European Space Agency satellite images reveal the domination of Lough Neagh by toxic blue-green algae. This environmental crisis has persisted for several months, with no immediate solution in sight, as experts assert that it has evolved over decades.

The repercussions have been dire, with reports of canine fatalities and devastating impacts on fish and bird populations that rely on the lake for sustenance, notably the largest freshwater lake in the UK and Ireland.

Additionally, the proliferation of this lethal bacteria has resulted in job losses, rendered fishermen unemployed, forced the closure of a water sports center, and prompted warnings against swimming in affected waters.

So, what exactly is blue-green algae, and why has it inflicted such damage on Lough Neagh? This toxic cyanobacteria, often referred to as blue-green algae, forms blooms when a combination of agricultural pollution, such as slurry, fertilizers, and sewage, intersects with elevated temperatures and ample sunlight, leading to a process known as eutrophication. The issue first emerged on Lough Neagh's radar in June, with a brief respite, only to resurge in July, posing severe threats to human health and proving fatal to animals.

Contributing to the crisis, the climate crisis has caused the temperature of Lough Neagh's water to rise, exacerbated by the hottest June and wettest July on record. These conditions created ideal circumstances for the algae to thrive. The ongoing expansion of the algae can diminish oxygen levels in the water, triggering fish kills and adversely affecting the entire ecosystem.

From a satellite perspective, Lough Neagh now appears predominantly green, highlighting the ecological havoc wrought by the algae blooms.

Furthermore, Lough Neagh is a vital source of water, supplying approximately 40% of Northern Ireland's water needs. Concerns about the health hazards posed by blue-green algae have prompted global health organizations, such as the Centers for Disease Control (CDC), to advise against contact with harmful algae and cyanobacteria. These substances can rapidly prove fatal to animals and, if ingested, can also harm humans. Symptoms of exposure include gastrointestinal discomfort, headache, fever, tiredness, skin and respiratory irritation, and neurological issues.

Questions have been raised about the safety of drinking water sourced from Lough Neagh, but Northern Ireland Water has expressed confidence in the quality of their treated water.

However, disinfecting naturally sourced drinking water with chlorine can produce by-products like Trihalomethanes (THMs), which can also pose health risks. The concentration of THMs varies depending on the organic material present. Northern Ireland Water has a statutory duty to test for THMs, and according to their 2022 statistics, only a small fraction of samples breached regulatory limits.

Despite the prevalence of algae in Lough Neagh, there has been no indication of an increase in THM testing frequency from the current standard. Nevertheless, concerns about the safety of food sourced from Lough Neagh, particularly fish, have arisen, prompting inquiries to the Food Standards Agency. The Ulster Angling Federation has called for measures to protect the public from the toxins found in fish caught from the lake.

In response to the crisis, the Department for Agriculture, Environment and Rural Affairs (DAERA) is establishing a Water Quality Steering Group to address the proliferation of blue-green algae in Lough Neagh. However, the budget cuts in 2022/23 have raised concerns about the department's capacity to adequately address water quality monitoring and related commitments.

Lough Neagh's hypertrophic status, characterized by a high nutrient concentration, has facilitated the thriving of blue-green algae and has contributed to its ecological classification as "bad" by DAERA. Research in 2021 suggested that it could take several decades to achieve a substantial reduction in phosphorous levels in the lake.