SINN Féin Councillor Paul Fleming commenting following the news that over 1,000 fish have been killed by pollution in the River Faughan.
Councillor Fleming said: “It’s important that a full investigation is carried out to find the source of this pollution.
“Sinn Féin is committed to the prevention of pollution of Ireland’s water systems and rivers.
“Anyone who is found to be in breach of operational standards and environmental regulation must be investigated and prosecuted.”
This afternoon the NI Environment Agency said it believed the fish kill had been caused by silage effluent leaking into the Faughan River.
The toxic pollution was found at two areas – one near Claudy and one near Campsie.
Norman Henderson, from the Northern Ireland Environment Agency (NIEA), said it would take many months for the river to recover.
“I’ve seen worse fish kills but this would be towards the top end,” he said.
“It’s a significant kill, there’s no doubt about that. The latest figures we’re getting from the Loughs Agency is several thousand dead fish,” said Mr Henderson.
“We believe it is agricultural and we have narrowed it down to a particular part of the river and we are following a definite line of inquiry.
“It would obviously have to be a fairly strong effluent, something like silage.”
But there was no risk to public health, said Mr Henderson, who is a senior scientific officer with the NIEA.
“The river is safe in the sense that it has affected the fish but there is no risk to drinking water,” he said.
“The river will recover, its difficult to put an exact timescale on it but you’re certainly talking many months or possibly longer before the river is back to normal.
“Certainly the overall stocks in the river will still have taken a hit.”
The River Faughan is an important waterway for breeding salmon.
It also contains sea trout, trout, lamprey, eel and many other fish species.