It's not as simple as blaming farmers for the potentially
toxic algal bloom returning to waters in Otago, baffled Otago
Regional Council staff say.
The council warned the public last week to avoid contact
with, and keep their dogs away from, Lake Waihola and
Tomahawk Lagoon after discovering the algal bloom.
Otago Regional Council director of environmental information
and science John Threlfall said he had taken samples of the
blue-green algal bloom on Monday, but was waiting on the
However, the algal bloom could change quickly from being
toxic to non-toxic, or vice-versa.
There was no correlation between the increase in the
blue/green algal bloom and the increase in nutrient-use by
farmers, Mr Threlfall said.
''It's not that simple."
The native algae had been found in waterways far away from
farming before and the blue/green algal bloom was last seen
in Lake Waihola in 2002.
The conditions at Lake Waihola had not changed since last
year so council staff were unsure why it had returned this
year, he said.
''We don't know why it blooms."