Among the six is Youghal in Co Cork, which continued its poor performance for a second year.
Untreated sewage in the water was the main culprit for the failures, with e. coli and other bacteria, making swimming and other water sports inadvisable and, in some cases, prohibited.
The Environmental Protection Agency (EPA) and Irish Water are working to see what can be done to ensure that the beaches are given a clean bill of health before the summer season, but there are concerns they could remain no-go areas this year.
Matt Crowe, director of the EPA’s Office of Evidence and Assessment, said: “The relevant local authorities, in conjunction with Irish Water, have management plans in place to tackle the main pollution risks at these beaches and these plans are designed to return these beaches to at least ‘sufficient’ quality in the next year or two.”
The EPA also warned, however, that in some cases significant investment in infrastructure will be needed to get standards up to acceptable levels.
Some of the beaches are repeat offenders — Youghal, Co Cork; Duncannon, Co Wexford; and Ballyloughane, Galway City, failed for the second year in a row, while Rush, Co Dublin, failed for the third time in the last four years.
Newcomers to the bathing blacklist are Merrion Strand in Dublin Ccity and Loughshinny, which is close to Rush in north Co Dublin.
EPA inspectors who carry out the quality survey annually stressed the vast majority of the country’s most popular beaches and lakes were clean and clear of harmful pollutants.
Of the 137 inspected, 101 were rated as ‘excellent’ quality, as measured by EU standards, while a further 13 were classed as ‘good’ and 14 were ‘sufficient’.
Two that failed the previous year, Clifden, Co Galway, and Lilliput, Lough Ennell, Co Westmeath, improved enough to escape the blacklist this year, but further tests are awaited before they get a final rating.
The rest are rated as ‘poor’, which under EU regulations means they haven’t met the minimum standards required to give a green light for bathing and recreation.
Trá Inis Oirr in the Aran Islands was inspected for the first time last year and has not been tested enough to be ranked, but the EPA said sampling so far showed excellent results.
Failing the inspections does not automatically mean the beaches are off limits. Peter Webster, EPA senior scientist, said it meant there was “a risk of periodic microbiological pollution”.
“Local authorities are required to put in place notifications for the entire bathing season advising the public against bathing, which could include a bathing prohibition if a serious pollution incident occurs,” said Mr Webster.
During the bathing season, June 1 to September 15, current water quality information and details of any restrictions on bathing are displayed on the national bathing water website, splash.epa.ie, as well as on local beach notice boards.
Bathing restrictions applied on 131 out of 14,659 ‘beach days’ last year, but most suspected pollution incidents resulted in precautionary, short-term restrictions and no evidence of pollution was subsequently discovered.