Water resources in the ACE Basin include rivers, streams, estuaries, wetland impoundments, and ground water. We use these waters for different purposes such as swimming, fishing, drinking, agriculture and industry. The quality of the water resources is affected by natural events and human activities. Natural events include the timing, duration and intensity of rainfall and major storms, while human influences include runoff from urban and agricultural land, failing septic systems, and point source discharges, such as sewage outfalls. All waters in the United States are required by law to be designated for beneficial uses. These uses establish a level of quality that is monitored and evaluated through various water quality management mechanisms. Waters classified for support of aquatic life and contact recreation should be usable for fishing and swimming. Some waters are designated as public water supplies, which are used for drinking and bathing.
Poor water quality can limit the extent to which we use surface waters for drinking and harvesting fish and shellfish. Reducing the risk of drinking contaminated water is a goal of the Environmental Protection Agency (EPA) and state health agencies, such as the South Carolina Department of Health and Environmental Control (SCDHEC). Consumption of contaminated fish and shellfish due to poor water or sediment quality can pose significant risk to human health. Chemical concentrations in fish/shellfish tissues can bioaccumulate to levels much greater than found in surrounding water or sediments. Bacterial contamination can also be a factor in closure of beaches in order to prevent outbreak or spread of disease from contact recreation (EPA 1996).
Good water quality is critical to the health and survival of most plant and animal species. Aquatic habitats can become impaired, causing a decline or even extinction in local populations of many species. The structure and function of biological communities can be valuable indicators of stressors in a waterbody. Although conditions might appear suitable for aquatic life, the absence of healthy and diverse communities may indicate the existence of water quality problems that have not been detected (EPA 1996).
In this synthesis of water quality issues, we present each in the context of its importance nationally, regionally, and in the ACE Basin. We also discuss the relationship of water quality issues to the ACE ecosystem, and possible mechanisms to mediate the problems. These issues are discussed in detail in the following subsections.
The advent of industrialization and rapidly increasing human population has increased the demand for water and necessitated higher water quality standards. The history of legislation dealing with water quality standards dates to the 1899 Rivers and Harbors Act and the 1924 Oil Pollution Act. The first Water Pollution Control Act was enacted in 1948 in light of concerns over water-born diseases such as typhoid and dysentery and their effects on beaches and shellfish beds. In the mid-1950's, and again in the mid-1960's, Congress passed amendments to the Water Pollution Control Act. In 1972, Congress passed the Federal Water Pollution Control Act, which strengthened federal water pollution controls. The 1972 amendments created a national permitting program that required discharges to navigable waters to have a federal-or state-approved permit. Through further substantive amendments in 1977 and 1987, the Clean Water Act and the Water Quality Act included protecting and restoring coastal resources. A discussion of the key sections of the law may be found in Coastal Challenges: A Guide to Coastal and Marine Issues (Environmental Health Center 1998).
The Clean Water Act assigns primary authority to the states to set their own standards but requires that all states comply with the fishable and swimmable goal of the Act through establishment of beneficial uses and water quality criteria. The EPA recommends that states include the following beneficial uses:
The SCDHEC classifies waters to reflect both existing and intended uses. Criteria stringent enough to protect those uses are assigned to each class. SCDHEC routinely evaluates ambient water quality data against these criteria to summarize the degree to which surface waters support the designated uses overall. This assessment is submitted to EPA every two years. Data from the reports of each state are aggregated to form the National Water Quality Inventory Report to Congress which portrays the status of the nations waters assessed during the reporting period (EPA 1996).
A watershed is defined as a geographic area into which the surrounding waters, sediments, and dissolved materials drain, and whose boundaries extend along surrounding topographic ridges (SCDHEC 1997). The South Carolina Department of Health and Environmental Control grouped the state’s watersheds into eight major basins and is charged with managing surface and groundwater quality throughout these basins (See DHEC watersheds ). Each basin is subdivided into management units that are regularly monitored by SCDHEC. A Watershed Water Quality Management Strategy has been created for each of the five major drainage basins. The ACE Basin is included within the Salkehatchie and the Edisto drainage basins, which comprise approximately 4 million acres. (See related sections: SCDHEC Water Quality Assessment, Surface Water.)
The southern two-thirds of the ACE Basin is in the Salkehatchie water management area (See Edisto and Salkehatchie watersheds ). This drainage basin covers much of the southwestern corner of South Carolina. Most of the subwatersheds in the study area lie within this water management area. The Salkehatchie River basin originates in the Sandhills region and joins with the Little Salkehatchie to form the Combahee River which empties into St. Helena Sound and the Atlantic Ocean. This basin also contains drainages for the Ashepoo, Coosawhatchie, Broad and New Rivers (SCDHEC 1997).
The northern third of the ACE Basin is in the Edisto Basin watershed management area, which is completely contained within South Carolina. The Edisto River Basin originates in the Sandhills and forms the South Edisto and North Edisto Rivers which drain into the Atlantic.
At least 37% of the population in the US is located within 100 km of major estuaries or the oceans (Cohen et al. 1997). Most coastal water-quality problems result from waste associated with concentration of the human population along the coasts and from land-use practices in coastal watersheds. The upward trend in population growth within coastal areas is expected to continue well into the future (National Research Council 1993). (See related section: Land Use Module.)
