Toxic blue/green algae has been spotted in the Mangatainoka River in southern Tararua and the toxins produced by the algae, also known as cyanobacteria, can be harmful to people and animals if swallowed. Dogs are particularly sensitive and young children may inadvertently swallow algal material while playing in shallow water.
Horizons Regional Council is advising people to take care at popular swimming and recreational spots along the river during the current low flows as monitoring shows the amount of blue/green algae seen at some places on the river has climbed to a level where guidelines for recreational use are close to, or being exceeded.
Horizons water quality spokesman Barry Gilliland said although not all cyanobacteria produce toxins, it is best to take a precautionary approach before using the river.
"This means checking the river before letting dogs off the leash or jumping in for a swim. Look for slimy, dark coloured, musty smelling growths on river bed rocks," Mr Gilliland said.
"I can understand it is frustrating for users, but these growths are not uncommon in the river after a spell of fine weather and low river flows.
