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History of Water-Quality Conditions in the South

This section is confined to key points about the history of water quality in the South. A discussion of the history of southern forests and land use change in the South is included in chapters 6 and 24.

Little information is available on water quality in the South prior to the 20^th century. Erosion resulting from Native American transportation and agricultural practices has been characterized as minimal (Binkley and Brown 1993, Sedjo 1991). Causes of erosion during this period included fires, mass soil movement, natural stream erosion, and animal trails. For example, migration of buffalo was correlated with an increase in stream turbidity (Trimble 1974).

Early descriptions repeatedly characterized streams as clear and dark as opposed to the brown or red color that now dominates southern streams (Trimble 1974). Early explorers described a shiny substance in streams, which may have indicated the presence of mica (Trimble 1974). Mica is no longer abundant in the majority of streams in the Southeast, presumably due to manmade erosion of upland soils into streams. The average soil loss in the North Carolina Piedmont was less than one-tenth inch per 1,000 years prior to European settlement. Current rates of soil loss from clean cultivated land are 80 to 300 inches per 1,000 years (Trimble 1974).

Settlement by Europeans resulted in large-scale ecological changes that continue to affect water quality (Trimble 1974). Throughout the early settlement period, water quality declined as land cover shifted from mature forests to agricultural fields (Trimble 1974). Sedimentation and erosion were the primary causes of water-quality impairment. It has been estimated that an average of 5.9 inches (15 cm) of soil have been lost in the Southeast due to erosion since the time of European settlement (Binkley and Brown 1993). Cotton, tobacco, and small plots of corn dominated agricultural crops through 1860. Cotton plantations were the primary source of water-quality impairment during this period (Trimble 1974).

The period between 1860 and 1920 was the most destructive in the South with regard to water quality due to widespread clearing of forests for fuel, timber, wood products, and crops (Trimble 1974). Forest clearing without erosion control measures resulted in increased sedimentation and severe water-quality impairment (Mac and others 1998). Logging activities peaked in 1909 and remained high until 1920. By 1920, only a small area of virgin forest remained. After the Civil War, agriculture continued to be the most important land use in the South. Increased soil erosion rates due to inadequate conservation practices and increased use of fertilizers accelerated the degradation of water quality (Trimble 1974). Southern rivers filled with sediments from upland soils.

Comprehensive water-resource research was largely initiated during this period. The first watershed experiment, called the Wagon Wheel Gap study, was conducted in 1909. This Colorado study focused on the effects of deforestation on the volume and timing of streamflow, soil erosion, and sediment loading (Megahan and Hornbeck 2000).

Between 1920 and 1972, people migrated to cities as industry became the dominant force in the United States economy. Less wood was used for fuel and roads, resulting in a decrease in the demand for wood (Sedjo 1991). Due to this decreased demand, logging and land-clearing activities were significantly reduced. Therefore, adverse effects on water quality from these activities also declined.

The effect of agricultural land use practices became evident in the 1930s with the onset of the Great Depression (Mac and others 1998). Losses of fertile soil due to the intensity and types of agriculture practices, as well as drought conditions, resulted in the Dust Bowl of the 1930s and the abandonment of farmland (Meyer 1995). Soil erosion during this time period adversely affected water quality, primarily due to sedimentation of rivers and streams.

Draining of wetlands, which serve as filters for surface-water runoff, was another contributing factor to water-quality impairment. Between 1950 and 1970, 11 million acres of wetlands were lost in the United States (Meyer 1995). A complete discussion of the history of forested wetlands in the South is provided in chapter 20. Flooding was also a problem during this period, and the Flood Control Act of 1936 brought about the modification of major rivers, such as the Mississippi. River channels were widened and dredged to facilitate navigation. These practices had devastating effects on many aquatic species, by removing or covering benthic habitat. A complete discussion of aquatic species and habitats is included in chapter 23.

In the late 19^th and early 20^th centuries, waterborne disease occurred in urban centers as populations came into contact with water bodies contaminated with sewage. Diseases such as cholera were transmitted through inadequate disposal of human waste, and typhoid fever outbreaks occurred as cities began to develop (Chase 1952, Cowdrey 1996). As a result, sanitary engineering (later called environmental engineering) developed technologies to reduce waterborne illnesses by treating sewage prior to discharging it into water bodies (Chase 1952). Industrialization in the South also created water-quality problems during this period. The petrochemical, paper, and automotive industries are a few of the industries that impacted water quality by discharging industrial wastes directly into water bodies (Cowdrey 1996).

Pesticide use increased dramatically after World War II. Overspraying resulted in numerous instances of harmful levels of pesticides in soil and water. Toxic compounds such as dichlorodiphenyltrichloroethane (DDT) were used without restrictions. In 1962, Rachel Carson’s “Silent Spring” highlighted the effects of DDT, which include contamination of water supplies and thinning of predatory bird eggshells. In 1972, the use of DDT was banned (Cowdrey 1996).

As a better understanding of the interdependence of water quality and land use practices was developed, legislation at local, regional, and national levels was passed to address the management and preservation of natural resources. According to the USEPA, only a third of the Nation’s waters were safe for fishing and swimming in 1972 (U.S. Environmental Protection Agency 2001a). In response to the situation, the Federal Water Pollution Control Act, or Clean Water Act (CWA), was passed in 1972. This act significantly changed the way the Federal Government and individual States regulated and reported on water quality. In addition, State and local mandates were developed to regulate sources and causes of water-quality impairment on a local level. Land-disturbance activities and urban development are subject to regulations and guidelines at the State and local level via sedimentation and erosion-control management plans, zoning, permits, and implementation of best management practices (BMPs). The CWA and other laws and regulations that affect water quality in the United States are summarized and discussed in detail in chapter 8, primarily as they relate to silvicultural practices.

Subsequent to the passage of the CWA, a comprehensive analysis of water quality in rivers was conducted (Smith and others 1987). This study utilized data from the National Stream Quality Accounting Network (NASQAN) and the National Water Quality Surveillance System (NWQSS). In general, results of this study indicated that point-source pollution had decreased on a national scale, and nonpoint-source pollution had increased since passing of the CWA (Smith and others 1987). A complete discussion of point and nonpoint sources of pollution is included in the section “Leading Sources of Impairment (1988-98).”

In the South, decreases in bacteria associated with municipal wastewater discharges were noted, especially in parts of the Gulf of Mexico, central Mississippi, and Arkansas. However, localized increases in bacteria were noted in association with point-source livestock waste discharges. A dramatic increase in suspended sediment, nutrients, phosphorous, and nitrate was observed due to increased fertilizer applications, other agricultural practices, and high soil erosion rates. In addition, atmospheric deposition was positively correlated with increases in nitrate concentrations, especially in forested basins. In contrast, a decrease in phosphorous concentrations was noted in the upper Mississippi Valley. An increase in contaminants such as metals was observed primarily due to fossil fuel combustion, metal manufacturing, pesticides, and herbicides. However, a widespread decrease in lead concentrations was observed due to a 67-percent drop in leaded gasoline consumption (Smith and others 1987).