Three years after devastating floods in Tolaga Bay, Gisborne District Council says 20km of Mangatokerau Rd will be permanently closed.
"There are a number of washouts, there are a number of slips and dangerous undercuts that we don't want people accessing," Gisborne District Council director community lifelines David Wilson said.
"It would be millions of dollars to open that road," he said.
"It would need a huge geographic and engineering assessment to see whether or not we'd be even able to open the road.
"For some parts of it we would need to move it on to private land.
"For other parts we would have to look at how we were going to keep it so it could be maintained going forward.
"It would be a significant cost."
The road follows the Mangatokerau River, which carried logs and other forestry debris in the 2018 flood, threatening lives as logs inundated riverside residents.
Wilson said road washouts were upstream of residents and because Mangatokerau Rd led to forestry land that could be accessed through other forestry roads, there would be little inconvenience.
Gisborne District Council would maintain the closed road section of road downstream of residents.
"If the road washes out we have crews to maintain it for people to have access up to their properties," Wilson said.
Mangatokerau Rd landowner Paul Te Kira said he welcomed the road closure because it deterred poachers.
Forestry company Aratu, formerly Hikurangi Forest Farms, owns the surrounding land.
Last year it was fined $379,500 in the Environment Court for discharging forestry slash to the environment in the 2018 weather event.
It was ordered to make emotional-harm reparation to three residents, including Te Kira.
They were forced to climb on to their roof in the early hours of the morning when floodwaters rose to within 30cm of the ceiling in the Queen's Birthday weekend event.
The court heard a raft of forestry debris inundated the Mangatokerau River, battering their home beneath them while they waited for a helicopter to rescue them.
The Mangatokerau River flows into the Uawa River and brought slash to Tolaga Bay beach, blocking public access.
Forestry companies helped clear the beach, but last year another flood also brought a large amount of slash to the beach.