The presence of blue-green algae in Okawa Bay has seen a health warning issued for the area.

Routine monitoring results provided by the Bay of Plenty have confirmed blooms of blue-green algae which are potentially toxic.

People are being advised not to come in contact with the water at Okawa Bay.

Medical Officer of Health Dr Neil de Wet says blue-green algae are present in Okawa Bay at levels which may result in adverse health effects.

He says it's advisable for people to avoid contact with the water.

'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 Okawa Bay advising potential lake users about the algal bloom. Monitoring will continue and any changes in advice will be communicated accordingly.”