South Carolina Code of Regulations
Chapter 61 - DEPARTMENT OF HEALTH AND ENVIRONMENTAL CONTROL
Subchapter 61-110 - Total Maximum Daily Loads for Pollutants in Water
Section 61-110.B - Definitions

(1) Other than those terms defined below, any term used in this regulation shall mean the same as defined in S.C. Regulation Regulation 61-68 or Section 48-1-10 et seq. of the Code of Laws, 1976, as amended.

(2) "Total Maximum Daily Load" (TMDL) means a written quantitative analysis of water quality for a pollutant at one or more sites in a watershed. A TMDL shall include identification of the pollutant, a calculation of the maximum amount of the pollutant that a waterbody can receive and still meet state water quality standards, load allocations for nonpoint sources and natural background, individual or categorical wasteload allocations for point sources, and a margin of safety.

(3) "Margin of safety" means a consideration of any lack of knowledge concerning the relationship between load and wasteload allocations and water quality. The margin of safety may be implicit, i.e., incorporated into the TMDL through conservative assumptions in the analysis, or explicit, i.e., expressed in the TMDL as a specific loading, or both. If the margin of safety is implicit, the conservative assumptions in the analysis that account for it shall be described. If the margin of safety is explicit, the loading set aside shall be identified. The Department shall present a detailed justification and rationale for use of the selected margin of safety.