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National forests and grasslands provide drinking water to millions of people

Forests are a reliable source of clean drinking water, much more so than any other land type. Scientists, land managers, and other experts from the USDA Forest Service are showing how forests provide drinking water supplies across the conterminous U.S. The work can help land managers prioritize watersheds for fuels reduction, restoration, and other projects to protect or enhance water supplies.

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Aerial view of Lake Meade, with the Hoover Dam in the foreground.
Almost 70% of the water in Lake Meade originates on national forests and grasslands. These lands provide drinking water to millions of people in the western U.S. including people who live in Las Vegas, Los Angeles, and Phoenix. Across the country, national forests provide so much water that in one year it would fill Lake Meade eight times. Courtesy photo by U.S. Bureau of Reclamation.

The USDA Forest Service manages more than 193 million acres of forests and grasslands. These lands play a significant role in providing clean water for ecosystems and economies. Water from forested lands is sometimes transferred hundreds of miles away to serve large cities through inter-basin transfers.

Southern Research Station scientists compiled a national database of all inter-basin transfers and linked it to a hydrologic model, tracking water from forests to surface water intakes for more than 5,000 public water systems in the U.S.

Forested lands provide 83 million Americans with more than half of their surface drinking water, as the study shows. National Forest System lands were particularly important for provisioning water supply in western states, providing more than 10% of the water supply for more than 83% of those who obtain their drinking water from public water systems.

Products of this work include multiple peer reviewed publications, a Research Data Archive, summaries for individual units of the National Forest System, and forthcoming online mapping tools. Land managers can use these products when planning restoration treatments funded by the Bipartisan Infrastructure Investment and Jobs Act of 2021. The work also supports the Chief’s Wildfire Crisis Strategy by helping managers prioritize watersheds in national forests for fuels reduction or restoration treatments.