Rivers
Clear regional patterns observable in ecological conditions in Finland’s rivers
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Hydropsyche
Photo Kari-Matti Vuori
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There is no precise figure for the number of river formations in Finland. Databases compiled in 2008 listed almost 2,000 river formations, but monitoring data was only sufficient to enable evaluations of the ecological states of about a fifth of these formations. On the basis of monitoring data or expert evaluations, just over half of the evaluated river stretches have been classified as being in a good or high state. This means that these rivers provide favourable conditions for the natural reproduction of migratory fish populations and the occurrence of sensitive fish and benthic animal species. Other rivers in Finland suffer from poorer water or riverbed quality, due to excessive nutrient loads or artificial changes to their channels such as riverbed clearance, channeling and embankment construction, so they do not provide such favourable conditions for aquatic wildlife. Almost half of all larger river systems’ basins (with catchment areas of more than 1, 000 km2) and nearly half of all smaller river systems are in a poorer state than “good”.
Most rivers in Northern Finland are in a good or high state. Exceptions include certain tributaries of larger rivers, where conditions are only classified as moderate.
Rivers in a bad or poor state are particularly found in coastal areas of Southern and SW Finland, where river systems have been altered in many ways. Factors harmful to aquatic life include:
- Eutrophication due to nutrient inputs from diffuse sources, notably farmland
- Increased acidity and metal concentrations due to the artificial drainage of areas with acidic sulphate-rich soils.
Fish deaths are common events in many rivers along Finland’s west coast, which are classified as being in a bad condition. In many unfavourably rated rivers the prospects for fish and benthic animals are also often harmed by artificially altered channels and regulated water levels.
Ecological status of rivers assessed by water bodies
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Source: Regional Environment Centres and SYKE. © SYKE
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Link to a more detailed picture:
Ecological status of rivers assessed by water bodies.pdf
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