There has been significant damage to SH63 in the Bankhouse area, west of the Waihopai Bridge and Renwick, due to the heavy rain.
Contractors are currently clearing gravel to try and get the road reinstated at least to one lane but the road will probably remain closed from Renwick to Wairau Valley township for the remainder of the day.
Marlborough Roads Systems Manager Wayne Oldfield said he recognised it was vital for those communities to be reconnected as soon as possible.
Marlborough Emergency Management is hoping to have the Bankhouse section open as soon as possible with a single lane and stop/go or traffic signals.
A crane has been used to help deal with a power pole damaged by flooding and Marlborough Lines was working to reconnect power to homes.
Once the crane work is finished crews will continue inspecting the road between Bankhouse and Wairau Valley Township and the washout at Anderson Spillway.
Elsewhere contractors are continuing to assess damage and respond to incidents across the roading network.
While the weather has improved areas remain flooded and the ground is saturated with potential for further slips and flood closures.
Flooding continues to affect roads across the top of the South Island and surface water can be expected. Drivers are urged to use caution and drive to the conditions.
People are encouraged to check for updates from local authorities for the latest information, and to report any state highway faults or damage to 0800 4 HIGHWAYS (0800 44 44 49).