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Water ecosystems

Helsinki’s water areas comprise large sea areas and freshwater areas, which include the Vantaanjoki River, streams, ditches, ponds and springs. Helsinki’s archipelago of 300 islands stretches from the sheltered inner archipelago to the open sea.
SDG 14: Life below water
SDG 6: Clean water and sanitation

SDG 6, Clean water and sanitation, is one of the goals that Helsinki has achieved to a large extent. In Helsinki, clean drinking water and efficient wastewater management are available to everyone. In addition, wastewater treatment is of the highest quality. SDG 14, Life below water, is particularly related to the Baltic Sea in Helsinki. The state of the sea has improved in recent decades, but it is still one of the most sensitive and polluted seas in the world, particularly affected by eutrophication.

State of water ecosystems must be secured

The water quality and the ecological status of small bodies of water and sea areas are affected by nutrients and harmful substances, litter, water traffic, treated wastewater and the condition of the open sea in the Gulf of Finland. The city’s water protection is guided by the Baltic Sea Challenge action plan, small water programme, rainwater management programme and flood instructions.

The nutrient load in coastal waters has decreased in recent decades, but the coastal ecosystem has not yet recovered and eutrophication is also a key problem in the sea area off the coast of Helsinki. Key actions have been the development of wastewater treatment technologies and centralisation of treatment plants.

The Viikinmäki wastewater treatment plant, located in Helsinki, is the largest treatment plant in the Nordic countries with world-class treatment efficiency. The Viikinmäki treatment plant treats all wastewater from Helsinki and, in addition, wastewater from other municipalities in the Helsinki region, i.e. the wastewater of approximately 860,000 residents.

Baltic Sea under threat

Despite the reduction in external loads, phosphorus concentrations in the coastal waters of Helsinki have been increasing since the early 1990s, mainly due to scattered loading from the large catchment area of the Vantaanjoki River and internal phosphorus loading from the seabed. In addition, an alarming number of harmful chemicals and microplastics are found in the water environments.

For these reasons, many ecosystems and habitats in the Baltic Sea are under threat. The underwater nature of the Helsinki sea area is not yet known well enough for important habitats to be taken into account in the planning and use of the sea area.

The aim is to improve the state of the Baltic Sea not only through the development of the city’s own activities but also through the Baltic Sea Challenge. The Baltic Sea Challenge is a network initiative of the cities of Helsinki and Turku, which invites organisations to voluntarily commit to the protection of the Baltic Sea and to draw up their own Baltic Sea action plans.

Small bodies of water in Helsinki are important habitats and pathways for various organisms as well as recreationally valuable destinations for city residents. The ecological, recreational and landscape value of small bodies of water has increased considerably, and it is important that they are better taken into account in urban planning and ecology.

Indeed, efforts have been made in recent years to restore streams and ditches to more natural conditions and, at best, they have managed to attract the extremely endangered sea trout to settle in them. However, the situation of ponds has deteriorated and they are eutrophicated.


  • Itämerihaasteen kautta on strategisesti ja poikkihallinnollisesti kehitetty kaupungin vesiensuojelutoimintaa ja kannustettu muita toimijoita mukaan jo 14 vuotta.
  • Helsingin seudun jätevedenpuhdistus on maailman huippuluokkaa ja kattaa 860 000 asukkaan jätevedet.

Development targets

  • Hulevesien hallinnassa on kiinnitettävä enemmän huomiota myös merialueen kuormitukseen ja roskaantumiseen, erityisesti mikromuoveihin.
  • Sekaviemäriverkoston saneerausta erillisviemäröinniksi on jatkettava jätevesipäästöjen vähentämiseksi