Specialist testing of the lake source water for the Cleggan/Claddaghduff Public Water Supply has indicated the presence of algae, but the water has been declared safe to drink
Uisce Eireann says the presence of algae has contributed to the recent taste and odour issues reported but customers are assured that it's not harmful to human health.
The water utility says the Supply continues to meet regulatory standards, and is safe to drink once it is running clear.
It adds that monitoring will continue until the issue is resolved.
Chemical and biological results demonstrate compliance with legislative requirements and an extensive network flushing programme has also been completed.
In addition, all monitoring data and operational updates have been provided to the regulatory stakeholders and Uisce Eireann says that practice will continue.