Safe swim spots

Horizons Regional Council routinely tests water quality at popular swimming spots in the Region between 1 November and 30 April each summer season. A traffic light colour code is used to indicate the health risk.

What do these results tell us?

• Coastal beaches are very low-risk swimming spots all the time, except for Kai-Iwi Beach, which has a higher risk due to contamination from the Kai-Iwi Stream after rainfall.
• Bacteria concentrations in Lakes Dudding and Wiritoa are very low all the time, but there is a potential health risk from toxins from blue-green algae blooms.
• Swimming spots in smaller rivers close to the ranges are low-risk almost all the time. The risk increases after wet weather, but only takes 24 rain-free hours to recover.
• Swimming water quality in the Region’s larger rivers is very dependent on the weather. No recent rain means low risk, but rain in the catchment can cause risky water quality for swimming and recovery takes 2 - 3 rain-free days.
• Extended low river flows provide favourable conditions for potentially toxic benthic mats of blue-green algae to grow in some rivers. This can result in river use warnings being issued by the Regional Council.
• The Mowhanau and Kai-Iwi Streams just north of Wanganui generally have poor compliance with the guidelines, but neither MidCentral Health or the Mowhanau Beach community are aware of any significant adverse health effects from existing use of the stream.