However, the roundabout was on schedule to be opened about the end of the year, Waka Kotahi NZ Transport Agency project managers said.
The taxpayer-funded roundabout is being built on State Highway 6, where it turns off to Albert Town and Haast, opposite the intersection with Riverbank Rd.
Last month, project managers Brendon French and Richard Hilliard updated the Wānaka-Upper Clutha Community Board about the project since construction began in February.
"We had a slight issue with a Chorus cable that has to be relocated but that is going to happen in the winter ... and we are aiming to have it open by the end of the year, so long as the Chorus component goes as planned," Mr French told the board.
"So — the only thing that came from left field is that cable? That sounds quite significant," board chairman Simon Telfer said.
"It was the main West Coast lead," Mr French admitted, as board members burst out laughing.
"Yes, not a little one."
Mr Telfer suggested project managers should have identified the issue in advance.
"It is substantive."
"It was," Mr French replied.
Chorus spokesman Steve Pettigrew confirmed Waka Kotahi had asked Chorus to move its cable connection on the West Coast at the Mt Iron intersection in Wānaka.
"Chorus has given Waka Kotahi a quote for the work, which will start once the details are agreed upon.
"It is unclear whether there was any damage to the cable during work in the area.
If the link was damaged, it might have caused an unplanned network outage.
"However, because Chorus has resilient links in the South Island, a complete loss of communication is unlikely.
"Chorus’ work to relocate the cable can happen whenever Waka Kotahi decides, and the cost of this work is confidential.
"The time taken to move the cable will depend on Waka Kotahi’s schedule for the work," he said.
Meanwhile, construction of the roundabout is continuing "off line", beside State Highway 6.
Waka Kotahi project managers said more significant disruption to traffic would occur in winter, including disruptions to crossings.
The project managers would give a presentation at a board workshop in May.
