Flooding worst in 150 years

About 25 houses in Golden Bay were struck by a 150-year flood, farmers are cleaning up, roads are closed and bridges washed out after yesterday's fast-moving storm brought heavy rain and strong winds to much of the country.

The extent of the damage to roads and infrastructure in Tasman and Marlborough is still unclear, but councils and civil defence staff in the regions met this morning to plan the clean-up.

State Highway 1 is still closed at the Rakaia Bridge in Canterbury, and a detour is in place.

Flooding also closed SH6 between Havelock and Canvastown, where an 80-metre slip is blocking the road. Contractors began work about 5am and aimed to open one lane by tonight.

Traffic between Nelson and Marlborough was redirected along SH63. "It's a really big slip and a really narrow, difficult area to work in, so that's why it's taking so long," Marlborough Civil Defence spokesman Mark Wheeler said.

Many roads throughout the Marlborough Sounds were also closed by slips, and it would take up to two days to clear some of them.

Drenched campers were forced to flee at Pelorus Bridge campground, 59km north west of Blenheim, as the river surged through the campground, lifting a caravan and tents before receding yesterday.

Other parts of Marlborough were also badly hit, including the Rai Valley, Canvastown, Northbank and the Marlborough Sounds.

One site in the Sounds measured 230mm of rain in 24 hours, and there was extensive flooding of small rivers and streams, Mr Wheeler told NZPA.

About 20 people had been stranded and were being cared for by locals.

Farmers were worst affected in the Pelorus area, and last night the Marlborough Rural Trust was trying to get generators to dairy farmers.

In Golden Bay at the top of the South Island, the Aorere River reached record high levels in the worst flooding to hit the region in 150 years.

The river can normally be forded on foot during summer, but was flowing at 3500cu m per second at the peak.

The 100-year-old Salisbury Swing Bridge and the James Bridge were swept away, and the river had changed course in the lower Aorere Valley, Tasman District Council spokesman Chris Choat said.

It was unclear at this stage whether people were cut off, but 25 houses were affected.

Power was restored through Golden Bay about 11.30pm yesterday, but many farmers were still struggling to start milking again as buildings were damaged and some stock needed to be rounded up.

Stock losses were not as bad as first thought.

Staff from the Ministry of Social Development, Federated Farmers, volunteers and other groups were establishing what aid was needed.

About 40 trampers stuck on the Heaphy Track in two huts at the Collingwood end of the track were likely to leave the park today.

Department of Conservation staff were inspecting the condition of the track. Wellington was hit by hurricane force winds yesterday and strong winds also blasted many parts of the country.