asked the Secretary of State for Scotland how many miles of the River Tay are estimated to be (a) unpolluted, (b) fairly good quality, (c) poor quality and (d) grossly polluted.

The most recent readily-available information is in map E of the report "Towards Cleaner Water 1975" published in 1976 by HMSO on behalf of the Scottish development department. The hon. Member may wish to seek further information from the appropriate authority, the Tay River purification board.