A Perthshire loch which was once best known for being polluted has recorded its best water quality for more than 20 years.
Back in 1992 Loch Leven was visibly affected by algal blooms which was so unpleasant one weekend that the event was nicknamed Scum Saturday.
It was estimated to have cost the local community more than £1m in lost revenue. As a result, there were strong calls for action to stop this happening again and plans to clean up the loch were put in place.
The latest report on Wednesday shows that levels of pollution, caused by excessive amounts of phosphorus entering the loch, have been falling over the last 20 years. This has led to improvements in water clarity, an increase in the number and diversity of aquatic plants, and better habitat for fish and birds.
Scottish National Heritage (SNH) reports that pochard diving ducks, which eat aquatic plants and are in decline Scotland-wide, have increased in number on Loch Leven from 1000 wintering birds in 1990 to 2400 in 2007. The increase is thought to be down to the proliferation of underwater plants.
Loch Leven trout fishery, which went into decline in the 1990s due to the pollution, is also improving.
The results were obtained by NERC Centre for Ecology & Hydrology (CEH) for SNH. Denise Reed, SNH Tayside & Grampians operations manager, said: "This is terrific news and is thanks to the hard work of many organisations and people in the Kinross area. But, we can’t be complacent; we have to keep up our efforts to make sure that the loch’s water remains clean and healthy so that wildlife can thrive and people can enjoy the loch even more."
Dr Linda May, who has led the monitoring programme for the last fifteen years, said: "The long term monitoring programme at Loch Leven has given us a good understanding of the links between pollution, climate change and ecological response and this has ultimately led to better water quality. As an added bonus, the lessons learnt are helping managers improve shallow lakes across the world."
Loch Leven is Scotland’s largest lowland loch and one of the most important sites for waterfowl in Britain. Its unique environment attracts not only the largest inland concentration of breeding ducks anywhere in the UK, but also many thousands of migratory ducks, geese and swans every autumn and winter.
The site was made a Site of Special Scientific Interest (SSSI) in 1956 for its large number of wildfowl, and the outstanding number of higher plant species and rare insects that it supported.