Strategic restoration-development for biodiversity-inclusive hydropower expansion

Achieving global decarbonization goals will require substantial expansion of renewable energy infrastructure, including hydropower. Yet hydropower dams fragment river ecosystems, threatening freshwater biodiversity and the communities dependent on freshwater fisheries. Reconciling renewable energy development with biodiversity conservation remains a critical challenge for sustainable energy transitions.

Our recent global assessments quantified dam-induced habitat fragmentation for approximately 10,000 lotic fish species across 40,000 existing large dams. Current fragmentation hotspots are concentrated in regions with legacy hydropower development, including North America, Europe, South Africa, India, and China. This fragmentation has severe consequences for population persistence: approximately 3,500 fish species face potential extirpation in portions of their range due to habitat fragments too small to sustain viable populations. Furthermore, planned future hydropower developments threaten to intensify these impacts in tropical biodiversity hotspots, with projected connectivity declines of 20–40 percentage points across species in the Amazon, Niger, Congo, Salween, and Mekong basins.

To address these challenges, we propose a strategic restoration-development paradigm that combines targeted dam removal, fishway retrofitting, and strategic planning for future infrastructure. Using multi-objective optimization and species-level habitat connectivity modeling for 710 fish species in the Lower Mekong Basin, we demonstrate how this integrated approach can break locked-in environmental impacts from past ad-hoc development. Our results show that removing 12 high-impact dams increases basin-wide connectivity by 60%, effectively restoring conditions achievable had strategic planning been adopted before hydropower deployment began. Lower-ambition scenarios that do not include dam removal, but still combine strategic planning with fishway installation, resulted in modest improvements of up to 17%. Importantly, restoration-development outcomes varied across targeted species groups, highlighting the need for tailored conservation objectives in river basin planning.

Our framework offers actionable pathways for mitigating legacy impacts while enabling limited, low-impact hydropower expansion. Strategic restoration-development can guide biodiversity-inclusive energy transitions in major river basins worldwide, balancing climate mitigation benefits with freshwater ecosystem conservation.