Hunter Water says seawater samples were at the highest rating amid last week's mass fish death event on the region's beaches.
Large numbers of dead fish washed up on Belmont, Redhead, Dudley, Merewether and Bar beaches, last week.
The Environmental Protection Agency said it had not detected any pollution incidents from land-based activities and is working to determine the cause of the event.
The affected beaches are located on either side of Hunter Water's Burwood Beach wastewater treatment plant, but the water corporation said the plant had been operating as normal over the past week and continues to do so.
"We continuously monitor the plant's performance and all data and observations show there's been nothing out of the ordinary that could contribute to fish deaths," a Hunter Water spokesperson said.
Hunter Water monitors and samples seawater at the region's beaches for the NSW Government's Beachwatch program, which provides information about where and when to swim.
Last Tuesday's sample results indicated a 'good' rating - which is the highest score - for Newcastle and Lake Macquarie area beaches, Hunter Water said. Newcastle beaches were also sampled on Friday, with those results showing a 'good' rating.
The EPA has collected fish samples, which have been sent to Department of Planning and Environment for analysis. NSW Fisheries and DPE Science have obtained offshore water samples.
"The EPA is currently awaiting the results from the sampling and will keep the community informed," an EPA spokesperson said.
