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Goal: Deliver Benefits to the Public Forested lands dominate drinking water supply in the conterminous United States

Forested lands provide a cleaner and more stable water supply, more than any other type of land. Forested lands have been shown to make significant and disproportionate contributions to the total water supply for downstream communities. This study provides a complete account of the contribution of different forest ownership types to surface drinking water supplies in the conterminous U.S. using state-of-the-art datasets and modeling tools.

Director’s Choice
A mountain ridge rises over the Colorado River in Utah
About 460,000 people living upstream of the Colorado River in Utah obtained more than 50% of their surface drinking water from forested lands. USDA Forest Service photo by Peter V. Caldwell.

Forests provide the most stable and highest-quality water supplies among all land uses. Quantifying the benefits of forest water supply is important to effectively mitigate impacts of land development, climate change, and population growth. By integrating a water balance model and national drinking water data, researchers determined the amount of surface water originating on different forest ownership types, then tracked that water through river networks to drinking water intakes and the populations they serve across the conterminous U.S.

The team found that forested lands comprised 36% of the total land area but contributed 50% of the total surface water yield. Around 150 million people received some surface water from forested lands, and 60 million people received more than half of their water supply from forested lands. Federally-owned forest lands were the dominant water source (52% of all drinking water supply) in the western U.S., with 22 million people receiving more than 10% of their water from these lands. In contrast, privately-owned forests were the most important water source among forests in the eastern U.S., providing 34% of the total water yield, with 80 million people receiving more than 10% of their water from privately-owned forests.

Privately-owned forests are the most vulnerable to land use change and associated water supplies. Continuing programs that maximize benefits for private forest landowners could help them to retain their forests, thus minimizing the loss of critical ecosystem services, including a clean, reliable water supply for the American public.

Principal Investigators
Ning Liu, ORISE Fellow Hydrologist
Peter V. Caldwell, Research Hydrologist
G. Rebecca Dobbs, ORISE Research Fellow
Ge Sun, Research Hydrologist
RWUs
4353 - Center for Forest Watershed Research
4854 - Eastern Forest Environmental Threat Assessment Center
4855 - Center for Integrated Forest Science
Strategic Program Areas
Resource Management and Use
Water, Air, and Soil
Publications
Forested lands dominate drinking water supply in the conterminous United States
Research Partners
Chelcy Ford Miniat - Rocky Mountain Research Station
External Partners
Paul V. Bolstad - University of Minnesota
Stacy Nelson - North Carolina State University