A study led by researchers from McGill University and WWF identifies that only 36% of the world's longest rivers (>1,000 km) remain free-flowing, with just 23% connected to the ocean. The research highlights the urgent need for global and national strategies to protect and restore free-flowing rivers, as infrastructure such as dams and reservoirs have significantly reduced river connectivity. The study defines free-flowing rivers as those with high connectivity, allowing unobstructed exchange of materials, species, and energy. It uses a Connectivity Status Index (CSI) to assess river connectivity, with values above 95% indicating good connectivity. The study finds that many rivers, especially long ones, have suffered major connectivity losses due to dam construction and other human activities. The results emphasize the importance of maintaining free-flowing rivers for ecosystem services, including fisheries, sediment transport, and biodiversity. The study also notes that while many rivers are not free-flowing, some contain significant stretches with high connectivity. The research underscores the need for comprehensive assessments and planning to minimize the negative impacts of infrastructure development on river ecosystems. The findings highlight the critical role of free-flowing rivers in sustaining aquatic and riparian ecosystems, and the importance of global efforts to protect and restore them.A study led by researchers from McGill University and WWF identifies that only 36% of the world's longest rivers (>1,000 km) remain free-flowing, with just 23% connected to the ocean. The research highlights the urgent need for global and national strategies to protect and restore free-flowing rivers, as infrastructure such as dams and reservoirs have significantly reduced river connectivity. The study defines free-flowing rivers as those with high connectivity, allowing unobstructed exchange of materials, species, and energy. It uses a Connectivity Status Index (CSI) to assess river connectivity, with values above 95% indicating good connectivity. The study finds that many rivers, especially long ones, have suffered major connectivity losses due to dam construction and other human activities. The results emphasize the importance of maintaining free-flowing rivers for ecosystem services, including fisheries, sediment transport, and biodiversity. The study also notes that while many rivers are not free-flowing, some contain significant stretches with high connectivity. The research underscores the need for comprehensive assessments and planning to minimize the negative impacts of infrastructure development on river ecosystems. The findings highlight the critical role of free-flowing rivers in sustaining aquatic and riparian ecosystems, and the importance of global efforts to protect and restore them.