Twenty years ago Loch Neagh in Northern Ireland turned green, suffering from the kind of algal overgrowth that is now causing problems in many of England's lakes and reservoirs. As Chris Baines reports, research in Northern Ireland has probably solved the problem there and opened the way to controlling other forms of water pollution. But will the newly privatised water industry have the courage and far-sightedness to invest in a radical and unusual method of keeping our water clean?
Introduced by John Craven.

Plus the weather for the countryside at 12.55pm with Bernard Davey.