Thousands of fish die in disaster at Evans
By ZOE SATHERLEY
MORE than 25,000 fish have died at Evans Head in a catastrophic fish kill.
Adult mullet, bream and longfinned eels, as well as juvenile freshwater species, were yesterday strewn across Airforce Beach along with a stinking, slimy sludge from Salty Lagoon, which burst its banks.
The Evans Head sewerage treatment plant (STP) discharges its effluent into Salty Lagoon.
While yesterday's incident was not thought to be related to any malfunction of the ancient STP, toxic sediment on the bottom of the lagoon was dredged up when it breached its beachside bank following a heavy overnight downpour.
Marcus Riches, senior conservation manager, northern region, for the aquatic habitation protection unit of the NSW Department of Primary Industry, said his department had been asked to assess and manage the disaster.
"We estimate that well over 25,000 fish have been killed. It is quite catastrophic," he said.
"It seems the lagoon broke the sand barrier to the sea and rushed out at high speed on a low tide.
"The great velocity caused sludge on the bottom of the lagoon to be stirred up and the water level has dropped by two metres, exposing black sludge."
Mr Riches said the fish had died for three main reasons: a lack of oxygenated water in the lagoon (levels were at less than 1mg per litre when fish need 8mg per litre); high water temperatures in the lagoon (35 degrees when ocean temperature is around 19 degrees) and the speed of the emptying process stirring up toxic sludge.
Brian Wilkinson, general manager of Richmond Valley Council, said the extent and nature of the incident determined it would necessitate the Department of Primary Industry (Fisheries) being the lead agency on the matter.