A bloom of potentially toxic blue-green algae has prompted a health warning for Lake Okaro, near Rotorua.
The health warning comes after routine monitoring results provided by the Bay of Plenty Regional Council confirmed a bloom of potentially toxic blue-green algae.
"The health warning means that people should avoid any activity which results in significant contact with the lake water," Toi Te Ora medical officer of health Dr Neil de Wet said.
Contact with algal blooms can cause asthma and hayfever attacks in susceptible individuals, as well as skin rashes, stomach upsets, and in some cases neurological effects such as tingling around the mouth, headaches, breathing difficulties and visual problems.
Signage will be erected at Lake Okaro advising potential lake users about the algal bloom.