By Luke Voogt
Authorities have warned swimmers and pet-owners to stay away from the Barwon River as a toxic flush of acidic water moves toward Geelong.
“Dogs should be kept away from swimming in or drinking river water in affected areas,” said Graham Phelps, Corangamite Catchment Management Authority’s (CCMA) chief executive officer.
“People are advised to avoid direct skin contact with the affected water in this area until further notice as this may cause eye or skin irritation.”
Heavy rain flushed acid sulphate soils from Big Swamp into Barwon River causing very low pH levels of 3.4 in Boundary Creek, Mr Phelps said.
The authority detected low pH levels of 4.8 and 5.2 in Barwon River downstream of Boundary Creek.
Barwon Water’s groundwater extraction at a nearby borefield and droughts had dried out the swamp exposing the soils, Mr Phelps explained.
Barwon Water in 2016 acknowledged its groundwater extraction over the past 30 years had caused two thirds of the reduction of base flow into Boundary Creek.
At Winchelsea CCMA detected a pH level below the normal range for Barwon River and Mr Phelps said the authority would “keep a very close eye” on contamination downstream.
But the contamination would likely dilute as it moved toward Geelong, he added.
The acidity could kill fish and aquatic animals, destroying food supplies for local platypuses, he said.
“Low pH levels can kill fish – there’s no two ways about it.“
The contamination was unlikely to kill platypuses, were “very mobile creatures“ that would move to less harmful waters with greater food supply, he said.
But angry farmers have slammed Barwon Water’s groundwater pumping and the CCMA’s monitoring of Barwon River.
EPA was issuing notices to Colac region farmers for effluent pond infringements but “doing nothing” about Barwon Water’s “deplorable” groundwater extraction, Kawarren’s Malcolm Gardiner said.
The “unsustainable” extraction was killing fish, wiping out platypus colonies and turning farmland into “unproductive wasteland”, he said.
Fellow local farmer Andrew McLennan criticised CCMA’s lack of testing for heavy metal contamination which could also harm fish and platypuses.
“Boundary Creek is a one of the worst contaminated sites in Victoria and as such should have competent water sampling and analysis undertaken,” he said.
“Why doesn’t the CCMA provide some professional integrity regarding this issue?”
