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Wetlands to the rescue of Port Phillip Bay

Wetland systems have been part of our natural landscape for millions of years. They play an important role in natural water treatment. Constructed wetlands are now featuring as an effective tool in improving the water quality in Melbourne's Port Phillip Bay.

The Bay is one of Victoria's most precious natural assets and a significant feature of the Australian coastline. It is one of Australia's busiest ports, supporting major commercial and recreational fishing activity.

The Bay is also the focus of a growing tourism industry and an important part of the life of many Victorians with over 35 million visits annually. Around three and a half million people live around the Bay.

In the late nineties, CSIRO's $12 million Port Phillip Bay Environmental Study confirmed the Bay's condition had improved due to catchment and industrial discharge sewering. The study also identified stormwater as the major threat to the Bay's health. Each year stormwater discharges add about 500 truckloads of nitrogen to the Bay. Stormwater is one of the major sources of nitrogen, increasing the risk of algal blooms.

Improvements in water quality require better management of urban stormwater. This is being achieved in a world class project in Melbourne. Port Phillip Bay Stormwater Quality Improvement Project involves the construction of a series of large treatment wetlands in Melbourne's rapidly growing south east corridor.

The project has been jointly funded by Melbourne Water ($4m) and the Commonwealth Government's Clean Seas Program ($3.5 million). It forms part of Melbourne Water's $130 million Healthy Bay Initiative.

The project demonstrates best practice stormwater management on a regional scale through partnerships between Melbourne Water, Local Government, the Environment Protection Authority, developers and community groups.

Elements found in natural wetlands are being introduced in a number of waterways in the Cities of Casey, Kingston, Frankston, Knox and Greater Dandenong. These will improve the runoff quality before it reaches coastal waters. The constructed wetlands will slow the flow of water, allowing sediment to settle out and filtration to occur as the water passes through the wetland vegetation. Sunlight and time combine with bacterial and algal processes to cleanse the water.

The project is especially important given that Melbourne's south eastern suburbs are expanding rapidly, with an additional 200,000 people expected to be living there by 2010. These new residential estates offer the opportunity for innovative stormwater management to be integrated into the urban landscape.

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