An Environment Protection Authority investigation into the second incident that wiped out thousands of marine creatures last August remains ongoing.

Meanwhile, residents and volunteers will conduct their own research into the impacts of thermal power stations this Sunday as part of the annual seagrass survey.

Participants in kayaks will cast 60 random quadrats to estimate overall seagrass coverage in the bay. Notes on the condition and extent of seagrass beds, algal growth and bare patches will be taken. They also hope to take core samples to determine if roots systems are present in areas of bare ground.

Previous surveys have shown that seagrass in Wyee Bay has all but disappeared due to excessive thermal pollution.

Environment groups and many residents also believe a discharge from Vales Point Power Station was responsible for last year's fish kills, however, a conclusive link has not been proven.

"There are so many unanswered questions about what happened in the bay as to result in such a large and seemingly unexplained event. I expect and hope that the authorities follow through with the investigation. The fish kills were shocking and it's frustrating not to have any more answers six months on," Mannering Park resident Julie Hopley said.

EPA officials inspected the power station in the days following the second fish kill and secured several items of equipment. Affidavits have also been taken relating the incident.

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An EPA spokeswoman said on Thursday that its investigation was ongoing.

"The EPA understands the community is concerned about the mass fish kills in Wyee Bay and is undertaking a thorough investigation with a view to taking appropriate regulatory action," she said.

"The EPA needs to follow due process and procedural fairness. To maintain the integrity of this ongoing investigation, the EPA is not able to provide any further comment at this time, however information including real-time water quality data is available on our website."

A Delta Electricity spokesman said the company was cooperating fully with the investigation.

"As the EPA has not yet finalised its process and reached any conclusion it is inappropriate for Delta to make any further comment at this point," he said.

Delta Electricity announced last Septmber that it proposed to sell a 100 per cent stake in the plant and the associated Chain Valley coalmine to Czech-based Sev.en Energy.

A coalition of environment groups urged the federal government to block the sale citing Sev.en Energy's poor environmental track record as well as the need to update the plant's environmental controls.

"The Vales Point power station is a known source of numerous pollutants contaminating southern Lake Macquarie,including up to 1.2 tonnes of chlorine per day, yet the NSW EPA has been slow to bring the facility up to the standards expected by the community," Hunter Community Environment Centre coordinator Jo Lynch said.

"Several upgrades are required to reduce heavy metal leachate from the ash dump contaminating groundwater, as well as to limit the power station's impacts on aquatic life.

"Now is the time to reset the regulation of Vales Point power station."

The State Government previously confirmed that a contentious air pollution exemption from meeting some pollution standards for nitrogen oxide would be carried over to the new owner.

Sev.en has a 50 per cent stake in United Kingdom-based InterGen, which owns the Callide and Millmerran coal-fired power stations in Queensland and four gas-fired plants in the UK.

The Hunter Community Environment Centre will host the Citizen's Seagrass Survey: Summer Edition in Wyee Bay, 10am Sunday 19th February. RSVP at: hcec.org.au/seagrass

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