A Queensland Government investigation has found a large spillage of coal at a mining port in waters near the Great Barrier Reef.

The investigation, which found the spillage from a ship loader at the Port of Hay Point, was launched after complaints that coal and fine black dust were washing up at East Point beach near Mackay.

Coal was also found at Louisa Creek Beach near Hay Point's two export terminals.

Hay Point is the largest coal port alongside the Great Barrier Reef, housing two separate export terminals.

Scientists say coal dust can kill coral and damage the growth of seagrasses.

Environment Minister Steven Miles confirmed to the ABC that he has seen photos and video footage sent in by local people.

"I will seek advice about how this coal could be impacting on local marine life," he said.

"The footage I've seen suggests it's in a pretty solid state and is washing up onto the beach."

Officers from the environment department conducted two inspections of the two bulk coal terminals at Hay Point last month.

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"That investigation has found one larger and one smaller source of coal spillage," Dr Miles said.

"But it's not possible yet to say if [Hay Point] is the source of the coal that has washed up on those beaches."

The ABC understands that during the inspection of Hay Point, departmental officers saw significant spillages of coal from one of the ship loaders at one of the terminals.

Locals were finding coal and fine black dust washing up on beaches. ( Supplied: Lance Payne )

Other, smaller spillages were noticed from trestles transporting the coal to the ship loaders at both terminals.

Coal samples found on the beach have now been sent to a laboratory to try to confirm the origin of the coal.

"There are multiple terminals, multiple ships running through those terminals," Dr Miles said.

"So we do need to see this investigation proceed. I am seeking and receiving regular briefings.

"So nobody should doubt that this is being taken very seriously, and when the source is identified then the environment department will take appropriate action."

The Australian Maritime Safety Authority, which has jurisdiction offshore, is also being brought into the investigation.