The Far North District Council is to erect signs at Lake Rotopotaka (Coca Cola Lake), behind Tokerau Beach, warning that people and animals, in particular dogs, should avoid contact with the water after sampling by the Northland Regional Council found it unsuitable for swimming.

The algal bloom that now covers substantial part of the possibility of exposure to cyanobacteria, which can cause symptoms including skin rashes, nausea, stomach upsets, tingling and numbness around the mouth or tips of fingers.

Anyone who experiences any adverse symptoms after contact with contaminated water should call a Northland DHB health protection officer, or Healthline (0800 611-116), and visit a doctor immediately.

Boiling does not remove toxins, and drinking contaminated water should be avoided at all times.