Issue 5

Water Pressures Build in the Southeast

The water you drink today has literally been around for eons. The same water has been cycling around and around through the hydrologic cycle since before the time of the dinosaurs—falling as rain, flowing through streams to rivers to oceans, evaporating back into the atmosphere.

Water, its availability or lack, determines where—and in what forms—life exists on our planet. We expect water to be available to us all the time: we humans can only live 4 or 5 days without it. Less than 1 percent of the Earth’s water is accessible fresh water, present on the surface in rivers and lakes, in ground water stored underground, and in the atmosphere. This water is renewed daily by precipitation, cleansed daily by forests and soils.

Across the world over a billion people do not have access to clean drinking water. In the United States, most of us assume our supplies of water are secure, but just over a century ago, clean drinking water was starting to look scarce. From East to West, vast areas of American land had been clearcut and unsustainably farmed, leaving land with no vegetation, the bare soil deeply scored by erosion. Streams and lakes were polluted with sediment and waste; urban water supplies smelled bad and had become a source of disease.

The connection between forests and clean water was clear to the writers of the 1897 Organic Administration Act, which recognized the importance of forest reserves in protecting and enhancing water supplies and reducing flooding. When the National Forest System was established in 1905, one of its first mandates was to restore the watershed function of forests. Today an estimated 80 percent of U.S. freshwater resources originate in forests, with much of the nation’s drinking water coming from the estimated 192 million acres of our national forests, which actually make up only 30 percent of U.S. forested land. According to the U.S. Environmental Protection Agency, more than 60 million people in 3,400 communities rely directly on national forests for their drinking water.

The quality of water draining from national forests is typically the highest in the country. Healthy forests provide the best protection against sedimentation and other pollutants, better and more cost-effective filtration systems than any municipal treatment plant. How do forests do it? The tree canopy dissipates the energy of raindrops, reducing landslides, erosion, and sediment. The litter layer maintains a porous soil surface, allowing water to filter in and through, minimizing erosion and supporting nutrient cycling. Multiple levels of vegetation—ground covers, shrubs, trees—also intercept rain, while roots slow runoff. Roots and soil work together to filter out pollutants, and in some cases, trap and store water.

In the South, nearly 90 percent of forested land is held by private nonindustrial landowners; publicly owned lands, though producing highquality water, can hardly ensure future availability. With increased population and loss of forest cover projected for the South, what will happen to our water supplies?

Water Wars Come to the South

If you live in the South, chances are good that some of the water you drink—whether from the tap or that bottle on your desk—first comes out of the Earth either as ground water or as a trickle over moss-covered rocks, gathering into a stream that passes down through forests of hemlock and spruce, oak and poplar, rhododendron and laurel. In the Southern Appalachians, the headwaters of major rivers and streams often as not lie in national forest lands, which provide plentiful and clean sources of drinking water. Until recent decades, you could take your water sources for granted.

Because of plentiful rainfall in the South, water has rarely if ever been a limiting factor for development. Most people living in the area don’t think about water scarcity at all unless there’s a summer drought and they’re asked to stop watering their lawns—which is what happened in areas of North and South Carolina in the summer of 2002.

During the drought of 2002, rivers were so low that some towns came within feet of shutting down municipal water supplies. Fights broke out between neighboring municipalities over the effects of water removals on those downstream. Power plants and other industrial users came under fire for not releasing more water from their dams. Across the southern region, communities came to realize that they had to find ways to get more water—by importing it from somewhere else, planning better, or regulating more.

The years since have found the States of Georgia, Alabama, and Florida embroiled in “tri-State water wars” over water supplies that cross State lines. Other States like Tennessee have begun drawing up plans to protect the waters of their major river basins from being siphoned off by urban areas outside their borders.

“Periods of drought in the last two decades have pushed concerns about water quantity to the forefront,” says Jim Vose, project leader for the SRS Coweeta Hydrologic Laboratory in Otto, NC. “But drought is only part of the picture: A second factor is population growth. We’re looking at a 20 to 30 percent increase in demand by 2040."

