As part of the larger project “The effects of the Kola air pollution sources in the areas of the Kola Peninsula and Finnish Lapland”, this study presents water quality data for 30 small lakes in Finnish Lapland during 1990–2006.

From 1990 to 2003, sulphur emissions decreased 68 % and 82 % at Nikel and Monchegorsk, respectively. During the same period, the number of lakes with measured alkalinity below critical level (20 μeq/l) have declined in Finnish Lapland close to pre-acidication level.