Wastewater treatment at 10 large towns and cities have failed to meet EU standards.
The latest EPA report shows the number of towns and villages discharging raw sewage each day has fallen from 29 to 16 since the beginning of 2023.
It says Uisce Éireann’s delay in delivering improvements at priority areas is prolonging risks to water quality.
Falcarragh, Ramelton, Moville and Rathmullan in Donegal are among the 16 included in the report.
Programme Manager at the Environmental Protection Agency, Noel Byrne says sewage is polluting our rivers and coastal waters.