Water Supply from Southern State and Private Forest Lands

State and private forest lands in the South supply at least some portion of drinking water for  55 million southerners – and 1.8 million people outside the region. Photo by Patrick Mueller, via Flickr.

Forests provide the most stable and highest quality water supplies among all land uses. A report by the Southern Research Station of the USDA Forest Service quantifies the role of state and private forest lands (SPF) in providing drinking water supply across the southern United States.

About half of the South’s land area is forested, and SPF account for about 90 percent of total southern forest area. This includes land owned by state and local governments, corporations, families, and other private entities. Approximately 55 million people in the South – or about 49 percent of the total population – derived some portion of their drinking water from SPF lands.

“The goal of this study was to provide land and resource managers with up to date information about the role of forest lands as water providers for people in the South, “says Ning Liu, lead author and postdoctoral research fellow at the Coweeta Hydrologic Lab.

Most of the South has plentiful rainfall, which makes the region less water stressed than other parts of the U.S. However, population growth and associated urban development in some areas, along with climate change, might exacerbate future shortages or degrade water quality.

“Forests and water are closely linked, and people are dependent on forested lands to provide clean and reliable drinking water and to support local economies,” says Peter Caldwell, research hydrologist and report co-author. “It’s critical to maintain forest lands in the region so they can continue to provide water-related and other ecosystem services.”

Researchers modeled water supply originating on SPF lands and traced the water through river networks to surface drinking water intakes. “About 91 percent of surface drinking water intakes received some portion of their water from SPF,” adds Liu. “Across the South, almost 98 trillion gallons of water originate on SPF per year, enough to fill Lake Mead 11 times.”

More than 90 percent of surface water drinking intakes receive some of their supply from state and private forest lands. USFS image.

SPF lands contributed more than 44 percent of the total available water supply generated in the region. Nonindustrial private forest was the dominant source of water supply from SPF for 11 of the 13 southern States, all but Florida and Louisiana. In Texas, about 16.7 million people were served by SFP lands, more than any other southern state.

The report includes case studies for several cities, including Austin, Texas; Jackson, Mississippi; and Tuscaloosa, Alabama. These snapshots of communities served by SPF lands include details about the population served, the area and type of SPF provisioning water, the number and location of public water supply intakes, and more.

The report includes an executive summary and appendices with state maps, graphs, and tables. Individual state summary reports are available for Alabama, Arkansas, Florida, Georgia, Kentucky, Louisiana, Mississippi, North Carolina, Oklahoma, South Carolina, Tennessee, Texas, and Virginia.

“This work will help forest managers, landowners, and the public recognize and convey the importance of forests for maintaining clean, reliable supplies of drinking water, and we hope will ultimately inform forest management and conservation decisions that will keep healthy forests on the landscape,” adds Caldwell.

The research was funded by and developed in partnership with the Southern Group of State Foresters. In addition to the report, the team developed an ArcGIS StoryMap – a collection of interactive maps, data tables, and videos for the region and each state in the analysis – with support from the South Carolina Forestry Commission.

Read the full report, including state summaries.

Visit the StoryMap: Benefits of state and private forest lands for the South.

For more information, email Peter Caldwell at peter.v.caldwell@usda.gov.

Access the latest publications by SRS scientists.