Works carried out to improve water quality in important Far South Coast oyster estuary
July 2019
Shannon Brennan
Senior Land Services Officer
Work has been carried out to reduce sediment and improve water quality in Wapengo Lake, an important oyster producing estuary on the Far South Coast.
The area was subject to heavy erosion from water flow and a lack of vegetation along the banks.
Poor water quality can have a real impact on oyster production, recreational fishers and community use of these priority catchment areas.
This project is one of three bank protection sites in the South East that have been completed through funding from the NSW Government’s Marine Estate Strategy. At this site it complemented funding provided by NSW DPI’s Recreational Fishing Trust's Habitat Action Grant and the land manager.
The risk of erosion, and sediment release into the water, increases if there are no root systems to stabilise the bank when there are high flow events.
A number of log and rock deflection structures (groynes) were installed along a 100 metre stretch of Wapengo Creek to help stabilise the bank.
Log rootballs (the stumps and roots from large trees) were retrieved from the 2018 Tathra Bushfires and recycled at this site. The rootballs were placed out from the banks at right angles and were weighed down with rock to create complex ‘groyne’ structures that now deflect flows away from eroding river banks and provide shelter and food for fish inhabiting the creek.
A working bee held with local oyster growers, fishing club members, contractors and land managers was then held to replant the bank area. Not only will this further improve stability and reduce the risk of erosion, it will increase biodiversity both on land and in the water.
There have already been reports of a number of schools of fish swimming around the groynes.
A further six priority sites from the Shoalhaven in the north to the Pambula River in the south will be treated over the coming year.
Implementation of project works was managed by Soil Conservation Service, Sapphire Coast Wilderness Oysters and South East Local Land Services.
To learn more about the priority catchments and other work underway in the South East contact me at Shannon.brennan@lls.nsw.gov.au.