The photos of the Murray River at the Swan Hill bridge (below) show the river in 2003 during the worst drought in 100 years, and the river during the drought of 1914. The difference is stark. The dams, locks and weirs that were built over the past 80 years mean that today the river is flowing, even in drought time.
Prior to those in-stream constructions, the river regularly ran for only a few months of the year during the wet season and the snow melt. It then stopped flowing. In drought time the mighty Murray became a series of pools, often saline and stagnant. Records show that the river dried up in 1913, 1914 and 1929.
While politicians and environmentalists have made much of the closure of the Murray River’s mouth, it would have closed naturally anyhow during this current drought. It ceased to flow at Swan Hill in 1902, 1914, 1915 and 1923. The river mouth closed in 1930 and partly closed in 1967-68.
The variations in water flows saw large fluctuations in the fish stocks, as well as native animals that lived within a short distance of the river.
Human intervention has done more than keep water in the river. Irrigation channels fan out from the rivers of the basin, irrigating 1.5 million hectares of farm land, and servicing towns, cities like Adelaide (which is 80% dependent on Murray River water) and industries.
These irrigation channels also support native wildlife. Ducks and water fowl populate and breed along these channels. Native birds and animals are watered from these channels.
These aspects of the Murray’s environment have been ignored by the Wentworth Group (backed by the World Wildlife Fund), The Economist magazine, everyone in Ticky Fullerton’s book, Watershed, some CSIRO reports, and the Murray Darling Basin Commission’s (MDBC) paper, The Living Murray.
All variously claim that the major problem in the basin is deteriorating water quality, in particular a worsening salinity problem.
A recent report by Jennifer Marohasy, from the Institute of Public Affairs Environment Unit, has scientifically challenged the deteriorating Murray scenario.
Regarding salinity, there is a public perception that Adelaide’s water will be undrinkable in 20 years. Yet, Marohasy says that the MDBC’s own monitoring shows that at Morgan in SA, just upstream from where Adelaide draws its main water supply, salinity levels have been falling for 20 years. Water quality is improving, and is well below the World Health Organisation recommended salt levels for human consumption. Nor has there been any deterioration in salinity upstream at Swan Hill or Yarrawonga. Levels there are low, falling at Swan Hill and stable at Yarrawonga.
Marohasy took up her findings with the MDBC. In response, Dr Pradeep Sharma, Senior Modelling Engineer said that “thanks to major investments in the salinity mitigation works undertaken in the Murray Darling Basin over the last decade, I would like to concur with the conclusion that average salinity in the River Murray has in effect improved during the last decade.”
Another measure of river health is turbidity, or sediment load, which affects light absorption and water temperature. Marohasy said that Australia’s inland rivers are considered to be naturally turbid.
The introduction of sheep, cattle and rabbits, and early settler land clearing, increased sediment flows. However, “as a result of improved management practices over recent decades, erosion is likely to have stabilised or reduced to pre-European levels”.
According to MDBC data, turbidity levels at both Morgan and Swan Hill appear to be relatively stable. Average turbidity levels “have not increased” since measurements began in 1978.
Another river issue is algal blooms due to elevated nutrient levels, especially nitrogen and phosphorus.
Research published by the MDBC indicates that phosphorus may come naturally from basalt-derived soil. Nitrate can come from excess runoff from farm fertilisers. Data show that levels of both have been stable in the river since they were first collected in 1978.
If science is showing Murray River water is not deteriorating in quality, then the Council of Australian Governments (COAG) must reject the MDBC Living Murray proposals to take up to 15% of farmers’ water allocations over 10 years, and up to 30% over 20 years, for environmental flows.
- Pat Byrne