Adani has been fighting to hide details of what it told the Queensland Government about the risk of pollution to the Great Barrier Reef ahead of Cyclone Debbie in 2017.

Key points: FOI documents appear to show Adani, Queensland Government knew polluted spill likely to breach licenced levels

FOI documents appear to show Adani, Queensland Government knew polluted spill likely to breach licenced levels Adani applied for temporary licence to pollute wetlands as Cyclone Debbie rolled in after realising potential for overflow

Adani applied for temporary licence to pollute wetlands as Cyclone Debbie rolled in after realising potential for overflow Environmental NGO said: "They knew they would break the law, and they did it anyway"

Now, conservationists say documents and a series of emails obtained through freedom of information laws appear to show the company and the Queensland Government knew the pollution would be so bad it would break the law.

The details are revealed in an exchange over the company's temporary pollution licence and it starts on March 27, 2017.

On the wet and blustery morning, Queenslanders were making sure their loved ones were safe.

Cyclone Debbie — what would become the most dangerous storm to hit Queensland since 2011 — was quickly approaching the coast.

That day, Adani was preparing too.

It was seeking a temporary licence to pollute wetlands around its coal export terminal at Abbot Point near Bowen with coal-laden water.

Documents uncovered using freedom of information laws show that morning, Adani realised the large amount of rain falling into its storage pools would likely cause them to overflow onto important wetlands next door to the site.

Satellite imagery released a few months later shows the wetlands covered in polluted water after the storm.

The ABC can now reveal the content of those documents, including a section Adani has fought for the past year to keep secret.

That section suggests that later on March 27, while Adani was applying for a last-minute extension to its temporary pollution licence, it appeared to know the water it was likely to dump would be so polluted it would breach the licence.

Satellite photo of the Abbot Point coal terminal beside the Caley wetlands, taken in May 2016. ( Supplied: Queensland Government )

As rain and wind was bearing down on the town of Bowen, and forecasters warned of Debbie's impending landfall, Adani received its temporary pollution licence.

But, at the last minute, late that afternoon, Adani realised its application for permission to pollute the wetland was not enough.

It would also likely dump polluted water directly into the ocean and into the Great Barrier Reef World Heritage Area.

"Sorry I just noticed W2 wasn't included in the [temporary emissions licence], is it possible to include this location?" an Adani employee wrote in an email to the Queensland Environment Department that afternoon.

The department quickly indicated that would not be a problem:

"Just give me a little detail and we can include and update [the temporary emissions licence]," a department staff member replied.

Satellite image of the coal terminal and wetlands after Cyclone Debbie. ( Supplied: Queensland Government )

The email chain shows about 5:00pm on the following day — hours after Cyclone Debbie had crossed the coast — Adani sent that extra information to the department.

Among the documents were also details the company then fought tooth and nail to hide because Adani said it would "cause extreme and unfair prejudice" against it.

On the other side of the battle was the Mackay Conservation Group, who applied for the documents under freedom of information laws back in April 2017.

The small environmental NGO has a big history of fighting Adani.

Mackay Conservation Group successfully overturned the first federal approval for Adani's Carmichael coal mine in 2015.

"We were quite curious as to why there had been two temporary emissions licences issued," the group's Peter McCallum said.

"We were curious as to what the timing was and why subsequent to the cyclone crossing the coast, the licence was amended."

So the group applied to get the documents under Queensland Right to Information laws.

Sorry, this video has expired Peter McCallum explains why he wanted to know more about Adani's reef spill

Wilful breach 'likely to be a live issue'

At the heart of Adani's extreme reluctance to allow the documents to be released is the fact the company was fined for the pollution they did release.

The Queensland Government said Adani admitted to breaching its licence, spilling polluted water into the Marine Park that was 800 per cent dirtier than was allowed.

Adani told the ABC it challenged that interpretation and that "no breach occurred", but details the company fought to keep secret appear to suggest it knew it would breach the licence it was applying for and the Queensland Government knew too.

According to lawyers from the Queensland Environmental Defenders' Office, this means the breach of the licence could be a much more serious matter.

"Under Queensland law, a wilful breach of a temporary emissions licence can occur if it was reckless or as a result of gross negligence. "Given the recently released RTI documents include an email from Adani staff demonstrating knowledge of the sump contaminant concentrations, and that it appears Adani did not treat the water prior to the discharge, wilfulness is likely to be a live issue for any prosecution decision."

Government is 'letting them get away with it'

In one email to the department, when seeking permission to release polluted water from the second location, Adani outlined how polluted that water was likely to be.

And it turns out it was likely to be up to 900 per cent more polluted than would be allowed under the terms of the licence the company was seeking.

Despite applying for a licence to spill water into the ocean with up to 100 mg of coal per litre, in emails to the department, Adani revealed the water that would spill was likely to be up to 900 mg per litre.

Adani told the department:

"Releases from this location are small in volume however the [total suspended solids] is always greater than 30mg/L (approx between 500+ to 900 from memory!) as this location is actually a sump and prior to any treatment process (a historical legacy discharge location)."

Mr McCallum said: "It shows they knew they would break the law, and they did it anyway."

But the released information also casts a shadow on the conduct of the department ahead of the spill, he said.

"What it shows is that both the Government and Adani were aware that there was very high chance of the breach of their licence during the cyclone, that could lead to the pollution of the Great Barrier Reef World Heritage Area," Mr McCallum said.

"Adani is wilfully managing its site in a way that could damage the environment and the Government is letting them get away with it."

The Queensland Department of Environment declined to comment to the ABC.

Adani 'categorically deny any wrongdoing'

In Mackay, protesters shouted "stop Adani, that's an order, we are sick of coal pollution, solar and wind are the solution". ( ABC News: Lara Webster )

In fighting the release of the details, Adani claimed it would exacerbate "ongoing public vitriol".

In submissions to the Queensland information commissioner, the company claimed it would pressure the department to be seen to be "cracking down" on Adani, and alleged the Government was "conferring" with environmental groups.

Adani claimed the information would cause "extreme and unfair prejudice to" Adani, in the dispute over its fine.

But the acting commissioner found Adani's claims to be "wholly speculative in nature" and said there were not "real and substantial grounds" for those claims.

Adani did not directly answer a series of questions put to them by the ABC, but did supply a statement.

"We categorically deny any wrongdoing in this matter, we complied with the limits imposed by the Temporary Emissions Licence issued by the regulator and no breach occurred," the statement read.

"We have elected to have the matter heard by a magistrate rather than pay a $12,000 fine, which should not have been issued in 2017 following Cyclone Debbie, and we look forward to resolution of the matter."