Function: State of surface water and groundwater
The ecological state of water is classified with a scale bad-high that bases on biological quality factors (algae, benthos, water plants, fish) and water quality factors (i.a. nutrients, acidity). The intensity of human impact is evident in waters of lower quality.
In 2013 the ecological state was evaluated as excellent or good in 85% of the lake area. There have been no significant changes in water quality or microalgae production caused by nutrient loading. The state of 13% of lake area was classified as moderate and 1% as poor or bad. Lakes in these categories are located next to extensive farmlands or below industrial or urban areas and are often small or medium sized. Most commonly these lakes have been affected by nutrient run-offs from agricultural land especially in south-western Finland where arable lands are mainly erosion sensitive clay soils. Additionally, the old sediments rich in nutrients from past decades still affect water quality at present.
Between 2008–2013 a higher proportion of lakes were classified as declining rather than improving in quality. On the contrary, most changes in river quality were positive. Changes in the factors that affect inland water quality are slow. Ditch cleanings in peatland forests and increased winter time runoffs from agricultural fields due to shortened period of snow cover increase the loading of nutrients and organic matter. However, the management of sewage from the scattered dwellings is becoming more efficient and many water protection measures have been applied in forestry and agriculture.
There are about 3 800 groundwater deposits in Finland that are suitable for water supply. Coarse-grained and porous soils in eskers and terminal moraines filtrate water most efficiently and generate the largest groundwater deposits in Finland. Eskers are commonly used for taking gravel and the groundwater areas have been compromised to some extent. In the 1980s a conservation program for eskers was established and it covers at the moment 159 esker areas containing 970 km2. In addition to taking gravel, for example road salting and old waste tips, saw mills and gas stations have weakened the quality of groundwater.
Nevertheless, most of the 3 800 groundwater deposits suitable for water supply have been assessed as good in quality. About 350 deposits were considered being at risk and 98 of them had bad water quality in 2013. In recent years the water quality has weakened in about a hundred deposits. Usually these deposits are situated in Southern Finland and nearby population centres.
State of the surface waters. Environmental Administration.
Pintavesien ekologinen tila. Ympäristöhallinto / Environmental Administration.[In Finnish]
Pohjavesialueet. Finnish Environment Institute. [In Finnish]
Pohjavesien tila ja riskialueet 2013. ELY Centres, Finnish Environment Institute, National Land Survey of Finland. [In Finnish]
- Updated (26.01.2015)