The facility was originally expected to be open next month.
The latest delay comes after an announcement in April the project would be delayed because contractors had indicated the work would take longer than expected.
Otago Regional Council support services manager Gerard Collings said construction workers this week addressed the unexpected need to move the key water pipe, but in the course of these works, ground conditions were found to be not as expected.
The combined impact of these factors, as well as other challenges from location of underground wiring and infrastructure, is now being assessed.
"While the actual delays to siteworks are relatively minor, the timing of the project, in relation to the holiday season, will mean that the bus hub will not be operational until the new year," Mr Collings said.
"We're working closely with our contractors Fulton Hogan on an updated schedule that will minimise disruption as much as possible.
"Siteworks schedules are now being reviewed and will determine the updated timeline."
Directly affected businesses were being informed of the delay yesterday, he said.
"No decisions on how to best manage the delay will be made until their views are known."
