Now the Scottish Greens want to see it given designated bathing water status to make the loch, near Kinross, a protected wild swimming hotspot.
Mark Ruskell, an MSP for the Mid Scotland and Fife region, said it is “one of Scotland’s natural treasures” and giving it extra protection could help combat pollution.
The national nature reserve is home to more freshwater breeding ducks than anywhere else in inland Europe and also has links to Mary, Queen of Scots.
She debated with John Knox in the great hall of Lochleven Castle, and was later imprisoned in the island fortification before escaping with the help of her jailer’s sons.
However, Mr Ruskell said the loch has been plagued by rising levels of toxic blue-green algae blooms across parts of its 3,600 acres of water, leading to it being closed off during peak season when visitors, bathers and dog walkers are out in force. He said the algae bloom – actually a bacteria called cyanobacteria – can kill wild animals, livestock and domestic pets and cause problems for humans.
Designated bathing status could spark action to tackle pollution and other water quality issues, he said.
Mr Ruskell said: “Loch Leven is one of Scotland’s natural treasures and a truly wonderful example of environmental restoration work, after it was brought back to health after issues with pollution back in the early 1990s. Its importance and popularity really came into its own during the global pandemic as people flocked to its shores to enjoy its open spaces, spend time in the water and among the trees and hills that flank it.
“Ever since its popularity has grown, but all too often we are seeing the signs going up warning of this horrible and potentially fatal bloom, and all the indicators are it’s being allowed to get worse.”
He added: "The deadline for applying to SEPA [the Scottish Environment Protection Agency] for bathing water status is March, and we need to show exactly how well loved and used Loch Leven is. I'd love to hear from everyone who swims at and uses Loch Leven to let me know exactly which parts of the shoreline we should look to have as designated spots.”
Mr Ruskell insisted it “cannot be right that we stand by and do nothing when all the evidence is clear that our mental and physical health benefits from being engaged with nature”.
He said: “There are also potential good economic knock-on effects for some local businesses, nature charities and the wider area as whole, in the same way we see places like the Cairngorms and Loch Lomond benefit.
“Loch Leven, with all its history of Mary, Queen of Scots, the winter curling Bonspiels and its key role in protecting our nature and biodiversity, deserves to be afforded all the protection available to us, and I hope people will work with me in achieving this.”
At its longest point, Loch Leven stretches for 3.7 miles. It is already a Site of Special Scientific Interest, a Special Protection Area and a Ramsar site [a designation allocated to important wetland areas], which Mr Ruskell said further strengthens its claim to designated bathing water status.