The €10 million redevelopment of the Dursey Island cable car has hit a roadblock over fears about the impact of the project on nesting birds on the island.
An Bord Pleanála has written to Cork County Council about the project, raising concerns about the ecological impact of the scheme, which aims to increase tourist numbers on the island in the coming years.
The cable car has grown in popularity in recent years, increasing from 12,000 visitors in 2015 to 22,000 in 2018.
The Dursey Island cable car in West Cork is at the centre of a multi-million euro proposal that would see two independently operated cable cars in operation, as well as a visitor centre, café and improved car parking on the mainland side.
Announcing the project last year, Cork County Council claimed it would be "a strong economic driver for both the area and the wider West Cork region".
They said it would protect "the ecology of this area which is what makes this place so unique".
It was hoped the new system would be operational by 2023, with the current system remaining virtually unchanged for half a century.
However, the project could now be delayed after An Bord Pleanála requested further information on the impact of the expansion project on nesting birds on the island.
The board said it "is not satisfied" that the mitigation measures proposed to address the potential impact of increased visitor numbers on Dursey would be sufficient.
Specific concerns were raised regarding the impact of more tourists on the chough bird and its feeding habitat on the island.
It requested Cork County Council submit "a more precise and evidence-based calculation of the seasonal availability of foraging areas for the chough", as well as specific details of how a nesting site in a derelict building will be protected and how flush distances - the distance from a visitor that disturbs birds - would be managed.
Responding to the further information request, the Friends of the Irish Environment said the area at the extreme end of the island, where most tourists go, is also the main area where the choughs gather, feed and breed.
The chough population has declined by 30% since 2003. The species has special protection under national and EU law and is listed as a bird of conservation concern.
Friends of the Irish Environment Director Tony Lowes said, "The Board’s questions highlight the protection of the ecology which cannot be reconciled with the impacts of mass tourism."
Concerns were also raised about the traffic impact of attracting additional tourists to the island for those living on the mainland near the cable car departure point.
Cork County Council has until July 31 to respond to An Bord Pleanála.