Watersheds and National Forests

Excluding Alaska, about two-thirds of the Nation’s runoff comes from forested areas. National forest lands contribute 14 percent of the total runoff. National forest lands are the largest single source of water in the United States and contribute water of high quality. More than 60 percent of the Nation’s runoff is from east of the Mississippi River, where 70 percent of the Nation’s private and State forests are located. National forests in the East are responsible for 6 percent of this runoff. National forests in the West provide proportionately more water (33 percent) because they include the headwaters of major rivers and forested areas of major mountain ranges. Forest Service literature from the 1940’s to the present has claimed that 50 to 70 percent of the Nation’s runoff comes from national forest lands. It is now clear that those claims are overstated.¹

References