The Independent Expert Scientific Committee (IESC) has expressed “extreme concern” about the proposed Central Queensland Coal (CQC) project, which it said posed “very significant risks” to reef waters and other “internationally recognised assets”.

CQC wants to build a mine of up to 10 million tonnes of coal a year — as big as Adani’s Carmichael project — 10 kilometres from the World Heritage Area.

But former IESC member Jim McDonald said the expert panel’s advice to Queensland and federal environmental officials last month was one of its most damning assessments yet.

“They’re quite blunt about the loss of environmental asset,” McDonald told the ABC.

“Essentially, they’re saying if you go ahead with the mine as proposed, you will lose [some] environmental assets, because there’s no way you can offset it.”

Palmer is the sole owner of CQC through companies including Fairway Coal and Mineralogy.

CQC has hit back at the IESC, arguing its own draft environmental impact statement “specifically states that there will be no significant impact to any values in these areas”, including the World Heritage Area.

“Given the findings of no significant impact to these areas, the IESC should state what their ‘major concerns’ and the ‘very significant risks’ are,” Central Queensland Coal said in a formal reply on Christmas Eve.

But in its third evaluation of the mine proposal since 2017, the IESC said it had previously raised those concerns.

It said it was especially concerned about the “discharge of mine-affected water” into the World Heritage Area and Queensland’s largest fish habitat at Broad Sound, north of Rockhampton.

It said the miner’s plans to minimise environmental impacts were “likely to be completely inadequate for this region because of its relatively undisturbed setting”.

“The IESC cannot envisage any feasible mitigation measures, including offsets, that could safeguard these irreplaceable and internationally significant ecological assets and their associated water resources,” it said.

The IESC acknowledged Palmer’s companies had done “substantial further investigation and analyses” in response to the panel’s previous concerns.

But it said nothing would “alter the material risks associated with this project, in particular the potentially severe consequences for local and downstream water-related assets”.

The IESC said the mine risked “significant and irreversible damage to internationally valued estuarine and near-shore ecosystems subjected to mine-affected water”.

There was also a potential “legacy water quality issue” from contaminated surface waterways, the “direct loss of 8.35 kilometres of waterways that provide fish passage”, and a drop in groundwater of up to 60 metres along an 11.8km stretch of land.

Mining giants such as BHP and Rio Tinto have been divesting from coal assets for several years and telling investors this was due to concerns about climate change.

CQC is hoping to mine both energy coal and steel-making coal for 18 years.

Cattle farmer Jacqueline McCamley said prime grazing land, including her property near the proposed mine site, should not be sacrificed “for the sake of a temporary coal mine”.

“Tooloombah would be unable to produce organic beef with coal mine dust polluting grazing pastures and our water,” she said.

While the IESC advice is not binding, McDonald said it could have a decisive influence on government decisions.

“It’s a panel of wide-ranging experts [who] carry a lot of weight in their own different fields,” he said.

McDonald said until now the panel had been “very helpful” in directing Palmer’s venture towards “what the IESC needs to properly assess the project and to properly show impacts and how you might mitigate those impacts”.

“In the third one, they essentially said, ‘You still haven’t convinced us’ … and the proponent’s quite open about the impacts that they propose will happen — the IESC’s essentially said, ‘Well, there’s just no way you can mitigate those impacts’,” McDonald said.

Ellie Smith from Queensland anti-mining group Lock the Gate said the IESC report “really stands out in terms of its criticism of a coal project”.

“The unprecedented severity of the IESC’s criticism of the Central Queensland Coal project clearly demonstrates how destructive this project would be,” she said.

“We hope that the Government rejects this project. It’s clearly unacceptable.”

Smith said Palmer “seems to have a knack of picking projects that are destructive”.

“First, he proposed a mine on top of a nature refuge … and now, he’s proposing this mine here in the catchment of the Great Barrier Reef,” she said.

“We have to take him seriously because obviously he has billions of dollars to fund these projects himself, if he wants to.

“But we do think that he should stick with his other projects, other interests, and stay away from coal mining in Queensland.”

In 2017, Palmer threatened to take the Queensland Government to court if it tried to stop the CQC mining venture.

Palmer did not answer calls from the ABC in relation to the CQC proposal.

Nui Harris, a co-director of Palmer’s venture company Fairway Coal, could not be reached for comment.

A spokesman for Queensland’s Department of Environment and Science said it was due to decide by the end of next month whether the miner could move on the next stage of its application.

“DES will be considering the advice received from IESC in its decision,” he said.

A spokesman for the federal department of Agriculture, Water and the Environment said state officials were taking the lead in assessing the mine plan.

“The proponent has engaged closely with DES and the department in relation to the issues raised in the IESC advice,” he said.

– ABC / Exclusive by investigative reporter Josh Robertson