Uisce Éireann admits polluting river at Clones plant

STATE-OWNED water utility company Uisce Éireann has been fined for causing a water pollution incident to a small river near Clones, Co Monaghan in May of last year.

The company, whose official address is at Corvill House, 24-26 Talbot Street, Dublin 1, had been summonsed to Monaghan District Court following an incident at the Clones Wastewater Treatment Plant, Legar Hill, Clones on May 12, 2025, which had resulted in the volumes of ammonium found in an adjacent stream to have been 1,500 times the permitted level at one point.

In a case taken by Inland Fisheries Ireland, itself a State agency, Uisce Éireann had pleaded guilty to causing deleterious matter to fall into the Legar Hill Stream, a tributary of the Finn River, contrary to Section 171 of the Fisheries Consolidation Act, 1959. Three similar summonses relating to throwing, emptying or allowing such material to get into the waterway were struck out on that basis.

IFI officer Jimmy O’Reilly told the court, in response to Kevin McElhinney, solicitor, prosecuting, that when he visited the sewage plant at Legar Hill on Monday, May 12, he noted that the adjacent stream was “very badly polluted”, and took three samples. The second of these showed levels of ammonium that were 560 times higher than the limit permitted by the plant’s licence; while in the third sample the ammonium content was 1,500 times in excess of that limit.

Photographs of the pollution were handed into court, some of which showed thick sewage fungus on the water downstream from the treatment plant.

Another photo showed that the plant’s trickle filter was “not functioning properly”, Mr O’Reilly stated. He said the filter should have been letting the water out over a broad area, but that it was just “piling up in the centre and flowing straight back out”.

He agreed with Mr McElhinney that the condition of the stream showed that, “something wasn’t working correctly for some time”.

The court heard that Uisce Éireann was fully co-operative with the investigation.

Addressing the court directly, counsel said the issue with the trickle filter had probably arisen because of temporary emergency measures that were put in place to identify a leak further up on the network. On the week before the incident, Uisce Éireann had been jetting (using high-pressure water), and carrying out a CCTV survey of the network to identify the source of this leak.

A pumping station was shut for this purpose and a load had been taken from it to the Clones Wastewater Treatment Plant, the barrister explained, adding that it was believed this additional load might have put pressure on the trickle filtering system and caused it to stop working. A partial blockage had been cleaned the next day.

Significantly, the barrister said it was accepted there were “issues with this plant being able to meet its emission limit values as per its licence”.

She also emphasised that Uisce Éireann itself had notified the Environmental Protection Agency in accordance with the terms of its licence.

This was a plant built in the 1960s and last upgraded in the 1980s, counsel stated. But funding had now been approved for the installation of new inlet screens, a storm tank and drying beds, and she said it was hoped all this would go some way towards the optimisation of the water treatment.

Judge Gerry Jones was told by Mr McElhinney, prosecuting, that the maximum fine for the offence before the court was €5,000, and that costs were also sought.

Judge Jones imposed the €1,500 fine as stated.