Two farms in Co Laois and Co Kerry are being investigated by Inland Fisheries Ireland as the potential cause of major fish kills in rivers.

Thousands of fish were killed in an incident in the River Owenass and a minor tributary of the Owenass near Mountmellick, Co Laois.

The fish kill was reported to Inland Fisheries Ireland (IFI) by a member of the public on Saturday 22 June. It said thousands of fish were killed along a 6.5km section of the river, with brown trout understood to be worst affected.

Although the investigation is ongoing, IFI said “it would appear at this early stage that silage effluent was the potential cause of the mortality”.

Second kill

A second fish kill is being investigated in Co Kerry that is believed to be connected to agricultural practice.

IFI appealed to farmers to remain vigilant when harvesting silage and spreading slurry to avoid water pollution.

“Silage operations will be ongoing all summer and silage effluent has the potential to cause devastating pollution in streams and rivers,” it said.

“Such effluent is a significant polluting substance, starving fish and invertebrate life of oxygen, resulting in potentially massive fish kills if it enters a watercourse.

“With some rivers low during summertime with little dilution capacity, the effect of a small leak can cause huge damage.”

Last year there were seven fish kills relating to agricultural practice.

IFI hosts a confidential hotline for reports of water pollution, fish kills and illegal fishing, which is 1890 34 74 24.

IFI advice

1 Use round bales as the most environmentally friendly way to store silage.

2 If a silage pit is being used, ensure it is properly sealed to prevent leakage of effluent.

3 Spread slurry in dry weather and never when heavy rain is forecast.

4 Never spread slurry close to a watercourse, be aware of the slope of land to the watercourse.

5 Don’t clean tanks beside any watercourse.

6 Don’t allow any effluent or washings to enter any rainwater gully.