Mallow, Co. Cork – An extensive inter-agency investigation into the mass fish kill that occurred on the River Blackwater near Mallow, County Cork, last month has concluded without identifying a definitive cause for the disaster.
A summary report released today by the inter-agency group, led by Inland Fisheries Ireland (IFI), estimates that up to 32,000 salmon and brown trout died after an unknown environmental irritant entered the water.
Key Findings of the Report:
- Cause Undetermined: Despite a significant and thorough investigation, the specific pollutant or the source that caused the mass mortality could not be identified.
- Irritant Suspected: The main conclusion is that a waterborne irritant likely entered the River Blackwater at an upstream location approximately 72 hours before the first dead fish were observed.
- No Detectable Trace: Analyses of deceased brown trout found no evidence of disease, chemicals, pesticides, or heavy metals. Investigators believe the irritant dissipated quickly, which explains why it was not detectable in water or fish tissue samples taken later.
- Serious Impact: Minister of State for Inland Fisheries, Timmy Dooley, acknowledged the “serious impact” the event has had on local fish stocks and surrounding communities, but added that the report suggests the event was a “once off.”
The Department of Climate, Energy and the Environment confirmed that angling is continuing on the Blackwater. Ongoing monitoring has detected no current water quality issues, and test results from the Mallow water treatment plant show that the drinking water remains safe.
The initial incident occurred in August, and the State watchdog reportedly did not test the waters until the day after the first mortalities were observed, raising questions about the time-lapse for initial response. The agencies involved have stated that the learnings from this incident will inform future approaches to investigating water body incidents across the country.
