MONEY so far set aside to offset the potential impacts of dumping three million cubic metres of dredged spoil in the Great Barrier Reef Marine Park may be more than $98 million short, internal government documents have revealed.
The internal marine park authority documents reveal senior staff at the authority believed the cost of offsetting the effects of the dumping of the spoil would cost in the realm of $100 million.
Other documents also released earlier this year through a Senate Order for the Production of Documents, estimate the cost could be as high as $200 million, despite no official cost benefit analysis being released to date.
The offsets were made as part of approval conditions on the sea dumping application from North Queensland Bulk Ports Corporation for the port expansion, to help offset and mitigate effects on water quality.
Environment Minister Greg Hunt had previously put conditions on it that 150% of the project's effects on water quality effects be offset.
But the documents show the port's estimates were set at just $2 million, a far cry from the cost the authority had calculated.
A port spokeswoman however said the any suggestion the port would only spend $2 million was "incorrect", and that "the exact details and costs are still being worked through with the department".
It is understood the port may increase the amount set aside to deal with the proposed offset program, but a specific figure was subject to internal negotiations.
But the revelations have raised the ire of conservationists, with North Queensland Conservation Council's Jeremy Tager calling on Mr Hunt to ensure no taxpayer's money was spent to cover any damage caused.
"We are asking for an unequivocal statement that taxpayers would not be paying in any way for dumping and dredging that is going to further damage the reef," he said.
Mr Hunt's office had not responded to questions about the issue by deadline on Friday.
However, an authority spokeswoman said that the port was "required to develop an offsets plan for the Burdekin and Don catchments", but did not confirm or deny there was a shortfall.
"Once the Department of the Environment receives the offsets plan, the Great Barrier Reef Marine Park Authority will review its content and provide advice," she said.
The port spokeswoman said the corporation could not comment further, given the project is subject to action in the courts.