built a series of barrages. The river first flows into a lake, Lake Alexandrina and Lake Albert, and then past a string of islands, eventually emerging into the sea via a very narrow mouth. The barrages blocked the gaps between the islands and, for several decades, the level of the lake was maintained at roughly a metre above sea level as it always had been. The reason for the height above sea level was that the current of the river forced water to bank up as it flowed through the narrow channels between islands. In dry years, when the river flow was low, brackish water would come further inland (as far as Tailem Bend). From 1941 and for the next 50-60 years the barrages did what the river's current could no longer do. About 6 years ago, however, the mouth closed up. The reason is that the lake level has been dropping and is now, apparently, half a metre below sea level! Whereas fresh water used to flow through the barrages, keeping the water between there and the sea and, most particularly in the Coorong, brackish, now seawater leaks through the barrages in the other direction, turning Lake Alexandrina brackish, but leaving the Coorong increasingly saline. The southern end of the Coorong (a 90 km long lagoon that runs parallel to the beach) is now 6x more saline than the sea. Although some of this increased salinity can no doubt be attributed to lack of freshwater entering from other sources as well, the other sources are tiny compared with the Murray.

In the last few months, alarm bells have been ringing loudly over Lake Albert which has sulphate soils in the lake bed. Apparently if these are exposed to the air, the lake will turn into sulphuric acid (I'm not certain of the chemistry here, but it's toxic). Everyone agrees that this process is irreversible. They will probably have to cut a channel through from the Coorong and fill it up with sea water to prevent the acidification. I know somebody who is a farmer down by that lake - that'll be the end of his farm, and all the others! The SA government is now planning to build a weir at Wellington, just above where the river flows into the lakes to prevent sea water and/or acid flowing further upstream. They're hoping they won't have to build it. But Penny Wong, the Federal Minister for Water and Climate Change, says there simply isn't enough water in the entire system to save the lakes.

Some people have wild imaginations. People in NSW, Queensland and Victoria seem particularly keen to absolve their citizens of all responsibility for the health of the Murray estuary. One guy I read, I've forgotten where exactly, imagines that the lakes were actually created by the barrages out of naturally saline estuary and, moreover, that by creating the lakes the construction of the barrages increased evaporation, contributing to the present disaster. Well I've got news for him, Lake Alexandrina was named for a certain English princess and just a few years after it was named she became Queen Victoria. Queen Victoria ascended the throne 104 years before the barrages were built.

Cubbie Station in Queensland has come in for a lot of flak over the state of the river. This is a giant cotton plantation, some 40 km across and they have constructed 500 gigalitres of water storage. But huge as it is, Cubbie is by no means the only cotton plantation taking water out of the MDB. Earlier this year the Warrego, a major Queensland tributary of the Darling, flooded, but almost none of the floodwater reached the Darling! In addition, a number of natural lake systems occur along the course of the Darling. The Menindee Lakes are said to be currently holding 600 GL. The NSW government deliberately keeps them just below the level at which the Commonwealth can take charge of them under the new water sharing agreement (and meanwhile the released extra water is used to provide irrigators in NSW with 100% of their allocation). If all of that water was released into the system, without any irrigation takeout, there would be an addition of 1000 GL to the current flow. It would be better than nothing, but it wouldn't come anywhere near the 13,000 GL that people are saying are needed to restore the river to a really healthy state. Meanwhile the government has purchased 35 GL of allocation rights back from various farmers and other water users - or potential water users since, in all likelihood, those who are willing to sell their rights are people who don't actually use them. They'd have picked up a nice $10 million windfall for the air in their dams. Pre-election promises were to buy back from 500 to 3,500 GL!

Some scientists are arguing that instead of a cap on water allocations from the river, there should be a minimum guaranteed inflow into the river. This is a very nice idea, but with politics the way they are I don't give it much chance.