The Dunedin City Council has been told reinstatement of the structure cannot occur as a permitted activity under coastal plan rules and a resource consent would be needed.
This might cost the council up to $250,000, as it would need to present a robust justification for the project.
The council had suggested consenting costs could be as cheap as $15,000, when it presented a range last year of $15,000 to $250,000.
The cheaper figure was based on the possibility a resource consent might not be needed and the council might instead be able to confirm it was allowed to repair the structure.
City council staff will now look to present options for councillors, possibly for a meeting at the end of this month. It seems likely one option will be to pursue a resource consent.
Dunedin Mayor Jules Radich has been a consistent advocate for restoration of a groyne or line of poles that, when planked together, prevent sand from being lost from the beach, he has argued.
Groynes have been a feature of St Clair Beach since the early 20th century, although they have periodically fallen into disrepair.
The mayor has argued photographic evidence is clear historically that sand accumulated after groynes were repaired and the beach eroded when they were allowed to deteriorate.
Mr Radich, who could not be reached for comment last night, has also argued remnants at the beach amount to an existing structure.
The Otago Regional Council, which is the consenting authority, does not agree.
Regional council consents manager Joanna Gilroy confirmed advice provided to the city council was reinstatement of a groyne at St Clair could not be considered a permitted activity under coastal plan rules.
"This is because the rule does not permit the reconstruction or replacement of those parts of a structure that have been absent for many years," Ms Gilroy said.
Back in December last year, the city council voted 9-5 to direct staff to "proceed with an application for a certificate of compliance for reinstatement of the St Clair groyne from the Otago Regional Council and if granted proceed with reconstruction in the most cost-effective manner".
It was then determined an application should be preceded by a pre-lodgement meeting.
Ms Gilroy said a "constructive" pre-application meeting with city council staff was held on February 16 this year. A resource consent would be required for the proposal, she said.
The proposed reconstruction was based on the original 1919 design drawings for a groyne at the beach. Double-row groynes were deployed in 1920 after advocacy from a Dunedin city engineer, but a single line of poles is proposed now.
The estimated cost of construction was $180,000 to $320,000, depending on the materials used.
Obtaining consent, if councillors choose to pursue this, could take up to a year.
