Photograph by Amazon-Images/Alamy
Read Caption

The world's largest freshwater fish, the Arapima gigas, swims in its natural habitat in the Amazon Rainforest. The fish is endangered due to overfishing.

Photograph by Amazon-Images/Alamy

Freshwater Threats

Freshwater habitats face a multitude of threats, but it's not too late to save these environments.

Freshwater ecosystems are essential for human survival, providing the majority of people's drinking water. The ecosystems are home to more than 40 percent of the world's fish species. Despite their value and importance, many lakes, rivers, and wetlands around the world are being severely damaged by human activities and are declining at a much faster rate than terrestrial ecosystems.

More than 20 percent of the 10,000 known freshwater fish species have become extinct or imperiled in recent decades. Watersheds, which catch precipitation and channel it to streams and lakes, are highly vulnerable to pollution. Programs to protect freshwater habitats include planning, stewardship, education, and regulation.


  • The creation of dams and water-diversion systems blocks migration routes for fish and disrupts habitats.
  • Water withdrawal for human use shrinks and degrades habitats.
  • Runoff from agricultural and urban areas hurts water quality.
  • Draining of wetlands for development depletes habitats.
  • Overexploitation and pollution threaten groundwater supplies.
  • Invasion of exotic species can harm native animals and plants.
  • Global warming may lead to devastating floods and droughts.
NG Live!: Sandra Postel: Troubled Waters

National Geographic Fellow Sandra Postel views the world through a water lens, advocating for all to make simple and easy changes to their everyday lives that will help "Change the Course" of the Earth's precious supply of freshwater.

The National Geographic Live! series brings thought-provoking presentations by today’s leading explorers, scientists, photographers, and performing artists right to your YouTube feed. Each presentation is filmed in front of a live audience at National Geographic headquarters in Washington, D.C. New clips air every Monday.


  • Restrict the construction of dams.
  • Provide incentives for farming business to reduce the use of pesticides.
  • Establish protected wetlands areas.
  • Regulate water withdrawal for human use.