It should be the busiest time of year for Shoalhaven oyster farmers. A sewage spill forced them to close (2025)

Oyster growers in the Shoalhaven area south of Sydney were forced to suspend their busy Easter trade because of a sewage spill upstream at Berry.

Some businesses remained open this week, selling oysters harvested a few weeks ago or reselling oysters from other estuaries while others were forced to shut their doors in one of the busiest weeks of the year.

“It couldn’t have happened at a worse time, but you can’t choose what Mother Nature does,” said oyster farmer and Shoalhaven quality assurance program co-ordinator Anthony Munn, who regularly tests the water.

He said barring any significant rainfall, the farms should reopen on Monday based on testing this week. The quality assurance program is partly funded by Shoalhaven Water.

Munn said this was a rare event, especially since Shoalhaven Water had upgraded nearby sewerage plants to minimise the impact on the oyster industry. No one had thought that Berry, 30 kilometres away, would affect the oyster farms, but modelling suggested that the volume of water combined with tidal in-flows could have an impact.

Other oyster farmers shared private frustration that this was not the first time they had been affected by sewage overflows. A common dilemma was that talking about the problem could be off-putting to customers, especially for those businesses still selling oysters.

Shoalhaven Water serves 100,000 to 200,000 customers, depending on the time of year, and manages a network of 1300 kilometres of pipes and 13 wastewater schemes from Berry in the north to Ulladulla in the south.

The utility, like other sewerage network operators including Sydney Water, faces the challenge of leaks in the wastewater pipes and illegal connections where people have their drainpipes rigged to the sewers rather than the stormwater system. This causes sewage overflows during heavy rainfall.

A spokesperson for the NSW Department of Primary Industries and Regional Industries said Shoalhaven Water reported overflows from the wastewater treatment plant in Berry on March 30-31.

This was assessed as “posing a risk to the downstream shellfish harvest areas”, resulting in the Shoalhaven and Crookhaven River shellfish harvest areas closing for a 21-day period to end on April 21.

Acting director Shoalhaven Water, Matthew Kidd, said the oyster farms were actually closed for two weeks because of stormwater run-off, and because of high turbidity and low salinity caused by fresh water entering the estuary. He said the overflows from the sewage treatment plant extended it by an additional week.

Munn said this was correct and a number of growers had harvested their oysters before the rain came, but they had only planned for two weeks, not three. The additional week means the oyster trade misses Easter entirely.

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Kidd said the inflow at Berry Sewage Treatment Plant reached 5.5 times its normal level and a storage pond filled up and overflowed.

“Dry weather overflows are minimised and below the national average, however, during wet weather events the system can become overloaded due to infiltration, flooding and illegal connection,” Kidd said.

“In high rainfall events, overflows are still managed; however, it can be unavoidable given the volume of flows which can overload the network.”

The status of NSW shellfish harvest areas is available from the NSW Food Authority website.