Federal Environment Minister Mark Butler is expected to decide on Friday whether to allow the dredging of millions of tonnes of soil in the Great Barrier Reef World Heritage Area.
However, Mr Butler may decide to extend the deadline.
North Queensland Bulk Ports want to dredge three million tonnes of seabed at Abbot Point, near Bowen, to make way for proposed expansions at the coal port.
Green groups have been campaigning for months - via television ads, public meetings and rallies - urging the minister to reject the plans.
They say dredging will damage coral and other marine life.
Felicity Wishart, of the Australian Marine Conservation Society, says if the plan is approved it will pave the way for construction of a mega-port at Abbot Point.
"We'd obviously be delighted if the minister did recognise the foolishness of approving this dredging proposal," she told AAP.
Ms Wishart says the plan should be rejected as Bulk Ports has not identified a specific site where the soil will be dumped.
Bulk Ports boss Brad Fish has previously said dredging could possibly make the water cloudy over a short period and may damage seagrass, but was unlikely to affect other flora and fauna.
A spokeswoman from Mr Butler's office told AAP the minister wouldn't comment until a decision had been made.
Applications to dredge the seabed are considered separate to the port expansions which have been proposed but not approved.
Earlier this year the World Heritage Committee told Australia to present a plan on how to protect the reef from increasing coal and gas extraction and shipping.
If improvements aren't made the reef would be listed as "in danger" when the committee meets in June next year.
Thousands of people are expected to march through Brisbane in two weeks to demand better environmental protections for the reef.
