Greens Senator Larissa Waters said the government marine research agency warned back in June last year that the proponent's modelling on how far the dredge spoil would travel was inadequate.

“It's incredibly alarming that all of this dumping in the reef has been approved without accurate modelling to measure how far it will travel, factoring in the impacts of wind, tides and ocean currents,” she said.

“We're talking about the Great Barrier Reef here – you can't just dump 5 million tonnes of dredge sludge into this World Heritage Area without even knowing where it will end up.”

Waters said the federal government should revoke the approval of the Abbot Point coal port immediately and require the proponent to provide accurate modelling that showed how far the dredge spoil would really travel.

Queensland Greens candidate Anne Boccabella said more than 60,000 Queenslanders relied on the reef's health for their job.

“Yet the Abbott and Newman governments have ticked off on dredge spoil dumping without even knowing how far the sludge will travel,” she said.