Plans for a housing development in Castlemartyr have been rejected because of the inadequacy of wastewater treatment facilities in the East Cork village.
The board said that the Environmental Protection Agency had already found that the existing wastewater treatment plant serving Castlemartyr was significantly in breach of emission limit values which affected water quality.
The development firm, Solas Partnership, had appealed the decision of Cork County Council to refuse a 10-year planning permission for the project.
It disputed claims by council planners that there was uncertainty about plans by Irish Water to provide water services to the development.
It has originally sought to build 209 houses consisting of two, three and four-bed houses as well as a crèche, first-floor office units and playground.
It would have been linked with an existing housing estate at Gortnahoma More at the eastern edge of the village through two new pedestrian ways. However, the Solas Partnership subsequently scaled back its plans to 30 houses, the recommended limit for each new development in the East Cork Municipal District Local Area Plan.
Bord Pleanála said it was not satisfied that there was any certainty about when the existing constraints about wastewater treatment capacity could reasonably expect to be addressed.
Irish Water claimed there was capacity in the water network to cater for the first phase of 30 houses with projected full capacity by 2024.
An Bord Pleanála said that there was limited capacity at the proposed location of the new housing estate for development.
The board said that it could not be satisfied, based on the information provided that the proposed development would not have a significant effect on the Ballymacoda Special Area of Conservation because of the wastewater issues which precluded it for granting planning permission for the project.
It also expressed concern at the lack of clarity about part of the location which is identified as a high-risk area for flooding.
Several residents also made submissions opposing the development because of the proposed pedestrian connections through the Castlemanor estate.