Environmental design in regulated lakes

Regulated lakes and reservoirs play a crucial role in Sweden’s hydropower system by storing energy and balancing electricity production over time. However, these aquatic environments are heavily affected by regulation, causing major changes in ecosystems and threatening biodiversity. A future climate with altered precipitation patterns and increased demand for renewable electricity makes it even more important to understand and mitigate these environmental impacts.

Our goals in the project

In this research project, we investigate how environmental design and restoration measures can be used to improve ecological conditions in regulated lakes and reservoirs. Through an interdisciplinary approach and close collaboration with both Norwegian and Swedish stakeholders, we aim to develop develop recommendations for implementing environmental design in regulated lakes and reservoirs, balancing ecosystem and societal needs under future climate conditions.

We focus on three key rehabilitation measures: lake-in-dam, environmental flows, and geomorphological improvements. A central goal is to increase knowledge of environmental impacts in regulated waters and how to mitigate them for sustainable hydropower. The project builds on HydroCen’s work and promotes close collaboration between scientists, power producers, and managers, using pilot reservoirs as detailed case studies.

Our study combines field surveys and existing data to assess biodiversity, habitat, hydrology, and hydropower, and will be expanded nationally through additional sites and environmental databases.

What we do

We will conduct ecological surveys in key lake and reservoir habitats (littoral, pelagic, profundal) and their tributaries using standardized methods:

• fishing surveys: with age and genetic analyses based on scale, otolith, and tissue samples; 
• macroinvertebrates and macrophytes surveys;
• local fishermen will contribute data through journals and sample collection, providing broader seasonal coverage;
• additional data from national databases, historical records, and archived material at SLU Aqua will support temporal analyses;
• biological data will be analyzed using multivariate and statistical models to assess ecological responses to regulation and environmental change, including climate effects.

Project facts

Participants

Swedish University of Agricultural Sciences (SLU) – Lead academic institution

Dr. Karin Nilsson (SLU), Dr. Gunnar Öhlund (SLU, Prof. Anti Vasemägi (SLU), Karlstad University, Umeå University, Norwegian Institute for Nature Research (NINA) through HydroCen, Dr. Håvard Helland (HydroCen)

Industry group: Vattenfall (Henrik Viklands), Uniper (Johan Tielman), Fortum (Marco Blixt), Skelleftekraft (Sandra Åström), Swedish Hydropower Centre (SVC)

Project collaborations

Environmental design in hydropower reservoirs (HydroCen (Norway)), FunkyFish project, FÅK revisited – Fish management measures in regulated lakes (SLU), Bevarande av Norrlands stora sjöar – Conservation of large northern lakes (FORMAS, Gunnar Öhlund), HÅVA project – Ecosystem changes in hydropower reservoirs (Gunnar Öhlund), Interacting threats to Swedish salmonids – Prof. Anti Vasemägi (FORMAS), Multiple SLU projects funded by SwAM – Eel management, restoration strategies, monitoring, etc.

Authorities and stakeholders

Swedish Agency for Marine and Water Management (SwAM), Swedish Environmental Protection Agency (EPA), County Administrative Boards (CAB), Water Authorities, Land and Environmental Courts, Energy and forestry companies, Sámi Parliament of Sweden and Sami reindeer herding communities, Municipalities, Landowners and farmers, Fiskevårdsområden (local fisheries management groups), Non-Governmental Organizations (NGOs), Small and Medium-sized Enterprises (SMEs) – including environmental consultants.