Riverside fears over pollution
The Swan River next to Heirisson Island is far more polluted than originally thought, sparking fears the $2 billion Riverside project could release toxic sludge into the waterway.
A report by the Department of Water has laid bare the alarming finding and prompted calls for urgent work to determine the extent and source of the contamination.
Little known until now, the report was prepared on behalf of the Swan River Trust.
The report found that a site known as CBI06 "adjacent to Point Fraser wetland and Heirisson Island" was filled with poisonous material including heavy metals and toxins, particularly hydrocarbons.
It was even more polluted than Claisebrook Cove, an infamously contaminated area that once housed the East Perth gasworks.
Although the trust was unsure why the site was so polluted, it noted the area was downstream of Claisebrook Cove and may have been a spot where toxins from other areas built up.
Ahead of site works for Riverside in the vicinity of the polluted area, the trust called for further investigations into the pollution "as a priority" because it was concerned that disturbing it would be harmful to marine life.
"The investigation should assess the extent of contamination in this area and attempt to establish likely sources," the report said. "Where guidelines are exceeded, toxicity assessment should be conducted to determine whether the sediments are toxic to aquatic organisms and therefore likely to affect ecosystem health.
"Investigation of this site is particularly important given the planned development and subsequent disturbance to this area of the Swan Estuary."
Project proponents the Metropolitan Redevelopment Authority said it "works closely with the trust to ensure the health of the river remains a priority during any construction activities".
"The MRA is not currently undertaking any construction in the Swan River as part of the Riverside project," a spokeswoman said.
"In order to undertake any future works, the MRA will work with the trust and a number of other government agencies to obtain the necessary approvals."
She noted site CBI06 was outside Riverside's boundary.
