SLU news

After 40 years: new research on the impact of hydropower on regulated lakes

Published: 31 May 2024
Portrait of Johan Östergren

Most of the larger lakes in northern Sweden (Norrland) are regulated lakes or power plant reservoirs. They are crucial for Sweden's electricity production, but also heavily influenced by hydropower. In a new research project, researchers from the Swedish University of Agricultural Sciences will now study the long-term effects of hydropower regulation, and identify measures that can reduce its negative effects.

- We know that water regulation has a major impact on lake ecosystems. The otherwise highly productive bottoms and shores are eroded and aquatic plants die, says Johan Östergren, a researcher at the Department of Aquatic Resources and leader of the project.

Between 1950-1960 and 1976-1985, extensive research was carried out on the impact of hydropower regulation on the environment, fish and small animals that fish eat (nutritional animals). Since then, little has been done in this area and, in particular, there is a lack of knowledge about what environmental improvement measures may be appropriate in heavily regulated lakes.

- This is the first time in 40 years that these environments are in such focus again. The measures implemented then were mainly fish stocking and new nutritional animals. Now we want to broaden the perspectives and examine the long-term effects of regulation but also of past actions on fish, bottom fauna and aquatic plants, says Johan Östergren.  

The project will combine data on fish, aquatic plants, habitats, hydrological measurements and changes in climate and power production. The new knowledge will form the basis for working on new measures to improve biodiversity and reduce the long-term impact of hydropower regulation.

- The aim is to identify possible environmental design solutions and provide recommendations for which environmental improvement measures may be appropriate and what the expected effects of the measures may be. We will also look more closely at the effects of groundwater dams in collaboration with other SLU projects and Vattenfall, says Johan Östergren.

- It was obvious for us to enter into this collaboration and contribute to the research. SLU will have access to our facilities to be able to take part in our measures and evaluate them. It will be an important contribution to our work with biodiversity and result in concrete measures in regulated watercourses when hydropower is to receive new modern environmental permits, says Henrik Viklands, head of Vattenfall's hydropower program for biodiversity.

About the project

The project "Environmental design for rehabilitation of regulated lakes and reservoirs" is financed with funds from the Swedish Center for Sustainable Hydropower (SVC) and Vattenfall.

More ongoing SLU projects with focus on hydropower


Johan Östergren, Researcher
Department of Aquatic Resources, Institute of Freshwater Research, SLU, +46 10 478 42 46, +46 703-46 14 29