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Lush forests of pine and spruce, broad lakes, deep glacial depressions and breathtaking ridges – Lahti’s natural heritage needs understanding and protection.



The unique nature and scenery of Lahti were formed by the last ice age. Lahti is the only city in Finland built on a significant groundwater area. The city is surrounded by 55 lakes and rivers and 1,200 hectares of nature reserves. The Salpausselkä glacial ridge system, situated close to the city, is covered by beautiful forests – and Lake Vesijärvi is a gateway to the largest lake district in Finland. With its location as a high-latitude northern city, Lahti also faces a host of environmental challenges.

Biodiversity is vital to our natural environment: when biodiversity is supported, the productivity of ecosystems is boosted. All species, no matter how big or small, have crucial roles to play in our ecosystems. Ecosystems provide humans and animals many necessary natural services such as pollination, food, and nutrients. Our forests and lakes give us berries, mushrooms, fruit and fish. The loss of just a single keystone species can cause an entire ecosystem to collapse, bringing the loss of many other species.

Water quality plays a key role in maintaining Lahti’s biodiversity. Lahti is working to conserve its waterways and to return them to their natural state in order to restore endangered salmonid populations. Riverbeds have been restored by adding rocks and gravel to stream sites and by removing man-made barriers to species migration. As an exemplary case, River Seestaanjoki has now a healthy trout population that can enjoy the entire river as their habitat. In river Vääksynjoki an eel trap has been built on an important migration route for endangered eels. The eels can now be transported safely to sea past the dangerous turbines of hydropower plants. In total, 1862 eels have been caught and safely transported to sea between the years 2014 and 2019.

Another important way of improving water quality is by managing the stormwater runoff from urbanised areas. Stormwater is a significant source of surface water pollution and, to address this challenge, an ambitious stormwater programme was set up in 2011. The programme utilises urban wetlands, infiltration basins and green roofs to supplement traditional conveyance-based solutions. Lahti also actively participates in stormwater research and development projects.

Forests, plants and the soil act as carbon sinks: their importance in controlling air quality and pollution is crucial. Because the city centre of Lahti is located in a valley between the Salpausselkä ridges, during episodes of low weather pressure air pollutants get trapped close to ground surface. Pollution levels rise in the winter season as energy consumption and traffic increase. Air quality has improved greatly after Lahti switched from coal to renewables in its energy production. As a result, in 2019 the city’s air quality was classified as good or satisfactory for more than 90% of the year.

As we take care of our nature, it takes care of us in return. Nature provides busy city people with a place to exercise and to relax and recharge. Lahti is a city with easy access to silence; more than 30,000 hectares within the area are considered quiet on the decibel scale. Quiet areas in beautiful natural surroundings are easily accessible from the city centre for anybody wanting to escape the bustle and get close to nature.


Pirunpesä (“Devil’s Nest”) is a canyon in Hollola.