In the recent article 'Why demonising cotton doesn't wash in the debate over Murray-Darling water use' (CWD, October 1, 2021), Michael Murray from Cotton Australia makes a number of statements that need clarifying.
Agriculture is the largest user of water in the Murray-Darling Basin. Cotton is the largest user of water in the Northern Basin. Cotton is mainly grown under flood irrigation, an ancient method of watering crops that is very wasteful.
Mr Murray explains that through various management techniques, cotton is now using 48 percent less water per bale than in 1992.
However, he fails to mention the expansion of area and infrastructure used to grow cotton over the last 30 years.
The argument that floodplain harvesting only occurs in wet years and has no influence on river health during dry years is disingenuous, to say the least.
The NSW Government is also using this same 'spin' message.
Floodplain harvesting diverts rainfall runoff before it enters rivers and also captures overbank flows when rivers are running high. The capture of these important natural flows means they don't get downstream to top up water holes, billabongs, lagoons, wetlands and groundwater in preparation for the next dry sequence.
The capture of flood flows below the major storages in the Northern Basin causes prolonged drought and dry seasons for downstream ecosystems and communities. They are denied important natural 'top ups'. This is particularly an issue in medium wet years when very large, uncontrolled flows through the entire system do not occur.
Mr Murray highlights that no cotton was grown at Bourke in the 2018/19 season when the catastrophic fish deaths occurred at Menindee. This is because Bourke is on the Darling/Baaka and suffers the same as everyone else from upstream interception of river flows.
Some people will remember the huge campaign against the Cubby Station cotton farm, just over the border in Queensland. It is the largest irrigation farm in the southern hemisphere and can capture 460 billion litres (gigalitre GL) of water in on-farm storages. Sydney Harbour holds 500 GL. This large cotton operation is now owned by a Chinese company. The opportunity to get this water back into the Darling/Baaka River has been well & truly lost.
The cotton industry in the Northern Basin does have a lot to answer for. Investment in more efficient irrigation methods such as sub-surface or trickle irrigation would go a long way to solve the industry's thirst.
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