Keeping Land Forested Lowers Water Treatment Costs

Photo Credit

Photo courtesy of Thomson200, CC0, via Wikimedia Commons.

Forested headwaters of the Chattahoochee River (pictured) protect water quality and reduce drinking water treatment costs for Atlanta, GA and many other communities in the watershed. Photo 

Forests provide the cleanest and most stable supply of water compared with other land-uses. A new USDA Forest Service report, Benefits of Southern Forests for Drinking Water, connects forests, water quality, and drinking water treatment costs, providing data to build partnerships between forest managers, private landowners, and water utilities. Most forest lands in the South are privately owned, so providing economic incentives for private landowners could help them keep their land forested and reduce treatment costs for downstream water utilities.

There is a growing recognition among water utilities that forests are critical green infrastructure in the water treatment process. “Forests stabilize water flow, filter nutrients and sediments and have less pollutants than other land uses,” notes lead author Research Hydrologist Peter Caldwell. Less nutrients, pollutants, and sediments in streams and intake facilities results in lower water treatments costs. 

“This is the first study we know of that combines observed and modelled water quality data with future land use projections and detailed information about water utilities obtained through broad ranging surveys,” says Caldwell. This study was done in cooperation with Southern Group of State Foresters and Keeping Forests. 

Future land use projections suggest that forest cover in the South could decrease 2-3.9% between 2020 and 2070. This could affect quality and quantity of water downstream at water utility intakes, potentially increasing water treatment costs for those utilities with large reductions in upstream forest. The assessment estimates that for every 1% forest loss upstream of a water utility, drinking water treatment costs could increase 1.7%.

This work builds on a series of studies linking upstream forests to downstream drinking water utilities and the populations they serve. Across the US, a General Technical Report led by ORISE Fellow Hydrologist Ning Liu found that over one-quarter of the US population received over 50% of their surface water drinking supply from National Forest Service and other forested lands. Private forested lands, which make up 87% of forested land in the South, are critical to reliable and clean water in the region. In another study Liu notes that State and private forest lands in the South provide more than half of the available water supply for 14.0 million people in the region and beyond.

“If privately owned forests are divided into smaller and smaller tracts, it gets harder and harder for landowners to generate income from those forest lands,” said Caldwell. When the costs to own forest lands exceeds income earned from them, landowners may be forced to sell their land, leading to conversion and decreasing water quality. This study suggests that conserving and expanding forests can sustain this essential ecosystem service and reduce drinking water treatment costs. An ecosystem services market, where landowners could be provided with economic incentives to maintain forest land could make this possible. 

The companion story map helps make connections between forest, water quality and drinking water treatment costs. 

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