St Kilda mangroves and saltmarsh dieback spreads awaiting pumping of hypersaline acidic water out of leaky ponds

A salt miner is being blamed for dead mangroves around the St Kilda boardwalk as drone footage reveals how far the destruction has spread.

Immediate action must be taken to remove super-saline brine that has killed dozens of hectares of mangroves and salt bush around the St Kilda boardwalk, local experts and the Opposition say.

Salt miner Buckland Dry Creek Ltd’s pumping of hyper saline water into nearby salt ponds, believed to have leaked acidic material, is being blamed for the dieback of at least 10ha of mangroves in the Adelade International Bird Sanctuary and 35ha of other vegetation.

St Kilda resident and scientist Peri Coleman, of Delta Environmental Consulting, said time was running out to take action before heatwaves killed off “the small little areas of the saltmarsh that are left”.

“What we have to do now is get as much brine out of the ponds as possible,” she said.

St Kilda resident and scientist Peri Coleman. Picture: Alex Mausolf

St Kilda mangroves along the boardwalk are dead and dying. Picture: Alex Mausolf

Drone footage reveals damage to mangroves and saltmarsh at St Kilda. Picture: Alex Mausolf

“Get the brine out of there and do it quickly because the longer you leave it, the larger the impacts, and they’re not going to go away.

“The brine is crystallising. You can’t pump crystallised brine because it’s solid. (And) if you try to pump a liquid that’s on the verge of crystallising, it will snap the (pump) shaft.”

The Opposition agreed “a critical point” would soon be reached when pumping the brine would be impossible.

“This destruction is unacceptable and the government need to take ownership of the issue and fix it immediately,” Labor’s environment spokeswoman Susan Close said.

Ms Coleman first prepared a report on the problem for Salisbury Council in early Spring, when she “still had some hope” that it would be addressed in a timely manner.

But she was now convinced Buckland Dry Creek was “out of its depth” and called on the Energy and Mining Department (EMD) to “get involved and take responsibility”.

The department called in the Environment Protection Authority to investigate in mid-September. The EPA has since confirmed salinity levels “many times higher than seawater in the saltmarsh and associated mangrove areas” was likely to blame.

Drone footage reveals damage to mangroves and saltmarsh at St Kilda. Picture: Alex Mausolf

Drone footage reveals damage to mangroves and saltmarsh at St Kilda. Picture: Alex Mausolf

Drone footage reveals damage to mangroves and saltmarsh at St Kilda. Picture: Alex Mausolf

“While it is not known for certain what is causing the dieback, salinity and the management of water in the salt fields is an obvious focus,” the EPA website says.

On December 24, the EMD issued a direction requiring Buckland to remove brine from the ponds next to the St Kilda mangroves.

“The company’s planning works to satisfy the direction have already commenced with on ground works expected early next week,” a State Government spokesman said on Wednesday.

“Government regulators are actively monitoring the site, including vegetation mapping and hydrological analysis.

“Formal investigations into the cause of the mangrove dieback and any compliance actions continues.

“Government shares community’s concern regarding the environment surrounding the salt fields, and is focused on stabilising the site in both the short and long term.”

Attempts to contact the company Buckland Dry Creek Ltd by phone yesterday were unsuccessful.