Lake Macquarie fish kill investigation concludes

An investigation into a fish kill in Lake Macquarie has concluded that it was likely a natural event.

Hundreds of fish were found dead at Mannering Park on August 5, prompting the full investigation by the Environment Protection Authority, Central Coast Council and NSW Fisheries.

Samples were sent to the labs testing for a full suite of metals and pesticides, which were found at levels below the marine water guidelines.

However, a sampling for nitrogen and phosphorus were above guidelines. This along with weather conditions at the time are being attributed to the likely causes of the deaths.

The EPA says the bay at Mannering Park has elevated temperatures compared to the rest of the lake due to the cooling water discharged from Vales Point Power Station.

The Authority also pointed to the cool nights and northerly winds which preceded the kill in the first week of August, which may have caused the cold lake water to enter the bay.

“Our results suggest the combination of the temperature and sulfide stress likely overwhelmed fish, acclimatized to higher temperatures,” the EPA said.

As part of ongoing monitoring in the area, a smart buoy has been deployed at Wyee Point.