The High Court has ruled that Aer Rianta breached its planning permission for a new terminal at Shannon Airport.
The court ruled Aer Rianta did this by discharging 300,000 cubic metres of untreated sewerage into an estuary over the past three years.
Mr Justice William McKechnie refused to grant an injunction restraining the company from continuing to engage in the practice - a move which could have closed the airport.
The case was taken by Independent Kerry Councillor, Billy Leen, who argued the practice should be halted pending the completion of a sewerage treatment plant because the estuary was a candidate EU Special Area of Conservation.
Speaking after the judgement, Councillor Leen said he felt 'vindicated' because while he did not secure an injunction, a finding of breach of planning permission had been secured and he was awarded his legal costs.
Mr Justice McKechnie declined to grant the injunction, in part, due to the inconvenience it would cause the travelling public, but left it open to Councillor Leen to return if water quality in the area deteriorated significantly.
Aer Rianta said it 'welcomed' the judgement and 'fully accepted its responsibilities' in relation to the matter.
A spokesman said they were spending €2.4 million on developing a treatment plant, had engaged in detailed consultations with Clare County Council and hoped to complete construction before the end of next year.
Aer Rianta opened a new terminal in March 2000, but the permission granted by Clare County Council was conditional on a sewage treatment works being put in place.
Aer Rianta has claimed that its intention has always been to put the sewage works in place, but that it had not happened due to 'matters outside our control'.
