A SIGNIFICANT PRESENCE of algal blooms on Blessington Lake in Co Wicklow have raised local concerns in the wake of an environmental disaster in Lough Neagh in Northern Ireland.

Algae are tiny organisms that can build up to form large clumps with a green colour known as algal blooms, which can be potentially harmful for human and animal health and damage the surrounding environment.

Lough Neagh, which borders five counties and is the largest freshwater like on the island of Ireland has been hit by a major algal bloom that has killed wildlife and raised questions about the safety of drinking water. 

Algal blooms have been seen in recent days on Blessington Lake, known more formally as the Poulaphouca Reservoir, which supplies water to Dublin. The area around the lake is popular with visitors and locals, including dog walkers.

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The blooms are known to temporarily occur on the lake periodically and usually do not require any extra steps to be taken in the water treatment process. The current Blessington blooms are not believed to be as insidious as those in Lough Neagh but have raised concerns nonetheless due to their potential risks for humans, animals and nature.

Wicklow TD Jennifer Whitmore told The Journal that multiple locals have contacted her abou the blooms, which thrive in warm, wet weather conditions and may become more frequent with climate change.

Speaking to The Journal, Whitmore, the Social Democrats’ biodiversity spokesperson, said that “a number of constituents have been in touch worried about the potential impact on water supply and on their pets, because certain algal blooms can be toxic”.

“We’re going to see more and more of this. Algal blooms are caused by nutrification – nutrients running off the land and into the water. There are also naturally occurring ones, but primarily, following heavy rainfall you get this level of leaching [from the land],” Whitmore outlined.

This is an area on the Blessington lakes today, it supplies 50% of the water for the Greater Dublin Area.

We may not have an equivalent to Lough Neagh in the republic yet, but we will if we keep going on our current trajectory. pic.twitter.com/Ni0uZM3RLh

— Elaine McGoff (@ElaineMcgoff) October 3, 2023

“We have seen a number of lakes, not just Lough Neagh but a number of lakes, over recent months where there have been severe blooms.

It’s another alarm bell ringing to let us know that how we are managing our land and our water sources is not sustainable.

“As temperatures rise, we will see more and more of these kind of issues impacting water supplies and it has impacts on biodiversity as well.”

Whitmore has written to Uisce Éireann to ask it communicates with local residents to “either allay their fears or to outline what they are doing and what potential impacts there are”.

In a statement to The Journal, the water utilities company said that the raw water supply taken from the lake and brought to the Ballymore Eustace Water Treatment Plant is monitored continuously with “24/7 instrumentation, a laboratory sampling program and visual inspections of the reservoir”.

“Further quality analysis and checks take place through each step of the treatment process and in the distribution network to ensure the water supplied to customers is safe to drink. Algae blooms do periodically occur for a variety of reasons, but do not typically impact the treatment process at Ballymore Eustace Water Treatment Plant.”

Niall Sargent / Noteworthy/The Journal Niall Sargent / Noteworthy/The Journal / Noteworthy/The Journal

ESB signs at the lake that have been in place prior to the current blooms warn visitors of the risks of algal blooms, cautioning that contact with affected water can cause skin rashes, vomiting and diarrhoea.

It also warns the blooms can be toxic to dogs and other animals and advises farmers and dog owners to prevent their dogs from drinking or swimming in the affected water.

In a statement to The Journal, ESB said that it “places signs at all public entrances to Poulaphouca reservoir warning of the potential for, and risks associated with, algal blooms which are a natural phenomenon”.

“The reservoir is a significant water body with a large perimeter, localised patches of algal bloom can appear and disappear very rapidly on the reservoir due to prevailing weather conditions.”