Dog owners in some regions are being warned to watch out for toxic algae in rivers and streams.
Dog owners have been advised against letting their pets into the Hutt River. Photo: RNZ / Diego Opatowski
In Marlborough, council staff have spotted high concentrations of algae in parts of the Omaka and Wairau rivers.
Warning signs have been placed at some access points, but not all sites are monitored.
People walking their dogs should be alert for any riverbeds covered in a thick brown, or black, mat with a velvety appearance.
Dogs are attracted to algae's musty, earthy smell and but can die if they eat it.
People, especially children, should avoid touching or swimming near algae, as it can cause vomiting and skin irritation.