An algal bloom affecting Lake Waihola appears to have
disappeared but the Otago Regional Council is warning it
could come back.
The toxic blue-green algae, which occurs naturally in a
variety of water-quality conditions, was discovered at toxic
levels in the lake and at lower levels at Tomahawk Lagoon in
The algae turned the lake very green and had the potential to
produce a series of toxins which could then be passed to the
water. If humans or animals came into contact with it, the
algae could cause illness or skin reactions.
Residents and visitors were warned to take care in and around
the lake. However, yesterday the council announced samples of
algae taken from the lake this week had shown no signs of the
toxic bacteria found in other samples.
Warning signs put up in November, when dangerous levels of
the algal bloom, known scientifically as cyanobacteria, were
found in Lake Waihola and Tomahawk Lagoon, were taken down
recently. Council engineering, hazards, and science director
Dr Gavin Palmer said the results of recent tests meant the
risk of people and animals becoming ill was negligible.
Algal blooms were not predictable and could return at any
time so the council would continue to take samples from the
lake through to the new year and would provide the community
with weekly updates on the results.
People should contact the council's pollution phone line if
they saw large amounts of green algae on the lake, Dr Palmer