One of Ireland’s biggest and best-known lagoons has become so polluted it would take “millions of euro” to reverse it, the authors of a scientific study have said.
The study, for the Environmental Protection Agency (EPA), indicates a “major collapse” in the health of Lady’s Island Lake in Co Wexford over the past five decades.
Ireland could face EU fines over the state of the lagoon as it is a priority area under the EU Habitats Directive.
Botanist Dr Cillian Roden, one of the authors of the study, said the eutrophication — which occurs when water becomes over-rich in plant nutrient — is so bad that the lagoon would appear as “glowing blue/green” from space.
“We feel like undertakers to Ireland’s natural heritage as we keep writing these obituaries,” Dr Roden said.
Nutrient levels would have to reduce by over 85pc to return Lady’s Island Lake to its state in the 1980s, said fellow author Dr Brendan O’Connor, of Aquafact Consultancy.
Lady’s Island Lake is a saline lagoon and pilgrimage site in Co Wexford and extends over 300 hectares. Named Cluain na mBan, or “meadow of the women”, in Irish, it is believed it was inhabited by female druids in pre-Christian times.
No improvement… will be possible without a large reduction in nutrient run-off from land
It was founded as a pilgrimage site in the sixth century by St Abbán and was the location of a massacre by Cromwellian forces in 1649. The annual August 15 pilgrimage dates back to 1897.
The lagoon is now so polluted it stands to lose many “specialised species” along with feeding grounds for migratory birds, the study says.
The cause of eutrophication is severe damage by nutrient over-enrichment, mainly from agriculture. This has resulted in harmful algal blooms and fish kills and so little oxygen that few species can survive.
Aquafact Consultancy was commissioned to carry out the study as part of the Coastal Lagoons: Ecology and Restoration research programme.
The results show a “five- to sevenfold reduction in nitrogen and phosphorus inputs to Lady’s Island Lake will be necessary to return the lagoon to its previous condition”.
The authors warned that “no improvement… will be possible without a large reduction in nutrient run-off from land”.
They suggested some amelioration may be possible by protecting the lake shoreline with tree planting, the use of artificial wetlands and the removal of nutrient-rich sediments, but warned that a full restoration could cost “millions of euro”.