Toi Te Ora Public Health issue health warning for Lake Rotorua, Ohau Channel, part of Lake Rotoiti

The algae in Lake Rotorua, the Ohau Channel and the Okere arm of Lake Rotoiti could be toxic. Photo / Andrew Warner

Toi Te Ora Public Health has issued a health warning for Lake Rotorua, the Ohau Channel and the Okere arm of Lake Rotoiti.

The health warning is based on visual assessments and satellite imagery provided by the Bay of Plenty Regional Council which indicate an extensive algal bloom throughout much of these areas, a Toi Te Ora Public Health media statement said.

The bloom was likely to be of blue-green algae which could be toxic and it was important to avoid any activity which results in contact with the lake water, medical officer of health Dr Neil de Wet said.

Contact with water affected by blooms of blue-green algae could cause asthma and hayfever attacks.

It could 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 statement said.

"Algal mats and scum may also accumulate along the shorelines and so it's especially important that parents ensure that children avoid contact with these as they may be toxic," he said.

Dogs were particularly at risk and should also be kept away from the shorelines. Elsewhere in New Zealand there have been reported deaths of dogs that have eaten algae on shorelines, the statement said.

Sampling is underway to confirm the type of algae causing the bloom. Up-to-date information on health warnings for the Bay of Plenty and Lakes districts can be found on Toi Te Ora's website.