An Taisce said the Environmental Protection Agency made "a landmark ruling" for nature conservation in Ireland following its refusal of a landfill site in Co Waterford.
The planning body echoed the EPA's assertion that a dumping ground would seriously affect a species of endangered freshwater pearl mussel in Lickey Lake.
Waterford County Council has until February 10th to appeal the agency's opposition to the development of a 50-acre landfill in Garrynagree, seven miles west of Dungarvan.