North Tipperary County Council has confirmed that blue-green algae, sometimes found on the surface of Lough Derg in warm weather, was the cause of the deaths of two Labrador dogs near Youghalarra Quay on the lake three weeks ago.
The council has been advised by the Department of Agriculture's Regional Veterinary Laboratory in Limerick that the investigation into the dog fatalities which occurred on June 22nd has been completed and has identified the neurotoxin, Anatoxin-a, as the cause of the animals' deaths.
Anatoxic-a is a neurotoxin produced by some species of blue- green alga of cyanobacteria and the laboratory considered that the lake water was the probable source of the neurotoxin ingested by the animals.
Senior environmental engineer with North Tipperary County Council, Frank O'Halloran, who headed the investigation into the deaths, said the council commissioned the EPA's Regional Water Laboratory in Kilkenny to carry out a follow-up investigation with samples being taken from 50 locations around the lake on June 27th and 28th; 23 of which were tested for the presence of blue-green algae.
Following analysis, it was revealed that blue-green algae was not present in the lake at the time of sampling, although the weather conditions had deteriorated notably in the intervening days which would have led to the dissipation of the algal bloom.
The council confirmed that the majority of the results were satisfactory and found that the quality the water in Lough Derg had improved substantially since the 1990s.
However, the council did admit that the despite the improved water quality of Lough Derg, the development of toxic algal blooms can be harmful to animals who drink the water and can cause skin rashes in humans who swim in it.
The council added that it was taking all necessary steps to ensure that drinking water taken from the lake remained safe.