Retailer Pete O’Neill, manager of the Skin Ski and Surf shop on Belmore Street, said the blue-green algae bloom and subsequent red alert from late February adversely affected trading.

“There's been a noticeable drop in foot traffic,” he said. “It hasn't been as bad as I was expecting, but that said, we only really get three or four months of the year to make money and we lost two of those months.

“We wiped off a bit of the profit margin – we were maybe 20 per cent down on what we were for those same months last year.”

Luckily, Mr O’Neill could trade for the bulk of summer until the bloom spread to Yarrawonga.

“If it had happened over January it would've killed a lot of business,” he said.

But his shop also runs a water skiing school, which was seriously affected.

“That took a huge hit, because most of our customers are tourists,” he said.

“We were open and honest about the warnings and most people decided not to go in.”

Similarly, bookings at Yarrawonga Holiday Park declined, but not drastically so. 

Sara Clarke, who works at the caravan park, said there was an initial slump after the red alert was first issued.

“We had Easter after that and everybody had already pre-booked,” she said.

Fellow worker Michelle Driscoll added Easter tourism in Yarrawonga was predominantly centred around a tennis tournament. 

“Given that the bloom is not going to be an annual thing, I think it can be absorbed,” she said.

Mr O'Neill stressed he had not heard of anybody getting sick from contact with the algae and the red alert was “a bit of overkill”.

“There were plenty of people in the water,” he said. “Lots of locals didn't care about it at all.

“Definitely the stories we were reading in the Melbourne papers painted it like it was a war-zone up here, when really it was normal. I’d say I was in the water five days a week.”

But the Victorian government cautioned contact with blue-green algae may lead to skin irritation, mild respiratory effects and hayfever-like symptoms.

CSIRO scientist Darren Baldwin argued a level of complacency existed regarding the public's perception of the bloom. 

“It is not a trivial issue,” he said. “There's potential for public harm so I think the government was wise to warn people.

“I certainly would not have swum in the river.

“Twenty per cent of the population are susceptible to contact dermatitis if they contact the water.

“Some research has suggested blue-green algae is linked to neurological effects similar to Parkinson’s. The jury is still out as to whether or not that's true, nevertheless these things can cause some significant issues.”

Incident controller Steve Grant said the government’s role was to inform the community of the potential danger.

“Ultimate it's their decision to take the risk,” he said.

“I certainly wouldn't do it myself, all we can do is inform people and then they can make the decision.

“Our estimate would be about 30 people got sick – that we've been told about – but I’d be almost certain it would be more than that.

“But we don’t necessarily know if it was the blue-green algae.”