Rivers Under Siege

Freshwater ecosystems are the most endangered on Earth:

• Pollution — agricultural runoff creates oxygen-dead zones, like the vast dead zone the Mississippi feeds in the Gulf of Mexico
• Dams — over 58,000 large dams worldwide block fish migration and trap sediment that downstream ecosystems need
• Water extraction — humans withdraw so much water that many rivers run dry before reaching the ocean

Since 1970, freshwater species populations have declined by 83% — more than any other habitat type.