Connectivity, i.e. the ability of fish and other aquatic animals to move freely in a waterway, is a prerequisite for achieving good water status under the EU Water Framework Directive. Fish and other aquatic animals need flowing water to survive and reproduce. But many of Sweden’s natural rapids have disappeared. Our waterways have been dammed and cleared of stones. This affects biodiversity. Simply put, we end up with a poorer aquatic environment. In the North Baltic Sea Water District alone, 60 percent of lakes and waterways contain obstacles that threaten biodiversity.
The county administrative boards of Västmanland, Örebro, Södermanland, Stockholm and Uppsala have worked to increase collaboration across county borders, create consensus and dialogue between different interests, and produce better data for prioritising actions. For example, the project has compiled information on more than 40 implemented measures in which dams have been removed. This compilation provides an overview of cost items and the factors that influence the total cost. For each action, a description is presented of the dam, its original purpose, the purpose of the measure, and the results of removing the dam.
Many obstacles to fish migration, such as mill dams and small-scale hydroelectric power plants, constitute valuable cultural environments that stand as monuments to how life was lived in the past and to the technical solutions that contributed to our prosperity at the time. How can we best combine measures to free up migration routes while also preserving our cultural environments for future generations? This is something that the project has addressed throughout the implementation phase.
Publications:
Strategy for Free Migration Routes – final report (25 March 2025)
Key issues regarding river connectivity and restorations measures in NDWD (31 May 2018)
Many Swedish cities have developed around streams, rivers and other waterways that have been important for electricity supply, transport, and other hydropowered activities. Dams and power plants are often valuable cultural environments that bear witness to a city’s history.
How, then, can we work to recreate free migration routes for fish in urban environments while simultaneously taking into account other important societal interests? Perhaps the most important issue is the actual change in the cityscape, often in a cultural heritage-rich environment. Roads, buildings and cables buried in the ground also limit the available space.
The Turbine House in central Västerås was built in 1891 and bears witness to the city’s rich industrial history and the establishment of ASEA over a century ago. When Mälarenergi AB and the City of Västerås began planning to open the Svartån River up for fish migration, great care needed to be taken to protect the cultural environment. Thanks to good planning, a painstaking construction process, and the open-mindedness of both politicians and Västerås residents, the 180-metre-long fauna passage was inaugurated in 2019. Further upstream, the City of Västerås has also constructed a similar fauna passage past the dam at the Falkenbergska kvarnen watermill. In total, about nine kilometres of free migration pathways, from Lake Mälaren up the Svartån River, have been recreated thanks to the project.
Publication:
Experiences and results of the building of two fauna passages in a city environment (4 October 2024)
Hydropower provides climate-friendly renewable energy. But its generation also dams up waterways, and this affects fish, animals and plants that need flowing water. Biodiversity is decreased. For a few years now, work has therefore been underway to adapt hydropower to environmental standards throughout Sweden.
In the Rällsälven River, for example, there are several endangered and threatened species. Here, Mälarenergi has created a 350-metre-long, naturalistic stream – a fauna passage – that leads water past the Rällsälv power plant dam. The passage winds through the landscape, creating as natural an environment as possible for trout and other fish. The river is also home to around 70,000 freshwater pearl mussels. This highly endangered mussel, which can live to be several hundred years old, now has better chances of surviving and reproducing.
A similar fauna passage has been built in the Hedströmmen River, near the Östtuna power plant. These fauna passages are fine examples of how power production can be adapted to minimise the impact on the aquatic environment. They have also attracted a great deal of attention in the industry. The designs, technology and lessons learned from the project have been used in connection with current research trials aimed at advancing the environmental adaptation of Swedish hydropower.
Publication:
Faunapassages for adaptation of hydropower at Rällsälv and Östtuna – description and results 2017 – 2021 (28 August 2023)
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