Mystery slick spotted in Swan
Authorities do not know what caused a 500-metre long diesel slick in the Swan River, but are working on a few theories.
The slick appeared on Thursday morning between the Barrack Street jetty and the Narrows Bridge.
A spokesperson from the Department of Parks and Wildlife (DPAW) said the cause was unknown, but could have been a refuelling accident from a vessel at the jetty.
The agency conducting the investigation into the spill, the Department of Environment Regulation, maintains that the source is yet to be determined.
Environmental inspectors have examined fuel pumps and pipes at around the jetty, but appears not to have found any clues.
DPAW said heavy rainfall had broken up most of the slick overnight, and so there was no risk to fish, dolphins or seabirds in the river.