Lake Cathie residents are being advised to avoid an area on the southern side of the lake’s entrance, due to the discovery of building materials which could contain asbestos.
The area, near the corner of Bundella Avenue and Illaroo Road, has been restricted and signposted.
Port Macquarie-Hastings Council says the location had been used as a dumping ground for building materials close to 30 years ago.
The Environment Protection Authority has been notified and remedial action has been taken.
The lake remains safe to use.