Swan River on track for a healthy summer

By Bree-Anna Finlay The iconic Swan River is known for providing West Australians and visitors with an abundance of activities during the warmer months. According to the Director of Environmental Engineering at UWA, Professor Jorg Imberger, this could shortly become a thing of the past, as he stands by his claim that the river is on a serious environmental decline. Professor Imberger said the Swan River Trust is in denial and that having artificial oxygen pumped into it is not the answer. “A long-term solution for this is available by building a barrage at Fremantle with an automatic lock, similar to what Singapore and Italy have done.” “Such a barrage would have the added advantage of stopping the salt water from intruding upstream mitigating the bottom water oxygen depletion.” “Initial simulations show that the oxygen depletion problem could be solved within two summers after constructing the barrage,” said Professor Imberger. But Mark Cugley of the Swan River Trust says Professor Imberger’s claims of the river being at a high risk are far from the truth. “Such claims are factually incorrect and not supported by current monitoring and science,” he said. The Trust says Mr Imberger has not provided to them any details of the barrage that he is proposing as a solution. “Limiting the tidal exchange that has occurred since the estuary became permanently open in the late 1890s when the Fremantle harbour was created could potentially have significant effects on the Swan and Canning rivers’ ecology,” said Mr Cugley. “Oxygenation has a range of proven benefits to the estuary, including improving nutrient cycling in the river, speeding up the breakdown of organic matter and reduction of the nutrients available for algal growth.” The oxygenation plants at Guildford and Caversham have the ability to oxygenate more than 10km of the river, depending on tidal movement. The Government is investing $2.4 million to significantly upgrade the two existing plants and construct a third plant at the Nicholson Road Bridge.