Imagine if a company dumped millions of tons of rubbish right next to the Grand Canyon.

That's the closest analogy we can think of to describe a decision by the Great Barrier Reef Marine Park Authority to approve a plan that would dump up to 106 million cubic feet of mud near the reef.

To give you some perspective, that's enough sludge to rebuild the Hoover Dam and more than the amount of stone used to make the Great Pyramid at Giza, according to the Wall Street Journal.

The authority's decision sparked outrage Down Under on Friday.

What's behind the proposal? Two Indian companies, Adani Group and GVK, along with Australian mining magnate Gina Reinhart want to build one of the world’s largest coal ports.

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Environmental groups have condemned the decision, which they said was “an international embarrassment” and would further damage the reef and its rich biodiversity, already under attack from climate change and land-based pollution.

"This go-ahead for dumping is one more body blow for the reef, which further threatens marine life, its World Heritage status and Australia's tourism and fishing industries," Greenpeace Reef Campaigner Louise Matthiesson said in a statement.

The reef is the world's largest living organism, stretching 1,430 miles along Australia's east coast. It's so big it can been seen from space.

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The decision by the GBRMPA comes after the Australian government in December approved the expansion of the Abbot Point coal terminal near Bowen in North Queensland, which sits adjacent to the marine park.

Dredging is needed to allow big ships into the port to collect the coal that has been extracted from the Galilee Basin.

Earlier this month, a petition signed by 233 scientists and conservationists was sent to GBRMPA chairman Russell Reichelt urging the authority to reject the expansion proposal.

"The best available science makes it very clear that expansion of the port at Abbot Point will have detrimental effects on the Great Barrier Reef. Sediment from dredging can smother corals and seagrasses and expose them to poisons and elevated nutrients," the letter said.

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In a statement, Reichelt said he recognized the “community concern” about the project and “shared with everyone a strong desire to ensure the Reef remains a great natural wonder into the future.”

To that end, the authority has imposed dozens of environmental conditions to try to minimize the impact on the reef and its marine life — which, by the way, includes some 600 types of soft and hard coral, more than 1,600 types of fish, 133 varieties of sharks and rays, and more than 30 species of whales and dolphins.

“It’s important to note the seafloor of the approved disposal area consists of sand, silt and clay and does not contain coral reefs or seagrass beds,” Reichelt said, reasoning that Abbot Point is better placed for expansion than other areas.

But critics accused the GBRMA of caving into pressure from powerful mining companies and a government desperate to inject some life into a flagging economy.

“This decision runs contrary to the marine park’s charter and we are firmly of the view it reflects political pressure exerted by mining interests and the government,” Felicity Wishart, campaign director at the Australian Marine Conservation Society was quoted as saying.

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Even before this decision, the outlook for the reef wasn’t looking too bright.

UNESCO warned last year that it would consider placing it on the List of World Heritage in Danger unless it saw “urgent and decisive action” to improve water quality and stop the approval of coast development projects that posed a threat to the reef.

The latest change probably wasn't what the body meant.

Here's the reaction on social media: