A serious water incident in Southland has seen at least one patient being treated, St John Ambulance has confirmed.
Emergency services were called to Lake Monowai, a large lake in the southern part of Fiordland National Park shortly after lunchtime.
Three St John units were sent to the accident and treated one patient who did not require transportation.
A helicopter was dispatched in response to the accident, fire crews from Blackmount were also called.
