The Queensland Government says it is poised to act against Indian energy giant Adani over the release of coal-laden floodwaters from its coal port at Abbot Point in the state's north.

Key points: The DES is investigating whether Adani breached its environmental licence at Abbot Point for the second time in two years

The DES is investigating whether Adani breached its environmental licence at Abbot Point for the second time in two years DES will now issue a show cause letter, inviting Adani to make representations as to why enforcement action should not be taken

DES will now issue a show cause letter, inviting Adani to make representations as to why enforcement action should not be taken Abbot Point operations chief executive says the water released into the Caley Valley wetlands is not "coal-laden sludge"

The Department of Environment and Science (DES) on Wednesday released test results confirming floodwaters diverted from the port into the sensitive Caley Valley exceeded the authorised level of coal concentration.

A spokesman told the ABC that the department would give Adani a "show cause" notice ahead of potential enforcement action, which may include fines or prosecution.

It comes after Adani revealed it had not applied for an emergency permit to dump more polluted water into the sensitive Caley Valley wetlands during the north Queensland floods last week.

The company told the ABC that Abbot Point operators were confident they could manage floodwaters with new infrastructure, but were then overwhelmed by flows from neighbouring properties.

The department continues to investigate whether Adani has breached its environmental licence at the port for the second time in two years.

It is already prosecuting Adani over its 2017 release of coal-laden water from the port during Tropical Cyclone Debbie.

The ACF says this photo shows eroded coal stockpiles and drainage channels at Abbot Point on February 9. ( Supplied: Gary Farr/Australian Conservation Foundation )

A departmental spokesman said a sample taken by officials at a release point flowing to the wetlands had 33 milligrams per litre of "suspended solids", which included coal sediment.

Adani's environmental licence allows up to 30 milligrams a litre.

Differences in sampling results found

The company released its own testing on Tuesday, showing water released into the wetlands on February 7 had almost double the authorised concentration of suspended solids.

Adani revealed on Tuesday its samples taken at a release point into the wetlands showed 58 milligrams per litre.

The department spokesman said the "difference in sampling results may be caused by the time between testing on 7 February [by the company] and 8 February [by DES]".

The ACF says this photo shows eroded coal stockpiles (foreground), drainage channels and settlement ponds (at back) at Abbot Point on February 9. ( Supplied: Gary Farr/Australian Conservation Foundation )

The spokesman said the department had launched an "investigation into the alleged non-compliance".

"DES will now issue the coal terminal operator with a show cause letter, inviting the company to make representations as to why enforcement action should not be taken," the spokesman said.

An Abbot Point spokesperson for Adani said in a statement on Wednesday afternoon it acknowledged the Department of Environment and Science's test results and "as always, we will cooperate fully with their enquiries".

"A show cause notice, which is otherwise known as a pre-enforcement letter, is part of the standard process when there has been a release," the statement said.

"We welcome the opportunity to explain in further detail the facts and circumstances surrounding the release of floodwater into the Caley Valley Wetland, following floodwater entering the port site from neighbouring properties during the extreme weather last week."

Abbot Point operations chief executive Dwayne Freeman said in a statement on Tuesday that the water released into the wetlands was not "coal-laden sludge".