Media release

Potentially toxic algae sighted at Lake Hayes

Thursday 28 May 2020

UPDATE 29.05.20 4:30pm: Good news ahead of the long weekend! The laboratory results are in, and confirms the algal bloom that is present in Lake Hayes is at concentrations that pose a low risk to human or animal health. We wanted to err on the side of caution while we awaited the laboratory results, especially with our four legged community members in mind. The warning signs will be taken down over the weekend. Learn more about algal blooms and what to look out for here:

During monthly state of the environment sampling, Otago Regional Council (ORC) staff observed an algal bloom at Lake Hayes, suspected to be a potentially toxic algae (cyanobacteria). Warning signs will be in place later today.

Exposure to toxic algae for humans may cause symptoms such as skin rashes, nausea, tummy upset, and tingling and numbness around the mouth or tips of fingers. Anyone experiencing health symptoms after contact with contaminated water should visit their doctor.

For dog owners, when a toxic algae alert is in place it is important that dogs are kept on a lead, out of the water and that they do not consume vegetation from the water’s edge. Signs that a dog has been poisoned by toxic algae can include lethargy, muscle tremors, fast breathing, twitching, paralysis and convulsions. It is important to treat the first signs of illness as an emergency and contact your vet immediately.

ORC encourages dog owners to familiarise themselves with toxic algae and know what to look for when exercising dogs in or around rivers and lakes. People should avoid any contact with the water while warning signs are in place.

Anyone who suspects they are experiencing a reaction due to contact with toxic algae should seek medical attention.

If you spot green algae in lakes, or dark mats in streams and rivers, contact ORC on our 24/7 pollution hotline, 0800 800 033.

For more information on potentially toxic algae, see LAWA’s factsheet: