Story | 03/16/2023 09:16:50 | 6 min Read time

UPM's stream water programme progresses - Sapsokoski and Arvajankoski rapids restorations improve living conditions for fish

Viivi Viitanen

UPM aims to improve the condition of the entire stream ecosystem. In 2022, the Sapsokoski and Arvajankoski rapids were restored, providing migratory fish with significantly more spawning areas.

The habitats of migratory fish in Finland have changed due to the dikes and dams on rivers. UPM aims to limit the environmental impact of its hydropower plants, and since 2016 the company has been running its own voluntary programme, which aims to restore and recover migratory fish stocks by, among other things, clearing migration routes from unnecessary infrastructure.


With our programme, we want to contribute to improving biodiversity.

Our aim is to improve the situation not only for migratory fish but also for the whole stream ecosystem", says Mikael Rytkönen, Environmental manager and programme coordinator at UPM Energy.

The stream water programme aims to release or restore 500 km of stream waters by 2030. The verification and monitoring of released and restored stream waters as part of the programme is based on the Finnish Environment Institute’s (SYKE) geospatial data. The baseline year for our 500 km goal is 2015. The EU’s goal is to unblock 25,000 kilometres of river water in total, but the calculation method has yet to be determined.

Fish-friendly hydropower

UPM's approach is to rebuild fish stocks where they have the best conditions for natural success. Measures must be designed to best suit each water body and their effectiveness must be carefully assessed.

The biodiversity of inland waters not only concerns migratory fish, but also entails the restoration of the habitats of other endangered species such as green club-tailed dragonfly, freshwater pearl mussel and thick shelled river mussel. Stream waters form a crucial bridge between different habitats, which is why free-flowing water is important for the vitality of stream water ecosystems.

In 2022, the programme funded several research and innovation projects. The biggest projects were the restoration of the Sapsokoski rapids and the dismantling of the Arvajankoski dam and its restoration for fisheries.

UPM supports restoration of migrating fish stocks

A better habitat for salmonids through the restoration of Sapsokoski

In 2020, UPM Energy dismantled the old dam and mill at Sapsokoski in Sotkamo. This opened up a 96-kilometre long waterway for migratory fish, with at least 12 rapids. The improvement of the natural life cycle of salmonids was continued in 2022 with the restoration of the Sapsokoski rapids. The work was completed in August.

"We moved the stones we had removed from the rapids back into the watercourse, making it more natural. In addition, a total of thirty spawning ponds were formed in different parts of the rapids, which are now waiting for migratory fish, especially the endangered trout, to spawn", notes Rytkönen, describing the project that has improved the biodiversity of the Sapsokoski.

The project involved UPM Energy, Fortum, the Kainuu Fisheries Centre and the ELY Centre of Lapland. The work was carried out by a local engineering company.

"The work progressed as planned and was completed ahead of schedule. We are very pleased with the end result. We will monitor the success of the restoration in the coming years through spawning surveys and electrofishing. If necessary, we will carry out additional restoration measures."

The next step is to turn the area into a nature reserve, and UPM Energy has already held discussions with the municipality of Sotkamo and the Sapsoperä village association. 

"The project has been important for the people in the area and has been long-awaited. We have received lots of positive feedback from residents about the work we are doing."

UPM’s water management

More spawning and nursery areas for trout in Arvajankoski

In 2022, UPM launched a project in Jämsä to dismantle the dam on the Arvajankoski. The aim was to restore the rapids as a fishway.

"The Arvajankoski rapids route is 19 kilometres long. It is an important spawning river for trout in the Päijänne lake, and we wanted to ensure more spawning and nursery areas for this endangered species", says Mikael Rytkönen, describing the locally and nationally significant project.

The project involved demolishing the old dam and building a mirror dam on the rapids. In addition, the old fishway was replaced by a natural fishway and new spawning and nursery areas were formed in the area. A fishway will allow fish to go upstream of the rapids and a mirror dam will smooth out the fluctuations in the surface level.

In total, the restoration of the Arvajankoski rapids has freed up more than 55 kilometres of waterway for migratory fish. The restoration project involved the Central Finland Water and Environment Association and the North Savo ELY Centre. The work was carried out between August and October and was carried out by Oteran Oy, using local subcontractors.

"The work progressed as expected, and trout have already been seen swimming upstream from the Päijänne lake along the new fishway to the Arvaja rapids", says Pekka Rantala, Environmental engineer and project manager at UPM Communication Papers.

The best results come from working together

“Our stream water programme promotes biodiversity through the removal of migratory barriers such as defunct dams and the replacement of old culverts with new ones, as well as by restoring rapids and streams to their natural state. We are also participating in pilot and research projects in cooperation with local expert organisations, companies, and local centres of economic development,” says Mikael Rytkönen.

According to him, there has recently been a clear increase in social interest in streams habitat and migratory fish. UPM is committed to transparency and open dialogue with local communities and authorities on the condition of water bodies.

Work to protect migratory fish will continue in the coming years.

"We are constantly looking for new sites to include in our stream water programme. Our primary restoration sites are in areas owned by UPM or close to UPM's hydropower plants. It is a pleasure to promote restoration projects when the goal is to improve the living conditions of migratory fish and increase biodiversity", says Rytkönen.


  • There are approximately 220 hydropower plants and connected dams in Finland
  • All in all, there are up to 5,000 structures listed as dams along river routes
  • The total number of road culverts is estimated to be around 90,000, of which 30% are estimated to be stream water barriers
  • An estimated 5% of Finland's threatened species are native to inland waters

Source: SYKE

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