Stormwater in Perth purified through a treatment wetland

Perth (Australia) has taken the major initiative of installing a constructed wetland to treat stormwater run-off into the Swan River.

The project aims to reduce phosphorus and nitrogen levels entering the Swan River through the development of a treatment wetland to purify stormwater from the East Perth area through a biological filtration system. 

Stormwater is directed into a large, permanent open water body where sediment is able to settle.  From there, water flows through an extensive system of vegetated shallows before entering a filtration zone of rushes prior to entering the river.  The choice and arrangement of plant species was designed to promote an even flow of stormwater through the wetland area, and to maximize filtration of sediments and the bacterial transformation of nutrients through a 'bio-filter' process.

As a result, it is anticipated that the water quality will improve.  Other benefits have already materialized; for instance, the development of an improved recreational area, habitat restoration, and increased public education through the on-site interpretation of the area's environmental and cultural heritage. 

Perth is one of 95 local governments in Australia that are currently Members of ICLEI – Local Governments for Sustainability. For more information on ICLEI and its activities in the Oceania Region, please visit www.iclei.org/anz.

Source: “Improving Water Quality through Stormwater Treatment Wetlands”, ICLEI Oceania Water Campaign Case Study, June 2005.