In the past few weeks the Port Macquarie man has lost half a million mature oysters, which he says will set him back three years at a cost of about $250,000.

At a time when Mr Dick should have his feet up he is working seven days a week to save his business, Charlie Dick's Oysters.

The long-time farmer said heavy rainfall and an influx of acid sulfate soils (ASS) were to blame.

"The council started a program to clean-up this area of the river, but I think it looks worse now than it did when the program started a few years ago," the frustrated business owner said.

"I'm probably going to have to leave this site because it just is not a safe spot."

ASS contain iron sulfides which can generate large amounts of sulfuric acid when exposed to air. These soils formed naturally over the last 10,000 years, and are safe unless dug up or drained.

Because Mr Dick's lease is in an acid discharge hotspot he has bought four other leases in lower risk areas to help sustain his business.

Port Macquarie-Hastings Council natural resources officer Thor Asso said the council had been working on minimising the discharge of acid into the river since 2001.

"We have reduced 85 per cent of the acid sulfate soil discharge and in terms of remediation that is one of the best outcomes on the NSW coast," he said.

Remedial works aim to contain acid groundwater by means of infilling drains, installing weirs and rehabilitating degraded wetlands by restoring the hydrology and promoting revegetation.

So far 62 drainage networks have been remediated in the Hastings at a cost $1.6 million.

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