Lough Neagh is the largest freshwater lake in the UK – it supplies half of Belfast’s drinking water and 40% of Northern Ireland’s overall.
And, for several months, it has been becoming increasingly green and toxic.
A blue-green algal bloom over the summer has caused havoc, not just in Lough Neagh but right up to Northern Ireland’s north coast.
But how did this happen? Watch above to get the lowdown in less than 120 seconds.
Follow our live page as BBC News NI focusses on the issues around Lough Neagh and how to fix them.
Video journalist: Matt Fox
Source link: https://www.bbc.co.uk/news/uk-northern-ireland-66998508?at_medium=RSS&at_campaign=KARANGA