The Department of Agriculture, Environment and Rural Affairs (DAERA) has issued a statement on the fish kill incident in Claudy, County Londonderry.
The incident occurred in a tributary of the River Faughan.
A spokesman for DAERA said: “The Northern Ireland Environment Agency (NIEA) is continuing to investigate a major fish kill near Claudy. NIEA was first alerted to this incident on Monday evening and staff have been investigating since then.
“Staff from Loughs Agency, who are leading this investigation, are working closely with NIEA to quantify the number and species of fish affected, and the cause, which is suspected to be silage effluent. The latest available figures are that in excess of 1,000 fish of a range of species have been killed over several kilometres of river. Assessment of the fish kill is still ongoing. Staff from Loughs Agency have commenced electro-fishing and further detailed investigations to help to narrow the area from where the pollution started, whilst NIEA staff are carrying out a river walk try to source the cause of the pollution.
“If anyone has additional information about this pollution incident they can report this through NIEA’s 24-hour Pollution Hotline (0800 807060).”