A South Australian senator has warned that taxpayers could end up footing the bill to fix an environmental disaster in the St Kilda mangroves, north of Adelaide.
The Environment Protection Authority (EPA) is still investigating the events of 2020, when water seeping from neighbouring salt ponds is believed to have caused a large section of mangroves to die.
Freedom of Information documents obtained by independent senator Rex Patrick show that salt ponds operator, Buckland Dry Creek, did not have a bond in place as part of its environmental agreement with the South Australian government.
"The government has spent $2.7 million just looking at how the site would be remediated," Senator Patrick said.
"I suspect remediating 28 kilometres of salt ponds is going to run into the tens of millions of dollars.
"Right now, the responsibility for that does rest with the miner but we don't know what could happen in the future.
Senator Patrick said a bond would normally be a standard part of a miner's environmental agreement.
In a statement, the state government said the former Labor government did not insist on a bond to cover the cost of remediating the site.
"The Marshall Government inherited that situation from Labor, and has made it clear to the site owner that a bond would now be required should there be a change to the plan under which the site is managed," it said.
Senator Patrick said the documents revealed that the risk of leaks from the ponds had been known for years, and that a consultation with SA Water in 2014 showed "there is some doubt about the ability to maintain the gypsum cap under the current drained-pond conditions".
Biologist Peri Coleman has been studying the mangroves for years and has been lobbying for more to be done to fix the leaking ponds since damage to the mangroves was first observed in 2020.
"You keep hoping. Tomorrow I'll be out again counting propagules [mangrove seeds] that have washed in, trying to work out whether any have taken hold or established in both the transition areas and the dead area.
"I'll keep doing that until I see signs of recovery."
'Community sick and tired of waiting'
While the ponds are now dried out, and there are green shoots among the dead mangroves, Ms Coleman said that salt would seep into the mangroves each winter, causing more damage.
She believes the FOI documents support her call for the brine to be pumped out.
"The Department of Energy and Mining did know that there would be a problem if the brine was left in the ponds, that salt would crystallise, and that we would have ongoing problems with dissolution of salt in winter and then re-leaking in winters to come," Ms Coleman said.
"All of the salt that the EPA pumped up hill in those ponds last summer has washed down and is now right against those embankments.
"This coming winter that again will dissolve up and we need to remove it as fast as it forms."
Ms Coleman and the Conservation Council of SA are also concerned with how long an EPA investigation into the disaster is taking.
It was launched in late 2020, and still has not reported, or provided, a timeline for when it is expected to conclude.
"It's been now over two years since the first danger signs emerged in this area and yet we still haven't seen signs of any prosecution or action against the company about what has gone wrong here," Conservation Council chief executive Craig Wilkins said.
"We've got to get the immediate problem sorted out with the salt and then we've got to work out how we can shift this area from an area which is struggling to one that actually gives it a fighting chance of survival."
In a statement the EPA said its monitoring so far shows "decreasing flows of hypersaline water to the impacted areas over time".
It said it is conducting a separate investigation into possible offences under environmental legislation and while typical investigations take six to 12 months, it is not unusual for more complex cases to take over a year.
"The Dry Creek site and coastal environment is a complex ecosystem, and while harm to the mangroves is obvious, assessing the causes and evidence for impact on vegetation is a long process," it said in a statement.
"It needs monitoring over the year, with seasonal changes in vegetation, groundwater and surface water.
"EPA scientists have continued to collect data and provide expert analysis. High level specialist expert advice is required to understand vegetation such as mangroves, and interstate expertise has been brought in."
