Council has been the lead investigator into the incident where Sikorsky Aircraft Australia, who provide maintenance services to HMAS Albatross, from the nearby Albatross Aviation Technology Park, had an unintentional waste water discharge into the local sewerage system.

The spill happened in March, however, council wasn't notified of the incident until May 16, which was then reported to the NSW Environment Protection Authority (EPA).

Council has been the lead investigator of the incident with EPA providing support and advice.

The issued clean-up notice requires a number of investigations and reports be provided to council regarding the operation of the company's wastewater system.

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A council spokesperson said the notice also requires actions to prevent any further non approved discharge.

The joint investigation involved council's Environmental Services Unit, Compliance Unit and Shoalwater and has included interviews with those involved in the operations at the time of discharge.

Any options regarding compliance action will be reported to the Council's Director Planning Environment and Development, Phil Costello and there is the possibility of fines over the incident or any similar incident in the future.

Mr Costello said an ongoing investigation had been conducted in regard to the previous discharge to sewer of water containing PFAS (Per and Poly Fluro Alkyl Substances).

"At this time, this has led to the issuing of a notice upon Sikorsky Aircraft Australia Ltd regarding the release," he said.

"The intent of this notice is to ensure that all necessary measures are taken to ensure such a discharge is not repeated.

"Council is continuing to work with Sikorsky Air Australia Ltd to investigate the potential source of the PFAS and the potential for formal compliance action."

The PFAS contaminated waste water flowed to the Nowra sewerage treatment plant which ultimately discharges into the Shoalhaven River near Terara.

Council has said by the time the waste water would have discharged into the Shoalhaven River it had been treated at the Nowra works and would have been "heavily dilluted".