A GROUP ESTABLISHED to look into the large fish kill on the River Blackwater near Mallow in Co Cork last month has found no definitive cause.

A report released by the inter-agency group today estimated that up to 32,000 salmon and brown trout died when an unknown environmental irritant entered the water.

But, despite a significant investigation, it said the pollutant or source that caused the large fish kill could not be identified.

Analyses of deceased brown trout from the river found no evidence of disease, chemicals, pesticides or heavy metals.

The main conclusion from the report is that a waterborne irritant likely entered the river Blackwater at an upstream point 72 hours before the first mortalities were observed.

The report estimates the irritant dissipated quickly, explaining why it was not detectable in water samples and fish tissue samples, but The Journal previously reported that the State watchdog for the country’s rivers did not test the waters until the day after the first mortalities were observed.

‘Serious impact’

Minister Dooley, as the Minister of State with responsibility for inland fisheries, said that the fish has had a “serious impact” on local fish stocks and surrounding communities.

“Inland Fisheries Ireland estimate that up to 32,000 salmon and brown trout mortalities may have occurred,” he said.

However, he added that the report suggests the event was a once off.

“The investigation has now concluded. In this instance, a definitive cause could not be identified despite the extensive and significant investigation by members of the inter-agency group.”

The Department of Climate, Energy and the Environment have said that angling is continuing on the Blackwater, with no water quality issues currently detected and monitoring results from the Mallow water treatment plant to date have shown that the water is safe to drink.