Concerns over the spraying of the weed was raised by councillors after they received a letter from the Environmental Protection Authority (EPA) about the proposed use of a herbicide called Glyphosate 360 over waterways. 

The label puts limits on the use of the chemical over waterways and concerns were raised about the decision to spray aerially. 

Councillor Brian Simpson put a question to general manager Brett Stonestreet at the most recent council meeting after information emerged staff had already sprayed with the same chemical in the past. 

Mr Stonestreet confirmed staff sprayed Roundup Biactive on Lake Wyangan  around 18 months ago. 

“My staff advised me that approximately 18 months ago they did use Roundup Biactive in a 100 litre mixed with the appropriate mixture. They did that within a small boat. It was a glysophate that they used,” he said. 

“They got in a small boat and sprayed cumbungi in a small area immediately in front of the picnic/camping area.” 

Council voted to spray the lake aerially using Glyphosate 360 in February. The idea to spray the weed was initially raised by Australian wetlands expert Geoff Sainty, who says the weed “causes a major ecological problem” through both lakes. 

When the decision was made to rescind the initial motion, Cr Simpson said Glyphosate was often used by irrigation companies to combat weed problems in channels. 

He said council could have applied for a Australian Pesticides and Veterinary Medicines Authority (APVMA)  for an off-label use of the product, allowing them to spray it to combat the weeds in the lake.

Mr Stonestreet said he had not been made aware of the move until the question was raised by Cr Simpson. 

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He said there was “no reason” parks and gardens staff hadn’t raised past spraying when cumbungi weed came up for debate. 

“What I’m looking for is for the council to move forward and get answers to blue-green algae,” he said. 

“I’d rather seek out answers rather than conduct some sort of investigation about who said what to when and where.”

Mr Sainty says the cumbungi weed creates a poor habitat for birds, out-competes other water plants and limits area of shallow habitat where water plants can compete with bacteria and expand into deeper water. 

Lake Wyangan’s ongoing issues also extend to concerns surrounding water quality and the high levels of blue-green algae found within the Lake. 

Griffith City Council plan to call for expressions of interest for businesses or individuals to put forward their solution to the Lake. They also plan to employ a project officer, whose would be to oversee and monitor Lake Wyangan.  

A plan put forward by Mr Sainty last year would see a natural wetland habitat on the eastern shore to help fight the Lake’s ongoing problem. 

Similar projects have seen huge success in Shepparton and Winton Wetlands near Benalla. According to a recent Fairfax Media poll, over 90% of respondents support Sainty’s plan. 

He said a key issue is Murrumbidgee Irrigation (MI), the privately owned irrigation company who manages the south lake’s water. 

“They don't give a damn about water quality. They never have”.