Health warnings have been issued for both Lake Okaro and Lake Rotoehu.
Toi Te Ora Public Health Organisation has issued the warning because of the presence of blooms of potentially toxic blue-green algae.
Chief medical officer of health Dr Neil de Wet said contact with water affected by blooms of blue-green algae can cause asthma and hay fever attacks in some individuals. Contact can also cause skin rashes, stomach upsets, and in some cases neurological effects such as tingling around the mouth, headaches, breathing difficulties and visual problems.
"The health warnings mean that people should avoid any activity which involves contact with the water in Lake Okaro or Lake Rotoehu," de Wet said.
It is advisable not to paddle, wade, swim, or participate in any recreational activity that might involve any direct contact with the lake water.
