The Water quality (WQ) information tool was developed in an effort to assist stormwater managers in the preparation of a Notice of Intent (NOI) for construction activities, coverage under the industrial stormwater general permit or other stormwater management planning. Note that this tool should be used in conjunction with the statewide list of Sites Covered Under an Approved TMDL and Corresponding WQ Attainment Status (pdf) in order to accurately determine the water quality attainment status at each monitoring location. TMDL information may be updated in the WQ information tool at any time as additional TMDL documents are approved by the USEPA.
This application brings 90 layers of the Agency's most current and comprehensive watershed and water quality information into a user-friendly, statewide application. This searchable atlas includes watershed boundaries and descriptions; Bureau of Water permits and advisories; public water supply; water quality monitoring stations and assessments; water classifications; floodplains; National Wetland Inventory; county parcels; National Land Cover Data; Municipal Separate Storm Sewers (MS4s); TMDLs; and more. Note that the Water Quality Information Tool is recommended for the purpose of completing a Notice of Intent (NOI) for construction activities or coverage under the industrial stormwater general permit.
Table of Contents:
A) Impaired Waterbodies - 303(d) List
- What is the 303(d) List?
- How is the 303(d) List developed?
- How can a site be removed (or "delisted") from the 303(d) List?
- How can I find the current and past South Carolina's 303(d) List?
- What is the complete list of impaired water in South Carolina?
B) Total Maximum Daily Loads
- What is a TMDL?
- How are TMDLs calculated?
- What are water quality classifications, standards and designated uses?
- Which waterbodies require a TMDL?
- How many TMDLs are currently developed?
- What TMDLs are currently being developed in South Carolina?
- How are TMDLs Implemented?
- How is TMDL implementation evaluated?
- How does a TMDL implementation plan benefit citizens?
- How should an NPDES permittee deal with a discharge to a waterbody for which there is a TMDL?
A) 303(d) List
The 303(d) list is the list of impaired waterbodies. All states are required to develop a list of waterbodies that do not meet water quality standards. This requirement comes from Section 303(d) of the Clean Water Act, hence the common name for the list. The waterbodies on this list do not meet water quality standards even after controls for point and nonpoint source pollution have been put in place and/or a Total Maximum Daily Load (TMDL) for the pollutant has not been developed. The purpose of the list is to identify impaired waters so that the source of impairment can be described and corrective actions can be implemented to improve water quality.
EPA mandates that the 303(d) list of impaired waters be developed every two years and submitted to EPA for approval. South Carolina develops a 303(d) list every two years (1998, 2000, 2002, 2004, etc) for the waterbodies that fail to meet water quality standards.
How is the 303(d) List Developed?
DHEC solicits and considers all existing and readily available water quality data, including non-DHEC data, in developing South Carolina's 303(d) list. All non-DHEC data are accepted for consideration at any time during the listing cycle; however, only data submitted before May 6 of each odd-numbered year will be considered for the following year's 303(d) list (for example, data for the 2024 list must be submitted by May 6, 2023). To be considered for the 303(d) list, data must be representative of current water quality conditions and comparable to state water quality criteria. Any organization submitting data should use laboratories certified by the DHEC Office of Environmental Laboratory Certification for the test methods of record.
Persons wishing to collect water quality data for DHEC use are encouraged to contact the DHEC Office of Environmental Affairs and submit a Quality Assurance Project Plan (QAPP) for approval prior to initiating sampling. For the Department to use any non-DHEC data in development of the 303(d) list, submittal of non-DHEC data should be accompanied with an approved QAPP.
The 303(d) list is compiled using five years worth of data (e.g. for the 2024 list, data from 2018-2022 will be used). An assessment methodology is developed by DHEC and approved by EPA Region 4 and is used to assess data for 303(d) list development. This assessment methodology is included in the 303(d) document that is also approved by EPA Region 4.
If you have data that you would like DHEC to consider in developing South Carolina's 303(d) list, please e-mail Susan Waldner. Data must be submitted electronically by using the appropriate format. See Data Template (xls) for a downloadable Excel file.
How can a site be removed (or "delisted") from the 303(d) list?
Once a site has been added to the 303(d) list, there are only three ways for it to be removed or "delisted:
- The SC water quality standard has been attained
- A listing error has been identified
- A TMDL has been developed and approved. TMDLs must be developed and approved by EPA for all sites listed on the 303(d) list unless they are removed for one of the two reasons above. Please note that a developed and approved TMDL may not mean that the site/station has attained SC water quality standards.
How can I find the current and past South Carolina's 303(d) List
2020-2022 State of South Carolina Integrated Report Part I: Listing of Impaired Waters can be found at:
The official database for the approved 2020-2022 303(d) list is maintained by SCDHEC Bureau of Water.
SCDHEC has a priority and schedule for development of TMDLs on the 303(d) list.
