Hydropower is the world’s leading source of renewable electricity, generating more power in 2022 than all other renewables combined. But while hydropower is helping clean up our electrical grid, it’s not always a positive force for fish.

Dams that create reservoirs on rivers can change habitats. And for some species, especially those that migrate long distances, hydropower facilities can create dangerous or insurmountable barriers. In some parts of the world, including the US, Canada, and Europe, governments have put protections in place to protect ecosystems from hydropower’s potential harms.