Health warning issued for Lake Wiritoa


17 December 2018


Tests carried out by Horizons Regional Council have shown very high levels of potentially toxic blue-green algae at Lake Wiritoa near Whanganui.


These levels are similar to those recently found in Dudding Lake in the Rangitikei District where a warning is currently also in place.


Health warning signs will be placed at the lake and there will be regular monitoring. People are advised to avoid contact with the lake water until the warning is removed.


Blue–green algae may produce toxins that are harmful to humans and animals if swallowed or through contact with skin when swimming, water skiing or kayaking. Exposure to toxins may cause skin rashes, nausea, tummy upset and tingling and numbness around the mouth or finger tips.


Anyone who experiences symptoms following contact with contaminated water is advised to visit a doctor immediately and let them know you have been in contact with the lake water.


Blue green algae occurs naturally but can increase rapidly during summer, known as a ‘bloom’. If the water is cloudy, discoloured, or has small globules suspended in it, avoid all contact.


Boiling water does not remove toxins and drinking the water should be avoided at all times. Fish can concentrate these toxins and consumption should be avoided. If fish are eaten, the gut and liver should be removed and they should be washed in clean water.


Horizons Regional Council monitors blue-green algae in recreational lakes during summer. The public can access information and find out if any health warnings or cautions are in place, by visiting the Land, Air, Water Aotearoa’s (LAWA) website,