The Great Barrier Reef could soon be smothered in sludge if a plan approved by the Australian government goes uncontested, according to the Guardian.

The Great Barrier Reef Marine Park Authority (GBRMA) recently gave the North Queensland Bulk Ports Corporation (NQBPC) permission to dump 1 million tons of sludge from dredging projects on and around the reef over the next decade.

The sludge would come from a maintenance project for a port in Mackay’s Hay Point in Queensland, which houses one of the largest coal loading facilities in the world. The NQBPC is seeking to deepen and expand the port and has to dump the sludge it dredges up somewhere. Because of a loophole in federal law that otherwise restricts sediment dumping in delicate waters, the corporation is allowed to dump the sludge along the Great Barrier Reef, Smithsonian Magazine reports.

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Environmentalists warn that the sludge could cause serious harm to the already embattled reef by killing coral, contaminating water, and impairing recovery efforts.

“The last thing the reef needs is more sludge dumped on it, after being slammed by the floods recently,” Larissa Waters, a senator with the Greens party, told the Guardian. “One million tonnes of dumping dredged sludge into world heritage waters treats our reef like a rubbish tip.”

In recent years, the reef has undergone successive bleaching events because of warming ocean waters. Around 90% of the excess heat trapped in the atmosphere by greenhouse gas emissions gets absorbed by the oceans, and this resulting increase in temperature has devastated various marine species. Coral are especially sensitive to spikes in temperature and have begun to die en masse around the world.

The reef is also threatened by plastic pollution, ocean acidification, and other factors. A recent flood in Queensland caused large amounts of pesticides to contaminate areas around the reef.

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Because of these cumulative harms, the reef has been declared half dead and its precipitous decline threatens the survival of thousands of marine creatures that depend on the vast ecosystems it creates for food and shelter.

The loss of the reef also threatens Australia’s fishing, recreation, and tourism industries, which rely on the reef’s fecundity for more than $6.4 billion in annual income.

In an emergency round of funding last year, the Australian government approved $379 million for reef restoration projects, including programs to clean ocean water and prevent sediment from contaminating nearby waters.

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The news of the sludge-dumping project seems to undermine that mission and environmentalists say that an alternative plan needs to be found to prevent further damage to the reef. Waters, the Greens party senator, has called for the dumping permit to be revoked before the project commences, the Guardian notes.

“Government policy needs to change to ban all offshore dumping, so GBRMPA is not allowed to permit the reef’s waters to be used as a cheaper alternative to treating the sludge and disposing of it safely onshore,” Waters said.