At least 5,000 fish have been killed following a reported chemical spill into the River Allow in Co Cork.

Approximately 2,500 liters of polyaluminium chloride, a coagulant used in wastewater treatment, was discharged from a state-owned facility into the River Allow, local publication The Corkman reported on Tuesday.

Ireland's Environmental Protection Agency (EPA) was notified on Sunday by Uisce Éireann, Ireland's state-owned water utility company, of a spillage of the chemical at the water treatment plant in Freemount, located to the north of Kanturk, which went into the nearby river.

Early indications are that approximately 2,500 liters of PAC were discharged into the Allow from a burst pipe at the Uisce Éireann plant, the EPA said on Tuesday, according to The Corkman.

In a statement to the Irish Farmers Journal on Tuesday, Uisce Éireann said it "fully recognizes the seriousness" of the incident and that it is fully cooperating with Inland Fisheries Ireland, the State agency responsible for the protection and conservation of freshwater fish and habitats. It has also notified Ireland's Environmental Protection Agency as well as the National Parks and Wildlife Service.

There is no impact on the quality of drinking water, Uisce Éireann noted.

On Monday, Inland Fisheries Ireland confirmed they were investigating the pollution incident that occurred on the River Allow, a tributary of the Munster Blackwater catchment at Freemount in Co Cork.

It occurred in a Special Area of Conservation, and the location is a noted spawning habitat for fish.

Juvenile Atlantic salmon, brown trout, lamprey, eel, stone loach, roach, and dace have all been discovered dead.

IFI staff were on the site on Monday to investigate the pollution event and assess the extent of the impact on the local environment.

Water samples have been taken from the river to gather evidence of the discharge, and source point of contamination, to advance any potential prosecution.

The river supports a population of freshwater pearl mussel, as well as being an abundant salmon and trout habitat.

IFI continues to urge the public to report instances of fish kills, water pollution, habitat destruction, or illegal fishing to its confidential 24/7 number, 0818 34 74 24.

⚠️ @InlandFisherIE is continuing to investigate a major fish kill in Co. Cork in which at least 5,000 fish have died.

📍 River Allow, tributary of the Munster Blackwater catchment at Freemount, north Cork.

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— Inland Fisheries Ireland (@InlandFisherIE) June 10, 2024

Sean Long, Director of IFI's South West Region, told RTÉ Radio's Morning Ireland on Tuesday that the IFI received a call on Sunday afternoon from the operator of the treatment plant advising of a spillage, prompting an IFI inspection downstream of the plant.

"Unfortunately he was met with a scene of devastation, really the only way to describe it," Long said.

"The river was littered with dead fish - trout, salmon fry, lamprey, eel.

"There were no insects, even flies, beetles, anything, any indicators of life. Anyone who has looked into a river will know it's a living, dynamic habitat - insects and fish darting about. But the river was effectively sterilized for roughly about four or five kilometers which was mapped out on Sunday.

"It's an ecological disaster for fish in the river at a time of already significant biodiversity loss.

"A follow-up inspection yesterday [Monday], they identified that up to eight kilometers of the river has been affected."

Long believes the "damage was done" either Saturday or Sunday, and diluted and washed down the river.