The Department of Water and Environmental Regulation has closed investigations into the dumping of a blue substance into the Lower Vasse River that occurred in March 2023 due to insufficient evidence. If new information becomes available, the department will review it to determine whether any action is appropriate.
The substance, thought to be a dye compound, caused the river to turn blue upstream and downstream of the Strelly Street Bridge and downstream of the Causeway Bridge in Busselton.
Continual water quality loggers in the Lower Vasse River downstream of the Causeway Bridge showed an initial decline in dissolved oxygen to critical levels the night after the incident, recovering the next morning.
“We are fortunate that low dissolved oxygen levels improved the following day as prolonged periods of low oxygen can cause fish kills,” said DWER Executive Director Science and Planning Jason Moynihan.
Phytoplankton sampling undertaken in the days and weeks after the incident showed the substance had no impact on phytoplankton cells and was ineffective at reducing algal blooms.
Information gathered during the investigation suggested that the incident may have been an unauthorised attempt to combat blue-green algae in the river.
“Reducing algal blooms and improving water quality in the Lower Vasse River is a major challenge and one that is receiving considerable investment and effort from the Vasse Taskforce, the City of Busselton and partners,” Mr Moynihan said.
“Dumping substances into the river without the necessary approvals, monitoring or risk assessment poses a serious risk to wildlife and ecosystems.”
“We need to work together across government, with industry and the community to meet the challenges of improving water quality in the Lower Vasse River and other Geographe Waterways.”
Offences of this nature can result in penalties up to $125,000 under the Environmental Protection Act 1986 and may also trigger compliance action under a range of other legislation.
If you see any illegal activity, you can report it to Pollution Watch on 1300 784 782. To report deceased fish, contact FishWatch on 1800 815 507.
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