Round-the-clock monitoring of rivers, stricter industrial pollution licensing and training of volunteer “water wardens” are recommended in a report on Ireland’s largest fish kill.
The report by scientists in the EU’s joint research centre says valuable time was lost in raising the alert on the incident on Munster Blackwater last August, when up to 42,000 fish were killed.
This was exacerbated by an early focus on a fungal infection as the possible cause of the deaths, which meant the likely cause, a pollutant that spilt or was dumped in the river, was ruled out too quickly.
The poor condition of the river was also believed a factor, with several industrial facilities in the area in breach of their pollution licences. While direct involvement of these in the fish kill was ruled out, the report says rivers with high pollution loads, particularly when water levels are low, are less able to dilute any extra toxins.
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“This reduces the chance of fish surviving pollution events,” notes the report.
“Licences should be reviewed in the context of the low flows, and reduced capacity for dilution, observed in the catchment during the summer of 2025.”
The report was commissioned by Inland Fisheries Ireland (IFI) on behalf of the State to examine the response to the incident, which has caused long-lasting damage to the salmon and trout stocks in the Blackwater and the tourism and leisure operators dependent on them.
A multiagency investigation that followed was unable to determine what caused the deaths.
The EU report found that while the principal public agencies involved, including IFI, the Environmental Protection Agency (EPA) and Cork County Council, acted swiftly when notified of the incident, five or six days had passed before they were alerted.
It was “clear that the interagency response to major fish kills could be improved”, it says.
“It is recommended that major rivers [greater than 100km length] should have automated continuous monitoring with current and historical results available and downloadable online on a centralised website,” says the report.
Monitors should automatically flag changes in the chemical composition of the river as well as temperature, oxygen levels, algae and turbidity or cloudiness.
This data should be provided together with travel time estimates to show where a pollutant or problem is likely to have travelled from upstream and how soon it is likely to reach other locations downstream.
“Having continuous monitoring available publicly would also act as a deterrent to pollution, encourage compliance and thereby reduce the pollutant load on the environment,” notes the report.
It also recommends that one agency be designated to lead and direct the response to any incidents in future.
Nine Government departments, local authorities and public bodies were involved in responding to the incident in the different ways allowed under their remit.
The report notes that the alert was raised by members of the public and says the appointment of water wardens should be considered.
These would be local people, given training in basic fish and aquatic biology, water chemistry and sampling, who could respond immediately to capture evidence when an incident occurred.
Minister of State with responsibility for fisheries Timmy Dooley welcomed the report, saying it would help ensure that lessons were learned from the incident.
“The practical, forward-looking recommendations set out in the report provide a clear roadmap for action and improvement,” he said.
John Murphy of Salmon Watch Ireland also welcomed its publication and said the recommendation for continuous monitoring must be followed.
“It is deeply regrettable that such a devastating ecological event was required to trigger reforms long overdue,” he said.
