Exceptionally heavy rain in the Tararua Ranges has prompted Civil Defence officials in the Hutt Valley to activate an emergency plan for the Hutt River.
Hutt City Council says an alarm went off just before 5am on Monday when the level of the river rose too high.
However, it believes the worst is over. The rain has stopped and it's expected the river will start receding within the next two hours.
Block Road, which runs along the riverbank near the Melling Bridge and the riverbank carpark are closed.
There are gusts of 140km per hour on the Rimutaka Hill Road.