A temporary Prohibition Do Not Swim notice has issued for Portmarnock beach for the next four days.
The local authority has issued an advisory notice which states that the latest in a string of swim bans at the Velvet Strand in recent weeks is necessary "due to the possible effect on water quality due to stormwater overflow at [a] pumping station".
They add that this is "likely caused by heavy rain locally".
A sample will be taken tomorrow 3rd September and results will be available on 5th September, 2020 when the notice will be reviewed.
The north Dublin remains open but beachgoers are asked to respect the swim ban because "it has been put in place to ensure that the health of bathers is not compromised".
The beach has been closed to bathers several times over the summer after heavy rainfall - with an environmentalist pointing out that "this latest swim ban comes 14 months to the day after a massive sewage spill overflowed into Dublin Bay".
The spokesman from Portmarnock Drainage Awareness added: "Why are Irish Water contemplating building a monster sewage plant that threatens the future of the Velvet Strand - the only Blue and Green flag on the entire east coast of Ireland - when they should be upgrading the existing 13 pumping stations in Dublin that, if brought up to date, could see an end to these overflows?
"Irish Water don't seem to realise how serious it is and the damage caused to the delicate ecosystem of our waters when they release wastewater into the sea.
"If they have to close the beach after one day of rain because a smaller plant can't handle the excess wastewater, what damage will be done if a plant that can release 300 million litres a day will do?
"One day of rain and the beach is closed because of excess wastewater. It's very worrying."
Members of the public can check for water quality at any of the monitored bathing waters in Ireland in advance by accessing the EPA website at www.beaches.ie or by checking the notice board at the entrance to each beach.
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