Dog owners and swimmers are being warned to avoid the waters and shoreline of Lough Melvin, Garrison after several dogs died as a result of coming into contact with toxic blue-green algae at the site, the Northern Ireland Environment Agency (NIEA) has confirmed following tests.

Blue-green algae (cyanobacteria) is a type of algae that can occur naturally in lakes, ponds, canals, rivers and reservoirs. Unlike other types of algae, if it becomes too abundant it can pose a health risk to people, pets and wild animals who come into contact or ingest it.

It can cause skin rashes, eye irritations, vomiting, diarrhoea, fever and muscle and joint pain. Blue-green algae has also been attributed to the death of dogs, birds, fish and livestock in parts of the UK.

Following the reports of dogs dying after being in the Lough Melvin area of Garrison last week, the NIEA took samples from the lough and shoreline on Friday, June 2 and Monday, June 5, with tests confirming the presence of blue-green algae.

A spokesperson for the Department of Agriculture and Rural Affairs (DAERA) said: “The NIEA received a report on Thursday evening (June 1) of the death of a dog on May 31 at Lough Melvin, Garrison. A subsequent report of the death of another dog was received on June 2. A Water Quality Officer was tasked to investigate for evidence of water pollution.

"At the time of the inspection on June 2, the inspector did not observe any evidence of an algal bloom, dead fish or any other signs of water pollution including sewage in the water. However, as a precautionary measure a water sample was taken for algal analysis.

Three days later, on Monday, June 5, NIEA staff returned to Lough Melvin, where on this occasion they did observe an algal bloom on the lake and collected further samples from both the lake and shoreline.

The DAERA spokesperson continued: "Analysis by NIEA has confirmed the presence of ‘blue green algae’ of the genus Microcystis sp. and Anabaena sp. in the water as well as colonies of Oscillatoria sp. within decomposed material on the shoreline.

"All three genus of algae can produce toxins that are harmful to humans and often fatal to pets if ingested."

DAERA noted that the results have been shared with Fermanagh and Omagh District Council who have erected signage warning the public of the presence of blue-green algae.

Authorities in the Republic of Ireland have also been informed of the results.

Fermanagh and Omagh District Council has implemented signage in the Lough Melvin area to warn the general public.

A Council spokesperson said: "The Council has erected signage around the Lough Melvin shore area to advise visitors and users of the presence of blue-green algae and the precautions they should take. The signage also refers to avoiding the shore area.

"The Council is continuing to liaise with NIEA in relation to this matter and we would continue to advise residents and visitors to avoid contact with the water and algae on the shoreline."