Source: WWF-Canada

Canada home to vast majority of North America’s remaining longest and free-flowing rivers: new McGill University and WWF study in Nature

First ever global assessment of free-flowing rivers highlights severe degradation, offers amethod for tracking the status offree-flowing rivers

Toronto, May 08, 2019 (GLOBE NEWSWIRE) -- Just over one-third (37 per cent) of the world’s 246 longest rivers remain free-flowing, according to a new study published in the scientific journal Nature. Of those found in North America, 73 per cent are in Canada. Dams and reservoirs are drastically reducing the diverse benefits that healthy rivers provide to people and nature across the globe. 

This study, from a team of international researchers including two WWF-Canada experts, highlights Canada’s enviable position of a significant majority (92 per cent) of our river lengths being free-flowing.  


While this is positive news for Canada’s freshwater ecosystems and wildlife, recent research from WWF-Canada emphasizes that much needs to be done to ensure the health of these rivers into the future:  


  • In 2017 WWF-Canada’s Watershed Reports, a groundbreaking assessment of watershed stressors and health, found that two-thirds of Canada’s watersheds are lacking necessary data to understand the health of the ecosystem, or make evidence-based water management decisions.  

  • WWF-Canada has identified Canada’s 10 longest wild rivers, those free-flowing rivers that are not negatively impacted by pollution, habitat loss, habitat fragmentation, overuse of water, invasive species, climate change or alteration of flows. These provide essential ecological, cultural and community benefits, but are largely unprotected.  

  • WWF-Canada’s Wildlife Protection Assessment measured the extent to which habitats across the country are represented in Canada’s protected area network and found we are not safeguarding critical species freshwater habitat including lakes, rivers and wetlands. 


 Elizabeth Hendriks, vice-president freshwater at World Wildlife Fund Canada says: 

“This study confirms what many of us think: Canada is uniquely endowed with wild and free-flowing rivers. With this wealth of freshwater, Canada has a great responsibility to protect it. And yet, our river protection is severely lacking. It’s like we have inherited a priceless jewel and are neglecting to insure it.  


In many cases we simply don’t know how freshwater health and wildlife are responding to stress from human activities. And, for the most part, our protected areas have overlooked freshwater ecosystems and habitats. This is all happening at a time when climate change is dictating that we must transition away from fossil fuels, creating new and increasing demand on our sensitive freshwater systems.  


We believe in science-based solutions and working with industry and government to ensure that Canada’s transition to the low-carbon economy doesn’t come at the expense of our free-flowing rivers. Now is the time to identify those areas that should be protected for wildlife and communities into the future. Let’s not leave the fate of our wild and free-flowing rivers to chance.” 


About the new study in Nature: 

A team of 34 international researchers from McGill University, World Wildlife Fund Canada (WWF) and other institutions assessed the connectivity status of 12 million kilometers of rivers worldwide, providing the first ever global assessment of the location and extent of the planet’s remaining free-flowing rivers.  


Researchers determined only 21 of the world’s 91 rivers longer than 1,000 km that originally flowed to the ocean still retain a direct source-to- sea connection. The planet’s remaining free-flowing rivers are largely restricted to remote regions of the Arctic, the Amazon Basin and the Congo Basin.  


“The world’s rivers form an intricate network with vital links to land, groundwater and the atmosphere,’’ says the study’s lead author, Günther Grill of McGill University’s Department of Geography. ‘’Free-flowing rivers are important for humans and the environment alike, yet economic development around the world is making them increasingly rare. Using satellite imagery and other data, our study examines the extent of these rivers in more detail than ever before.” 


Dams and reservoirs are the leading contributors to connectivity loss in global rivers. The study estimates there are around 60,000 large dams worldwide. More than 3,700 hydropower dams are planned or under construction. They are often built at the individual project level, making it difficult to assess their real impacts across an entire basin or region.  


“This first ever map allows us to prioritize and protect the world’s remaining free-flowing rivers, as these are lifelines for wildlife and people across the globe,” says Michele Thieme, lead freshwater scientist at WWF. “Rivers provide diverse benefits that are often overlooked and undervalued. Decision makers must consider the full value of rivers when they plan new infrastructure.” 


Healthy rivers support freshwater fish stocks that improve food security for hundreds of millions of people, deliver sediment that keeps deltas above rising seas, mitigate the impact of extreme floods and droughts, prevent loss of infrastructure and fields to erosion and support a wealth of biodiversity. Disrupting a river’s connectivity often diminishes, or even eliminates, these critical ecosystem services. 


Protecting remaining free-flowing rivers is also crucial to saving biodiversity in freshwater systems. Recent analysis of 16,704 populations of wildlife globally showed that populations of freshwater species experienced the most pronounced decline of all vertebrates over the past half-century, falling on average 83 per cent since 1970. 


The study also notes that climate change will further threaten the health of rivers worldwide. Rising temperatures are already impacting flow patterns, water quality and biodiversity. Meanwhile, as countries around the world shift to low-carbon economies, hydropower planning and development is accelerating, adding urgency to the need to develop energy systems that minimize environmental and social impact. 


“While hydropower inevitably has a role to play in the renewable energy landscape, countries should also consider other renewable options,” says Thieme. “Well-planned wind and solar energy can have less detrimental impacts on rivers and the communities, cities and biodiversity that rely on them.”  


The international community is committed to protect and restore rivers under Agenda 2030 for Sustainable Development, which requires countries to track the extent and condition of water-related ecosystems. This study delivers methods and data necessary for countries to maintain and restore free-flowing rivers around the world. 



What are Canada’s longest wild rivers? 
Canada has a wealth of wild rivers. The majority are in the North, where fewer people live. Canada’s longest wild rivers are: 

·       Liard River (Yukon Territory, British Columbia, Northwest Territories) 

·       Kazan River (Nunavut) 

·       Dubawnt River (Nunavut, Northwest Territories) 

·       Thelon River (Nunavut, Northwest Territories) 

·       Horton River (Northwest Territories) 

·       Anderson River (Northwest Territories) 

·       Taltson River (Northwest Territories) 

·       Stikine River (British Columbia) 

·       Ekwan River (Ontario) 

·       Birch River (Alberta) 


Why wild rivers are worth safeguarding 
Wild rivers provide numerous ecological and community benefits, including: 

·       Benefit wildlife (including species at risk) that rely on intact river ecosystems; 

·       Facilitate climate change adaptation; 

·       Allow for the unhindered transportation of nutrients for plants and animals; 

·       Maintain a healthy food supply for communities; 

·       Support native biodiversity; 

·       Provide pollution control; 

·       Support vibrant industries;  

·       Provide substantial cultural and spiritual value. 


Wildlife, including many species at risk, rely on the health and resilience of wild rivers as a source of water, food and habitat. Wildlife that benefit from wild rivers include: 

·       Threatened caribou herds

·       wolverines

·       grizzly bears 

·       wood bison

·       Chinook salmon 

·       lake sturgeon 

·       muskrat  

·       green-winged teal 

·       Arctic grayling

·       tundra swans  

·       The tiny hot water physa — a prehistoric snail found only in Liard River Hot Springs Provincial Park, British Columbia.  

About World Wildlife Fund Canada

WWF-Canada creates solutions to the environmental challenges that matter most for Canadians. We work in places that are unique and ecologically important, so that nature, wildlife and people thrive together. Because we are all wildlife. For more information, visit


For further information

Rebecca Spring, senior communications specialist,, +1 647-338-6274




Rebecca Spring