Menindee fish kill described as ecological disaster as residents cart water again

Millions of fish, including golden perch and cod, have been killed in the lower Darling-Baaka River near Menindee due to hypoxic blackwater, a naturally occurring phenomenon that causes extremely low dissolved oxygen levels.

"It's potent ... the smell, it's hard to find a word for it, it's just putrid," Menindee Lakes resident Graeme McCrabb said, who received notification on Thursday afternoon about the "shocking" fish kill.

Mr McCrabb, who was out in a boat today along the river system, said government officers had made some changes and increased flows to reduce the risk of death downstream.

"We still have some fish dying...but a massive amount of dead fish are making their way downstream heading to weir 32," he said.

"Those at Pooncarie are waiting and seeing."

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Mr McCrabb, who lives downstream of Menindee, local residents were no strangers to fish kill incidents with many occurring over the years.

But he said this would have to be the worst.

There were three significant fish kills in 2018/19 and there have been several smaller events since then.

"There is 10 times the amount of dead fish from 2018/19, it's startling. There is fish everywhere," he said.

He said the fish kill had impacted the town's domestic water supply as the water was not useable for purposes like showering.

"We live on the Darling River, we've had a massive flood with five Sydney Harbours coming through our township," he said.

"They lost control of the lakes at Christmas when it flooded the town on December 29, we've only just finished cleaning houses and now there are millions of dead fish.

"Now we will be relying on delivered water again...this could go on for months...this will have a devastating impact on Menindee," he said.

The fish kill has prompted a number of calls from politicians to clean up the dead fish immediately before it becomes an ecological disaster.

Independent MP Justin Field said what was unfolding was an ecosystem in crisis.

"No one should think fish kills on this scale is natural," Mr Field said.

"We are living in the age of climate change with more extreme floods and more extreme droughts.

"This is compounded by poor government decisions that allow riparian zones to be cleared, wetlands drained and a self-regulated pesticide regime that is funnelling unknown quantities of chemicals into our river systems".

The NSW Greens' water spokeswoman Cate Faehrmann said the fish needed to be removed before they decomposed and caused an ecological disaster.

"This is categorically a catastrophe, regardless of whether this is a consequence of receding floods or water mismanagement, the NSW and federal governments should be acting now to clean up the millions of rotting fish which are spanning kilometres of the river," Ms Faehrmann said.

"We are experiencing a natural disaster in the Darling-Baaka river right now and government departments and agencies are ducking responsibility and writing this off as a natural event - that is utter nonsense and is doing nothing to help.

"Right now, every natural aspect of the river and the communities that rely on it for water are threatened with cascading collapse and these millions of fish that are rotting away are a harmful tragedy and will further degrade the system and quality of the water."

A spokesperson for the NSW government said an emergency operations centre had been activated at Menindee to co-ordinate the multi-agency response to a fish death event on the Lower Darling-Baaka.

"These deaths are due to low oxygen levels in the water, driven by increased biomass in the system as flood waters recede. Hot weather can also exacerbate these events," the spokesperson said.

While active steps are being taken where possible to alleviate pressure on the system, the spokesperson said events like these were not uncommon after large scale floods and were often unavoidable, even with active water management processes being implemented.

State Emergency operations controller, deputy commissioner emergency management, Peter Thurtell, said the immediate focus was to provide a clean water supply to residents.

"There is no need for community concern as the initial assessment has determined multiple viable solutions to maintain water supply to the Menindee township and surrounds," he said.

"Importantly, there is ongoing testing of the water quality which will ensure immediate action if a switchover for supply is required."

Residents will be briefed on the operation at a community town hall event on Tuesday.