Water Quality

Water quality refers to the physical and chemical characteristics of water, which can be quite pure in mountain streams of the southern Appalachians. The dissolved and suspended material transported by stream water is determined by a number of factors, such as the quality of rainwater and the characteristics of the drainage basin such as geology, land cover, and human activities present. Materials are concentrated by evaporation and altered by chemical and biological interactions within the stream.

Many management practices, such as clearcutting, surface mining and acid mine drainage, industrial and municipal wastes, riparian disturbances, agricultural practices, impoundments, and the potential problems of acid precipitation and nitrogen saturation, influence water quality of Appalachian streams. The U.S. Geological Survey Water-Data Reports for the various states are good sources for additional information on stream chemistry in various areas of the Appalachians (Wallace and others 1992).

Clearcutting, logging, and subsequent regrowth of vegetation influence stream nutrient concentrations. For at least 10 years after cutting, logged catchments in various stages of natural revegetation show elevated stream nitrate concentrations. But, within two decades of regrowth, stream nitrate levels appear to return to baseline levels (Swank and Douglass 1977).

Human influences on water quality are often distinguished as point source pollution, which comes from a pipe, and nonpoint source pollution, which generally enters streams in runoff from surrounding land. In the southern Appalachians, approximately two-thirds of water pollution is from nonpoint sources (SAMAB 1996).

Typical problems with water quality involve erosion and sedimentation, nutrient enrichment, temperature elevation, and contamination with toxic substances. Water quality issues do not occur in isolation, and cumulative impacts of multiple sources of pollution are of increasing concern in the nation. Impoundments also affect water quality.

Drastic and long-term changes in aquatic habitat can lead to imperilment of species.