Echuca Moama Regional Tourism chief executive officer Tom Smith said while accommodation sites in his area had seen some cancellations, particularly from Melbourne fun-seekers, most visitors were continuing with plans to holiday beside the Murray. 

"I think most people are smart enough to know that, as long as you don't go in the water, it's safe," he said.

But not even the warnings had deterred all swimmers, with Mr Smith saying many people were still paddling in the river yesterday. 

He said blue-green algae was not uncommon in the Murray River, especially during periods of hot weather and low water levels, and reminded visitors boats and paddle steamers remained in operation throughout the outbreak.  

Moama Riverside Holiday Park owner Jenny Warnett, whose site is located on the northern bank of the river, said this was the first serious outbreak of the algae since she started at the park four years ago. 

She said the majority of her clientele were "people wanting to sit and watch the paddle steamers", and were less likely to be deterred by the outbreak than those keen on speed boating and swimming. 

The only sign of the bacteria from Ms Warnett’s park was a slight discoloration of the water.

“There's not even a smell coming off it,” she said. 

Her site, which was 70 per cent full on Thursday, remains fully booked for the next two weekends and Labour Day.

None of those staying at the park on Thursday had complained about the water's condition.

Likewise, spokespeople from both Echuca Holiday Park and Merool on the Murray said while they had received calls from visitors with upcoming bookings, they had not recorded an increase in cancellations because of the toxic outbreak. 

People cursing the latest algae outbreak in Victorian rivers are being urged to remember its ecological function.    

Interim director of La Trobe University’s Murray-Darling Freshwater Research Centre, Gavin Rees, said waterborne algae are an important part of a river’s ecology.  

“Its often the algae on rocks or pools that is the primary food source for the small creatures, which feed the bigger animals,” he said.  

Asked whether climate change could cause more algal blooms, Mr Rees said river management was more likely to impact the frequency of outbreaks.

“One of the ways of improving water quality is moving water in and around our rivers, which can cause the occurrence of these types of things,” he said. 

He also said it was difficult to determine precisely when the algae will disperse.

“I'd be thinking as we come into the end of summer, it may be we see things disappear sooner than had this happened during January.”