Uisce Éireann fined €4,000 for causing 'significant' Mayo fish kill

A DISCHARGE of raw sewage from an overflow tank in a south Mayo wastewater pumping station resulted in the death of nearly 1,000 fish in a Claremorris lake.

Uisce Éireann, the state owned water utility company formerly known as Irish Water, appeared before Castlebar District Court where they were fined €4,000 for allowing raw sewage to enter the Clare Lake in Claremorris on April 26, 2024.

The 'significant' fish kill in the lake located on the outskirts of Claremorris occurred after raw sewage from the Mayfield waste water pumping station in Claremorris overflowed from a holding tank and entered the water network close to the lake.

Local anglers reported the fish kill to Inland Fisheries Ireland (IFI) on the morning of April 26, 2024 after dead fish including perch and roach started appearing on the surface of the lake.

David Harrington, a senior environmental officer with IFI, who took the prosecution against Uisce Éireann, told the court that such was the level of the fish kill that it may take up to a decade before the number of fish in the lake return to the level before the discharge occurred.

The court heard that a hole in old underground piping resulted in ground water entering the network which resulted in excess water entering the stormwater holding tanks resulting in the discharge.

Uisce Éireann pleaded guilty to the charge of allowing a pollutant to enter the water contrary to the Fisheries Consolidation Act. In a statement following the court case Uisce Éireann claimed that since the incident they have invested €1.5 million in the pumping station to ensure a similar discharge does not occur.

“Uisce Éireann is committed to safeguarding public health and protecting the environment in all our activities. Following an overflow incident in April 2024 which regretfully resulted in a fish kill in the Clare Lake, Claremorris, we put in place a number of measures to reduce overflows at Clare Lake and ensure such an incident does not recur,” the statement read.

They added that infiltration works which saw an investment of €1.5m included the 'rehabilitation' of 2km of sewer pipelines in Claremorris town to reduce the volume of ground water entering Mayfield pumping station; replacement of foul pumps to increase throughput at Mayfield Pumping Station; and improvements to telemetry and monitoring at Mayfield and connection to the INTS (National Telemetry system).

“In addition, Uisce Éireann also recently completed works to reconstruct a section of sewer near Mayfield where significant ground water infiltration was occurring. Reinstatement works on site will be completed shortly,” the statement read.

The Clare Lake was described in court as a ' high public value amenity' where in 2016 IFI invested in wheelchair accessible angling stands around the lake. Mr Harrington explained that before the fish kill, up to 3,500 people would use the lake on a weekly basis for angling and other activities.

“As an environmental officer this is a worst case scenario from our line of work. It doesn't get any worse from that. It is such a small lake and the population of fish will take years to recover...we don't stock that lake so we will have to let nature take its course,” he said, adding that the number of anglers using the lake has significantly reduced since last April.

Mr Harrington said the investigation into the fish kill took two weeks to complete as more fish were being found dead on a daily basis.

Samples of the water were taken to determine the level of pollution. The biological oxygen demand which measures how much oxygen is taken from a watercourse by pollutant showed that upstream from the discharge point it was at 3mg per litre of oxygen which indicated a healthy water system.

The reading at the discharge site was 280mg per litre and this increased to 833mg per litre where the stream enters Clare Lake.

Mr Harrington said that Uisce Éireann were very co-operative when the pollution was brought to their attention and work was carried out to prevent further discharges. However, the court heard that after remedial work to a hole in the pipe failed, it resulted in another discharge on May 22, 2024.

Mr Harrington described this as an 'unfortunate event' and confirmed that there has been no further fish kills at this location.

Mr Jonathon Moore, counsel for IFI told Judge Fiona Lydon that this is the 15th prosecution that IFI has taken against Uisce Éireann for similar type offences around the state since 2019.

Ms Aoife Sheehan, counsel for Uisce Éireann outlined the steps the water utility company has taken to prevent a repeat occurrence and added that as a result of the investment, the capacity of the pumping station has been increased. She added that before this incident occurred, Uisce Éireann were investigating infiltration of the network and examining the underground pipes.

She asked Judge Lydon to take into account that early plea and the investment in the network when deciding on the sentence.

Judge Lydon imposed a fine of €4,000 and ordered Uisce Éireann to pay agreed costs of €7131,31 to IFI to pay for legal costs as well as costs into the fish kill investigation.