“The ecosystem was sitting on the edge and the 2012 flood was the catastrophic event that pushed it over the cliff,” says Fulton.

Although floods like the one in 2012 happen once or twice a century, clearing of vegetation on the stream’s edge had left the Goobarragandra vulnerable when flooding came.

Picturesque trees lining a cool stream are not just for aesthetic benefit, says Fulton.

“Without the vegetation on the banks, the floods scour the banks. The sand and soil that should be held in place gets ripped away and deposited into the stream,” he says.

“The sunlight hits the stream and warms it up and it loses dissolved oxygen, which the crayfish are very sensitive to.

“The trees would have dropped twigs and leaves and insects which are food for the all kinds of species, from bacteria up. So when you remove them it’s a triple jeopardy going on.”

It’s not just crayfish that have suffered. Fulton lists many species throughout the river system that are now in heavy decline, such as the two-spine blackfish, the silver perch and the Macquarie perch.

“There’s a long, sad list of Murray-Darling species that are on their way out,” says Fulton.

He believes the emergency is easily comparable with the threat to the Great Barrier Reef and is growing across the world.

“Freshwater systems are considered one of the most vulnerable on the planet,” he says.

“We’re seeing the decline of so many things crayfish, fish, waterbirds… It’s because fresh water is being squeezed from so many directions.”

Agriculture and mining siphon off water, dams even out natural variations and cut flows to a tiny fraction of the natural levels.

Amidst these threats, Noble, MEnv (Rsch) ’15 found a ground swell of hope for freshwater species, while presenting the results of their research at a conference.

A series of talks on freshwater species, such as eels – not usually the top of public opinion polls – caught her eye.

One after another, traditional leaders from the US, New Zealand and Australia spoke, outlining the importance of their local freshwater species to their culture and how they were managed.

Noble was struck by how the species that were culturally most significant to indigenous peoples were also the ecologically most significant species.

“In the Pacific north west of the US, people identify themselves as Salmon People,” she says.

“Salmon are a very important species, they’re habitat engineers that bring in nutrients from the oceans. They regulate the ecosystem because they are apex predators.”

Meanwhile, Indigenous peoples’ of Australia management of freshwater eel species had extraordinary insights.

“The Kooyang people of south west Victoria have cultural practices and ceremonies that have come out of their interactions with this species over thousands of generations,” says Noble.

“Their stories described how eels have adapted since the ice ages.”

In the Murray-Darling Basin, the local cultural traditions talk about how the Murray Cod created the basin.

“That makes sense. The Murray Cod is the apex predator,” says Noble.

She collaborated with her new contacts, resulting in a landmark paper in Ecology and Society, co-authored by herself and eight traditional owners from the three countries.

Environmental management agencies are also engaging with traditional owners with indigenous management skills, which gives Noble a lot of hope.

“In the past, the government has blocked access to these species. Restoring that has had really, really good outcomes.”

As well as empowering traditional people, some governments are making serious moves in their own right to get freshwater systems back on an even keel.

The decline in US salmon numbers became such a concern, not only for the Indigenous Salmon people but the local fisheries and the tourist market, that the US Government began destroying dams so salmon can travel the rivers again.

And in Australia, the Federal Government is poised to strike a blow in the push to return waterways to their pre-European state.

In the last 50 years, as weirs and dams were added to create reliable water levels for human use, the Murray-Darling system has become progressively murkier and silt-choked, perfect conditions for European carp to flourish in.

Fulton estimates carp now make up 80 per cent of the biomass in the Murray-Darling Basin.

But Federal Science Minister Christopher Pyne announced that will end in 2018 with “carp-ageddon”, the release of a virulent strain of carp herpes.

“Suddenly, there will be literally hundreds of thousands, if not millions of tonnes of carp that will be dead in the River Murray,” Pyne said.

While Fulton is optimistic about carp-ageddon, he does not think it will be the magic bullet. Isolated programs need to be united to rebuild ecosystems, he says.