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St Annes Lagoon/Mata Kopae cyanobacteria warning

Permanent Health Warning for Algal Bloom at Mata Kopae/St Anne’s Lagoon.

Issued: 7 July 2022

Long term water testing indicates that potentially toxic cyanobacteria bloom periodically in Mata Kopae/St Anne’s Lagoon.

There is a permanent health warning advising people (and animals) to avoid contact with water at this lake.

Environment Canterbury continues to monitor the lake on a regular (quarterly) basis.


Exposure to cyanobacteria toxin may cause skin rashes, nausea, stomach cramps, tingling and numbness around the mouth and fingertips. If you experience any of these symptoms visit your doctor immediately and please let your doctor know if you have had contact with the lake water.

No one should drink the water from the lake at any time. Boiling the water does not remove the toxin.

Animals that show signs of illness after coming into contact with algal mats or scums should be taken to a vet immediately.

Fish and shellfish can concentrate toxins and their consumption should be avoided. If fish are eaten, remove the gut and liver and wash in clean water.

Further information on gathering Mahinga Kai can be obtained below.

https://www.cph.co.nz/wp-content/uploads/saf0112.pdf