Scientists say they have observed signs that coal pollution in the Royal National Park could be damaging the health of a native frog population.
The NSW Environmental Protection Authority is reviewing the licence of the Metropolitan colliery at Helensburgh, south of Sydney, after coal sludge leaked into nearby waterways which flow into the Royal National Park on multiple occasions last year.
Scientists Shannon Kaiser and Chad Beranek have been surveying the health of the local frog population as part of their work analysing the impact of foreign chemicals introduced to freshwater ecosystems.
Mr Kaiser is currently completing his PhD at Macquarie University and said the pair observed green stream frogs which appeared close to death near the site of the pollution.
"We have spotted a frog which was on its back and not able to return to its feet," Mr Kaiser said.
"That is a pretty strong indicator that the frog is close to death and is actually used as an end point for a time when you would euthanise the frog because it is obviously suffering and doesn't have long to live.
"It is pretty alarming that is happening in sites along the Hacking River but not along any other sites where the coal sludge hasn't been detected."
Frogs vulnerable to pollution
The surveys were carried out between September and December last year at Camp Gully Creek and the Hacking River, one of the main rivers running through the Royal National Park.
Mr Kaiser said it was difficult to conclusively link the frogs' poor health to the coal pollution however the animals were particularly vulnerable to disturbances in their habitat.
"Frogs are particularly sensitive to environmental change because of the way their skin works; any chemicals that get into the water can go straight into the frog and that can cause pretty nasty damage," he said.
"Whether this coal sludge does that I can't say for certain, but it could be reducing their immune response because we have a disease that is killing frogs worldwide called chytrid.
"If that disease is in the area and the coal sludge has come through that could have reduced the frog's immune system and it could mean that they may be dying of that disease as a response."
The clean-up of polluted waterways is still ongoing.
The EPA said work had now moved from Camp Gully Creek downstream into the Hacking River.
"The EPA has been collecting water samples downstream of the discharge location since mid-2022," an EPA spokesperson said.
"These are being analysed for a range of substances to understand the environmental impact and to inform the investigation.
"Results indicate there is no risk to human health.
"The EPA has not observed or received reports from the community of any impacts to local wildlife, including frogs.
"We encourage anyone with information to report it to our Environment Line on 131 555 so we can investigate."
A spokesperson from Peabody Energy, the company which owns the Metropolitan coal mine, said test results indicated the pollution had had little effect on the local wildlife.
"Comprehensive, independent water tests taken between September and December 2022 showed aquatic biology counts taken downstream of the mine were very similar to results taken upstream, indicating negligible impacts from the coal sediment on local aquatic species," they said.
"Peabody is fully cooperating with the EPA to address discharges from the mine that occurred as a result of extreme rainfall conditions in 2022.
"Peabody is also pleased to report that a successful clean-up operation in local waterways was completed by the company late last year with sediment now not visible on banks and in stream."
