Lakes provide a critical service, both to human health and the economy. As well as providing drinking water they also serve as popular tourist attractions, with more than 15 million people visiting the English Lake District every year.
When their quality deteriorates it can be devastating – single algal bloom events at Loch Leven and Windermere cost millions of pounds and damaged their reputation for many years. Similarly, lake biodiversity can take decades to recover after periods of acidification and eutrophication, and in some cases may never return.