A Do Not Swim Notice has been issued for Portumna Lake.
Galway County Council have been notified of the visible evidence of aquatic weed in the Bathing Place.
A red flag has been put up at the area, based on the recommendation of the Water Safety Awareness Officer
The County Council says it will continue to provide Lifeguards in the short term to actively advise against swimming.
The provision of the Lifeguards to be reviewed again next week, and the notice is in place until further notice.