Fears of a major pollution event were mounting this week as the endangered pearl mussel showed signs of “extreme distress” on the Owenriff River in Conamara.

Local environmental campaigner John Gibbons said there were clear signs of pollution on the river last Thursday morning when he went down to carry out water testing, and while the cause was unknown, it was clear that the protected molluscs were in danger on the Owenriff Special Area of Conservation (SAC).

“We do regular water testing to be sent off to Europe,” said Mr Gibbons who is secretary of the Corrib, Mask and Carra Water Protection Group.

“The pearl mussel is a mollusc – they stand in the gravel and only put up about one-third of their body to filter the water. If anything happens to them, they come up out of the gravel,” explained the Glengowla resident.

That was the sight he was met with on Thursday morning last, leading to an alert being sent to Inland Fisheries Ireland and Galway County Council.

The cause of this pollution event was yet to be determined, he said, but “over-farming” in the area has led to pollution of the river, with “nutrient run-off from farming” having led to algae growth in the past.

“We can’t have this continue. This is one of the most heavily protected species, the pearl mussel, under the European Habitats Directive,” said Mr Gibbons, and the Owenriff was regarded as the second-most important river in Europe for the pearl mussel.

The authorities were not taking seriously enough the threat to the river from over-farming, he said, “and responsibility for the protection of the river is ultimately with the County Council”.

A National Parks and Wildlife Service Officer visited the site on Thursday after the alert was raised, said Mr Gibbons, but other agencies were “not stepping up to the plate in general”.

“Coming three days later when the pollution has washed through and the damage is done is too late.” Inland Fisheries Ireland (IFI) didn’t arrive until Saturday.

Mr Gibbons said he had been involved in three different cases brought to Europe in the past, to protect the pearl mussel.

Lough Corrib Angling Federation were due to have a hearing with the Petitions Committee of the EU Court of Justice in Brussels on Tuesday, to highlight pollution and the infestation of noon-native pike on the Owenriff.

Mr Gibbons said its campaigners would do all that was necessary to protect the river and added that the greatest threat from agriculture was coming from a “small number of farmers”.

A small farmer himself, Mr Gibbons is a former trout hatchery manager and said failure to act on these pollutants would be the death-knell for the Owenriff’s precious pearl mussel, and to the trout hatchery on the river.

He called on the authorities to step up their efforts to enforce stringent EU regulations on protection of the river.

“We can have all the rules and regulations in the world, but they mean nothing if we don’t have inspection and enforcement.

“Our concern is that what happened last Thursday might be the first sign of what’s to come this summer and if that is the case, we will have major problems, whatever the pollutant is,” said Mr Gibbons.

Acting Director of Services with responsibility for Environment at Galway County Council, Kieran Coyne, confirmed to the Connacht Tribune that they were aware of the report of a pollution event on the Owenriff.

“Galway County Council is in communication with IFI in relation to this and IFI carried out a site inspection on Saturday. To the best of Galway County Council’s knowledge, nothing has been identified,” said Mr Coyne.

The Owenriff River Owenriff river rises south of Maam Cross and flows through Oughterard into Lough Corrib.