§ Mr. Alton
To ask the Secretary of State for the Environment (1) what assessment has been made of the effects of agricultural uses of fertiliser on British lakes in increasing nitrogen and phosphate contents;
(2) what assessment has been made of the effects of eutrophication on species diversity in British lakes; and what steps are being taken to reduce eutrophication;
(3) what studies his Department has made into the eutrophication of British lakes; and what causes of eutrophication have been identified.
§ Mr. Heathcoat-Amory
[holding answer 13 March 1990]: A number of surveys have been carried out in recent years by the water authorities into the eutrophication of British waters. These have concluded that eutrophication is not increasing in the United Kingdom and is limited to a small number of areas, for example, the Norfolk Broads, Loch Leven and Lake Windermere. In nearly all cases it is phosphorus which is the cause of eutrophication. To reduce eutrophication action is best taken at local level because the sources contributing to excess nutrients vary from place to place. Phosphorus stripping at sewage works is nearly always an effective control option.