DUNBOGAN: Oyster farmer Brett Harper glides over the water to his lease, checking on what remains after devastating floods left his business on Australia's east coast in tatters.

Harper has farmed the Sydney Rock oyster for 27 years in Dunbogan, 370 km (230 miles) north of Sydney, producing about 45,000 dozen a year.

Now he faces a repair bill of about A$300,000 ($228,000) after floodwater washed away his oysters and ripped up infrastructure.

"It was too dangerous to go out and try and stop anything from being washed away and things were breaking up, so it was a difficult time just watching it happen on the river," Harper told Reuters from his oyster shed on Gogleys Lagoon.

Over a week after the flooding, Harper is still finding infrastructure washed up on surrounding beaches.

"It will take us probably three months to get all our infrastructure back in place and rebuilt for the main river. As far as finances are concerned it will be up to two to three years," said Harper, who runs the farm with his son Jackson.

"Our sellable product for the next selling season which starts in October is the one that's been decimated. It was in the main river and we re-lay it there for early fattening. Obviously with the flow of water and the force, most of that was either washed out or lost," Harper said.