The decision by An Bord Pleanala to grant permission for housing at Laraghcon, in west Dublin, has been described as a disaster for Lucan and the Liffey Valley.
Cllr Derek Keating, an independent member of South Dublin County Council, said it was also a "severe blow to local democracy", given that more than 90 per cent of Lucan residents had voiced their opposition to the development in a local referendum.
Plans to build housing on the elevated Laraghcon site just north of the river Liffey had also been opposed by the Lucan Planning Council, the Lucan Community Council, the Liffey Valley Park Alliance Project, An Taisce and local residents' associations.
Cllr Keating said previous decisions by Fingal County Council to approve plans for the 72acre site had been successfully appealed by the local community.
"This time, An Bord Pleanala has even ignored its own earlier decisions on Laraghcon."
Among the many consequences were that Lucan village, already "at crisis point" with traffic, would be put under additional pressure. There were also questions as to how long Lucan bridge could sustain the traffic volumes it carries.
"But the most serious consequences of all are for the Liffey Valley," Cllr Keating said.
The board's ruling dealt a severe blow to a long-running campaign by 15 local and national bodies to promote the concept of a Liffey Valley National Park.
Cllr Keating blamed former Lucan councillors who had ignored the views of residents and supported "the worst decision ever taken by Dublin County Council" when it voted to rezone Laraghcon for residential development in 1993, against all planning advice.
An Bord Pleanala made its latest decision largely on zoning grounds.
Shannon Homes, which owns the site, now has full planning permission to develop 282 houses as well as a local distributor road, subject to complying with 20 conditions.
