BELFAST - For the third year running, toxic blue-green algae blooms that look like pea soup and smell like rotten eggs have covered much of Lough Neagh, the largest lake in the UK and Ireland.
But this summer, the thick green veneer -- so widespread it is visible from space -- has been worse than ever, according to locals living near the Northern Ireland landmark.
The algae growth -- fuelled by industrial, agricultural and sewage pollution, as well as climate change, according to experts -- has ravaged fishing and watersports, and prompted concerns about drinking water safety.
Signs banning bathing dot the lake's shoreline, including at Ballyronan, 54 kilometres west of the Northern Irish capital Belfast.
Nutrient-rich fertiliser and slurry run-off from farms supplying mega-firms like chicken processor Moy Park are being blamed for contributing to the pollution.
Untreated sewage spills and septic tank effluent are also suspected.
Moy Park deny polluting the lake and say the poultry sector is "highly regulated with strict limits set for wastewater quality" at all its local sites.
The algae growth is a "complex issue not specifically linked to any one sector," a spokesperson told AFP.
The invasive zebra mussel species, a recent arrival in the lake's waters, filter water but any benefit is far outweighed by the molluscs also stimulating algal photosynthesis, worsening the green water effect.
Meanwhile, the algae has decimated the Lough Neagh fly, a staple for fish and birds, local fisherman Mick Hagan told AFP while casting a line in a nearby tributary river.
Europe's largest eel fishery -- also on the lough -- suspended operations this year due to quality concerns.
Hagan's is the first of many generations in his family not to fish for eels in Lough Neagh.
Now he runs a pizza truck at a campervan site near Ballyronan, but the powerful stench from the lough kept most tourists away this summer.
According to Gavin Knox, whose paddleboard small business also fell victim to the sludge, the foul smell can reach miles inland.
The 48-year-old launched his venture in 2022 to help people safely have fun on the water.
Working with people with learning disabilities and brain injuries as well as families, Knox said bookings gradually dried up after the algae appeared.
"Doing business became impossible," he told AFP. "Even if there are safe places to paddle, nobody wants to do it when the fish are dying and the birds are covered in green slime."