Review Paper

Balancing hydropower production and ecology − ecological impacts, mitigation measures, and programmatic monitoring

¹ Institute of Freshwater Research, Department of Aquatic Resources, Swedish University of Agricultural Sciences, Drottningholm, Sweden
² River Ecology and Management Research Group RivEM, Karlstad University, Karlstad, Sweden
³ Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, Uppsala, Sweden
⁴ Department of Ecology and Environmental Science, Umeå University, Umeå, Sweden
⁵ Department of Wildlife, Fish, and Environmental Studies, Swedish University of Agricultural Sciences, Umeå, Sweden
⁶ Tekniska verken i Linköping AB, Linköping, Sweden

^* Corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.

Received: 3 July 2025
Accepted: 26 August 2025

Abstract

Hydropower is a vital renewable energy source but has substantial ecological impacts on rivers, lakes, and surrounding ecosystems. It alters hydrogeomorphology, disrupts connectivity, and changes water physicochemical properties such as temperature and dissolved gas concentrations. Historically, the environmental impact has been of less concern compared to energy production, and there is an urgent need to adapt hydropower production to reduce impacts on aquatic ecosystems. While various mitigation measures exist, a systematic understanding of their efficiency is lacking. Here, we extensively review both the environmental effects of hydropower and the scientific base for mitigation measures. We then list key abiotic and biological candidates for systematic monitoring before outlining a programmatic monitoring approach to evaluate the efficiency of mitigation measures. This programmatic monitoring approach involves monitoring packages based on specific mitigation measures. A set of abiotic parameters and biological indicators are monitored with standardized methods and monitoring designs over the long-term and at several sites, covering different river types and hydropower configurations. The proposed program serves to inform ongoing and future remedial measures, expand our mechanistic understanding of the ecological effects, facilitate knowledge transfer, and allow for more reductionist monitoring approaches outside of the program.