The Hunter Community Environment Centre has called on Delta Electricity to explain why the second fish kill in one month has taken place in Wyee Bay at Mannering Park.
In early August, thousands of fish were found washed up on the shores of Wyee Bay and the Environment Protection Authority (EPA) said the combination of elevated temperatures in the bay and the weather at that time caused the fish kill.
The EPA says the bay at Mannering Park has elevated temperatures compared to the rest of Lake Macquarie due to the water discharges from Vales Point Power Station, owned by Delta Electricity.
An EPA investigation of the August fish kill concluded that cool weather and strong northerly winds pushed cold water into the bay resulting in a turnover of the water column and sediment disturbance which happened rapidly enough to overwhelm the fish acclimatised to higher temperatures.
Just one month later, on Tuesday, September 6, a Mannering Park resident reported dead fish again in Wyee Bay.
Members of Hunter Community Environment Centre (HCEC) investigated and found hundreds of dead fish, mostly mullet, some bream, bat fish and whiting and juvenile White spotted eagle ray concentrated near the Vales Point thermal outlet in southern Wyee Bay.
“In light of the NSW EPA finding that thermal pollution from the Vales Point outlet was a contributing factor to the August 6 fish kill, it’s incumbent upon Delta Electricity to explain their role in these fish deaths,” HCEC Co-ordinator Jo Lynch said.
“This second fish kill could be an indicator that there could be far greater impacts caused by thermal pollution than is understood by us or the NSW EPA,” she said.
HCEC Senior Researcher, Paul Winn says the EPA’s results of the August investigation raises more questions than answers, particularly around the effects of thermal pollution on the lake ecosystem.
“Thermal pollution is known to have caused an almost total loss of seagrass in Wyee Bay, however studies into the broader ecosystem effects have not been undertaken,” he said.
“The August fish kill has revealed that the full extent and risks to marine life in southern Lake Macquarie of thermal pollution are largely unknown.
“Water temperatures taken in Wyee Bay by HCEC citizen scientists on August 6, reveal 10-17 degrees Celsius above ambient lake temperature.
“Readings in Wyee Bay ranged from 21-27 degrees Celsius,” Winn said.
“Scientific literature suggests that to avoid impacts on aquatic ecosystems, thermal discharge should be less than five degrees Celsius above ambient temperature.
“The installation of a smart buoy at Wyee Point is a good start, but we believe that the Lake Macquarie community deserves a more detailed study into the full effects of thermal pollution on the lake’s marine life,” Winn said.
Company Secretary at Vales Point Power Station, Steve Gurney said the HCEC was once again short on facts and big on sensationalism.
“Delta has undertaken its own investigations and there were no abnormal operations at the power station,” he said.
“We have been in touch with the EPA to offer any assistance required as part of its investigations and unlike some, we won’t jump to conclusions, and we’ll await the EPA’s investigation.”
Gurney said that the HCEC claim that thermal pollution from the power station outlet was a contributing factor to the August 6 fish kill is selective and misleading, ignoring the EPA’s statement that it was “likely a natural event”.
“Vales Point has been operating for over 40 years and lake temperatures in the southern end of the lake are well documented and the EPA notes that the fish have acclimatised to higher temperatures,” he said.
“Discharge limits are rigorously set by EPA in Delta’s licence and are based on scientific data.
“Vales Point is compliant with EPA licence limits that restrict discharges to 35 degrees generally, with an additional allowance to discharge up to 131 hours per year at up to 37.5 degrees (reserved for summer operation).”
Gurney says the discharge temperature can vary with the seasons, in winter the water will cool to 15 degrees or so and in summer the lake water can be as high as 30 degrees.
“Vales Point uses attemperating pumps to reduce the water temperature, particularly in summer months.
“These attemperating pumps move water directly from the inlet canal to the outlet canal, bypassing the power station, so that cooler water is mixed with the warmer water to lower the overall temperature before it is discharged into Wyee Bay.
“Events such as August are rare and have combined with other natural events such as wind and previous storm events washing matter into the lake, as confirmed by the EPA, and are not just restricted to areas around power stations.
“The EPA’s website suggests that increasing the amount of poor-quality runoff entering our waterways during significant rain events … can have a range of impacts on water quality including depleted dissolved oxygen levels, increased sedimentation, algal blooms and fish kills.
“The power station operations are just one part of a complex situation,” Gurney said.
HCEC’s Paul Winn also says it is a complex situation and wants the EPA to conduct a detailed study on the implications of thermal pollution.
“We as a community really need to stand up and be heard to make sure the EPA follows through on this and just doesn’t brush it over like they have, by characterising thermal pollution as a natural event,” he said.
“The EPA has recognised that thermal pollution is causing problems and Wyee Bay already has been denuded of seagrass – it is causing unknown disruptions to the eco system and that’s the concern we have.
“Let’s do a more detailed study to understand what thermal pollution is actually doing to the lake and find a solution to this.
“We want to work with the EPA to encourage them to do better, and in turn encourage Delta to do better, and build up their understanding of what the community wants for the health of the lake,” Winn said.
He said the HCEC would raise the matter at one of their regular meetings with the EPA and the HCEC report on the topic would be coming out later in the year.
Meanwhile, EPA officers were at Wyee Bay on Tuesday, collecting more water and fish samples as part of the continuing investigation into the cause of the dead fish.
Swansea MP, Yasmin Catley said urgent government action was required and has requested to speak urgently with the Environment Minister and Agriculture Minister to ensure they make every resource available to investigate the matter.
Sue Murray