A precautionary evacuation is now underway for 64 homes in the Tokomaru Bay township, with authorities fearing an imminent dam failure due to heavy rain.
Roadblocks have also been set up to stop access to "areas of concern" around the Mangahauini River catchment and Tokomaru Bay.
Tairāwhiti Civil Defence Controller Ben Green said that there is an immediate risk of the failure of the debris dam upstream of the township due to the rain forecast for tonight.
"The incoming rain amplifies the risk given the ground is very unstable and saturated following the damage done by Cyclone Gabrielle," he said.
"The community is being evacuated to local marae or to stay with whānau in areas outside of the Mangahauini River catchment.
"Our Civil Defence team on the ground in Tokomaru Bay went door to door this afternoon. The safety of our people is paramount.
"We are bringing in experts to assess the dam site and provide options that might alleviate the risk."
Green says a community hui will be held at the Tokomaru Bay club rooms at 6pm tonight.
"We want to make sure everyone stays well-informed and that this evacuation is well-managed."
Police and local Civil Defence are supporting the evacuation.
Hawke's Bay authorities warn of evacuations
Down further south in Hawke's Bay, authorities are warning of further evacuations though rivers are not expected to burst their banks.
The region's emergency management controller, Ian Macdonald, said hydrologists were comfortable that "major rivers" would remain within their existing channels, but that authorities "are not taking any chances".
"Although we take confidence from the advice we are receiving, we are planning for all eventualities. That includes contingency plans for evacuations."
"Trigger points are being set for alerting at-risk residents and ordering evacuations.
"Civil Defence will issue an emergency mobile alert to any areas that may need to be evacuated. Evacuation orders will also be issued over the radio and all broadcast and online media," he said.
He stressed that people did not need to wait for an official evacuation order, and should move early if they did not feel safe at home.
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