An expert in estuarine biology says a recent high tide has brought some much-needed sea water into the ailing water body at Lake Cathie.
Dr Deb Geronimi said on Tuesday, January 14 the lake opened briefly to the ocean for about an hour due to the high tide and large ocean swell.
While she said it's not enough, for now the clean water source will provide some relief for the marine species who reside at the lake.
Dr Geronimi has previously spoken about her concerns for the future of the lake's species.
In particular, she named the Estuary Stingray, which are listed as vulnerable under the International Union for Conservation of Nature Red List and are considered to be threatened with extinction.
At the moment, Dr Geronimi said the water in the lake is very polluted and not able to provide animals with the nutrition they need to survive.
"The stingrays along with the fish that are still remaining in the lake have Epizootic Ulcerative Syndrome (EUS) or 'Red Spot Disease' usually caused by poor water quality," she said.
"Red Spot Disease is caused by a fungus (Aphanomyces invadans) and shows as red lesions (sores) or deep ulcers."
Dr Geronimi said she's hoping some more high tides will continue to help provide clean ocean water, as this will help marine life to fight off their Red Spot infections and provide them will food.
She said usually the stingrays move over mudflats to feed with the incoming tide. She hopes the recent high tide would have brought some food for the animals.
In November Dr Geronimi contacted council to ask if the sand could be graded at the lake/ocean interface to allow some clean oceanic water into the lake at high tide.
She said if this had happened water would be trickling into the lake with high tides prior to Tuesday, January 14.
Port Macquarie-Hastings Councillor Peter Alley witnessed the lake opening on Tuesday.