Europe's highest court has ruled that the Government broke EU law by authorising a landfill in Wicklow despite knowing that potentially dangerous pollutants would seep into the Avoca river.
In a judgment yesterday the European Court of Justice (ECJ) also criticises the Environmental Protection Agency (EPA) and Wicklow County Council for not adhering to EU laws protecting groundwater.
"Ireland, in choosing for the Ballymurtagh landfill the method of diluting and dispersing leachate, has failed to take all the technical precautions required," ruled the ECJ, which noted the presence of heavy metals such as cadium and phosphorus at the Ballymurtagh landfill operated from the 1980s by Wicklow County Council.
The court found that the Irish authorities had not complied with the EU groundwater directive because they had decided not to seal the base of the landfill - on the site of a disused mine - despite the presence of the pollutants.
Instead, pollutants were allowed to leach into the Avoca river, a decision taken in part because the river was already polluted.
It found that the EPA's decision to grant a waste licence in 2001 to the Ballymurtagh municipal landfill was also in contravention of the directive.
It said a comprehensive study into "the risks of pollution and degradation of the quality of the groundwater entailed by the discharge of pollutants" had not been carried out by the agency. The judgment is just one of several outstanding cases at Europe's highest court related to water pollution in the Republic. In March the commission issued a final legal warning to the Government over its failure to abide by EU law to provide clean water supplies to its citizens.
The warning alleged that more than half of private group water supplies in Cavan, Kerry, Leitrim, Mayo, Donegal and Sligo breached the EU's E.coli standard in 2005.
It said animal waste, defective septic tanks and the absence of proper treatment were the principal causes of the high levels of E.coli bacteria.
However, the ECJ dismissed a separate case brought by the commission against the Republic yesterday.
The commission had claimed that there was not adequate prior scrutiny of potential pollution caused by septic tanks authorised in the Republic. It cited two specific cases of pollution in Wexford and the lakes of Killarney caused by leakage from septic tanks in its claim that Irish regulations on septic tanks were inadequate. But the ECJ found the commission had not proved that Ireland had failed to take all the measures necessary to comply with the groundwater directive.