South Australians seem to really know how to whinge -- now they are blaming an acid sulphate soil problem on NSW irrigators. The latest moaning is from star South Australian Senator and Federal Water Minister, Penny Wong, and her State colleague, South Australian Minister for the Murray, Karlene Maywald.
Both are both blaming upstream irrigators for a problem with exposure of acid sulphate soils (ASS) in the Lower Lakes and other areas adjacent to the River Murray's mouth. Potential acid sulphate soils (ASS) are common along much of the Australian coastline -- just ask sugar cane producers on the North Coast about their experiences in recent decades.
These soils formed after the last major sea level rise, which began about 10,000 years ago. The soils are harmless as long as they remain waterlogged. But, if the water table is lowered the sulphide in the soils will react with oxygen forming sulphuric acid. In the case of the lower lakes near the mouth of the Murray River in South Australia, the barrages built 80 years ago are stopping inundation from seawater; in the same way the dykes in Holland are used to reclaim land.
Indeed the Dutch have been managing associated acid sulphate soil problems for more than four centuries. ASS have been associated with fish kills in coastal Queensland and New South Wales when land has been inappropriately drained. For example, about 700 hectares of land near Cairns was drained in 1976, and since then it has been estimated that 72,000 tonnes of acid has flowed into Trinity Inlet.
Approximately 50 percent of the NSW cane land is underlain with potential ASS and inappropriate drainage of these soils caused a major fish kill in the Tweed River in 1987. NSW farmers have since solved the problem through the implementation of less intrusive drainage and liming.
The can-do NSW farmers got on and fixed their problem, but the South Australians have instead provided money to CSIRO Land and Water to undertake a study, including to, establish the severity and spatial extent of the problem.
In the interim there will be lots of media releases and whinging, including about how they should be received more stored irrigation water from the Hume Dam in the Upper Murray or else their lake turns to acid. There is in fact a simple solution to their problem, they could open their barrages and let seawater re-flood the area.
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