Ashburton council is hoping a three-month scientific study will provide a solution to the ongoing toxic algal bloom issues at Lake Hood.

The popular recreation lake is currently open but under a health alert after toxic algae surpassed safe levels.

It's the fourth consecutive summer of algae impacting the water, with two people falling ill from exposure to the toxic algae last year.

A scientific study gets underway next week to test possible prevention measures for the algae.

Infrastructure group manager Neil McCann provided an update on the trial at the council's activity briefing on Wednesday.

He said the containers placed into the water will have various products applied, and three sonic devices have been installed, ready to go on Monday.

“Then the full-on scientific work, monitoring and recording will begin.”

The council has called in the leading cyanobacteria scientist in New Zealand, Lincoln University-based Professor Susie Wood, to lead the investigative work.

McCann said he hopes to get Wood in for a presentation to the council to provide an update after a few weeks of the trial.

He said the trial is “to test if there is any product or device that can mitigate the bloom of the cyanobacteria”.

The shipping containers have had their tops and bottoms removed and will be mostly submerged in the canal,

“It’s totally enclosed and sitting on the sediment.

“Being in the container is probably making it better for cyanobacteria blooming.

“It's actually creating a worse situation, which is probably better for us because then you can check if it's effective.”

Asburton District Council chief executive Hamish Roach reminded the councillor of being swamped with potential solutions from all around the world, resulting in reaching out to Wood.

“She has guided, devised, and set up the scientific trial of what she believes are the five most likely best solutions.

“Now we're trialling them to see whether any of them actually will havean effect.”

McCann said the majority of the cost of the trial is being covered by the Canterbury and Lincoln universities and the Our Lakes, Our Future project.

The council has spent around $12,00, which included purchasing the containers, McCann said.

The recent rainfall hasn’t negated the blooms, with the lake under a health warning after surpassing a total cyanobacteria biovolume of 10mm3/L on January 8 and then 20mm3/L on January 15.

“The indicators we are getting from our CyanoFluor device is showing that the cyanobacteria is present and growing, particularly over the last few weeks.”

There has been a slight drop in the temperature of the lake due to the rain and cooler weather, but all it takes is a few fine, warm days to bloom further, he said.

“The cyanobacteria is embedded in the sediment in seed banks.

“You can move the water, flush water and reduce the temperature that largely affects the upper level of the lake.

“But in terms of the cyanobacteria, it's still there waiting for warm conditions to trigger.

“So all signs are there that it's actually blooming ahead of last year.

“It will be ideal for the trial.”

To get the health warning removed, they require consecutive samples of under 10mm3/L total cyanobacteria biovolume.

By Jonathan Leask