March 25, 2026
Health New Zealand lifted its algal bloom health warning issued for the Lake Hood, a popular spot for boaties in Canterbury.
Recent water testing at Lake Hood showed the quantity of potentially toxic harmful algae (planktonic cyanobacteria) in the lake has reduced, and concentrations are now below levels that are of concern to public health.
National Public Health Service’s medical officer of health Dr Claire Salter said the public will be informed if testing shows the concentrations have increased and there is a risk to public health again.
The warning was issued on January 14 after Environment Canterbury testing recorded total cyanobacteria biovolume of 10mm3/L at the water ski lane – with a reading of 10 or greater triggering a health warning.
It has been the fourth consecutive summer of algae impacting the water at the man-made lake.
It requires two consecutive tests below 0.5mm³/L for a warning to be removed.
The levels fluctuated January, including a reading of 20mm3/L on January 15.
Testing at the jetty on March 12 recorded 0.4mm3/L and at the ski area on March 19 at 0.09mm3/L meant Health NZ could remove the health warning.
Ashburton District Council infrastructure group manager Neil McCann said the warning signage will be removed, which is “great timing with Easter coming up”.
“There’ll be plenty of people keen to be on the water if the weather stays warm.
“The water quality has improved since the health warning was issued in January, and the back-to-back readings have confirmed it.”
The council is continuing to work with scientists on ways to manage algal blooms in the lake in the future, with a three-month scientific study starting at the end of January.
McCann said the recent summer had been cooler and wetter than the previous one, and as much information as possible was being gathered about how cyanobacteria blooms form in Lake Hood.
“We’ll keep the community up to date with the trial results once the scientists have analysed the data from the last three months.”
The council has called in the leading cyanobacteria scientist in New Zealand, Lincoln University-based Professor Susie Wood, to lead the investigative work.
The trial includes six containers being placed into the water to test various products, and three sonic devices have been installed.
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 spent around $12,00, which included purchasing the containers.
By Jonathan Leask
Health New Zealand lifted its algal bloom health warning issued for the Lake Hood, a popular spot for boaties in Canterbury.
Recent water testing at Lake Hood showed the quantity of potentially toxic harmful algae (planktonic cyanobacteria) in the lake has reduced, and concentrations are now below levels that are of concern to public health.
National Public Health Service’s medical officer of health Dr Claire Salter said the public will be informed if testing shows the concentrations have increased and there is a risk to public health again.
The warning was issued on January 14 after Environment Canterbury testing recorded total cyanobacteria biovolume of 10mm3/L at the water ski lane – with a reading of 10 or greater triggering a health warning.
It has been the fourth consecutive summer of algae impacting the water at the man-made lake.
It requires two consecutive tests below 0.5mm³/L for a warning to be removed.
The levels fluctuated January, including a reading of 20mm3/L on January 15.
Testing at the jetty on March 12 recorded 0.4mm3/L and at the ski area on March 19 at 0.09mm3/L meant Health NZ could remove the health warning.
Ashburton District Council infrastructure group manager Neil McCann said the warning signage will be removed, which is “great timing with Easter coming up”.
“There’ll be plenty of people keen to be on the water if the weather stays warm.
“The water quality has improved since the health warning was issued in January, and the back-to-back readings have confirmed it.”
The council is continuing to work with scientists on ways to manage algal blooms in the lake in the future, with a three-month scientific study starting at the end of January.
McCann said the recent summer had been cooler and wetter than the previous one, and as much information as possible was being gathered about how cyanobacteria blooms form in Lake Hood.
“We’ll keep the community up to date with the trial results once the scientists have analysed the data from the last three months.”
The council has called in the leading cyanobacteria scientist in New Zealand, Lincoln University-based Professor Susie Wood, to lead the investigative work.
The trial includes six containers being placed into the water to test various products, and three sonic devices have been installed.
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 spent around $12,00, which included purchasing the containers.
By Jonathan Leask
