Ritakoski Dam, River Hiitolanjoki, Finland

A free-flowing River Hiitolanjoki at last

The River Hiitolanjoki
Hiitolanjoki is a 53-km-long transborder river that runs for 8 km in South-eastern Finland before entering Russia to flow into Lake Ladoga. Its catchment area is approximately 1470 km² and on the Finnish side it is comprised of two river routes, with several lakes and tributaries (Figure 1). River Hiitolanjoki is of high ecological importance, since it inhabits the last remaining stock of the naturally landlocked salmon in Finland. However, its corridor has been dammed for over 100 years and access to upstream fish spawning grounds had been blocked. On the Finnish side of the border, three hydropower dams had been fragmenting River Hiitolanjoki, the Kangaskoski, the Lahnasenkoski and the Ritakoski dams (Figure 1).

Figure 1. (left) River Hiitolanjoki catchment area and (right) location of the three hydropower dams that were demolished within the Hiitolanjoki project

The Hiitolanjoki project
The first measures to restore the ecological continuity of River Hiitolanjoki were taken in the late 1990s, when the small – but with detrimental effects – barriers were removed on the Russian stretch of the river. Since then, migrating salmon have been seen below the Kangaskoski Dam, and thus the local authorities demanded that all hydropower dams in the area become equipped with fishways. The legal proceedings of this effort lasted about a decade, but in the end the power companies decided to sell the plants and dams.

To restore the free-flowing conditions of the river, an ambitious, multi-year project was initiated in Finland. The Hiitolanjoki project is the largest river restoration project ever planned in the country, and aimed to remove the three hydropower dams in Rautjärvi, South Karelia, in southeast Finland, and to restore their previously dammed rapids. During this project, all three operational hydropower plants were acquired by the South Karelia Foundation for Recreation Area between 2017 and 2019 to enable their demolition. Kangaskoski, the lowermost of the three dams, was demolished in September of 2021, and the ecological improvement was instant, with salmon spawning nests being spotted in the newly opened section of the river only a few weeks later. Lahnasenkoski, the largest of the three dams, was removed a year later, in July 2022.

The Ritakoski Dam
The Ritakoski Dam and plant were built in 1921 by Aktiebolaget Simpele, a local woodworking and paper mill, operative since 1906, which later became part of the United Paper Mills. Later the properties were passed on to M-Real factory, a cardboard manufacturer in Simpele. Ritakoski Dam was a 4-m-high and 15-m-long dam (Figures 2-3; Video 1) of 0.4 MW and an average annual electricity production of 2200 MWh. It was the most western of the three hydropower dams in Rautjärvi, South Karelia (latitude: 61.421572, longitude: 29.358559) (Figure 1) and an unsurpassable barrier to fish migration, since it was lacking any fish passage enabling structure. It was also modifying the water flow conditions, creating a large reservoir upstream of the dam (Figure 4; Video 1).

Figure 2. Ritakoski Dam at River Hiitolanjoki (photo by Mikko Nikkinen – Storymakers)

Figure 3. Ritakoski Dam and hydropower station at River Hiitolanjoki (photos by Mikko Nikkinen – Storymakers)

Video 1. Ritakoski Dam and hydropower station at River Hiitolanjoki (video by Niccolo Sala)

Figure 4. Water flow (left) upstream and (right) downstream of Ritakoski Dam at River Hiitolanjoki (photos by Niccolo Sala)

Dam removal
Ritakoski plant and dam were acquired from the previous owner Hiitolanjoki Voima Oy by the South Karelia Foundation for Recreation Area in October 2019. The planning phase (Figure 5) and the acquisition of the legal permit were complete in 2022. The removal works were initiated in August 2023 and lasted four months, till the beginning of December of the same year. In addition to the dam demolition, a wheelchair accessible viewing platform and trails were been built in the surrounding area.

Figure 5. Design of Ritakoski Dam removal and rapids restoration works at River Hiitolanjoki (design by Maveplan Oy)

Figure 6. Removal works of the Ritakoski Dam at River Hiitolanjoki (photos by Mikko Nikkinen – Storymakers)

Video 2. Removal works of the Ritakoski Dam at River Hiitolanjoki (video by Mikko Nikkinen – Storymakers)

The demolition works of the Ritakoski Dam (Figures 6-7), the restoration of the rapids (Figure 8) and the renovation of the removal site (Figure 9) costed ~750.000 euros (the purchase of the power plant is not included). The project was financially supported by both public and private donors, including the Finnish Ministry of Agriculture and Forestry, the Rautjärvi Municipality, WWF, EKSPsäätiö, OP Etelä-Karjala, LähiTapiola, Tuuliaisen säätiö, the forest industrial companies UPM and Metsä Group, and the Open Rivers Programme. The project was also supported by private individuals. 

Figure 7. Removal works of the Ritakoski Dam at River Hiitolanjoki (photos by Mikko Nikkinen – Storymakers)

Figure 8. Restoration of the rapids at the Ritakoski Dam site at River Hiitolanjoki (photos (up) Hanna Ollikainen and (down) Mikko Nikkinen – Storymakers)

Figure 9. Construction of a new bridge above the recently removed Ritakoski Dam removal at River Hiitolanjoki (photos by (up) Harri Keskinen and (down) Hanna Ollikainen)

Ecological benefits
The Ritakoski Dam was removed in autumn 2023 (Figures 10-11), while the salmon spawning season was occurring. However, the exceptionally strong water current at that time prevented the observation of any migrating or spawning salmon in the area. The area will be monitored in the following years to document the environmental effects of the dam removal and rapids reconstruction. The effects of the demolition of Kangaskoski and Lahnasenkoski dams have already been evaluated. In September 2023, a study was conducted on the number of salmonid fry (experimental electrofishing) at the site of the former Kangaskoski Dam and more than 200 fish per 10×10 m area were found to have been born, and most of them were salmons. In addition, spawning nests were observed at the restored Kangaskoski rapids in December 2023.

Figure 10. Removal site after the demolition of the Ritakoski Dam at River Hiitolanjoki (photos by Hanna Ollikainen)

Figure 11. Removal site after the demolition of the Ritakoski Dam at River Hiitolanjoki (photo by Mikko Nikkinen – Storymakers)

Despite some initial doubts from the local community, the final outcome of the project was pleasing for all. Following the completion of the Hiitolanjoki project, the Rautjärvi Municipality launched the RivTimes Master Plan, an initiative to promote the potential for recreational use of River Hiitolanjoki. The newly restored area also offers many opportunities for tourism operators as well as excellent opportunities for development of seasonal products and utilization of the distinctive local culture.

Before & After photo pairs

The removal site at River Hiitolanjoki: (left) before and (right) after the demolition of the Ritakoski Dam (photos by Mikko Nikkinen – Storymakers)

With many thanks to Hanna Ollikainen and The South Karelia Foundation for Recreation Area for providing the information and the visuals presented herein.

Written by Foivos A. Mouchlianitis