Flooding in North Otago's Waitaki Valley has been described as the worst seen in close to 40 years, and Waitaki District Mayor Alex Familton says the floodwaters have "scoured" rural roads.
"The shoulders of roads are dangerous. There's rubble about and there is still in places water on the roads, so people will need to be very, very careful driving."
It would be "costly" to fix the damage, Mr Familton told Radio New Zealand.
"I've seen some of the roads this morning and the water runoffs have caused a lot of damage - there's culverts that are blocked."
State Highways 82 and 83 were still closed, he said.
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Some rural residents were still cut off by flooded rivers.
"That is not serious and water levels are receding very quickly - in fact it's quite a pleasant day forming here.
"I can see today as a day where we'll regain our shape somewhat, but we still have to be somewhat wary because there'll be a cold break coming through later on tomorrow, which won't help the situation at all," Mr Familton said.
Yesterday, the State Hwy was closed from Otematata to Oamaru, with a lot of back roads closed due to major surface flooding and some were completely washed out and impassable.
The Otiake River bridge was under water and the Otematata river was flowing above bridge level. Kurow police Constable Craig Bennett said, in that area, water levels were higher than road markers on the side of the road.
Despite the closure of Grants Rd, one driver attempted to get through and found herself stuck in her vehicle.
"The water is not only deep, it is cold," Mr Bennett, who helped pull her out, said.
While some tourists were insisting on passing through, Mr Bennett said locals had been taking heed of Civil Defence media advice and acting responsibly.
In areas around the Otematata river, water was coming up to the door handles of 4WD vehicles.
"There's some pretty hard farmers that know that area well and are staying put," he said.
The Kurow Racecourse is being dubbed by locals as Lake Kurow.
"The amount of water that's flowing down is unbelievable," he said.
The old Waitaki Bridges were holding up reasonably well, with the worst flows south of Kurow.
"Meridian do a fantastic job of an even flow," he said.
State Hwy 82 was also closed - "jet boat only passable" - and the Waihao Forks Bridge was also over flowing.
Mr Bennett said he'd heard from a farmer in the area who hasn't seen flooding this bad for 35 to 40 years.
He said it had been great to see the locals come together in a time of crisis, with flooding no barrier for Meals on Wheels - which were delivered by tractor yesterday.
He urged people to follow Civil Defence advice and make sure they had enough provisions or contact emergency services.
The Otago Regional Council said, in a statement, most North Otago rivers have peaked, but are expected to remain at high levels for at least 24 hours.
- APNZ and Oamaru Mail