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About DHEC

Water Quality

DHEC maintains an extensive ambient water quality-monitoring network to assist in evaluating the quality of waters in South Carolina. Monitoring results are compared to water quality standards to determine if waterbodies are meeting the standards or if they are impaired. When a waterbody is impaired, it is targeted for water quality improvement.

DHEC has a comprehensive water quality-monitoring network. Over a five-year period ending in 2010, the Department monitored over 1,400 locations statewide and performed approximately 230,000 water quality tests. The monitoring data collected is compared to water quality standards to determine whether our waterbodies are attaining or "meeting" the water quality standards. By Federal law, the water quality standards are required to be reviewed every three years and updated as necessary.

When a waterbody is impaired, it goes on the 303(d) list of impaired waters. Section 303(d) of the Clean Water Act (CWA) mandates that every two years each state must compile of list of waters that do not meet water quality standards. Waters can be impaired for a variety of causes including, but not limited to: bacteria, nutrients, dissolved oxygen, dissolved metals, etc. In South Carolina, the majority of impairments to the state's surface waters, included on the 303(d) list, are due to fecal coliform bacteria. These are almost invariably due to nonpoint sources since all point source dischargers are required to disinfect their effluent and meet the water quality standard for fecal coliform bacteria at their point of outfall.

Once a waterbody is on the 303(d) list, it is targeted for water quality improvement and a Total Maximum Daily Load (TMDL) must be developed. A TMDL is a calculation of the maximum amount of a pollutant that a waterbody can receive and still meet water quality standards. TMDLs for a waterbody are calculated based on point source (industrial discharges, municipal discharges, stormwater discharges etc.), nonpoint sources (wildlife, pet waste, agricultural activities, septic tanks, runoff, etc.), and a margin of safety. To date, the Department has developed and established approximately 462 TMDLs, most of which address impairments of fecal coliform bacteria.

Once a TMDL has been developed, the next step is implementation. At this point, the TMDL can be used to formulate a strategy to reduce the pollutant loading. NPDES permits for point sources must be consistent with the TMDL. Generally DHEC does not have regulatory authority over the control of nonpoint sources. Rather, control of nonpoint sources is encouraged by using 319 grants to encourage landowners, farmers, and interested citizens to voluntarily work to improve the water quality.

Section 319 of the CWA provides grant money to states to support a wide variety of activities related to nonpoint source pollution reduction. South Carolina utilizes 319 funds for the implementation of nonpoint source TMDLs. To date, the Department has a total of 30 projects implementing 121 fecal coliform TMDLs that have received 319 funding. This represents a total investment of approximately $16 million in total funding to implement TMDLs in South Carolina. Organizations such as Clemson University Cooperative Extension Service, USDA-NRCS, US Forest Service, Friends of Lake Keowee (FOLKS), along with various Cattleman's Associations, Soil and Water Conservation Districts, Resource Conservation and Development Councils and local governments have all partnered with the Department for implementation projects.