An angling club has said a fish kill in a County Down river is the “worst environmental event” it has ever witnessed.
The Department of Environment (Daera) said 5km of the Kilkeel River in the Mournes area was impacted and they are investigating the incident which took place last week.
A spokesperson said trout, eels and lamprey were all confirmed dead.
Kilkeel Angling Club said the scale of the destruction was “devastating”.
Daera said “no active discharge was found” but “a definite line of enquiry is being followed regarding the source of the pollution”.
They added the number of fish killed remains to be confirmed.
Kilkeel Angling Club said “several generations of juvenile fish have been wiped out”.
“The incident could have serious consequences for the river’s salmon and sea trout populations for many years to come,” added the club.
“The Kilkeel River is an important local watercourse and wildlife habitat.
“Our club and its members have invested a great deal of time and voluntary effort in protecting and improving it, which makes the extent of this damage particularly difficult to comprehend.”
