A health warning has been issued for Lake Ohakuri and Lake Maraetai after tests confirmed a bloom of potentially toxic blue-green algae.
The blooms were confirmed through routine monitoring results provided by Waikato Regional Council.
Lake Ohakuri is south west of Ngakuru, while Lake Maraetai is in Mangakino.
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Favourable conditions for algal blooms in Rotorua
Medical Officer of Health Dr Jim Miller said the health warning meant people should avoid any activity which resulted in significant contact with the lake water.