NAGOORIN'S Norton Road Bridge is closed to vehicles exceeding 4.5 tonnes, meaning access is restricted to light passenger vehicles travelling at 20km/h.
Gladstone Regional Council engineering services portfolio spokesperson Councillor Rick Hansen said the restrictions had been imposed following further inspection of the damaged bridge this week.
After January's flooding the river bed was significantly eroded and the structure sustained undermining of both piers exposing part of the ground anchoring system.
"Inspections have revealed that continual rainfall in the area has further undermined the bridge abutment," Cr Hansen said.
"Further assessment will be undertaken as the Boyne River level recedes and remediation works will start as soon as the water level drops and slows.
"Protective treatments will be a priority as the river recedes with these works possibly requiring bridge closure.
"As a key linkage for the Boyne Valley community to the wider Gladstone region it is vital these work, although inconvenient occur.
"Speed and load limitations may be necessary for several months until permanent bridge repairs can be made."
Cr Hansen said investigation into the pier undermining could take several months, particularly if the river remained at current levels.
Residents are reminded that jumping or diving from the bridge is strictly prohibited.
In addition to the normal underwater hazards, temporary repairs will involve placement of rock protection underwater around the undermined piers.