Sediment Trap Trial

Environmental monitoring shows that the water quality in Waituna lagoon and the creeks that flow into it is under stress due to the cumulative impacts of surrounding land uses. The catchment and lagoon require on-going active management to improve their ecological condition. This is to reduce the risk of the lagoon experiencing a ‘regime shift’ from having clear water and an aquatic environment dominated by aquatic macrophyte plants such as Ruppia, to one which has turbid and murky water dominated by algal slime and other suspended phytoplankton. This change would have significant consequences for the natural, recreational and cultural values for which the lagoon is recognised.

Reducing the quantity of sediment and sediment bound nutrients entering the Lagoon is a key objective of the Trust and the local community who have a strong connection to the Lagoon.

The effectiveness of sediment traps and settling facilities is variable, and depends upon a complex interaction of a range of factors. Following initial investigations, a coarse sediment trap has been recommended on a trial basis, prior to a potential larger scale catchment wide investment and rollout.

The sediment trap is an off-stream design and was built on-farm in April 2023.

The sediment trap will be monitored to understand the effectiveness of trapping sediment, the quantity and size of sediment captured, how often the trap needs to be cleaned out and ensure any repairs and maintenance of the trap is carried out in a timely fashion.

The trial is expected to be completed in 2026. Initial monitoring has shown the trap is effective in reducing sediment from reaching the creek.