Dredging and Shipping Near Our Reef

Our stunning Great Barrier Reef is one of the most vibrant ecosystems in the world, but it is incredibly sensitive to human pressures.

Plans to expand several ports along the coastline will further damage our already vulnerable Reef. Port expansion plans require dredging of the seafloor, and will lead to a sharp increase in ship traffic crossing through our Reef’s waters. Just one collision, one mistake, or one spill could result in an environmental catastrophe in one of the seven natural wonders of the world.

What is dredging – and what is the danger?

Dredging means excavating the sea floor, removing sediment and dumping it in other locations. The material is removed through digging, big scoops, or high-pressure suction. It is mainly undertaken to dig new shipping channels (capital dredging) or maintain the depth of a port and it’s shipping channels (maintenance dredging).

Dredging is undertaken in coastal Reef waters so that large coal, gas and other bulk carriers can access ports. Capital dredging for port expansions is a serious threat to the waters of the Great Barrier Reef. The seafloor is dug up to make deeper channels for large ships. Fine sediments are thrown up into the water and can drift for over 100 kilometres, smothering coral, seagrass beds, and ruining water quality.

Many of the areas that are dredged are feeding and breeding grounds for turtles, dugongs and other sensitive species.

Dredging can more than double the level of coral disease, in particular white syndrome which causes coral tissue to fall off. Prior to 2015 all dredged material was dumped back into the waters of the Great Barrier Reef World Heritage Area. In 2015 the Queensland Government responded to community pressure and banned the dumping of capital dredge spoil (ie from new industrial activity) in the Great Barrier Reef World Heritage Area. Instead, the dredge spoil must be disposed of onshore.

Once an area has been dredged, it is vulnerable to clogging up with sediments, so it needs to be regularly re-dredged. This is known as maintenance dredging and the spoil from this activity can still be dumped at sea within the Great Barrier Reef World Heritage Area.

Dredging for new port facilities is still allowed in four ‘priority ports’ (Townsville, Abbot Point, Mackay-Hay Point and Gladstone) and within the port area of Cairns. Dredging for smaller projects like marinas or boat ramps can go ahead in most parts of the Reef coast.

How does increased shipping hurt the Great Barrier Reef?

Currently there are over 11,000 shipping movements through the Great Barrier Reef each year. Just one collision, one mistake or one spill could result in an environmental catastrophe in the Great Barrier Reef, one of the seven natural wonders of the world.

When the massive coal carrier Shen Neng 1 crashed into the Reef in 2010 it damaged an area covering 0.4 square kilometres – the largest ever recorded by a ship grounding in the Great Barrier Reef.

Not only do shipping accidents risk the Reef, they are terrible for tourism. No one wants to see ship after ship when they have paid to come and see the natural beauty of the Great Barrier Reef.

What are the dredging and port expansion plans?


Ports North is proposing to dredge 1 million cubic metres of seafloor from Trinity Inlet to allow access for larger cruise ships. The water quality of Trinity Inlet is already poor and sensitive habitats like seagrass are taking a long time to recover. A large dredging project, followed by increased maintenance dredging and disposal will stir up and suspend sediment in the area, further exacerbating the problem.

The local tourism industry is thriving – with regular visits by cruise ships to Cairns. Research has shown that whether a cruise ship docks in a port or anchors offshore and transfers passengers by smaller boats to land actually makes little difference to the number of people disembarking and coming to explore Cairns and its surrounds.


The Port of Townsville is proposing a major expansion, which includes channel deepening, widening, and development of a new outer harbour, wharves, reclamation, and associated infrastructure to support new berths. This will require 11 million tonnes of dredging, with the spoil to be disposed of onshore and in land reclamation projects. While other ports have reduced the amount of dredging, the Port of Townsville has increased its amount of planned dredging.

The Port of Townsville entrance is a particularly important foraging habitat for snubfin and humpback dolphins, turtles and dugongs, with Cleveland Bay listed as a dugong protection area. Habitat for Humpback and Snubfin dolphins will be permanently destroyed by reclamation, which has been increased under the new design from 100 to 152 hectares. There are believed to be less than 1000 Snubfin dolphins remaining, therefore any habitat loss for the species will be disastrous. Find out more about Australia’s Threatened Snubfin Dolphin.

Maintenance dredging spoil will be dumped in the water about 4 kilometres east of the northern tip of Magnetic Island, where currents and wind waves will keep the fine sediment suspended – further damaging water quality around the Island.

Abbot Point

There are plans to build large coal export terminals at Abbot Point to ship out coal from new mega-mines in the Galilee Basin 400 km inland. Adani’s Terminal Zero will be wedged between a turtle-nesting beach and the internationally significant Caley Valley wetlands – already threatened by pollution discharge at the existing coal port. The wetlands supports significant populations of waterbirds with over 40,000 birds and 154 bird species being recorded.

Expansion of Abbot Point will require over 1 million cubic metres of dredging, which will destroy seagrass habitats that dugongs and turtles of the area rely on for feeding. The plume from the dredging will muddy the waters of the area and inhibit light to local coral reefs and seagrass beds that need clear water to feed and grow.

Dredge spoil will be dumped in containment ponds beside the delicate Caley Valley wetlands. The base of the containment ponds will not be lined, which will allow seepage of water and any contaminants into the groundwater below. The groundwater is an important water source to the wetland therefore any pollutants entering the groundwater have the potential to impact the wetland and the species that are reliant on it.

Coal stockpiles will be built right next to beaches where threatened sea turtles nest. Nesting turtles are very sensitive to light and noise, both of which will increase with the development right next to their nesting habitat. Coal dust from the coal stockpiles will pollute the beaches and the surrounding waters that the turtles feed in.    

Coal will be shipped through the port causing hundreds more ships ploughing through the Reef’s waters and increasing the chance of an accident.

Hay Point

Hay Point is currently the largest existing coal port on the Reef, just south of Mackay. In 2014 a trans-shipping project was proposed in the area which would see coal transferred from barges to coal tankers inside the Marine Park.

After colossal pressure from the AMCS community in 2017, the Queensland Government has promised to ban transhipping in the Great Barrier Reef Marine Park.


There are plans to dredge a second shipping channel in Gladstone Harbour to handle increased shipping traffic in the port. The new channel would require many millions of tonnes of dredging and could go right through a dugong habitat protection zone.

A major dredging and dumping operation in Gladstone Harbour in 2010-11 has been blamed for serious environmental problems after dead dugongs, turtles and diseased fish were found. The situation was so bad that for three weeks the harbour was closed to all fishing.