The New South Wales EPA is investigating a large-scale fish die-off at Lake Macquarie. 

Hundreds of fish washed up dead on the banks of the lake last week, on a scale locals say they had never seen before. 

The Lake Macquarie saltwater estuary covers about 110 square kilometres on NSW’s Central Coast.

The state’s Environmental Protection Authority (EPA) says it has sent water samples for laboratory analysis. 

“Since initial inspections, the EPA has observed hundreds of dead fish of various species and sizes,” a spokesperson said this week.

“Field officers also noted greying around the gills, which could suggest oxygen depletion.

“A decrease in oxygen content in water is a natural event that can cause rapid fish deaths.”

The local council has been instructed to remove and dispose of the dead fish by the EPA.