Eutrophication in Finland

Lakes

About a tenth of all of Finland's smaller lakes (<5 km²) show clear signs of eutrophication, such as algal blooms and related deterioration in water quality in terms of taste and odour.

Thanks to improvements in wastewater treatment, eutrophication problems have begun to ease around major settlements and industrial facilities in recent years, and some badly affected lakes are already showing signs of ecological recovery - although this recovery may be slowed due to the repeated release of excess nutrients from lake-bed sediments. This vicious circle phenomenon, known as internal loading, is a consequence of many years of excessive nutrient inputs.

The water quality of previously unaffected lakes is meanwhile worsening in some areas due to excessive nutrient inputs from diffuse sources, particularly over-fertilised farmland and commercially managed forests.

Coastal Waters

The Finnish waters of the Baltic Sea are also affected by eutrophication - especially the Archipelago Sea and the Gulf of Finland, whose shallow waters are sensitive to ecological imbalances.

The Gulf of Finland is heavily burdened by nutrient inputs from farming, settlements and industrial facilities in the three countries around its coasts - Finland, Russia and Estonia. Sources in Russia account for more than half of the nitrogen and about 75 % of the phosphorus entering the Gulf of Finland. Estonia and Finland each account for about 10 % of these nutrient loads, and atmospheric deposition contributes almost 15 % of the nitrogen input.

Nutrient concentrations increase eastwards in the Gulf of Finland due to the high inputs in wastewater from St Petersburg and in the River Neva, as well as the limited inflows and circulation of water from the open sea. But the excessive nutrient loads that cause eutrophication in Finland?s coastal waters also originate from point sources and diffuse sources in the catchment areas of Finnish rivers - as well as from internal loading.