Proposals to build a major sewage treatment plant on the north Dublin coast would threaten the blue flag status of three beaches in the area, a report by a marine research consultancy has predicted.
The report, commissioned by a local group campaigning against the facility, said that the discharges from such a plant would impact negatively on the water quality of Portrane, Donabate and Malahide beaches.
Local authorities along the east coast are proposing the construction of a massive sewage treatment plant to cater for up to 850,000 homes in the greater Dublin area, which would be located in the Portrane area.
A study by Aqua-Fact International Services Ltd, a Galway-based research firm, examined the potential impact of the effluent from the facility on water quality along the coastline.
It has estimated that the new facility would still emit effluent containing harmful bacteria called faecal coliforms, which would contaminate sea water.
Using computer modelling, the report has predicted that the contamination levels in Portrane and Donabate would be in excess of that allowed for blue flag status.
"It is likely that these beaches would lose their blue flag status as a result of the proposed discharge," the report has said. It said contaminated water during the spring tide could threaten water quality at Malahide.
The report was commissioned by Fairshare, a group of local activists campaigning against the facility. The proposed plant has prompted strong opposition, with a meeting last week attended by 250 people.
The group has claimed that the proposed facility is an unfair imposition on a community, as it would be linked to a massive sewage pipe bringing waste from the rest of Dublin and parts of Kildare, Meath and Wicklow.
Fairshare chairman Dr Stephen O'Sullivan said: "The loss of three blue flag beaches is a high price to pay for a new sewage plant."
He said that expanding treatment facilities to deal with waste locally would be "more economical and sustainable" and that other countries were moving away from building facilities on the scale proposed for Portrane.
Fingal County Council said that the report was premature. A spokeswoman said that no decision had been made on whether to construct such a facility. She said that a Strategic Environmental Assessment was now under way to advise on the risks posed by such a facility.
She questioned how the report could judge the likely impact on water quality as there are no detailed proposals for the facility's design or operation. If it were built, discharges would have to be within specific parameters.