Toxic "algae" contaminates Killarney's largest lake
Published: 09 Aug 2018

Signs warning of a toxic blue-green "algae" have been erected by Kerry County Council following sightings over the past couple of days in Killarney's largest lake, and major tourist attraction.

The Irish Society for the Prevention of Cruelty to Animals (ISPCA) has advised pet owners that they must be vigilant and keep their animals away from the lakes or ponds that contain the bloom. It was brought into public attention by a social media post with pictures of a pea green-like soup at a number of locations on the lake, this is the tell-tale sign of the toxic substance in question, which is referred to as a "algae", but is actually made from Cyanobacteria which feed on nutrients on water. 

The council (who monitor the lake along with the Environmental Protection Agency) have placed signs around the lake as a precautionary measure, previously in 2016 a major outbreak of the toxic bloom led to the death of many dogs. The Environmental Protection Agency has warned that they have received many queries about the lake, and warn that dog fatalities are likely to rise. These natural blooms are intermittent, the persistence indicates there may be an external nutrient such as phosphates which is feeding them. These outbreaks occur now on a yearly basis, the reason for which revealed in a study 20 years prior. 

Septic tanks, farming and forestry are the prime culprits for causing euthrophication and enrichment by phosphates to the lake; a major programme saw a reduction in these phosphates from these sources, but questions remain to be raised at the Killarney town sewage treatment plant and its efficiency of disposal. Monitoring from last year around The Folly Stream, an outflow from this sewage plant revealed a mildly eutrophic result, meaning there is some contamination - despite the council insisting that the Killarney Wastewater Treatment Plant is "fully compliant" with Directive 91/271/EEC on urban waste water treatment and the Emission Limit Values.

Whilst the algae pops back up again each year, an ever present threat to the health of the surrounding wildlife, an assessment of the suitability of the existing wastewater treatment plant will be carried out by 2021. 

Are you wondering why we're discussing legislation in the Republic of Ireland? Watch this space...