Untouched lake forest, Eastern Karelia, Kuhmo, Finland
Source: M Rautkari, WWF
Finland has more than 55 000 lakes with a surface area greater than one hectare, many of which are set in catchments with little human impact and dominated by vast areas of peatland and forest. There are some 2600 mostly natural lakes in excess of 1 km2 in area, of which 500 are pristine, lacking measurable human impact other than atmospheric deposition (Sites 235 to 237 and 244 on Map 9.7). In total an area of 606 km2 is legally protected on account of high ecological quality, most of which (555 km2) is found in the Vätsäri wilderness area. A typical example of an oligotrophic lake occupying a near-natural basin is Lake Inari in northeastern Finland. The area is sparsely populated and used for reindeer herding and contains extensive pine forests. At 1050 km2 it is the second largest lake in Finland. Water quality is generally good and there are no indications of acidification, though there is localised wastewater discharge from lakeside settlements. The main impact on the lake has been regulation of water levels from the hydroelectric power plant constructed in 1934 on River Paatsjoki within the former USSR. Regulation has led to a decline in some fish species such as lake trout (Salmo trutta) and arctic char (Salvelinus alpinus, see also Box 9GG). Vendace (Coregonus vandesius) has developed into an important commercial fisheries species since its introduction in the 1960s. Severely polluted lakes in extensively developed or exploited catchments and with inadequate treatment of wastewater or agricultural runoff account for only one per cent of the total number of lakes in Finland.
The main impact on the lake has been regulation of water levels from the hydroelectric power plant constructed in 1934 on River Paatsjoki within the former USSR. Regulation has led to a decline in some fish species such as lake trout (Salmo trutta) and arctic char (Salvelinus alpinus, see also Box 9GG). Vendace (Coregonus vandesius) has developed into an important commercial fisheries species since its introduction in the 1960s. Severely polluted lakes in extensively developed or exploited catchments and with inadequate treatment of wastewater or agricultural runoff account for only one per cent of the total number of lakes in Finland.