Improving Water Quality Through Stormwater Treatment Wetlands

City of Perth Western Australia

: The stormwater treatment wetland and educational signage Source: Syrinx Environmental P/L

Synopsis

The City of Perth, a Water Campaign™ participant since 2004, has taken the major initiative of installing a constructed wetland to treat stormwater run-off into the Swan River, Perth, Western Australia.

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.

Construction of the wetland was completed in March 2004. Further recreational facilities and a visitor node are planned for the future in Stage 2 of the Point Fraser project.

Motivation for developing the stormwater treatment wetland

The Swan River runs through the centre of Perth and has long been a focus of activity for the Perth community. In the 170 years since European settlement of the area the river has suffered under human induced change. In particular, the use of fertilisers within the river catchment has increased the nutrient load through run-off to the Swan River and caused significant water quality problems including algal blooms (Government of Western Australia 1999).

The City of Perth engaged Syrinx Environmental PL to develop a stormwater treatment facility which not only improves stormwater run-off quality into the Swan River but also meets a number of other environmental and social objectives. The area utilises local plant species to provide habitat for native fauna, provides an attractive recreation area and incorporates educational displays to raise overall awareness of the way in which constructed wetlands can play a role in creating a more sustainable environment for the City of Perth.

: A drawing of the Point Fraser project Source: Syrinx Environmental P/L

How does the wetland work?

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 has been designed to promote an even flow of stormwater through the wetland and to maximise filtration of sediments and the bacterial transformation of nutrients through a "bio-filter" process.

The project enables best practice stormwater management techniques to be used and allows for on-going monitoring of urban stormwater discharge. The wetland designers are currently responsible for undertaking periodic monitoring of wetland health, including such parameters as soil quality, water quality, plant quality and habitat condition.

Costs

The overall cost of constructing the wetland and associated riverside restoration and interpretation work is estimated at $3.3 million over four years (City of Perth 2003). The City of Perth received a $234,000 grant under the Commonwealth Government’s Coast and Clean Seas program in order to assist with construction of the project.

Benefits

Water Quality Benefits

More will be known about the improvements in water quality resulting from the installation of the wetland after the water quality monitoring program has been running for a greater length of time. For more information contact the council for ongoing findings of the monitoring program.

Other Benefits

There are a number of additional social, cultural and environmental benefits resulting from the construction of the wetland. These include improved recreational amenity, habitat restoration and public education through the on-site interpretation of the area’s environmental and cultural heritage. The wetland should also improve public understanding of stormwater/water quality issues through its environmental education displays.

References

City of Perth (2003) Principal Activities Plan http://www.cityofperth.wa.gov.au/html/pub_pdffiles/PAP2003.pdf (accessed 27th June 2005)

Government of Western Australia (1999) Swan Canning Cleanup Program Action Plan Swan River Trust Perth WA

ICLEI-A/NZ would like to acknowledge the assistance of Ms Jessica Bayens and the City of Perth in the production of this case study.

For further information about this project contact:

Lisa Cooke
Environment Officer
City of Perth
Council House
27 St Georges Tce
Perth WA 6839
Email: lisa_cooke@cityofperth.wa.gov.au
Phone: (08) 9461 3243

To top

Search | Site Policy | Contact