Conservationists fear the federal environment minister is being pressured to approve the onshore dumping of dredge spoil in order to meet the construction timeline of a north Queensland port.
Deputy premier Jeff Seeney announced on Saturday that the onshore disposal plan, near Bowen, had been referred for federal approval.
But the Mackay Conservation Group says there is now a push for a "hasty assessment process".
"What they're trying to do is rely on previous assessments that were made in relation to offshore dumping," co-ordinator Ellen Roberts told AAP on Saturday.
"North Queensland Bulk Ports did look at whether onshore dumping was an option and found that there were environmental and engineering risks that were too great."
The group is concerned about the impact on a nearby wetland which is home to threatened species.
Dredging associated with the Abbot Point coal terminal expansion is due to begin in March 2015.
The onshore disposal strategy was devised after a backlash over the federal government's approval of a plan for three million cubic metres of dredged material to be dumped in waters off the Great Barrier Reef.
The Mackay Conservation Group is currently challenging the initial environmental approval in the federal court.
Documents referred to federal Environment Minister Greg Hunt say if onshore dumping is not approved "in a timely manner", the proponents will have no choice but to dispose of the material in the Great Barrier Reef Marine Park.
A spokeswoman for Mr Seeney said the approval would need to be granted by December or January to align with the current construction time frame.
Ms Roberts doubted whether a satisfactory environmental study could be undertaken in time.
"The ball is in Greg Hunt's court but he has to decide what level of assessment he's going to undertake."
Mr Seeney said the proposal balanced sustainable development against public concerns.