OSLO: The world’s rivers are in crisis including in North America and Europe where governments have invested trillions of dollars to clean up freshwater supplies, a study showed on Wednesday.

“Threats to human water security and biological diversity are pandemic,” Charles Vorosmarty of the , co-lead author of the report in the journal Nature, told Reuters.

The international team of scientists estimated that almost 80% of the world’s population — or about 5 billion people — lived in areas with high levels of threat to water security, caused mainly by river mismanagement and pollution.

“Rivers in Crisis,” Nature said on its front cover.

A map showed high levels of threat, in red, for much of the United States including the Mississippi basin, along with almost all of Europe. India, including the Ganga basin, and eastern China with the were also shown in red. Rising wealth often meant worsening threats, for instance from badly sited dams or rising pollution from fertilisers, pesticides and other chemicals. Rich nations then covered up mismanagement by installing costly treatment plants.

The authors urged a re-think to safeguard rivers, especially those now less affected in developing nations. The world population is on track to reach 9 billion by 2050 from 6.8 billion now.

The study said it was first to examine in detail a twin set of threats — to clean water supplies for people and to the biological diversity of life in rivers, from fish to crocodiles.

“Given escalating trends in species extinction, human population, climate change, water use and development pressures, freshwater systems will remain under threat well into the future,” they wrote. Least affected rivers were in parts of Siberia, Canada, Alaska, the Amazon basin or northern Australia, they said.