Mosman Municipal Council

Environment

• Environmental management
• CEC
  • Bushland
  • Stormwater
  • Seawalls
  • Integrated Projects
• Trees
• Bushland and Biodiversity
• Pests and Weeds
• Gardening
• Coastal and Marine
• Water Management
• Ecologically Sustainable Living
• Atmospheric Environment
• Food Safety
• Public Health
• Noise

The coastal boundaries of Mosman include over 3km of seawalls. Prior to the CEC, many of these century old walls were in poor condition after years of exposure to salt water and wave action.

CEC projects have repaired, restored and rebuilt Mosman’s seawalls to protect our coastal environment. In keeping with the environmental objectives of the CEC, Council placed emphasis on restoring seawalls in an ecologically sensitive manner.

Key Achievements

• Repairing damaged sections of Mosman’s seawalls;
• Redesigning and rebuilding Mosman’s seawalls to create a natural rocky shoreline and provide habitat for intertidal organisms;
• Establishing a salt marsh at the Spit West seawall – a threatened plant community in NSW;
• Improving access to the foreshore;
• Planting native species adjacent to seawalls to improve amenity and provide habitat;
• Partnering with the Centre for the Ecological Impacts of Coastal Cities to monitor the recolonisation of Mosman’s seawalls by intertidal species.

Case Study – Quakers Hat Bay Seawall

The Quakers Hat Bay seawall project restored an old, collapsing dry laid sandstone seawall, while also improving habitat for aquatic organisms that live in the intertidal zone.

Natural rocky shores created a range of habitat for intertidal organisms, including flat horizontal surfaces, overhangs, rock-pools and crevices. As more of the harbour foreshore has been modified for human use, these types of rocky habitats have been increasingly replaced by seawalls built with a vertical face to deflect wave energy.

Mosman Council conducted the Quakers Hat Bay seawall project in partnership with the University of Sydney’s Centre for Research on the Ecological Impacts of Coastal Cities.

Council redesigned and rebuilt the seawall using a boulder field design, creating more crevices and horizontal surfaces for aquatic organisms to inhabit. The Centre has continued to monitor the seawall after its completion.

This project also involved the construction of steps to provide access into the water for boat users, and the reconstruction of a dilapidated stormwater channel. Thanks to a separate grant, dinghy racks were built so that boat users are able to store their dinghys without harming vegetation in the foreshore bushland.

Pedestrian access to the Bay has been increased by the construction of a crushed sandstone walking track, meandering through the bushland and providing access to the bay and the dinghy rack.