Power has already been out for 14 hours in much of the Eastern Bay and there is no indication of when it will be back on, leading to calls co conserve water.
Whakatane District Mayor Tony Bonne said the power was a major issue because all four of the feeders that brought electricity to the district were out of action.
He said Horizon had not been able to say when power would be restored.
"This power outage could be a while," Bonne said.
"They are trying to still analyse the damage. There's significant damage over the whole network."
Horizon staff were trying to fix the problem and had a helicopter in the air trying to assess the damage. Neighbouring lines crews were also coming in to help.
"Hopefully we'll be able to flick the switch tonight, otherwise we'll be on the BBQ," he said.
Because there was no power the sewerage pumps were out so people were asked to conserve water and only flush the toilet when they had to, Bonne said.
"In Ohope, please don't even use the water if you can. We've got a major break at the top of Ohope Hill caused by a big tree coming out and ruining the pipe," he said.
Bonne advised people to look at the council's Facebook page or website for up-to-date details.
On the bright side, a large chunk of Edgecumbe would be open for people to return home from noon today.
Bonne said the southwest side of the town, south of the railway line would be opened and those in the dry zone would be allowed to remain in their homes.
He suggested people around the district stay home today and clean up around their properties.
There was limited access to Opotiki because of road closures and no access to Gisborne, he said.