Ewens and Piccaninnie Ponds remain closed amid concerning water level drops across Limestone Coast
Two SA freshwater ponds internationally renowned for their extraordinary swimming and diving are closed – with experts investigating falling water levels.
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Two internationally recognised freshwater ponds in the state’s South-East remain closed to swimming and diving as experts investigate why water levels are dropping.
Ewens Ponds and Piccaninnie Ponds are two freshwater pond systems globally renowned for their rare ecosystems and spectacular diving and snorkelling experiences.
Swimming was suspended at Ewens Ponds, about 20kms South of Mount Gambier in June.
It comes after the Limestone Coast’s water allocation plan was found to no long be sustainable in April after an 18-month review – while in March, a spring-fed drain ran dry for the first time in 90 years at a farm near Eight Mile Creek.
An Environment Department spokesperson said water levels at the ponds had dropped about 50cm below normal levels – prompting the decision to suspend swimming to protect the ponds’ nationally significant ecosystem.
“Lower water levels make snorkelling and diving difficult and increase the likelihood of delicate aquatic vegetation being damaged by water users as they move between the ponds,” they said.
“Investigations are underway to determine the cause of the significant reduction in water level but it is potentially due to a combination of very low rainfall, groundwater level decline and recent scheduled drainage maintenance to remove vegetation in Eight Mile Creek.”
They said department staff have undertaken initial monitoring of the ponds and will continue to monitor the site over the coming months.
About 20kms away, Piccaninnie Ponds has been closed to water activities for more than a year following an algae outbreak.
The ponds were closed to allow for the regeneration of aquatic vegetation and fauna species following the outbreak.
“Due to algae increase, the ponds are now closed for water-based activities, including diving and snorkelling – while not believed to be harmful, the algae has reduced visibility in the ponds and affected aquatic vegetation,” a spokesman said.
“The Piccaninnie Ponds site is a unique combination of karst rising spring and coastal fen (peat accumulating) wetlands fed predominantly from groundwater inflows.
“Monitoring has shown an increase in algae within the wetland that is believed to be partially in response to reduced inflows through the groundwater system into the karst springs, creating conditions that encourage increased algal growth and reducing water clarity.”
The Environment Department is working with the Limestone Coast Landscape Board, South-East Water Conservation and Drainage Board and local experts to explore why water levels had dropped and how to manage it.
The spokesperson said the National Parks and Wildlife Service was trialling site remediation techniques and monitoring water quality.
Dr Liz Perkins of the Landscape Board said declining groundwater levels were concerning and contributed significantly to the current amendments being made to the Lower Limestone Coast Water Allocation Plan.
She said the plan – which sets out rules for the use and movement of groundwater across the area – allocated more groundwater than any other SA plan, supported a diverse farming sector and protected the iconic wetlands.
“Changes in groundwater levels result from changes in how much water is going into the groundwater system and how much is being taken out of the system,” she said.
“There are ongoing declining trends in many places in the Lower Limestone Coast – they are a result of water use and a changing climate.
“Declining groundwater levels impact wetlands connected to groundwater, such as Piccaninnie and Ewens Ponds, this can impact water quality and aquatic vegetation and animals.”
The Landscape Board is amending the region’s water allocation plan after an 18-month review found the current plan was no long sustainable.
Despite both ponds being major tourism draw cards, data from the South Australian Tourism Commission showed their closure hadn’t deterred Limestone Coast visitors.
SATC shows that as of March 2024, visitor spending in the Limestone Coast reached $524m, already exceeding the region’s December 2025 target of $479m.
It also shows that in the year-ending March 2024, there was 333,000 interstate overnight visitors to the Limestone Coast – the highest number of interstate overnight visitors of any region outside of Adelaide.
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