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A much-needed flush of fresh water could flow into South Australia's iconic Lake Bonney as early as next week, if River Murray flood levels reach a suitable level to reopen a vital inlet.
Key points:
- Authorities say Lake Bonney in South Australia's Riverland region could reopen to the river next week
- Berri Barmera Council is calling for daily blue-green algae testing to return swimmers to the lake
- A local historian says the lake was not cut off from the river in the major 1956 floods
The lake is the sparkling jewel of the Riverland town of Barmera, and is usually packed with children swimming, families boating and locals fishing during a typical summer season.
But this summer, during the flood event, the SA State Emergency Service (SES) closed Nappers inlet where the river joins the lake, with a temporary levee.
It has been linked to some environmental issues including algae blooms and salinity.
"We do believe [closing] it reduced the risk of flooding in the Barmera community," SA SES chief of staff Rob Charlton said.
"[Reopening the inlet] is a possibility next week if everything aligns ... the flow rate and levels are the main factors."
Council calls for increased testing
Berri Barmera Council Mayor Ella Winnall said the local government had "contractors on standby" to dig out the levee when the directive comes from the SES.
The recent detection of blue-green algae in the lake prompted SA Health to issue a health alert, advising people to avoid swimming in the lake until safe levels were restored.
"If we can get that fresh water in, as the water recedes, it will hopefully draw some of the salt and algae out," Ms Winnall said.
Boating, fishing, canoeing and rowing are being encouraged by authorities as alternative activities to enjoy the water while the River Murray remains closed to all non-essential activity.
The mayor has called for daily testing of blue-green algae levels to ensure the most up to date information is shared and people can return to swimming as soon as possible.
"We received updated test results on Monday which show a reduction in algae levels from Friday, but they're still above the safe limit for swimming," Ms Winnall said.
"When we do get the all clear it's really important for our community to shout it from the rooftops and not keep circulating the old images and information because we really need the help at the moment."
Future-proofing the lake
The mayor also raised reinforcing Barmera's wastewater infrastructure to 1956 flood levels with the SA government to ensure the lake never needs to be cut off from the river again.
"It [might involve] raising or putting in bypasses, so we can get a proposal together and seek some funding from state or federal government during flood recovery," she said.
"Ensuring the inlet doesn't have to be closed again is the aim so we as a community don't have to go through this again."
Local historian Rosemary Gower said there was widespread inundation in the Barmera area during the 1956 floods, including houses that went under, but the lake was not closed from the river.
"They couldn't build anything big enough to stop the water going over...but when it receded, blue green algae broke out in the North of the Lake," she said.
"The floodplains are getting their first real soaking in nearly a half-century, and suddenly the river [system] is looking healthy again.
"Now it's up to the wider community to fight for some independent authority to be set up to look after the interests and the health of the river, and ensure regular environmental flows."