Algal bloom in a Co Mayo lake has led to a ban on consumption of water from a private group scheme.
Derryhick Lake, near Castlebar, is the source of water supply for more than 100 homes connected to the Parke private group water scheme. At present, the lake is affected by a serious growth of algal bloom.
The Western Health Board has warned consumers served by the scheme not to use the water for drinking or cooking, even if boiled, until further notice.
Mr Noel Mahon, a senior environmental health officer with the Western Health Board, said that weather conditions over the summer were a contributing factor to the algal growth on Derryhick.
"The toxins produced by the algae can be serious to health if consumed. Boiling water has no effect in controlling the potential danger from the water," he explained.
"If drunk, it has the potential to make people very sick, but the quantity of algae in the water would have to remain high for a prolonged period."
The Parke group water scheme is the only water scheme which sources its water from Derryhick.
The ban on the consumption of any water from the supply is likely to remain in place for some time.