Yet there are different strands that have been fluctuating in growth in Mount Isa’s water supply since the Pseudanabaena strand reached more than five million cells per millilitre in early 2015. It had been multiplying at a fast rate in Clear Water Lagoon. 

That level has dropped but another strand of blue green algae was present at one million cells per millilitre in the lagoon. Others were blooming too, said Mount Isa Water Board’s chief executive Stephen Farrelly. 

“Most of them are relatively harmless. We strain them out, filter them out of the plant. There is a couple of toxic strains,” Mr Farrelly said. “We’re managing all the water quality implications for our customers but it is something we have to monitor closely. The filtration plant is a very important part in that process and we actually remove any blue green toxins prior to filtration via oxidation.” 

Mr Farrelly said that water quality specialists and university laboratories had investigated the cause of the blue green algae and the cause was eutrophication. 

The Merriam-Webster Dictionary defines eutrophication as a process in which a body of water is filled with dissolved nutrients.

This causes growth to plant life. 

“But the particular trigger in Clear Water Lagoon we still have not been able to identify,” Mr Farrelly said. 

“Once the eutrophication process occurs in a body of water it is quite difficult to reverse. 

“The good news is the processes we have in place and the membrane filtration is working extremely well in dealing with it and in a water quality and safety point of view we have not had any concerns with the blue green algae.”