A Clutha District Council spokeswoman said contractors responsible for the work last week advised the council of the delay.
The MacLennan bridge connects the Papatowai Highway over the MacLennan River. It was closed in February and expected to open by Easter. It is now not expected to reopen until May 12.
In a letter sent to residents in the Papatowai area, SouthRoads took responsibility for the delay and said it had not achieved the expected ``productivity'' on the project.
``There had been hold-ups in sourcing the required high-grade timber materials,'' the letter said.
The spokeswoman said the council was disappointed by the delay.
``Due to the bridge having a restrictive work area, it has been difficult to simply add more resources to speed up the work,'' the spokeswoman said.
The council was also aware the closures were an inconvenience to local and visiting drivers.
The detour around the bridge added an estimated 30 minutes to Papatowai via an additional 17km of road.
The council thanked everyone for their patience so the necessary work could be done.
The delay in the MacLennan bridge project also impacted on the timeframe for the repairs to strengthen the Tahakopa Valley Rd bridge.
The Tahakopa bridge will now be closed from May 15 until June 23.
