Residents of Queenstown on Tasmania's west coast believe there has been an extraordinary polluting event that has turned the Queen River an even deeper shade of orange.

Loading

From the 1880s, and for almost a century, the river was used by the nearby Mt Lyell copper mines as a drain.

An estimated 100 million tonnes of sulfidic tailings were dumped into the river — the worst case of acid mine drainage in Australia.

The river's water is typically clear but rusty in colour, but Queenstown locals are saying the colour has intensified dramatically in recent months.

They believe a significant acid drainage event from the Mt Lyell copper mine has occurred.

They spoke to the ABC on condition of anonymity because they feared repercussions for speaking out against the mine, now owned by Copper Mines of Tasmania.

The mine has been in care and maintenance mode since 2014 after three miners were killed.

The Queen River's water is normally clear but rusty in colour. ( ABC: Lara van Raay )

The owners are hoping to reboot operations — and rehire some of those workers they had to let go — when conditions suit.

"I can't remember ever seeing it this bad, and I've been living in Queenstown on and off for 12 years," said one.

"This is the worst I've seen it in 13 years," said another

"We locals are beginning to call it 'Pumpkin Soup Creek'."

The ABC shot video of the Queen River last weekend and sent footage to Tasmania's Environmental Protection Agency.

The EPA said it had launched an investigation and would collect water samples for "testing and ongoing discussion with Copper Mines of Tasmania".

"Further information will be available next week, once the laboratory analysis of water samples has been done," the EPA said.

Copper Mines of Tasmania has been approached for comment.