Virtaankoski dam removal, Finland

Introduction

Virtaankoski is located in the village of Virtaa, Sysmä, an area recognised for its cultural, historical, and scenic value at the regional level.

The licence for the Virtaankoski power plant dates back to 1863, and the Tainionvirta River has been dammed since the 1910s. The current power plant, built in 1956, ceased operations in 2012 when fisheries authorities required the owners to construct a fishway past the dam before resuming electricity generation. At the end of 2021, Hiitolanvoima Oy acquired Virtaankosken Voima Oy, applied for a change of status to a public utility company, and renamed it Sysmän Tainionvirta Oy.

The Tainionvirta River, with an average flow of 14.5 m³/s, flows from Hartola Jääsjärvi to Päijänne (approximately 43 km). It is one of the priority sites in the National Fisheries Strategy for safeguarding the natural life cycle of the endangered migratory trout and Päijänne trout.

Project context and opportunity

The dismantling of the power plant dam and the restoration of spawning areas contribute significantly to achieving a good ecological state for the river. Removing the barrier enhances fish migration and allows for canoeing and boating along the river. As a result, the hydrological and morphological status of the Tainionvirta will improve.

The removal of the barrier facilitates the movement of migratory fish, which also positively impacts the ecological classification of the fishery. The return of benthic animals to the riverbed and the recovery of other organisms will take a few years, but the outcome will be a meaningful improvement in the river’s ecological condition.

Flow conditions have been carefully considered in the restoration plan. A more stable underflow, alongside natural flow variations according to the seasons, will enhance living conditions and improve ecological status. Additionally, natural flow variations are more beneficial to the physical and chemical state of the water body compared to the regulated flows of power plants.

Project aims

This project aims to develop Virtaankoski into a naturally recovering and fishery-rich area, transforming it into an attractive and diverse destination for nature, recreation, and tourism. This will have a positive impact on the Päijänne fish populations and natural ecosystem, contributing to the Salpausselkä UNESCO Global Geopark and enhancing the tourism offerings of Päijät-Häme and Sysmä in Finland.

Drawing on experience from successful rapids restoration projects, the newly created spawning area of nearly one hectare could produce up to 750-1,100 trout fry annually for Lake Päijänne and the Tainionvirta River. This represents a significant boost to the vitality and biodiversity of a highly endangered species.

With this restoration project at Virtaankoski, we aim to provide an inspiring and encouraging example for similar initiatives, both nationally and globally.

Project achievements

The overall wider project has progressed significantly, with major milestones reached in the dismantling of the old dam and restoration of the river’s natural flow. It began with the construction of a new submerged weir to control water levels, allowing for the safe and complete removal of the old dam. Despite the depth of the water (over six metres) and the need for additional gravel and crushed stone, the work proceeded effectively.

By the end of January 2025, 95% of the new weir had been completed, steel pontoons installed, and the dismantling of the old dam successfully carried out. Flow was re-established through the dam site, with shaping works ongoing. Restoration efforts included the opening of the old bridge bed to enhance downstream spawning areas – complex work due to heritage preservation requirements.

Several structural upgrades were also implemented, including a redesigned, accessible footbridge to accommodate safety standards and river users. The restoration of the historic bridge banks and the replacement of municipal water pipes were also integrated.

Work began in February on the creation of a paddling port and dedicated channel for trekking kayaks. The Finnish Rowing and Canoeing Association, along with a fisheries management expert, have been closely involved to ensure that migratory fish habitat and reproduction conditions are prioritised.

The final phase included paving the rapids with durable stone, completing the spawning area, and releasing the full river flow – expected by mid-April.

Overall, the dismantling of the dam and the creation of spawning areas support the recovery of migratory fish populations and improve the overall biodiversity of the river. Additionally, the site now contributes to achieving a good ecological state and has the potential to be developed into a UNESCO Global Geopark, an educational hub, and a reference site for future biodiversity monitoring and restoration efforts.