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Techly Explains

Techly Explains: What killed a million Darling River fish?

The finger has been pointed at drought, algae and the federal government for the death of over a million fish along the Darling River, but who or what is really to blame?

The truth is that, though it is frustrating for those seeking one fundamental answer, every event in history has multiple causes.

In A System of Logic (1843), John Stuart Mill writes of the impossibility of picking a single ’cause’ from the ‘conditions’ of any event.

Take, for example, a tennis ball flying through a window. What caused the break? The thrower? The ball? The weak glass? Gravity?

All of these factors count as a condition, but picking out one in particular is difficult and arbitrary.

This is a principle that is useful when considering the root causes of any event, be it World War II, human evolution or the death of a million fish in the Darling River.

Initially, algal blooms and shifting water temperatures were blamed, but locals are convinced the blame lays with state and federal government policy regarding water management and irrigation.

Leading academics from across Australia have analysed what is taking place and come to a unanimous conclusion.

While algae and drought both play a part, the main problem is that we are extracting too much water from the river and not leaving enough for the fish to survive.

“Dead fish and dying rivers are not because of the drought,” said John Williams, an Honorary Professor at the Australian National University in Canberra. “It’s because we are extracting too much water from our rivers.”

“Many of the large fish which are dying have lived for more than 50 years through many equally severe droughts. Drought is part of the system.”

Williams summarises the problem with a simple and coherent simile for what’s happening. Too much water is being taken out, and it isn’t being replaced.

“The river is like a piggy bank, if you keep taking money out without saving for the future you end up bankrupt, and just when you need it most.”

The problem is one of water reform – algae is a side-effect of low oxygen levels which is doing the real damage, and drought is just the icing on the cake.

When water is taken from the river, it depletes the oxygen levels in the water, disrupting the natural nutrient levels and flows in the streams, ultimately causing fish populations to die.

“We have been here before with the algal bloom of 1991 along the Darling River and the ‘blame game’,” said Professor Quentin Grafton, UNESCO Chair in Water Economics and Transboundary Water Governance.

“The NSW Irrigators Council would have us believe it is all about the drought. It isn’t. It about taking too much water upstream so there is not enough for downstream users, and the fish.

“It’s time to make those in charge (elected and appointed) accountable for lowering the volumes needed to increase stream flows, it’s time to call out the regulators who have been  ‘asleep at the wheel’ in relation to water theft and managing stream flows.”

Outlining the causes is one thing, but coming up with a solution is another. It just happens that the answers to our environmental goals are actually within the 2007 Water Act – they just haven’t been followed.

The measures that are urgently required include:

  1. Stopping any further money being put into infrastructure meant to improve water-use efficiency.
  2. Auditing the current environmental and socio-economic outcomes of water recovery.
  3. Establish an independent, scientific entity to publicly document what’s happening in the Darling River and create objectives to fix it.

With experts having identified the problems with the river, it is now up to the state and federal governments to act and restore the Murray River to its healthy, sustainable, iconic glory.

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