Canadian rivers are at risk from a variety of environmental challenges, including global warming, expanding agriculture, the construction of hydro-electric dams and increased urban consumption of water, a study showed.

Although Canada holds the world's largest freshwater reserves in thousands of lakes and rivers, this could quickly change as demands for water increase exponentially, warned the authors of the World Wildlife Federation report. The WWF examined 10 Canadian rivers and found some of them are "dangerously close to drying up".

It also outlined three main threats: changing precipitation patterns due to global warming, causing drought, flooding and the melting of glaciers; growing demand for water by cities for agriculture and industries; and increased demand for low CO2-emitting hydroelectricity, which could alter river flows and damage ecosystems.

"The combined threats of climate change and growing demand for fresh water by cities, agriculture and industry are converging on Canada's rivers," Tony Maas, WWF Canada director of fresh water, said in a statement.

"Even seemingly remote northern waters like the Mackenzie (river) are at risk. As temperatures rise, and industrial water withdrawals and interest in hydropower increase, we must start planning now to protect river flows to ensure water security for the communities and economies that depend on them."