Heavy rain fall has left families isolated in the Tapawera area, south-west of Nelson, with 20 households evacuated so far.
Evacuated families have taken refuge at the local rugby club rooms which has kitchen and bathroom facilities. Roads are blocked at Tapawera Baton Road between Twin Bridges.
Nelson City Council manager of public communications Penny Bloomberg said two households had been evacuated - a few families by helicopter with limited personal belongings.
Police and Civil Defence did not know when the families would be able to return home.
She said the police had taken the lead on the response and Civil Defence had set up an emergency station at Tasman District Council.
A Red Cross welfare team has been activated and will be established in Tapawera village to assist households affected by slips and flood.
Nelson Bays police and Civil Defence were asking people not to attempt to travel through the Motueka Valley. Anyone with concerns for the safety or wellbeing of residents were being advised to make contact by phone in the first instance.
The Motueka Highway and other roads had been blocked by slips with more slips likely as rain continues.
The Baton and Wangapeka rivers peaked earlier today and have receded slightly since.
Ms Bloomberg said the worst of the flooding had passed, though more rain was expected this evening on the eastern hills.
It was the fourth largest flood on record for the Baton River which received between 13mm and 17mm of rain in a 15 minute period earlier in the day.
Residents in the Motueka Valley who have evacuated their families are being asked to make contact with police to advise them of their safety.
NZPA