Vales Point Power Station licensee Delta Electricity has provided the EPA with new information relating to fish kills at Mannering Park in Lake Macquarie.

EPA officials inspected the power station on Tuesday and secured equipment on-site as part of an ongoing investigation. Unspecified testing was also undertaken.

"The EPA has requested a further report from the licensee and this information will form part of the EPA's ongoing investigation," a statement said.

"The EPA is treating this as a top priority and is using all available resources, including assigning specialist investigators to the issue."

Staff from numerous government agencies are involved in the investigation.

Water and fish samples were taken around Mannering Park following the most recent fish kill - the second such event in a month.

Data loggers have also been put into the lake to collect data on temperature changes and salinity.

EPA chief executive Tony Chappel told the Newcastle Herald last week that the authority would not hesitate to take action against Vales Point power station if it was found to have a case to answer.

"This kind of pollution and environmental damage are prohibited. If there is a particular source, whether it be toxin, a heavy metal or some other contaminant, we will act very quickly," he said.

He said he shared the community's dismay at the sudden death of hundreds of fish in the southern end of the lake.

"This is devastating for the community; it's depressing to see large quantities of marine life die. We take it extremely seriously," he said.

Delta Electricity has denied any wrongdoing and has said it is assisting the investigation.

Marks Point Fisherman's Warehouse owner Jason Nunn said he was concerned about the long-term impact of the two recent fish kills on the lake's marine life.

"I would say a fair percentage of the lake's fish have died in these incidents. The reason I say that is at this time of year, and certainly at the time of the first kill, a lot of fish are in the southern end of the lake," he said.

"We can't afford another kill. The size of the fish killed in the latest kill seem to be smaller, so it's a generational killing off of marine life. It's going to make a dent in the fish stocks.

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