Donegal County Council has been refused planning permission for a regional landfill site at Meenaboll, near Glenveagh National Park.
An Bord Pleanála said it was "not satisfied . . . that the proposed development would not result in an unacceptable risk of environmental damage due to landslides, with consequent significant adverse effects . . . in terms of water pollution".
It also ruled that the proposed landfill, given its proximity to Glenveagh, "would constitute an unwarranted intrusion into the landscape and would potentially have significant adverse effects on protected and endangered species".
Upholding appeals by An Taisce, local environmentalists and the heritage section of the Department of the Environment, the board concluded that the plan would be "contrary to the proper planning and sustainable development of the area".
An Bord Pleanála's ruling was in line with the recommendation of the planning inspector who dealt with the case. However, it ran counter to an Environmental Protection Agency (EPA) decision to issue a waste management licence for Meenaboll.
Gerry Mulgrew, spokesman for the local objectors, warmly welcomed the board's decision, saying it "calls into question the independence of the EPA", whose inspector's report on the proposal had "ignored every point, about 40, in 10 different submissions".
"Our ultimate concern about Meenaboll has always been that the location was so obviously wrong and could only lead to an environmental disaster. Everyone who visited the site could clearly see that - all except Donegal County Council."
The proposed landfill, in an upland site near Letterkenny, would have been located in view of Errigal mountain and Glenveagh National Park and would also have been visible from the peaks of the Bluestack Mountains, popular with hillwalkers.
One of the main points made by the objectors was that leachate from the landfill could contaminate Lough Gartan, from where Letterkenny draws its public water supply.
There were also concerns that it could pollute the Finn and Lennon rivers.
The county council had planned Meenaboll as a regional landfill site, with a capacity to take 24,000 tonnes of municipal waste a year for 20 years. It was identified as a suitable site for such a facility in the regional waste management plan, adopted in 2000.
County manager Michael McLoone yesterday said the board's decision to refuse permission was very disappointing and would have serious implications for the council's capacity to provide for sustainable waste management in Donegal.
He said council officials would examine the Bord Pleanála inspector's report before deciding the next steps that need to be taken and he was recommending that its consultants should make a presentation on their response.