Water, air, and soil, when combined with the organisms they support, form ecosystems. These ecosystems, when in good condition, provide numerous benefits to the nation including clean water and air, abundant food and fiber, and healthy ecosystems that support local communities. The Forest Service carries out research on water, soil, and air to help meet its mission of sustaining the health, diversity, and productivity of the nation's forests and grasslands to meet the needs of present and future generations.

Many of the national forests and grasslands were created as part of a national effort in the late 19th and early 20th centuries to protect and restore soil and water resources and associated forest and grassland ecosystems. Today, about half of the U.S. population relies on forested lands to capture and filter their drinking water while new challenges, such as climate change, confront resource managers working to sustain the long-term integrity of these lands and the resources they provide.