A “significant fish kill” in a County Antrim river has been described as an “environmental disaster”.
Alliance Party councillor David Honeyford said he believed up to 1,000 fish had died from pollution.
The incident in Glenavy River was reported by a member of the public on Friday at about 08:30 BST.
Pictures seen by BBC News NI show hundreds of fish lined up along the river banks, as well as several buckets of dead fish.
An investigation remains ongoing to identify the “source of the pollution”.
Mr Honeyford, who represents the area on Lisburn and Castlereagh City Council described it as an “environmental disaster for the village”.
‘This affects everyone’
Mr Honeyford, who visited the site on Friday, said he estimated 1,000 fish had been killed based on the number recovered from a small section of the river.
“Those in the buckets are from less than a 100m stretch of the river,” he told BBC News NI.
“The river feeds into Lough Neagh, which supplies drinking water for us, this will affect everyone,” he added.
The councillor said pollution has been a “recurring problem in the river over the years” and believes those responsible need more than a “slap on the knuckles”.
- ‘Major’ Glenavy fish kill confirmed in 2014
He called for “substantial fines” to be imposed on those responsible.
A spokesperson for the Department of Agriculture, Environment and Rural Affairs (DAERA) confirmed it and the Northern Ireland Environment Agency (NIEA) responded to a water pollution report on Friday.
The spokesperson said the NIEA immediately deployed a water quality inspector to the area to confirm the report and assess the environmental impact.
“A significant fish kill” was confirmed and DAERA Inland Fisheries staff were informed.
The spokesperson added that a joint NIEA and DAERA Inland Fisheries investigation remained ongoing to identify the source of the pollution.