Lough Talt boil water notice officially lifted

On the 26 November 2020, Irish Water announced the removal of the boil water notice on the Lough Talt water supply. The lifting of the boil water notice benefits 13,000 people in Tubbercurry, Ballymote and surrounding communities including Annagh, Aclare, Bellaghy, Curry, Lavagh, Ballinacarrow, Carrowneden, Kilmacteige and Coolaney, Cloontia, Doocastle and Quarryfield.

Communities in the region had been living with boil water notices since January 2019 following detection of cryptosporidium in the public water supply. The existing treatment was inadequate to address this risk. The Water Treatment Plant (WTP) is also on the Environmental Protection Agency's (EPA) Remedial Action List (RAL) due to unacceptable levels of trihalomethanes (THMs) in the water supply network. Extensive upgrade works at the Lough Talt Water Treatment Plant providing a robust disinfection barrier for cryptosporidium has enabled the boil water notice to be lifted.

The existing process has been replaced by filtration followed by UV disinfection which eliminates the cryptosporidium risk. The works also included implementation of secondary disinfection using monochloramination which mitigates against the formation of THMs in the network. This was the first use of monochloramination by Irish Water, and only the second known implementation in the Republic of Ireland. The conversion to chloramination allowed Irish Water to decommission at least twelve chlorine booster stations.

The Lough Talt source is an upland lake and has been used as the source of raw water since the 1950s. It's designated as part of the Lough Hoe Bog Special Area of Conservation (SAC) and the River Moy SAC. During periods of extended dry weather the lake level drops as a result of the abstraction operation, which impacts the Lough Hoe Bog SAC, potentially endangering the protected Geyer’s whorl snail.

The lifting of the boil water notice is the culmination of 14 years work by RPS on the Lough Talt supply scheme including the preparation of a preliminary report, Water Abstraction Order, detailed ecological and hydrogeological investigations over a number of years and preliminary and specimen designs.

In 2018 RPS prepared the full planning application for the upgrade of the existing WTP at Lough Talt including all hydrological and ecological assessments and reporting to inform the Habitats Directive 92/43/EEC Article 6(3) Appropriate Assessment (AA) and Article 6(4) Assessment of Alternative Solutions, Imperative Reasons of Overriding Public Interest (IROPI) and Compensatory Measures assessments to be conducted by the public authorities. In May 2019, Sligo County Council granted planning permission, resulting in the first project to be granted planning under the Habitats Directive Article 6(4) IROPI process in Ireland.

RPS also prepared contract documents for Irish Water and are administering the contract on their behalf which is entering its final stages. It's expected that the scheme will also be removed for the EPA’s Remedial Action List (RAL) for THM non-compliance by early 2021.

About RPS

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