Water quality at 12 beaches in Mayo is "excellent", while the quality is "good" at another three beaches in the county, according to a new report from the Environmental Protection Agency.
Its annual report for 2020 shows that 96% of Ireland's bathing waters are meeting, or exceeding, EU minimum standards.
In Mayo, Carrowmore beach in Louisburg, Clare Island beach, Dooega, Doogort, Golden Strand, Keel and Keem beaches in Achill, EllyBay -Belmullet, Mullaghroe Beach, Mulranny, Rinroe beach in Carrowtigee and Ross Beach in Killala are all deemed to have excellent water quality, while Bertra beach in Murrisk, Carrowniskey and Old Head beaches in Louisburg are described as "good" water quality.
Nationally, the report found that bathing water quality improved across the country last year - a time when more people took to swimming during the Covid-19 pandemic.
However, four locations - including Clifden beach - are classified as poor.
This is the 5th year in a row that Clifden beach was deemed poor water quality and will now be declassified as a bathing area.
The EPA says the issue at Clifden beach is a storm water overflow from the local wastewater treatment plant.
Irish Water has undertaken rehabilitation works on the Clifden sewer network and the waste water treatment plant, while other potential sources of pollution include discharges from septic tanks in the area.
Galway County Council will erect signage at Clifden beach indicating that it is no longer suitable for swimming.