Six beaches have re-opened to the public after a total of 12 were closed when heavy rain caused toxic waste to infect the water.
Prohibition notices have been placed on Balbriggan, Skerries, Loughshinny, Rush South and Portrane beach.
Twelve beaches in the area were subject to "no swim notices" since Tuesday.
Rainwater that would normally flow through the sewers and into the waste water treatment works, instead flowed out to sea.
Other beaches - including Balcarrick, Malahide, and Velvet Strand - have been given the all-clear.