It is estimated that a fish kill in a midlands river now numbers over 1,000 fish following the discovery of what is believed to be silage effluent in the waters.

A stretch of approximately 6.5km of river is understood to be affected by the pollution.

The incident took place near Mountmellick, Co. Laois, on the Owenass River, and came to light last week on Friday, June 21.

Issuing a statement on the matter, Mountmellick Angling Association said: “The number of fish dead has increased since the first report on Friday. It now stands at one thousand plus and affects approximately five miles of river.

Wild brown trout at all stages of development, minnows, crayfish and salmon parr have been killed.

“Silage effluent is highly toxic and will also kill the macro invertebrates that the fish live on,” the statement concluded.

The relevant authorities are currently investigating the matter.

In a statement to AgriLand, a spokesperson for Inland Fisheries Ireland confirmed that a large fish kill occurred on the River Owenass and a minor tributary of the Owenass, near Mountmellick.

The species affected include primarily brown trout, according to the representative.

“Fisheries officers attended the site after receiving a report from a member of the public on Saturday, June 22, and immediately commenced an investigation to identify the source of the fish kill,” the spokesperson said.

While the investigation continues, it would appear at this early stage that silage effluent was the potential cause of the mortality.

“We can confirm that 1,000s of fish have been affected over a 6.5km stretch of the river.

“Inland Fisheries Ireland has a confidential hotline number to enable members of the general public to report incidents of water pollution, fish kills and illegal fishing: 1890-34-74-24; or: 1890-FISH-24.”