Bathers looking to enjoy a dip at one of Dublin's best-known beaches will be left disappointed after Merrion Strand was declared a health hazard.
The city beach, loved by paddlers, strollers and water sports enthusiasts, has failed quality tests for the fifth year in-a-row and an indefinite ban on swimming has now been declared.
The Environmental Protection Agency (EPA) said the waters on the strand were being fouled with raw sewage, dog dirt and filthy drain water.
Likely effects on swimmers could include skin rashes and stomach illnesses.
Brook Beach at Portrane is on its last chance before it too could face an indefinite ban. Its waters have been rated poor for four years in a row.
Notices advising against swimming will be erected there from next Monday when the official bathing season begins but Dublin City Council will have to implement an outright ban at Merrion Strand.
If conditions improve, the council can apply to have the beach reinstated as an official bathing site but that is not expected to happen for years.
A task group was set up to investigate the problems last year but multiple sources of pollution have to be addressed and then two years of clean samples produced.
That means cleaning two heavily polluted streams that flow on to the beach.
The EPA said: "These streams are polluted by a combination of misconnections where domestic plumbing goes into the wrong pipe and directly into the stream; leaks, spills and overflows from wastewater collection systems; and run-off from roads.
"Other potential sources of pollution, that need more investigation, include urban wastewater discharges, birds and dogs."
EPA director Micheal Lehane said: "Local authorities must remain vigilant to ensure public health is protected and to identify and fix sources of water pollution which impact on our beaches.
"The declassification of Merrion Strand after five years at poor status is disappointing and action must be taken to ensure that no other bathing water is declassified in future."
By contrast, 89pc of the country's 147 official bathing sites were rated good or excellent.
The famous Forty Foot was rated for the first time and declared "excellent" as was White Rock Beach in Killiney, while Sandycove beach rated "good".
Beach-goers are being asked to help keep them that way by bringing home rubbish and food waste, cleaning up after their dogs and reporting any pollution.