‘Natural event’ blamed for killing hundreds of fish in NSW dam

A NATURAL event is being blamed for killing hundreds of fish in a dam in northern New South Wales.

Five-hundred Australian bass were found dead in the deepest part of Clarrie Hall Dam, south of Uki on Friday.

Council says the fish appear to have been starved of oxygen, with the dam having undergone a “seasonal overturn” in recent weeks.


Acting Manager Water and Wastewater Michael Wraight said deeper de-oxygenated waters had upwelled to the top of the water.

“This is a natural process and happens annually around the beginning of winter as the top water layers cool and sink to the bottom forcing the bottom layers up,” he said.

“Testing of water samples in the dam over the past two weeks shows very low oxygen levels near the spillway where the dead fish were found.

“It is likely that these low dissolved oxygen levels have resulted in the death of the fish. We don’t expect it to get any worse but will continue to monitor the situation.”

Mr Wraight said there had been several overturn events at the dam in the past, all resulting in similar fish deaths.

The fish have since been removed and disposed of appropriately.

New South Wales Fisheries has been advised of the incident.