In an effort to manage waste along the coast, more than 1400 municipal wastewater treatment plants are in operation nationally and discharge approximately 39 billion liters (10 billion gallons) of treated effluent per day. About 85% of this effluent is discharged into bays and estuaries (EPA 1992). In addition to this municipal discharge, industrial facilities discharge about 42.8 billion liters per day (11.3 billion gallons per day) of treated industrial wastewater and cooling water to marine systems. In the ACE Basin, industrial development is minimal with NPDES permits issued for 16 facilities. Municipal wastewater treatment plants that discharge into ACE Basin waters include the Walterboro plant on the Ashepoo River and the Yemassee plant on the Combahee River. The Walterboro publicly owned treatment works (POTW) is permitted to discharge up to 9.99 million liters per day (mld) [2.64 million gallons per day (mgd)], while the Yemassee POTW has a permitted discharge of 0.91 mld (0.24 mgd). There are also four, community-owned, domestic wastewater treatment systems located within the study area. Two of these facilities discharge into the Ashepoo River, one into the Combahee River and one into St. Helena Sound. These facilities have a combined maximum discharge of less than 0.15 mld (0.04 mgd).
Discharges from these municipal and industrial facilities constitute only a portion of the total pollutant input to the ACE Basin ecosystem. Runoff from urban, industrial and agricultural activities, either in the Basin or from areas upstream, is a significant source of pollution. Because the volume of runoff with its associated contaminants increases with increasing urbanization, the ACE Basin has not experienced the degree of water quality degradation that other areas of South Carolinas coast, such as Charleston Harbor, have experienced. Unfortunately, deposition of pollutants from the atmosphere is of increasing concern nationally and within relatively pristine areas such as the ACE Basin. Structural interventions in the natural hydrological cycle through diversion of water among drainage basins and the over-pumping of aquifers can also lead to problems with water quality, such as salinization.
Although most water quality degradation is due to anthropogenic influences, there are natural events, such as hurricanes and torrential rainfall, that can impact water and sediment quality. The effect of these natural events on water and sediment quality are often aggravated by mans activities, such as deforestation that results in soil erosion during heavy rainfall events.
Based on an assessment by EPA of the coastal states, the most common causes of not achieving designated uses in the Nations estuaries are nutrients, pathogenic organisms, organic enrichment and resulting low levels of dissolved oxygen and siltation (EPA 1990). Non-attainment of designated uses are common around urban and agricultural areas due to runoff containing metals and synthetic organic pollutants which may accumulate in sediments and be resuspended or released into the water column during disturbances. Metals and synthetic organic chemicals have been demonstrated to bioaccumulate in biota and produce health threats to the ecosystem and to humans. In an assessment of water resources of the Edisto River Basin, nonpoint source pollution was determined to pose the greatest threat to water quality (Beasley et al. 1996).
Water quality in the ACE Basin has not experienced many of the problems found in other more populated areas of the country. With expansion of South Carolinas coastal population, it is likely that deterioration of water quality will occur. Water quality problems of eutrophication, hypoxia, sedimentation, contaminant loadings, and salinity alteration presented in this module are influenced by a number of activities that occur in the ACE Basin, including urbanization, forestry practices, and agricultural development. Thus, it is important that a basic understanding of the potential effects from population and economic growth be achieved so that resource managers can capitalize on beneficial changes and prevent or minimize harmful ones.
Although water quality has improved nationwide since passage of the Clean Water Act, it is important that all levels of government, as well as public and private groups, work together to maintain or improve water quality in the ACE Basin and other coastal areas. The linkage between science and policy needs to be strengthened. Merely gathering and reporting scientific information does not guarantee its use in addressing concerns of society about water quality problems. Water quality problems should be couched in terms of human health and welfare, as well as ecosystem health and sustainability. A greater understanding of water quality issues with emphasis on educating the public about the linkages between personal action and water quality is imperative if the ACE Basin is to remain a relatively pristine ecosystem. This synthesis module has summarized many of these linkages with the goal that the public will take the steps necessary to protect the water resources and aquatic habitats of the ACE Basin.
E. Wenner, SCDNR Marine Resources Research Institute
M. Thompson, SCDNR Marine Resources Research Institute
Beasley, B. R., W. D. Marshall, A. H. Miglarese, J. D. Scurry, and C. E. Vanden Houten. 1996. Managing resources for a sustainable future: the Edisto River Basin project report, No. 12. SC Department of Natural Resources, Water Resources Division, Columbia, SC.
Cohen, J. E., C. Small, A. Mellinger, J. Gallup, and J. Sachs. 1997. Estimates of coastal populations. Science 278:1211-1212.
Environmental Health Center. 1998. Coastal challenges: A guide to coastal and marine issues. National Safety Council, Washington, DC.
[EPA] Environmental Protection Agency. 1990. The quality of our nations water: a summary of the 1988 National Water Quality Inventory. EPA 440/4/90-005. Office of Water, Environmental Protection Agency, Washington, D.C.
[EPA] Environmental Protection Agency. 1992. National Water Quality Inventory: 1990 Report to Congress. EPA 503/99-92-006. Office of Water, Environmental Protection Agency, Washington, D.C.
[EPA] Environmental Protection Agency. 1996. Environmental indicators of water quality in the United States. EPA 841-R-96-002. Office of Water, Environmental Protection Agency, Washington, D.C.
National Research Council. 1993. Managing wastewater in coastal urban areas. National Academy of Science Press. Washington, D.C.
South Carolina Department of Health and Environmental Control. 1997. Watershed water quality management strategy: Savannah and Salkehatchie River basins. Bureau of Water, SC Department of Health and Environmental Control, Columbia, SC. Technical report No. 003-97.