River levels around the Bay of Plenty town of Edgecumbe are dropping but the town is still likely to be under water a day after the Rangitaiki River breached its banks, officials say.

The town of around 2000 was evacuated yesterday when the river broke through the stopbank at College Rd, turning some streets into rivers about 1.5-metres deep.

Whakatane district Mayor Tony Bonne says the evacuation was a combined effort from police, firefighters and the public, and went smoothly.

Most were now staying with friends and family, he told Newshub this morning.

"You've got to feel for the people. You see those houses... I spoke to a couple of old people that got off the trailer only in bare feet. They only just had time to move."

The breach would need to be fixed and then water in the town removed. Council staff would be inspecting flooded homes today to determine if they are habitable.

Millions of dollars had been spent on stopbank protection, and Tony says he wanted to know why it hadn't worked.

"This has gone like clockwork. It shouldn't have happened though, it's the thing that really gets you."

Some residents may need to be out of their homes for 72 hours.

State Highway 2 through the town and SH34 was closed by flooding and around 2200 in the wider region were isolated, the council says.

Aerial food drops will be made to them.

On Thursday police and the fire crews went house to house searching for anyone needing help evacuating, while welfare centres were set up at the Firmin Lodge in Kawerau and at the Whakatane War Memorial Hall.

Boats were also used to rescue some residents in areas that couldn't be reached by trucks.

Council engineers have reinforced at-risk stop banks with rocks and say they were able to reduce the river flow by keeping water back behind the dam at Matahina Lake.

Engineers would start looking at how they might fix the breach in the College Rd stopbank.

Prime Minister Bill English will visit the area this morning to assess damage.

Rainfall from ex-cyclone Debbie, which has drenched the country this week, has led to unprecedented river levels throughout the Bay of Plenty, and the council has called Edgecumbe a one-in-500 year flood event.

After three days of heavy rains and flash flooding the MetService is predicting fine weather for much of the country on Friday.

- AAP