Wyong Shire Council is now urging residents to report activities of vandalism.

A council spokesperson said the vandals had decimated three years of saltmarsh regeneration within a five hectare (12 acre) site at Tuggerah Bay.

Fences were installed in late 2006 but in the latest rampage the vandals destroyed a gate and a section of the fence.

It was the third time the gates needed to be mended in as many weeks as a result of vandalism.

The vandals face penalties of up to $220,000.