The ESB will look at other options to supply additional electricity to Co Donegal following An Bord Pleanala's rejection of a 110Kv power line on scenic amenity grounds.
An ESB spokeswoman said it was studying the board's ruling and would examine the planning inspector's report when it became available later this week.
She said the appeals board had been examining the "difficult issues" raised by the proposed power line for the past six months, following an oral hearing in Dungloe last November. The hearing, conducted partly in Irish, lasted three weeks.
An Taisce and a number of local people had appealed against Donegal County Council's decision in May of last year to grant planning permission for the project, which would have affected almost 100 townlands in the north and west of the county.
In a detailed explanation of its reasoning, the board noted that the objective of the National Development Plan was to improve the infrastructure of the Border, Midland and Western Region.
It said the further economic development of Co Donegal was dependent, among other factors, on the provision of an adequate and reliable supply of electricity.
However, the board said, the line would cross many areas of scenic value along its route, including areas designated in the Donegal County Development Plan as highly scenic landscape areas or areas of proposed natural heritage designations.
And although it recognised the need to provide more power for Letterkenny, considered to have significant growth prospects, the board said it was "not satisfied, having regard to the significant adverse environmental effects" that the ESB's plan "constitutes the optimum solution to satisfy the electricity supply needs of the area.
"Accordingly, it is considered that the development as proposed would contravene materially the current Co Donegal Development Plan and would be contrary to the proper planning and development of the area." In a separate ruling, the appeals board refused planning permission for a 110Kv substation in the townland of Arduns.
The Green Party has called on the ESB to reconsider its proposal for 84 pylons around Cork Harbour, in view of the decision to refuse permission for pylons in Co Donegal, writes Dick Hogan.
The Cork Anti-Pylon Group has waged a six-year campaign against the proposal and has suggested the problem of unsightly pylons could be overcome by placing high voltage cables on the harbour bed. The ESB claims this option could add millions of pounds to the overall cost.
The proposal is now being examined by a review group.