Discussion paper

Owing down the river

Mortgaging the future flows of the Barwon-Darling/Barka River
Environmental health Environment Rivers Water conservation Irrigation Murray-Darling Basin

Drought, the Menindee fish kills and the South Australian Royal Commission have put the Murray Darling firmly in the public spotlight. The management of the northern Basin and the role of the cotton industry are central to ongoing policy debate.

One response has been Senator Rex Patrick’s private member’s bill to ban cotton exports. While this has facilitated debate, the Royal Commission argues that attention needs to be focused on overall consumptive take rather than any particular crop.

However, as cotton uses around 80% of irrigation water in the northern Basin, it is impossible to discuss the northern Basin without discussing cotton. The key argument in favour of crops like cotton or rice is that as annual crops, they are able to adjust to water availability in each year, unlike permanent plantings such as citrus and nut trees or grape vines. In theory, water markets will help allocate water to its highest value use between crops, bringing efficiency, diversity and prosperity to the Basin.

This is simplistic. Firstly, water trading options are limited in the northern Basin. Secondly, there are few crops other than cotton to trade between. The only real incentive faced by producers is to acquire and store water and grow more cotton – at least until some other crop becomes more profitable.

While cotton is an annual crop, cotton businesses don’t work on a one year timeframe. Despite the current drought, with record low rainfall and record high temperatures in parts of the Basin, over 100,000ha of irrigated cotton has been planted in the northern Basin. While down by almost half on last year’s crop, 1.2 million bales of cotton will be produced - still a substantial crop by historical standards.

At least 845 and perhaps as much as 1,135 gigalitres (GL) of water will be applied to this crop and a further 1,000 GL likely evaporated while in storage before irrigation use. In the meantime, only 40 GL flowed past Bourke and a little over 11 GL reached Wilcannia in all of 2018.

This year is not an anomaly. Analysis of records from 1989 show that while water availability is highly variable, cotton production can be remarkably consistent. From 1991 to 1995 there was minimal flow at Bourke, while cotton production remained steady at around 250,000ha. From 2001/02 it took nearly six years of very low water availability before cotton production was significantly reduced. By the time cotton reached its lowest point in 2007/08, the Darling had been virtually dry for seven years.

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