At a Glance

Water from floods in Queensland swept up sediment and pollution.Large plumes have reached the Great Barrier Reef.The plumes could prevent light from reaching the reef or cause harmful algae blooms.

Australia’s Great Barrier Reef is facing yet another threat.

Runoff from floods that have devastated parts of Queensland recently have created large polluted plumes that are reaching the reef, scientists say.

Frederieke Kroon, who leads the Australian Institute of Marine Science's (AIMS) water quality team, told the Australian Broadcasting Corporation the plumes, which are visible on satellite images,

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"If you look at the remote sensing images, the one that's standing out at the moment is the Burdekin, which is the biggest river in that area," she said. "But over the last two weeks other rivers have produced large flood plumes as well, which have dissipated since then, but are definitely still affecting large areas of the Great Barrier Reef."

Flooding in north Queensland, Australia, is carrying plumes into the Coral Sea that could harm the Great Barrier Reef. The Burdekin River plume can be seen here in this NASA Worldview image.

(NASA)

over two weeks left much of northeast Queensland underwater. Almost 3,000 homes were damaged in the city of Townsville. At least three deaths have been blamed on the flooding. Hundreds of thousands head of cattle were also killed in the deluge.

Damage estimates have topped , the Brisbane Times reports.

Now, much of the flood water is flowing some 35 miles into the Coral Sea and heading toward the Great Barrier Reef.

The reef is a United Nations that spans an area of 133,000 square miles and is the planet's most extensive coral reef ecosystem.

Previous threats to its survival have included in 2016 and 2017.

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Kroon said the flood plumes have the potential to kill coral and seagrass.

A plume from the Burdekin River in Queensland, Australia, is inundating Old Reef in the central Great Barrier Reef.

(Matt Curnock/Tropwater JCU)

"The two things we're mostly concerned about is sediment from erosion in the catchment that gets transported with rainwater into the rivers out onto the reef and nutrients such as nitrogen and phosphorus," she said.

Because the winds have been light in the area, the plumes are not dissipating quickly.

Jane Waterhouse, a scientist from , told the BBC, " is this reduced light - if it persists for much longer, in some cases we can actually see a smothering of the system."

The nutrients in the plume could also cause more algae growth that would also harm the reef.

One possible benefit of the plumes is that the cooler flood water could help prevent underwater heatwaves that "bake" the coral, Kroon said.

"If you want to have a flipside to the story that would be one, yes, but it's still a huge disturbance to the reef [after] the bleaching and the cyclones that we've had over the last couple of years. The reef doesn't even really get time to recover from any of these disturbances because it gets hit with something pretty much every year."