Wodonga-based CSIRO scientist Darren Baldwin said the outbreak occurred when Lake Hume contained a higher water level than previous events.

“We thought we had a really good understanding of what drives these blooms but we didn't expect to see a bloom this year,” he said.

“We keep coming back to the idea that it may be linked to climate specifically.”

Previous blooms occurred when Lake Hume water levels were about 10 per cent but this year levels were at 30 per cent when the bloom was first detected.

It was also a different strain of algae – chrysosporium ovalisporum - which had been found in the river system but never bloomed since records began in 1978.

“This particular algae starts to thrive in water temperatures above 27 degrees,” Dr Baldwin said. “We know there was a blue-green algae bloom in 1980, straight after monitoring, and then we didn't see another algal bloom until 2003.

“In that last 16 years we’ve had five blooms: 2003, 2007, 2009, 2010 and 2016.”

But the blooms between 2007-10 were during the millennium drought when Lake Hume was low. 

According to Dr Baldwin, with higher water levels in 2016, the cause could have been weather.

Bureau of Meteorology data revealed Border temperatures in February this year were 1.5 degrees above the long-term average, while March was 3 degrees warmer and April 3.5 degrees hotter. 

If warmer weather persisted Dr Baldwin said the likelihood of similar blooms was high. Asked if the latest bloom and climate change could be linked, Dr Baldwin said “it’s something that’s not beyond the realms of possibility”.

“What we do know globally and locally, is that February to April’s air temperatures were all significantly above average – not just the maximum temperatures but the minimum temperatures,” he said.

“What we think is happening – without proving it – is that this algal bloom is as much to do with climate as it is with normal factors that influence bloom formation.

“I’m trying to get some conversation about the potential that this may become the new normal.”