Water Sensitive Urban Design: Wetlands

Wetlands are constructed ponds that capture and treat stormwater prior to discharge into our natural waterways.

These treatment ponds are one part in a Water Sensitive Urban Design (WSUD) stormwater system.

They are different to our natural wetlands, waterways and nature reserves.


As rain falls to the ground and lands on roofs, driveways, roads, parks or gardens, it picks up soils, organic matter, litter, fertilisers and other contaminants. This rainwater has now become stormwater.

In urban areas, stormwater is directed into a drain, which sometimes connects to a wetland. The stormwater collects litter, debris and pollutants on its way to the WSUD wetland.

Treatment ponds

When stormwater reaches a wetland, a pond will capture, hold and filter the stormwater. There are often a series of ponds that stormwater will slowly make its way through.

This is a modern approach to managing stormwater in urban areas. Treatment ponds are designed to:

  • hold water, capture litter and sediment, and treat pollutants
  • slowly release decontaminated stormwater into our natural waterways
  • sustainably and responsibly manage urban stormwater to protect our natural waterways, wetlands and bays

Following large rain events, there may be an increased water level in a wetland – this is normal and it may take a few days for the stormwater to return to its natural water level.

When the stormwater moves downstream into our creeks, rivers, bays and oceans, it is decontaminated because it has been treated in the wetland.

Wetland maintenance

We inspect our wetlands and treatment ponds monthly to ensure they are functioning as designed and to undertake maintenance as necessary. Our monthly program reflects our aim to maintain a high standard for our wetlands and treatment ponds.

Our contractors will inspect drainage infrastructure (for example: inlets and outlets), collect litter, remove weeds, undertake seasonal vegetation pruning, etc. Site constraints sometimes make access to all parts of a wetland challenging, and our contractors will do the best they can.

Following large rainfall events, the volume of stormwater and litter flushing through the system will increase. It may take several site visits for all the litter to be removed safely by the contractor.

Page last updated: Thursday, 19 October 2023