Tidal and saltwater waterways do not appear to be affected at this stage.
Anderson Park was not "full of dead birds", the council said. Many species continued to use the waterways without effect.
NCC staff had also noticed some of the warning signs at Anderson Park have repeatedly been thrown into the water. The council said it would like the behavior to cease.
Owners of dogs registered in Napier who have supplied email addresses will again be contacted via email.
Dog owners should contact a vet immediately if their dogs show the following symptoms after drinking from, swimming or paddling in water: vomiting/being sick, diarrhoea, seizures/fitting, weakness/collapse/unconsciousness, disorientation/confusion, drooling, or breathing difficulties.