In short:
Two pond systems with rare biodiversity in South East South Australia are closed to snorkelling and diving due to lowered water levels.
SA Lieutenant Governor Richard Harris says he fears for the futures of the Ewens and Piccaninnie Ponds if action is not taken to manage water use.
What’s next?
Authorities are investigating the state of the pond systems and hope to reopen both sites to water activities soon.
Concern is mounting for the future of internationally recognised freshwater ponds in South Australia’s South East, with a prominent diver and former Australian of the Year worried it could be nearing a “tipping point”.
Ewens Ponds, about 30 kilometres south of Mount Gambier, is home to plants seen underwater nowhere else in the world.
But last month, low water levels forced the closure of the popular diving and snorkelling site to water activities.
Less than 20km away, Piccaninnie Ponds has also been closed to water activities for more than a year after a “significant bloom of filamentous algae”.
The plight of the ponds has drawn the attention of Thai cave rescuer and newly-appointed SA Lieutenant Governor Richard Harris.
“There’s a very large number of conservation significant species down there [in the parks where the ponds are found] — types of fish, eels, crayfish, a special parrot, some plants,” Dr Harris said.
“To lose the species and these springs, which are really beautiful and important to everyone, I think would be such a shame.”
Long-term consequences
Flinders University senior research fellow Margaret Shanafield said water moves through limestone into the ponds through tubes underground.
“That whole volume of water in the ponds pushes through in less than half a day,” she said.
“That’s really important to keep the water fresh, for the vegetation and the animals living in those ponds.”
Dr Shanafield said water was about 25 years old when it reached the pond.
“What it tells us is that whatever we were doing on the land 25 years ago is still having an impact today,” she said.
She said a 2014 study found water flows had decreased by about half from historic levels, and flows had continued to drop since.
Complex issues impacting ponds
Dr Harris said he was concerned the ponds could be nearing a “tipping point”.
“The pontoon at the start of the system [at Ewens Ponds] is pretty much beached, sitting on the floor of the spring,” he said.
“We all need to take a step back and look at the bigger picture of how it will affect us all in the long run.
“If this is at a tipping point … then one mistake, for example, in the management of the springs might actually result in a catastrophe.”
National Parks and Wildlife Service conservation and threatened species manager Jason Higham said investigations at both sites were ongoing.
He said a lack of rainfall, lower groundwater levels and the removal of reeds downstream of Ewens Ponds as part of drain maintenance could have contributed to the lower water levels at that site.
But he said the issues at Piccaninnie Ponds were a “complex story”.
“We’ve done some trials to try and understand whether we can increase flow through the system by lowering water levels,” Mr Higham said.
“It’s not a simple solution that we’ve been able to identify at this stage.”
However, he was hopeful both sites would re-open in the short-term.
“I think ultimately we will restore those wetlands,” Mr Higham said.
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