THE boil water notice which impacted around 8,000 households and businesses in June was issued because the River Ilen was too hot, Uisce Éireann has confirmed.

The operational fault at Ballyhilty Waste Water Treatment Plant near Skibbereen was down to a rise in temperature of the raw water supply, heavily sourced from the river.

Cllr Isobel Towse (SD) checked with the utility why the tap water was unsafe to drink, which resulted in the issuing of the notice at the time.

Cllr Towse was told in email correspondence seen by The Southern Star that ‘the turbidity was caused by the sludge blanket in clarifier No 2 rising and being carried over into the rapid gravity filters due to a rise in temperature in the raw water supply’.

‘The subsequent operational issues at the plant should have been resolved quicker,’ said Cllr Towse.

‘Nine days without drinkable water during a heatwave is not good enough. The effects were particularly severe for elderly people, and those who experienced power cuts at the same time.’

Cllr Towse added she sincerely hoped further operational controls will prevent similar issues during future heatwaves.

She added: ‘We also need to consider the ecological impacts of rising river temperatures, as warmer water can reduce oxygen and exacerbate algal blooms, causing additional stresses to the species present in the River Ilen.’

The Uisce Éireann boil water notice was issued on June 22nd and lifted on July 1st. It affected Skibbereen, Baltimore, Old Court, Church Cross, Kilcoe, Ballydehob, Schull, Drimoleague and surrounding areas.

Uisce Éireann was subsequently criticised for its lack of communication with elected representatives and for giving conflicting information about the lifting of the boil water notice to the public.

In March 2022, an upgrade to Ballyhilty Water Treatment Plant was completed as part of a €28m investment by Uisce Éireann, then Irish Water.

Last week, The Southern Star reported on suspected pollution and discolouration in the River Ilen and the Caol Stream in Skibbereen town centre, which a Cork County Council environmental officers later identified as algal bloom.

Uisce Éireann was contacted for comment but had not responded at time of going to press.