Members of Port Augusta City Council believe the ash is suffocating taxpayer-owned coastal areas around the power station and hospital.

Deputy Mayor Phil Greagen said it was up to 15 centimetres deep in some places and has demanded Flinders Power “clean up their mess”.

He first noticed the ash in 2007 and said the problem was now getting progressively worse, slowly killing saltbush plants in the area and making its way into surrounding mangroves.

“There’s tonnes of ash going into the Gulf,” he said.

“I think it’s time questions were asked about it. They (Flinders Power) just brush it off and say we’re working within the boundaries of the licence.”

The council is still yet to receive a reply to a letter they sent to the state Environmental Protection Authority two months ago requesting an explanation for the fly ash.

They now want an aerial survey of the area to establish how much of the substance, which is commonly used to make cement, is being swept into the Spencer Gulf.

However this request too has so far gone unanswered.

This month a spokesperson from Flinders Power said the power station complies with two environmental protection licences for the hospital creek site.

However Australia’s Clean Ocean Foundation chief executive Anton Vigenser described this as “a bit of cop out”.

“When something like this happens it’s a real concern,” he said.

“If it washes in to the mangroves, it’s getting into a very sensitive environment.

“When the base-line filter feeders and macro invertebrates get clogged up with ash they’ll die off and next up the food chain is the crabs and soft shell invertebrates ... so it’s an ongoing effect.

“The ecosystem is being damaged at the base line. Once we’ve started doing that fish stocks can be affected.”

Port Augusta Marine Advisory Committee deputy chairperson Robin Sharp described the fly ash emissions as a “disaster” and has been advocating a tidy up of the area for years.