An algal bloom in a reservoir that feeds into Dunedin's water
supply has resulted in "foul, mouldy-tasting water", and
technology to get rid of it could cost up to $25,000.
The Dunedin City Council has been monitoring the problem
since late March, but both the council and Public Health
South yesterday said there were no health concerns.
The algal bloom was found in a reservoir that feeds the
southern water treatment plant, near Brockville.
A Shiel Hill resident alerted the Otago Daily Times to the
problem, and said she and her flatmates had found the taste
of tap water "awful" for two to three weeks.
"We expect to be able to turn on the tap and drink the
water."
Asked if there was an issue in the area, council water
operations team leader Gerard McCombie said the council had
fielded 30 calls from residents concerned about water quality
from April 15 to April 20.
Scientists had been testing the water, trying to identify the
species and doing "cell counts", checking whether
cyanobacteria was above alert levels, and if it was, doing
additional testing for cyanotoxins.
The results did breach alert levels on March 31, which
prompted a call to Public Health South water assessors.
Otago-Southland medical officer of health Marion Poore said
blue-green algae was also referred to as cyanobacteria, and
that could produce cyanotoxins, which could cause health
problems.
Testing, which was ongoing, had shown levels of toxins well
below those that would raise concern, and there was no risk
to health.
Mr McCombie said the council was considering ways to deal
with the problem.
The Southern Water Treatment Plant supplied water to a wide
area of Dunedin, from Green Island to the Otago Peninsula.
- david.loughrey@odt.co.nz
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