River users are urged to keep an eye out for blue-green algae blooms this summer Blue-green algae (or cyanobacteria) are naturally present in many New Zealand waters and often grow as mats attached to the riverbed. Some blue-green algae can produce toxins that are harmful to humans, dogs, livestock and wildlife. Dogs are particularly susceptible to poisoning. In humans, contact with blue-green algae mats through activities such as swimming can cause rashes, skin and eye irritation, allergic reactions, gastrointestinal upset and other effects. It's also not safe to drink water containing toxins from blue-green algae. Toxins are not removed by boiling, normal filter systems or disinfectants. What does blue-green algae look like? Blue-green algae mats are a dense dark brown/black colour typically found on large rocks, stones and cobbles. They may have a "dreadlock" appearance in slow moving parts of the river, and can come loose from the riverbed and form floating "rafts". When the mats die and dry out, they become light brown or white in colour. The longer, bright-green algae commonly found in rivers and streams are harmless and do not produce toxins. Who should I call if I experience a reaction? Contact your GP and advise them of your potential exposure. Who should I call if my animal is sick? If you are concerned about your animals, contact a veterinarian immediately. The toxins can affect dogs very quickly. Who should I call if I think I've seen blue-green algae mats? Please phone Greater Wellington on 04 384 5708 or your local council. Where can I get more information? Phone your local council, Regional Public Health (04 570 9002) or Wairarapa Public Health (06 370 5020). | 
