04 Feb Hutt Bay Wetland – Flashback to the first hydrological restoration works in 2006
In 2005, as a wetland project officer in the lower South East, I became aware of a potential wetland restoration opportunity near Port MacDonnell, a 170 hectare wetland situated behind the coastal dunes near Middle Point. The owner of the area, Robert Thompson, invited me down to have a look. Rob had fenced several hectares of rare silky tea-tree (Leptospermum lanigerum) shrubland near the eastern end of the wetland and there was some encouraging recovery occurring. Silky tea-tree is indicative of freshwater springs and it was clear that the eastern end of the wetland was spring-fed.
There was also an old record of the nationally vulnerable Southern Bell Frog (Litoria raniformis, aka Growling Grass Frog) from the area. Despite the values it possessed, the hydrology of the wetland was clearly compromised by a drain running adjacent to the recovering shrubland and cut through the coastal dunes to sea. Robert and hisfamily were supportive of hydrological restoration and so a new wetland restoration project was born.
With the help of staff at the South Eastern Water Conservation and Drainage Board (SEWCDB) a regulator was designed and installed (right) across the drain where it passed under a track through the dunes. Construction supervisor Geoff Briggs and his team did a great job in April 2006, installing a box culvert with stop logs into the sandy substrate.
The completed structure (below) remains in place and is doing its job well 13 years later. As soon as the stop logs were dropped into position, the upstream water level in the drain rose by about 0.5 m, providing instant benefits for the wetland and emphasising how severely drainage had compromised the natural hydrology.
Another element of the project involved the redirection of flows that had previously been contained by spoil banks on both sides of the drain. An excavator was used to breach these spoil banks at the lowest point in the wetland, allowing spring flows to spill out of the drain and into the swamp at the natural surface elevation. The restoration of permanent, freshwater inflows to the larger wetland area to the west was achieved, influencing the ecology of a much larger area than the immediate vicinity of the drain.
Hutt Bay Wetland (which has also been known as Middle Point Swamp and Pascoe Swamp over the years) was still somewhat compromised at that time by another drain through the coastal dunes further to the west, but the freshwater spring at the eastern end of the wetland had been partly restored, and the wider restoration story for the wetland – which continues today – was underway.