Health New Zealand lifted its algal bloom health warning at Lake Hood.
The popular man-made lake near Ashburton was issued the health warning on March 20.
Recent water testing at Lake Hood has shown the quantity of potentially toxic blue-green 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 Ramon Pink said Environment Canterbury’s sampling of the lake will continue on a monthly basis.
“The public will be informed if testing shows that concentrations have increased and there is a risk to public health again,” Dr Pink said.
It was the third straight summer a health warning has been imposed on the lake due to algal bloom.
This year two people reported falling ill after coming into contact with the algae, prior to the health warning being in place.
As a result, Ashburton District Council closed the lake.
It had initially stated the lake would remain closed until the health warning was lifted.
The council then announced that full vehicle access to the road around Lake Hood was restored on June 19, signalling the lake was open despite the health warning remaining in place.
Ashburton District Council chief executive Hamish Riach said they reviewed their stance on opening access to the lake based on a range of factors.
“We reinstated lake access due to lower cyanobacteria test results and increasing dissatisfaction with the prolonged closure.”
The council took over management of the lake last year and is investigating ways to rid the lake of its algae issues.
A 75-page report went to the council meeting in May to provide an update on the water quality issues at the man-made lake and the work underway to address them.
Riach had summarised the report by saying the council will model water flows and trial some solutions.
The leading cyanobacteria scientist in New Zealand, Lincoln University-based Professor Susie Wood, has been called in to lead the investigative work towards a solution.
LDR is local body journalism co-funded by RNZ and NZ On Air.
