Litter, stormwater and the marine environment – how Helsinki is reducing pollution of the Baltic Sea

Our Baltic Sea is a closed and fragile system. It receives nutrients, pollutants and litter from both land and sea. Urban land use, transport, waste and water management and construction all directly affect the quality of sea water. 

Helsinki is a big player in this: the maritime area covers about 70% of Helsinki's total surface area, or about 502.5 km², with about 130 km of shoreline and around 300 islands. This is why the city's actions play a major role in improving the state of the Baltic Sea. When it comes to protecting the Baltic Sea, the City of Helsinki's long-term conservation measures and everyday choices go hand in hand.

The new nature conservation area programme aims to give a protected status to more than 10% of Helsinki's marine area.

Focus on catchment areas and the protection of the marine environment

Helsinki is shifting the focus of water protection work in the catchment area from general solutions to more targeted and site-specific measures. Utilising water quality and flow measurement data, Helsinki is identifying those streams, rivers and small bodies of water that transport the greatest amount of soil particles and other debris into the water system. This allows the city to target its restoration and conservation measures effectively. 

“In the future, increasingly large marine areas will also be protected. It is the above-mentioned valuable areas that are of particular ecological importance. The new nature conservation area programme aims to give a protected status to more than 10% of Helsinki's marine area. At the same time, coastal and marine habitats that are important for spawning, birdlife and submerged microbiomes will be reviewed and protected. Conservation is not just about demarcating areas, but also about practical management of the areas and invasive species control. Conservation also does not mean placing any significant restrictions on the recreational use of the waterbodies, says Miira Riipinen, City of Helsinki's Director of Environmental Affairs. 

Helsinki continues to actively restore nature in the urban landscape. The restoration of shallow bays, coastal grasslands and common eelgrass beds will be carried out to recover habitats that support fish spawning grounds, birdlife and the diversity of microbiomes. Restoration combines natural solutions with long-term management – the aim is to restore the natural workings of ecosystems and thereby reduce the effects of eutrophication.

“The city wants to take water sustainability into account in all its procurements, from construction projects to street maintenance. Requirements for reducing water pollution will be set for supply chains. Additionally, measures such as worksite water management guidelines, chemical handling procedures and supervision help reduce the amount of harmful substances entering waterbodies,” says Riipinen. 

Shore-side electricity is provided to ships in ports, and the city also receives wastewater from vessels. These actions will reduce emissions, as well as oil and waste pollution of the marine environment. The growing port services for cargo ships and stricter environmental controls are also part of the solution. Reducing transport emissions at the city level will also reduce airborne nutrient discharges to water.

Long-term monitoring of water quality provides valuable information

The City of Helsinki has been regularly monitoring the water quality of its coastal waters for 60 years. Long-term monitoring of water quality provides valuable information on the state of the Baltic Sea over the past decades. Regular monitoring of water quality can be used to assess, for example, the extent of eutrophication in coastal waters.

In Helsinki, the water quality of marine areas is monitored in a variety of ways. Examples include water temperature and water clarity measurements and water samples collected for laboratory analysis at observation sites. Measurements gauge factors such as the sea water’s salinity, oxygen content and oxygen saturation, as well as its concentrations of eutrophying nutrients, namely nitrogen and phosphorus.

During the summer season, from April to November, measurements are taken at two-week intervals, and during the winter season, at one-and-a-half-month intervals. During the summer season, the volume of algae in water samples is also measured.
 

Protecting the Baltic Sea is a collaborative effort

The Baltic Sea Challenge is a network that was established in 2007 by the cities of Helsinki and Turku. It invites all stakeholders to commit to protecting local waters by taking concrete conservation measures. Next year, the Baltic Sea Challenge will celebrate its 20-year anniversary.

"Helsinki is investing in monitoring water quality and beaches, as well as in research cooperation, both internationally and locally. All of the above actions that Helsinki is taking to improve the state of the Baltic Sea can be found in the Baltic Sea Action Plan 2024–2028. This is the fourth joint programme with the City of Turku. Baltic Sea Challenge is a network set up in 2007 by the cities of Helsinki and Turku, inviting all operators to commit to protecting their local waters through concrete water protection actions".

In June, the Baltic Sea Challenge was recognised in an article in the international scientific journal Nature Cities. The article praised the Baltic Sea Challenge as a good example of cities’ independent and comprehensive efforts to protect the planet’s bodies of water.

“Actions by the city alone are not enough; the commitment of residents and businesses is also needed. Helsinki is investing in environmental education in schools, at workplaces and in volunteer networks and organises events such as Baltic Sea Day workshops. We also invite the city residents to participate in beach restorations and clean-ups. Raising awareness will further help to change everyday choices and increase the pressure to make policy and procurement decisions that benefit the whole Baltic Sea,” says Riipinen, Helsinki's Director of Environmental Affairs. 

Join the Baltic Sea Day clean-up drive on 27 August

Baltic Sea Day will be celebrated on Thursday 27 August 2026 at Helsinki’s Citizen’s Square (Kansalaistori) and its surrounding buildings of Musiikkitalo, Oodi and Finlandia Hall. At 13.30, Mayor of Helsinki Daniel Sazonov will deliver the event’s opening words in Citizen’s Square and share instructions for the clean-up drive. After this, event participants will head out together to tidy up Töölönlahti Bay. Volunteers will be provided with rakes, garbage grabbers and trash bags, but are kindly reminded to bring their own gloves.

The Baltic Sea Festival is a free event. Visitors are invited to spend a summer day enjoying music, tasty food and beverages, workshops and games, and learning more about the Baltic Sea. The festivities will begin with a merry carnival parade. The fun will continue with activities for children, including musical theatre sessions and a kids’ disco. In the evening, live jazz and folk rock will create a relaxed afterwork atmosphere. The day will culminate with a Baltic Sea-themed pub quiz.

This article was originally published in August 2025 and was updated in August 2026.