THE EFFECTIVENESS OF CATCHMENT LIMING IN RESTORING ACID WATERS AT LOCH-FLEET, GALLOWAY, SCOTLAND

The Loch Fleet Project in Galloway, southwest Scotland, is a catchment liming study which started in 1984. The principal objectives are: (a) to demonstrate that the (acid) water quality of a lake and its tribut ary streams can be improved by liming parts of the lake catchment; (b) having improved the water quality, to confirm its suitability by rein troducing a self-sustaining brown trout population. Liming parts of th e catchment in April 1986 resulted in rapid improvement in the quality of drainage and runoff water from treated areas and shortly thereafte r, an improvement in the quality of water in the lake. Trout were rein troduced to the lake in 1987 and 1988 and a self-sustaining population has been established. Stream, lake water and soil data collected sinc e liming allow an estimation of the 'target soil composition' required to maintain a target water quality for trout survival. Predictions of treatment effectiveness times using soil data are consistent with tho se based on extrapolations of calcium flux and stream water calcium co ncentrations. Both suggest that liming at Loch Fleet will remain effec tive until at least the end of the century.