What is needed to Save Our Swan? Urban drains may not be the most lovable feature of our city but they are key to protecting one that is — the Swan-Canning river system.
The Swan and Canning rivers are on life support.
SAVE OUR SWAN ACTION PLAN
THE SWAN RIVER AND DRAINAGE
BETTER DRAIN MANAGEMENT FOR HEALTHIER RIVERS
Additional oxygenation machines have been installed in the rivers’ middle and upper reaches to try to breathe life back into low-oxygen water resulting from too many nutrients. While this has helped kept algal blooms at bay and fish alive, it has not fixed the underlying pollution problem, demonstrated by events such as the relatively recent deaths of river dolphins.
In 2009, an inter-agency report, the Swan-Canning Water Quality Improvement Plan, found that nearly double the sustainable levels of nitrogen and phosphorus was entering the system each year. The plan found that while the source of nutrients ranged from farmland run-off to excessive fertiliser use on urban parks and gardens, residential and recreational land was the biggest source of nitrogen and the second biggest source of phosphorus.
Our urban drain system is the main conduit whereby by this urban pollution enters the river.
While improving the quality of water that goes into the drain in the first place is essential — such as managing fertiliser use — it remains necessary to clean up the water before it exits the drain for the river.
One way to do this is to turn drains into ‘living streams’ where appropriate vegetation and drain design help strip nutrients from the drain water, at the same time creating a pleasant natural feature. Unfortunately, our drains were originally built with the sole purpose of moving water as fast as possible out of low-lying areas, and changing them is costly.
To date, implementation of such work has been piecemeal, inadequate and hampered by a lack of funds and buck-passing over who is responsible. Yet the necessary action has been researched and is known, and these improvements must be made now if we are to save our river system.
In the action plan a three-part strategy is detailed to improve our river system health, as well as some specific steps.
Authorised by Jess McColl & Trish Cowcher, the Greens (WA), Ground Floor 445 Hay St Perth