The infrastructure that helps bring drinking water to homes is an investment. For millions around the world, forests are part of the system behind their faucets. According to new research published in the journal Science of the Total Environment, many forested watersheds may be lost to development in the next decades, reducing water quality and increasing water treatment costs.
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The research concentrated on the forest-water connection in the southern United States, a complex, varied region that is, sadly, a good location for investigating forest loss and deteriorating water quality. More than 80% of the southern forest is privately owned, and the human population is increasing.
More southern forests have been lost to development than any other region in the United States. The loss of forests is essentially permanent when they are replaced with parking lots, neighborhoods, and other development.
To our knowledge, this is the first study to combine water quality data, land cover projections, and information about public water systems at a large scale. Our research team includes economists who will link water quality and water treatment costs. This line of research could one day inform programs that compensate private forest landowners for the ecosystem services their forested watersheds provide.
Peter Caldwell, Study Lead Author and Researcher, USDA Forest Service
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“We examined small watersheds across a broad region. From Virginia to Texas, and across different forest types, soils, topography, and hydroclimates, our results confirm that forests are important for water quality,” adds Katherine Martin, a researcher at North Carolina State University and a co-author of the study.
According to the research, water running off forested lands contains lower quantities of nitrogen, phosphorus, and suspended sediment than water running off any other type of land.
But there are intricacies to the connection between clean water and forests. Individual forested watersheds may have lower water quality due to soil and rock types in the watershed or sediment erosion in the stream channel.
These factors and others can make quantifying forest benefits challenging.
Peter Caldwell, Study Lead Author and Researcher, USDA Forest Service
The study suggests that losing forests to other land uses would likely result in lower water quality. For example, developing just 1% of the forest upstream of an intake could result in an increase of 0.4% in the concentration of suspended sediment in the water.
Municipalities that draw water directly from rivers are more likely to have poor water quality now and in the future. Water collected from a river rather than a reservoir already requires additional treatment before it is drinkable. Municipalities that take water from smaller watersheds face greater dangers as well because any forest lost in a small watershed might account for a greater proportion of its area.
Watershed protection can help ensure future drinking water supplies. In general, the better the water quality, the more forested land upstream of the intake facility.
The latest study adds to a growing body of research on how people rely on forested watersheds for drinking water.
The research team also collaborates with coalitions like Keeping Forests.
We bring scientists, business leaders, and conservation experts together to develop market-based approaches to support private landowners. By illuminating the economic and environmental benefits of southern forests, we are empowering people to keep forests as forests.
Laura Calandrella, Executive Director, Keeping Forests
Journal Reference:
Caldwell, P. V., et al. (2023). Forested watersheds provide the highest water quality among all land cover types, but the benefit of this ecosystem service depends on landscape context. Science of the Total Environment. doi.org/10.1016/j.scitotenv.2023.163550.
Source: https://www.fs.usda.gov