On Thursday, a royal commission found Australia's Murray-Darling Basin Authority acted unlawfully and recommended a complete overhaul of water allocations.
What is the Murray–Darling Basin?
Covering an area of more than one million square kilometres, or 14 per cent of mainland Australia, the Murray–Darling Basin is Australia's largest river system.
It runs from Queensland, into New South Wales and the Australian Capital Territory, then out through Victoria and South Australia.
It includes 77,000km of rivers and more than 25,000 wetlands.
Where the Darling River meets the Murray River at the town of Wentworth , Sunday, Dec. 7, 2008. Source: AAP
Why is the Murray–Darling Basin so important to Australians?
Much of Australia's "economy, food security and wellbeing depend on it, now and into the future", according to the Federal Government.
The government describes the basin as "the food bowl of the nation", noting that the agriculture industry that it relies on it is worth $24 billion annually.
"Over three million people have access to fresh, clean drinking water from the basin," it says.
For such reasons, ANU public policy expert Professor Quentin Grafton told SBS News on Thursday: "It's key to Australia".
"In one way or another, all Australians rely on the basin in some way ... I think the expression 'heart of the nation' is not an exaggeration."
What went wrong?
Professor Grafton said the problems in the Murray-Darling Basin "didn't happen overnight".
In 2006, then prime minister John Howard foresaw the effects of drought and climate change on the nation's largest river system and commissioned a CSIRO study into the water availability.
The findings showed the total flow of the river at the Murray's mouth had been reduced by 61 per cent. A model also predicted the south Murray Darling would see a "very substantial decline" in surface water availability due to the impacts of climate change by 2030.
Professor Grafton said our failure to plan and "limit" our extraction of available water has created a situation that has come to a loggerhead.
"Essentially what has happened, we as a nation have supported the increase in irrigation, extracting water from rivers systems into fields to grow crops," he said.
"It's a reasonable thing to do, but the problem is we over-extracted. We didn't limit ourselves to how much water we should extract."
The Murray-Darling Basin Authority, a government agency, was set up in 2008 to manage the basin in an "integrated and sustainable manner".
Then in 2012, the Murray-Darling Basin Plan was agreed to by the federal government and four states to manage the water in a system made up of the Murray and Darling rivers.
Signed into law by the Gillard Labor government, it determined the amount of water that can be taken from the basin for urban, industrial and agricultural use.
It was supposed to remove 2,750 gigalitres of water through irrigated agriculture and return it to the river system to help the environment.
But ABC's Four Corners in 2017 revealed allegations upstream irrigators in NSW were taking billions of litres of water designated for the environment.
Hundreds of thousands of dead fish in the Menindee weir pool and neighbouring waterways. Source: AAP
And problems persisted. Earlier this month, up to a million fish died in the Darling River.
The fish deaths were the result of poor water quality and drought, according to NSW Primary Industries Minister Niall Blair.
"This is due to a lack of oxygen in the water. Blue/Green algae have built up in some of the water because of the low flows. There was a sudden drop in temperate and the algae died," he told SBS News at the time.
Rob McBride and Dick Arnold were filmed standing in the Darling River at Menindee amid dead fish. Source: SBS News
"That then depleted the oxygen in the water which has led to the fish kill."
Locals, irrigators and politicians have been arguing over who's to blame for the catastrophe with residents pointing the finger at water mismanagement.
What did the royal commission find?
On Thursday, a royal commission found Australia's Murray-Darling Basin Authority acted unlawfully and water allocations must undergo a complete overhaul across the system.
The commission's report found river allotments were driven by politics and accused the basin authority board of maladministration over its disregard for science.
It said the Murray-Darling Basin Authority acted unlawfully when it "completely ignored" climate change projections for the determination of water allocations.
It said water levels must be made on a scientific basis and in accordance with reconstructed water laws.
