A Co Down beach has failed to meet minimum water quality standards for swimming for the second year in row.
Ballyholme beach in Bangor was the only bathing water in Northern Ireland to not meet the minimum standard.
The remaining 25 bathing areas met water quality regulations for swimming in 2023 when measured against the standards for faecal indicator organisms.
The new figures from the Bathing Water Compliance Report show that 18 beaches were classified as excellent, with another six found to be good and one sufficient.
To determine water quality, 20 samples were collected from each site to check for faecal indicator organisms, which are used to assess how much the water has been contaminated by sewage.
The water quality standards are compiled by the Department for Agriculture, Environment and Rural Affairs (Daera).
A Deara spokesperson said: “Even though the weather this summer was more unsettled than previous years, it is very encouraging to see so many of Northern Ireland’s bathing waters maintaining high standards for water quality.
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"Although there is some reduction in water quality, this is to be expected given the weather conditions, with the wettest July on record.
“The results from the new candidate sites are, however, disappointing.
"Sample numbers are low at the new sites, with only one season’s data, which has the potential to skew results.
"However, it also shows the vulnerability of all our waters to pollution during heavy rainfall events.”
The findings come after waters in Northern Ireland were affected in recent months by blue-green algal blooms, particularly in Lough Neagh.
The toxic cyanobacteria, which is lethal to some animals including dogs, spread across Ireland's largest inland body of water as a result of high temperatures and pollution.
Blooms of the algae were also reported in Lough Erne and some coastal areas.
The Deara spokesperson added: “Unfortunately, this season was also dominated by the blue-green algae events in Lough Neagh, which impacted the new Rea’s Wood site in Antrim and some of our north coast bathing waters.
"This is the first time that we have seen blue-green algae blooms affecting the quality of some bathing waters and we know this created significant impacts and disappointment for those who love to use our waters.
“Our bathing waters are a huge asset to Northern Ireland, valued by locals and visitors alike.
"We take our responsibilities for water quality seriously.
"While there are no quick fixes to the situation that occurred this summer on Lough Neagh, we are working closely with scientific and other experts on proposals that can deliver improvement for the future.
"In the meantime, we will not hesitate to take action where there is evidence that the laws in place to protect our bathing waters are not being adhered to."