Lough Neagh is the largest lake in the British Isles. It is a source of drinking water for 40 percent of Northern Ireland’s population, including half of Belfast. It is also known as a sanctuary for waterbirds, and in 1996 it became a Special Bird Protection Area under the Natura 2000 system. Paradoxically, the latter role weakened in the early 2000s, because water quality, thanks to measures to prevent agricultural pollution, improved, but by the same token its productivity declined. While 100,000 ducks wintered there in 2000/2001, a decade later the number had dropped to just over 20,000. Global warming also contributed to the change, reshaping the migratory habits of the animals.
Impact of human activity on Lough Neagh
In the fall of 2005. In Lough Neagh, the presence of five individuals of the variegated crayfish was found. The population of this invasive mussel developed over the next few years. The ragwort, by filtering the water, increases its transparency. The value of this parameter has tripled since 2019. This positively affects the bracken meadows present in the lake, but also facilitates the proliferation of phytoplankton. The destruction of submerged vegetation also contributes to its growth, as the lake is used for sand extraction. Lough Neagh is extensive (it is over 30,000 hectares), but quite shallow, with an average depth of 9 meters. Sand mining was essentially unregulated until 2021, leading to the deepening of the lake and the creation of zones devoid of bottom vegetation and deoxygenated.
Destroying benthic plants eliminates competition for phytoplankton, while disturbing sediments releases nutrients. Phytoplankton is also favored by warming waters. Their average temperature has increased by 1°C over the past 30 years. In June of this year, it recorded a record high of 17.4°C for Irish conditions.
Lough Neagh is a center for eel fishing. Water pollution and blooms threaten this activity. Anglers and fishermen point to declining fish populations. Despite improvements in water quality at the turn of the century, it is still polluted and in poor ecological condition. This problem is affecting more lakes in Northern Ireland. In 2020, out of 21 lake surface water bodies, only one had good ecological status. As early as February of this year, anglers recorded fish die-offs in the River Crumlin, which flows into the lake, but failed to identify those responsible for the pollution. In their view, the situation is complicated by jurisdictional disputes among the authorities responsible for various areas associated with the lake.
Water quality and tributary pollution are the responsibility of the Northern Ireland Department of Agriculture, Environment and Rural Affairs in cooperation with the Northern Ireland Environment Agency, while the land around Lough Neagh and beneath its bed belongs to Earl Shaftesbury. Local residents also accuse Northern Ireland’s political crisis of neglecting environmental policy, with calls for public management of the lake or strengthening the inspection role of Northern Ireland’s Environment Agency among the demands for repair.
Blooms in Lough Neagh
This spring and summer, Northern Irish lakes, including Lough Neagh, have experienced blue-green algae blooms. A bloom caused by Microcystis was found in May. It is suspected to have resulted in the deaths of several dogs, so warned against swimming in its waters. Despite the rainy summer, the bloom lasted the entire growing season. Further warnings were issued first in August and then in September. News outlets are writing about the death of the lake, which of course is an exaggeration, but experts say that even if the flow of nutrients from the catchment were completely cut off, the load inside the lake would be enough to sustain the poor ecological condition for decades to come.
Meanwhile, pollution continues to flow down, mainly down the Ballinderry River. According to experts, wastewater management in the area leaves much to be desired. It should be remembered that the lake’s catchment area covers almost half of Northern Ireland, also hooking into the Republic of Ireland, which determines the scale of runoff from diffuse sources. This year, for virtually the entire season, the water in Lough Neagh was unsuitable for swimming due to the potential risk of toxicity from the bloom. At the same time, the authorities assure that it poses no danger to people after treatment.