Swimmers on the Kapiti Coast are being warned not to cool off at the beach or river this weekend after tests found high levels of bacteria.
The district council's environmental standards manager, Jacquie Muir, said recent rain on top of a long dry spell had flushed more bacteria into the water.
It was important people stay out of the water to avoid getting sick, she said.
Dog owners are also reminded keep their pets on the leash near Kapiti streams and rivers, because of the pockets of toxic algae in many areas as a result of the hot dry weather.