Thousands of tourists are still trapped in Golden Bay as rain caused slips, with medical supplies delivered by helicopter.
Civil Defence Minister Kris Faafoi and Minister of Agriculture Damien O'Connor joined Civil Defence director Sarah Stuart-Black to assess the damage in Nelson today.
The state of emergency in Nelson and Tasman remains in place, despite weather conditions having eased.
Local civil defence officials said Takaka was not as badly affected as anticipated.
Takaka Hill Road is extensively damaged. pic.twitter.com/9Gaq8JpMPx— Jo Moir (@jo_moir) February 21, 2018
There were some blind spots where they initially thought some people were trapped but they had sent teams out to check those areas.
Barges with food supplies were being brought in this afternoon and larger coastal barges would also be available in areas further out.
Takaka Hill was expected to be closed for several days.
Medical supplies have been delivered to a clinic in Golden Bay to help local supplies that were starting to get low due to the difficult access.
Emergency teams were also still on the ground in Riwaka - near Motueka - checking any flood damage to properties.
The emergency operations centre said the area on the eastern side of Takaka Hill was also flooded, and teams were currently door-knocking homes to check on residents.
The centre said flooding in Motueka appeared to have receded but people were being warned of possible contamination from sewage and stormwater overflows.
An Air Force N-H90 helicopter flew from Woodbourne to Motueka this morning.
Major General Tim Gall said the helicopter was taking welfare teams, police and equipment to Golden Bay.
The helicopter's first task this morning was to look for a group of 11 people reported to be trapped by slips on Takaka Hill, but they found no one needing immediate help.
Overnight, Defence Force staff helped Motueka residents escape fast-rising floodwater and helped the police clear roads in Takaka.
Meanwhile, Fonterra is planning to send a barge in to pick up product from its Takaka factory.
Fonterra's upper south island operations manager Chris Win said they needed to get a route out to Nelson as soon as possible to avoid wasting milk.
The owner of Fresh Choice in Takaka said people trapped in the Golden Bay township were panic buying groceries.
About 6000 people are trapped in Golden Bay, due to three slips on State Highway 60.
That is the only road in or out.
Roger Tait said people were queuing outside his store well before the supermarket's opening at 8am this morning.
Mr Tait said the supermarket currently had no milk, bread, or toilet paper, and dwindling supplies of canned goods and baby products.
A staff member was working with Civil Defence to include groceries on a barge that was expected to arrive in the town tomorrow.
He said people should not panic as the supermarket would hopefully be restocked soon with the essentials.
Earlier today, dairy farmer Corrigan Sowman said 100ha of his farm flooded last night, and he could not believe how quickly the river came up.
"The river peaked at about 980 cubic metres and normal flow for that river would be about 10 cubic metres for this time of the year."
During milking last night Mr Sowman and his father watched the water gauge climb.
"My father went out around the district to check and see what was happening and it was coming up like a wall of water."
They called the neighbours to make sure everyone knew what was happening and had stock was on higher ground, he said.
"Then we stood back and watched, we had the best part of 80 to 100 hectares of the farm go under water last night to a reasonable depth, including most of my maize crop."
Mr Sowman said he had never seen the river come up that high or quickly.
"It was literally like a wall of water, we were looking at the river at 80 cubic metres at about 4pm thinking it was amazing that we'd dodged the bullet ... an hour and a half later it was 600 cubic metres, and it just kept going up to 900 from there."
He said this morning the river had come back down.
Tasman mayor Richard Kempthorne told Morning Report there was probably about 6000 people trapped in Golden Bay, and they may need to be evacuated by sea if the main road cannot be opened quickly.
"Ferry and barge and for some people air travel, but we've got a dairy industry, we've got a population of 5000 people who need to eat and we've got holidaymakers, and there's probably hundreds if not more than 1000 people in there at the moment who probably want to leave and continue with their trip."
He said many were waking up to a nightmare, with houses flooded, communities cut off and farms underwater.
He said the worst rain fell on Takaka Hill, which closed after flooding caused slips in at least three places.
"The Takaka Hill looks very compromised, there's a couple of very large slips."
He said engineers would be going in first thing this morning to check it out, but drone footage appears to show some of the road had gone.
Philip Rasquin, who owns Bay Lodge in Pohara, said he was urgently trying to find ways of getting his six guests - who included honeymooners married at the weekend, a German couple and another couple from Slovenia - out of the area by plane.
He said he had been trying to book on flights on either of the two small air operators in Golden Bay, but all services appear fully booked.
"And we tried to book them on the flight out of Golden Bay, there were two airline options but to be honest they can't handle it for the moment. They have 30, 40 people and they have only two small planes we can use."
Mr Kempthorne said with the road closed, options including commercial ferry operators were being discussed for supplying the dairy farms in the area and transporting their milk.
Federated Farmers' Golden Bay President and Takaka dairy farmer Wayne Langford said the Fonterra plant in Takaka would cope with immediate production demands, but the problem would be if the road could not be re-opened within a week.
"So at this stage it's all systems go but certainly if the road is not cleared in a few days we could have some issues with processing."
Takaka dairy farmer and district councillor Paul Sangster said the township itself was lucky to suffer no damage.
"The river level, we've got a little bank at the top of the town that the community has put in, and it didn't top the little bank.
"We had no power for a good hour and a half or something and a crossarm broke on one of the poles, but that was the only damage so we're very lucky with that.
He said it was probably a smaller flood than hit the area when Cyclone Fehi passed through just over two weeks ago.
- Additional reporting supplied by pool copy.