The issue

Gosford Council and the DECC share responsibility for a 15 hectare saltmarsh found along the foreshore of Patonga creek. The saltmarsh is part of a public reserve located at the foot of the steep sandstone escarpment of the Brisbane Waters National Park. This resource is enjoyed by bushwalkers, fishers, canoeists and picnickers.

Over the past five years, the area has been used for dirt bike riding which has created large wheel ruts across most of the saltmarsh. This has changed the way tides flood across the saltmarsh and destroyed the wetland vegetation. The damage has impacted on the value of the saltmarsh as a fish breeding area, as a feeding  round for wallabies and has allowed significant amounts of sediment to run into the creek.

The strategy

The HNCMA invested $50,000 (which was matched by Council) in the project aimed to prevent further damage of the saltmarsh, weed the marsh and fringing vegetation, restore the elevations of the marsh and revegetate the bare surfaces.

A remediation plan was developed which including consultation with the community and constructing a fence and gate. To repair damage to the saltmarsh the natural processes were enlisted. Using the fact that saltmarshes thrive on land that is situated in the 50cm height difference between the reach of a 1.5 metre tide and that of the king tides of 1.9 to 2.1 metres, the project use natural tide forces to:

Move sediment back into the wheel ruts which were up to 30 cm below the original elevation of the marsh. Distribute seeds and propagules from a number of healthy saltmarshes upstream so the vegetation would re-establish naturally

The movement of a 1.55 metre and a 1.88metre tides across the saltmarsh was mapped so that these natural forces could be understood and used to create the essential conditions for re-etablishing the area as a fully functioning wetland.

Saltmarsh restoration is a relatively new area of natural area rehabilitation and Gosford Council is also funding research by the University of Western Sydney to trial a number of saltmarsh restoration techniques on the site.

Project partner's perspective

Gosford Council has recognised the value of saltmarsh to a healthy estuary and was keen to harness learning from the works by involving the University of Western Sydney in research on the site.

According to Gosford Council's Coastal and Estuaries Management Officer, Dr Peter Freewater, saltmarshes are not only an endangered ecological community but also have high biodiversity values and ecosystem functions for fish, invertebrates, bats and wallabies.

"This project has allowed Council to restore a large area of saltmarsh and re-create the missing link between the land of the nearby National Park and the aquatic habitats of Patonga Creek. Support by the HNCMA for the on-ground works has provided Council with the opportunity to focus its resources on site planning and research so that learning from the project can benefit future saltmarsh restoration projects," said Peter.

The results

The project resulted in: