A Victorian water authority is urging calm after thousands of fish were found dead at Kangaroo Lake in the state's north west.
On Sunday, visitors reported bream and Murray cod floating dead on Kangaroo Lake, between Swan Hill and Kerang.
"There was mainly dead bream, but when you had a look there was actually a couple of cod," local fisherman Darren Scott said.
"We actually pulled one out of the water – it would have been a metre [long], which is pretty devastating."
Mystic Park resident Bill Bennett, who lives across the road from Kangaroo Lake, has never witnessed a fish kill of this scale.
He said the sight and smell of the fish kill was a "terrible" surprise to return to after a weekend away.
"It was real sudden," he said.
"We've had lime green water here for two to three weeks, with algae and we understand that, but no dead fish – the dead fish have showed up over the weekend."
The fish kill at Kangaroo Lake coincides with a mass-scale fish death event at Menindee, in far-west New South Wales.
Goulburn Murray Water customer service officer Paul Gilchrist doesn't believe that fish kill events are becoming more common, but suspects the recent floods are a contributing factor.
"We had hoped we'd seen the last of the impact of the floods," he said.
"We did certainly see some fish deaths last year and into this year, but sadly this has happened in the last few days too."
Mr Gilchrist said water quality testing could not have predicted a fish kill event, and noted the water was safe to use for irrigation.
Excavators began removing carcasses on Tuesday afternoon.
Mr Gilchrist said the site would be cleaned up as soon as possible.
"I can't guarantee what happens in the future in regards to [the fish kill], but ... Easter certainly won't be affected; we will have the site cleaned up," he said.
Council raises the alarm
At a meeting on Tuesday, Swan Hill Rural City Council voted in support of a motion to appeal to local MP Peter Walsh and the relevant environment and water ministers to draw their attention to the fish kill.
The day before, councillor and healthy river campaigner Nicole McKay raised concerns about normalising fish kills, in an interview with ABC Mildura-Swan Hill Breakfast presenter Debra Pearce.
"Mass fish kills should not be expected or thought of as just part and parcel of what happens in the river," Cr McKay said.
"This is a sign of really ineffective management of river operations and it shouldn't be seen after a really great flood.
"A flood should have brought good water, and that should be sustained with good flows.
"It's a real sign of something wrong."
However, Mr Gilchrist said the fish kill event was "beyond our control."
"Clearly this is a natural event in terms of what's happened," he said.
"This can happen through water temperature change, through algae blooms ... and obviously lower levels of oxygen in water.
"All we can do at this stage is continue to monitor.
"Once we get through this irrigation season, and we have a decent winter, some nice cold weather and rainfall, it'll certainly help," Mr Gilchrist said.
