Once we thought the Barmah Choke guaranteed a natural framework that set within-bank river flow rates which helped give ecosystem protection to other reaches of the Murray River. Most significantly it provided a globally unique ecosystem.
Sensible river operation shaped some of the emphasis driving early planners of our irrigation schemes. Priority went to developing most schemes where water best supplemented rainfall. Coincidentally these areas avoided arid zone regions where soils with higher salt content would be a greater problem. The shape of developments has changed markedly as the concept of irrigation schemes principally aimed at the public good has been surplanted by well heeled developers driven by dollar returns to themselves, or the private good.
Two decades ago our politicians set rules encouraging managed investment schemes and overseas investors. This accelerated the push to turn cheap arid zone country into horticultural plantations. At the time the politicians dismissed repeated concerns about these irrigation developments.
Inevitable threats included water being purchased from districts in upper parts of the southern Murray-Darling Basin. The threats extended to the tributaries of the Murray as water trade rules freed up water movements.
One example is the way in which arid zone irrigators purchased Eildon water that had to be run down the Goulburn River.
Belated limits in this have transferred part of the supply problem to Goulburn-Murray Water channels that can convey water to the Murray by circumventing the Goulburn beyond Nagambie. In the process local irrigators pay for this service to assist arid zone irrigators in a somewhat similar way NSW irrigators assist with their Mulwala canal.
Now this is not enough. The Barmah Choke is now regarded as the main cause of “delivery risk”.
The stark reality of inability to receive timely supply is giving immediacy to “delivery risk” thinking. This is predictable as arid zone plantings mature and need more water per hectare, and most disturbingly, as state authorities permit further irrigation developments for arid zone developers who purchase water from irrigators in the upper reaches of the southern Murray-Darling Basin.
But this is not all. The real national disgrace is the way in which these changes now waste water.
Firstly, six million more litres is required to water a hectare annually in 250 mm rainfall country than in 500 mm districts. This is just due to the extra evaporation and lesser rainfall.
Secondly, our arbitrators continue to dismiss the issue of conveyance loss and who should pay for this formerly productive resource when actually used closer to the dams. Thirdly, water for the arid zone has to be pumped from the river and run through pressurised distribution systems.
This is fossil fuel dependent. If it is done conservatively by burning 30 litres of distillate to deliver a million litres of water, it is worth contemplating how much diesel is used to distribute their 1000 or so gigalitres.
The carbon dioxide produced increases if fuel-dependent electricity is used.
So in acquiescing to the Barmah Choke being modified, we can be certain this embedded feature will for several reasons become a national disgrace.
— Barry Croke
Kialla
