Saltmarsh Restoration at Windermere Bay — Stage 1 Works Complete

On the banks of the Derwent Estuary north of Hobart is Windermere Bay. Here, the Glenorchy City Council has commenced a boardwalk extension and replacement project, in a saltmarsh area that suffered a significant contraction in area due to infilling with soil in the 1970s. As part of this work, NGT – in partnership with the Derwent Estuary Project – supervised Stage 1 saltmarsh restoration works in mid-March 2025 (see our previous article here).

Restoration plan for Windermere Bay saltmarsh.

Infill material in the southern inlet of the bay was removed from the eastern side of the planned boardwalk, stripping the surface back to elevations between 0.65-0.75 m above sea level, which was determined via comparative baseline data collection of suitable saltmarsh growing conditions nearby. The goal in removing this surplus material is to re-engage this area of historic saltmarsh with regular tidal inflows. This zone has not experienced natural tidal connectivity since the 1970s when half of the saltmarsh effectively disappeared under infill, most likely sourced from the levelling of housing blocks for developments nearby.

This step fulfils Stage 1 of the planned restoration works, by re-exposing the near natural surface level east of the boardwalk which will soon be inaccessible to machinery. Stage 2 of the restoration works (removal of further infill to the west of the boardwalk) will occur once the boardwalk has been built and associated contractors have cleared the site. This is likely to take place in May 2025 and result in areas of infill being removed to reinstate natural landform and encourage saltmarsh expansion and improvement in condition through increased hydrological connectivity.

The excavation zone in Stage 1 deliberately tapers into areas of existing saltmarsh to the east (on the estuary side). In Stage 2 the excavated area will extend that target elevation for the remediated area westward, to the edge of the excavation area, with a gradient of approximately 0.2 m over this distance (e.g. from 0.7 – 0.9 mAHD). The western edge of the excavated area will be tapered to tie into existing higher ground.

Stage 1 infill excavation works at Windermere Bay, mid-March 2025 (before – left; and after -right; finished result – panorama at bottom).

We look forward to completing works soon, and to observing the exciting trajectory of spontaneous saltmarsh recovery expected at this interesting urban saltmarsh site over the years to come. We are grateful for playing a small part in helping to reverse past ecohydrological changes at important remnant saltmarsh areas on the foreshores of the Derwent Estuary.

This project is being delivered by NGT in partnership with the Derwent Estuary Program, with funding provided by the Australian Government’s Urban Rivers and Catchments Program