The Swan River inlet was cloudy at least far as Melville last week, with dredging commenced on the second phase of deepening the Fremantle Inner Port.
Widely criticised, the dredging began earlier this month on removing layers of limestone from the river and depositing them 7km off Cottesloe Beach.
The first report, by environmental marine and estuary specialists Oceanica, said the water clarity at the monitored beaches met guidelines during the first week of dredging.
But People Against Dredging spokesman Barry Brennan said he was unhappy the dredging was allowed and had no faith in Fremantle Ports’ monitoring process. He said if the plume had reached as far as Melville it was likely to have drifted further upstream, past where it was being tested.
For Mr Brennan, who once fished, dived and enjoyed the river with his five-year-old son, the river is now out of bounds – even for his dog.
But director of UWA’s Centre for Water Research Jorg Imberger, who uses state-of-the-art technology to trace, in real time, the effects of the dredging, said people should not be concerned.
He said he “double-checked” Fremantle Ports’ monitoring system and was satisfied with the process.
The professor said the dredging impacts were similar to a massive wind storm hitting the area. Fremantle Ports’ general manager asset and infrastructure management Steve Wade said two dredgers were currently in use, one to break up the limestone and one to remove it.
He said to combat the plume, the authority had placed “silt curtains” beneath the Fremantle Traffic Bridge.
South Metro MLC Lynn Mac- Laren said while residents should be “delighted” to hear the sediment was not toxic, their concerns should not be discounted.
She said if locals were concerned about the water quality, it was important that it be tested, if not by the Fremantle Ports, then by the Department of Environment and Conservation, so that any other possibilities of pollution were ruled out.
( melville )
[mappress]
Source: melville, August 31, 2010;