The road to Totaranui was hit by massive slips in December and no date has been set for its re-opening.
The Nelson and Tasman councils will decide soon on priorities for recovery work following December's record floods.
Nelson mayor Aldo Miccio says Nelson's flood repairs will cost about $15 million, and Tasman's bill will be close to $25 million.
Mr Miccio says recovery projects will take up to 10 years to complete and the costs will be spread across that period.
More than 50 centimetres of rain fell in three days in some places, washing out roads, causing hundreds of landslips and leaving behind a mountain of debris.
About 70 families are still unable to return to their homes.
Mr Miccio says the repair bill in Nelson could add up to 1.5% this year's rates.
He says the city's water and sewerage systems and other infrastructure survived the 1-in-100 year event relatively intact.
Nelson councillors will work out priorities for flood recovery work later in February, he says.
Repairs to roads badly damaged by slips will be among the most expensive jobs.
The Totaranui road in Golden Bay is one of the major repair jobs.
The closure of the road has cut off some residents and the popular camping ground.
The Department of Conservation (DoC) campground is relying on campers arriving by water instead.
Manager Pam Mytton says people are treating it like an island holiday.
DoC is hoping the road can be re-opened in weeks, rather than months.
Another problem route is the road to Cable Bay, north of Nelson, that was cut off for several days.
One lane has been temporarily re-opened, but residents say the road may take up to a year to fully repair.
