It will cost at least $10 million to clean up the forestry debris strewn across roads and properties by flooding in Tolaga Bay, the Gisborne District Council estimates.
Tonnes of slash washed down from forests in heavy rains on Monday morning, clogging bridges, roads and damaging farms and homes.
The council said it could take up to six months to investigate whether logging companies operating in the Tolaga Bay area had breached their resource consents.
The council estimates 1 million tonnes of forestry debris, known as slash, has caused at least $10m of damage to roads and bridges, during flash flooding earlier this week.
Gisborne District Council chief executive Nadine Thatcher-Swan said it was investigating how the slash was being managed, and if it found companies had not complied with their consents, the council would consider prosecution.
The logging companies were helping farmers clean up, but they were still trying to work out what do with with all the debris, she said.
Tairawhiti Civil Defence Emergency manager Louise Bennett said this morning they would conduct welfare checks on those stranded in Tolaga Bay. However, the helicopter mission was aborted due to bad weather.
They managed to visit only six properties before they had to turn back.
Ms Bennett said the residents they managed to get to were happy to see someone and to get a loaf of fresh bread, and milk.
"They're very resilient up there and appear to be coping well," she said.
Civil Defence said a large amount of debris, sludge, silt was still on the roads and the public should stay off all closed roads.
The council said contractors had been working around the clock to clear silt and debris from roads and many were now open.
Yesterday they pushed through the major slip on Arakihi Road, inland of Tolaga Bay, to find another slip on West Ho Road. Arakihi, West Ho, Kiore and Rangikohua roads remain closed.
Structural engineers are travelling from Whanganui to help complete bridge inspections.