The ramp is the only one servicing the top half of the lake and now has no timeframe for its completion.
In June, Southland district councillors signed off on the $300,000 project which would sit within the footprints of the old ramp.
But after the council started work in July, senior project manager Phil Fahey said a request was made by Doc to have an archaeologist conduct a "stand-over" during excavation.
Mr Fahey said the delay had prevented the council finishing the job, which was about 65% complete, and had been further delayed by rising lake levels.
"That sort of blindsided us a bit.
"To be honest, I did consider writing to Doc and saying ... ‘leave us alone, we’re going to build this thing’."
Had the council been told it needed an archaeologist earlier, it could have organised it ahead of time, Mr Fahey said.
He described the assessment as "a waste of money" because it did not return any results and cost about $7500.
The comments were made at a council meeting on Wednesday, where several councillors expressed frustration at the delay.
But in response to questions, Doc explained why it required the assessment.
Doc operations manager Te Anau John Lucas said his organisation had sent a letter of authorisation for the ramp in 2022, but the council did not indicate it would go ahead with the build until July 2024.
By that point, an independent cultural heritage assessment had been carried out in the area just two months prior.
The assessment extended the area for potential artefacts from Te Anau Downs Stockman’s Hut.
"Like any natural or historic resource Doc manages, Doc is required to manage these resources when new knowledge arises even if consents have been granted," Mr Lucas said.
According to the council, work began on July 22 and was expected to take six to eight weeks, weather dependent.
A temporary ramp for lightweight vessels was made available, but has since been decommissioned due to high lake levels.
Issues with the old ramp included cracking and potholes.
