Kaitarannankoski dam removal, Finland

Introduction

Kerava River is located in the Uusimaa region. It is the longest tributary of the Vantaa River, originating from Ridasjärvi in Hyvinkää and joining the main course of the Vantaa River near the border of Helsinki and Vantaa just before reaching the sea. The river has a large catchment area, making it highly prone to flooding.

The upper sections of the river flow through forested areas, where several rapids and, in some places, steep riverbanks offer scenic views and experiences. In its lower reaches, the river flows through rural landscapes near urban areas.

Kaitarannankoski is the final barrier for migratory fish in the Kerava River. This over 100-year-old dam structure served as a bridge for all traffic until about ten years ago, but nowadays it is mainly used as a tourist attraction. Below the dam begins the Lemmenlaakso nature reserve.

Project context and opportunity

The removal of the Kaitarannankoski dam restores the headwaters of the River Keravanjoki to free flow, strengthening the natural lifecycles of many riverine species by reconstructing the dam area closer to original, and the dry riverbed below the dam. The dam removal also reconnects the upper stream with the sea, which leads to the return of migratory species such as salmon.

Project aims

The River Keravanjoki is one of the Uusimaa region’s most important flowing water ecosystems and recreational areas. The primary goal of the Kaitarannankoski Dam removal is to restore the natural flow of the river and open its entire length to migratory fish. This will be achieved by dismantling the old dam and rehabilitating the adjacent rapid area for aquatic fauna. As a result, approximately 100 kilometres of river habitat will become accessible to migratory fish. The project will also enhance the living conditions of many other aquatic and riparian species.

One of the most significant local benefits will be a reduction in flooding. The River Keravanjoki has a large catchment area, which leads to frequent high water levels, especially in spring and autumn. These floods often cause property damage upstream of the dam. Removing the dam will eliminate sudden water pulses caused by gate operations, which have been a major contributor to erosion along the protected riverbanks in the area.

In addition to ecological and flood management improvements, removing the dam will enhance recreational opportunities along the river. Activities such as fishing and canoeing will become more accessible and enjoyable, contributing to the area’s value as a public natural space.