Smoky Mountains National Park. Credit: Scott Basford

Forests are key to clean water. Trees’ hair-like root fibers help filter groundwater by absorbing nutrients and potential contaminants. The leaves and branches slow the movement of rain to the ground, allowing it to soak in slowly, while roots stabilize the soil so it doesn’t wash away. Mature trees reduce the costs of stormwater controls and drainage systems by filtering and slowing down the water before it washes pollutants into streets, down drains and into our rivers. Freshwater also feeds lakes and streams that we enjoy for recreation in forests and parks, and is a critical habitat for fish and wildlife.


Did you know?

  • Seventy percent of the Earth’s surface is covered in water. About 2.5 percent of the Earth’s water is freshwater. Less than one percent is in the form of groundwater.[1]
  • More than half of the country’s drinking water originates in forests. Approximately 180 million people depend on forests for their drinking water.[2]
  • A single front-yard tree can intercept 760 gallons of rainwater in its crown, reducing runoff and flooding on your property.[3]
  • On average, a mature tree can absorb 36 percent of the rainfall it comes in contact with.[4]



[1] Global Change. The Water Resources of Earth. (accessed June 7, 2013).

[2] U.S. Forest Service. Wildland Waters. Private Forests & Water Resources. (accessed June 4, 2013).

[3] U.S. Forest Service. Pacific Southwest Research Station. Urban Ecosystem and Social Dynamics. Urban Ecosystems and Processes. March 2001. (accessed June 4, 2013).

[4] Publications and products. Title and products (accessed June 4, 2013)