Napier dog owners are being warned not to let their dogs in the water at a Napier park, after cyanobacteria was found in the pond.
The Napier City Council confirmed a blue-green substance found in the Anderson Park waterways was cyanobacteria, and have warned dog owners to keep their animals out of the water.
A council spokesperson said the area of most concern is in the pond near the model railway and lighthouse, and the creek near the Anderson Park Playground.
A vacuum truck has been used to get rid of the worst of the outbreak, and warning signs have been put up.
If your dog has come into contact with water at Anderson Park and is vomiting, has diarrhoea, has seizures, is weak or collapses, is disorientated, confused, is drooling or is struggling to breathe, to contact a vet immediately.
"Do not let your dogs drink from or swim in the pond near the model railway and lighthouse, or the creek next to the Anderson Park Playground," the spokesperson said.
Cyanobacteria can be fatal to dogs.
It can also be toxic to humans.
The Hawke's Bay District Health Board medical officer of health, Dr Nicholas Jones, asked people to take the precautionary warning signs seriously.
"The bloom is likely to be toxic to people and animals and people should stay away from the water.
"For humans, any contact with the water may cause vomiting, diarrhoea and skin irritations. Dogs are very susceptible to the toxin and should be kept away or on a leash."
Cyanobacteria are single-celled creatures that live in water environments. In slow moving, warm water they can multiply quickly, turning into an algal bloom.
Large numbers of cyanobacteria can also grow as mats on river and lake beds and these mats can sometimes detach and float to the surface.