Add to that a reduction in the forested land streams and rivers flow through. The Southern Forest Resource Assessment recently projected that 12 million acres of southern forests will be converted to other uses by 2020, with new land uses just adding to demand for more water. At the current pace of growth, water supplies could be in serious jeopardy in just a few years. “For communities that depend on surface water, around 15 acres of watershed are needed to meet annual water needs for each person, about 30,000 acres for a small town,” says Vose.

Not Just Water, Clean Water

Water from the forested watersheds of national forests is consistently clean, providing not only quality drinking supplies for humans but also habitat for a wide range of aquatic species. The Southeast contains some of the most diverse populations of aquatic organisms—mussels, fish, crayfish, insects—in the world, with more being discovered each year. With declining supplies of clean water, we stand to lose this incredible natural diversity—as well as the security of knowing the water from our taps is clean enough to drink.

Water quality in the South has been shaped by three centuries of intensive land use, with clearing for agriculture starting in the 1700s, and unregulated logging beginning shortly after the Civil War and lasting through the 1920s. For water quality in the South, the period between 1860 and 1920 was the most destructive known, with widespread clearing of forests without any erosion control measures. Logging peaked in 1909 and stayed high until 1920, when only a few stands of virgin forest remained. Rivers were filled with sediment from mountain slopes; many still run muddy from those times.

The rather recent widespread draining of wetlands, which filter surface water runoff, also affected water quality. Urban expansion brought point-source pollution from factories and sewage plants. Though many of these point sources have been stopped, their legacy remains in the sediment layers of streams and rivers. Now pollution flows in from nonpoint sources, with untold contaminants leaking off roads, landfills, storm systems, and construction sites into surface and ground waters. The primary factor affecting the future of water quality in the South is the constant expansion of nonpoint-source pollution from urban sprawl.

Back to the Forest

Preventing contaminants from ever reaching the stream is the most effective way to deal with pollution. Undisturbed and well-managed forests do this very well. In fact, forest management practices have evolved from the “cut and run” approach at the turn of the century, to practices that help ensure water quality by preserving and enhancing forest health.

An example of forest water-cleaning efficiency can be found in nutrient cycling, the process by which chemicals essential to plant growth are moved through soil, water, and living trees. Nutrients such as nitrogen are important for plant growth; along with phosphorous and potassium, nitrogen is one of the main ingredients in fertilizers. But nitrogen easily transforms into nitrates that can have serious negative effects on human and ecosystem health. Fertilizer production and other human uses have doubled the input of nitrogen into terrestrial ecosystems since the preindustrial period, and have compromised rivers and streams, sometimes leaving the water and its inhabitants oxygen-starved.

Forested watersheds have consistently been shown to have lower sediment and nutrient levels than nonforested watersheds. Few nutrients such as nitrogen are lost from healthy forest ecosystems directly to stream channels because these systems are very efficient at cycling nutrients—especially young forests, which rapidly soak up nutrients from the soil as they grow. The lowest levels of nitrates are found in waters draining undisturbed wildlands, while the highest levels are found in water from agricultural and urban areas.

Water is a finite and necessary resource: as time goes on, even more will be needed. “Municipalities will rely more and more on forested watersheds to offset or mitigate the impacts of population growth, while land use change and climate variability will make it increasingly difficult to keep up with that demand,” says Carl Trettin, project leader for the SRS Center for Forested Wetlands Research near Charleston, SC. “The pressure is on for forest hydrologists to help municipalities find solutions. With our forested watersheds as resources, we can provide the standards for clean water.”

How can Forest Service research help secure clean water in the quantities needed across the Southeast? The answer to this question varies with the topographies and climates of the region. In this issue, we will find out what SRS scientists have learned from two distinct settings—the Southern Appalachian uplands and the Coastal Plain of South Carolina.