- 2020-2022 State of South Carolina Integrated Report Part II: Assessment and Reporting can be found at: 2020-2022 305(b) Report (pdf)
Previous SC 303(d) Lists:
- 2018 State of South Carolina Integrated Report Part I: Listing of Impaired Waters can be found at: 2018 303(d) List (pdf)
- 2018 State of South Carolina Integrated Report Part II: Assessment and Reporting can be found at: 2018 305(b) Report (pdf)
- 2016 State of South Carolina Integrated Report Part I: Listing of Impaired Waters can be found at: 2016 303(d) List (pdf)
- 2016 State of South Carolina Integrated Report Part II: Assessment and Reporting can be found at: 2016 305(b) Report (pdf)
- 2014 State of South Carolina Integrated Report Part I: Listing of Impaired Waters can be found at: 2014 303(d) List (pdf)
- 2014 State of South Carolina Integrated Report Part II: Assessment and Reporting can be found at: 2014 305(b) Report (pdf)
- 2012 State of South Carolina Integrated Report Part I: Listing of Impaired Waters can be found at: 2012 303(d) List (pdf)
- 2012 State of South Carolina Integrated Report Part II: Assessment and Reporting can be found at: 2012 305(b) Report (pdf)
- 2010 State of South Carolina Integrated Report Part I: Listing of Impaired Waters can be found at: 2010 303(d) List (pdf)
- 2010 State of South Carolina Integrated Report Part II: Assessment and Reporting can be found at: 2010 305(b) Report (pdf)
- 2008 State of South Carolina Integrated Report Part I: Listing of Impaired Waters can be found at: 2008 303(d) List (pdf)
- 2008 State of South Carolina Integrated Report Part II: Assessment and Reporting can be found at: 2008 305(b) Report (pdf)
- 2006 State of South Carolina Integrated Report Part I: Listing of Impaired Waters can be found at: 2006 303(d) List (pdf)
- 2006 State of South Carolina Integrated Report Part II: Assessment and Reporting can be found at: 2006 305(b) Report (pdf)
- 2004 State of South Carolina Integrated Report Part I: Listing of Impaired Waters can be found at: 2004 303(d) List (pdf)
- 2004 State of South Carolina Integrated Report Part II: Assessment and Reporting can be found at: 2004 305(b) Report
- 2002 Listing of Impaired Waters can be found at: 2002 303(d) List (pdf)
- 2000 Listing of Impaired Waters can be found at: 2000 303(d) List (pdf)
- 1998 Listing of Impaired Waters can be found at: 1998 303(d) List (pdf)
What is the complete list of impaired waters in South Carolina?
A complete list of sites or stations that does not meet the state's water quality standards comprises of:
- 303(d) list of impaired water (2020-2022 303(d) List (pdf)) and
- Sites where a TMDL is developed and water quality standard are not attained (Sites Covered Under an Approved TMDL and Corresponding Water Quality Attainment Status (pdf))
B) Total Maximum Daily Loads
What is a TMDL?
A TMDL, or Total Maximum Daily Load, is the amount of a single pollutant (such as bacteria, nutrients, metals) that can enter a waterbody on daily basis and still meet water quality standards set fort by the State. "TMDL" refers to both a calculation of a pollutant entering a waterbody as well as a document which includes this calculation along with a source assessments, watershed and land use information, reductions and allocations information, implementation and other relevant information, maps, figures, and pictures.
TMDLs are a requirement found in Section 303(d), of the Clean Water Act. Once a site is included on the 303(d) list of impaired waters, a TMDL must be developed within two to thirteen years of initial listing. In South Carolina, TMDLs are developed and proposed by SCDHEC and then forwarded to EPA Region 4 for final approval.
TMDLs are calculated by adding all the point and nonpoint sources for the pollutant causing the impairment. After a TMDL is calculated, the amount of load entering from point and nonpoint sources is compared to the water quality standards for that waterbody. Then this total loading is reduced to the levels where the water quality standards can be met. This reduced loading is then divided among all the point and nonpoint sources.
The goal of a TMDL is to identify potential pollution sources, calculate and quantify the reduction of those sources, and general implementation information, needed in order to meet water quality standards and improve water quality. After the approval of the TMDL, an implementation plan can be developed to realize the goals of the written TMDL document. Implementation of a TMDL has a potential to reduces sources of pollution within a watershed and a potential to restore the full use of the waterbody.
SCDHEC's TMDL Regulations (R 61-110) can be found at: TMDL Regulation
How are TMDLs calculated?
TMDLs are calculated as the sum of the allowable loads of a single pollutant from all contributing point and nonpoint sources and includes a margin of safety. The calculations must include a margin of safety to ensure that the waterbody can be used for purposes that have been designated.
TMDL = Wasteload Allocations + Load Allocations + Margin of Safety
Wasteload allocations are loadings from point sources, such as an industrial or domestic treatment plants. Load allocations are from nonpoint sources. Examples of nonpoint sources are agricultural activities, runoff due to rainfall, etc. Allocations are determined through the review of monitoring data, load-duration curve, watershed based modeling, or other appropriate tools and methods. Margin of safety accounts for the scientific uncertainty and is incorporated into the calculation of the TMDL.
What are water quality classifications, standards and designated uses?
Water quality standards for South Carolina (R.61-68 and R.61-69) are promulgated by the SC General Assembly, approved by EPA, and implemented by the South Carolina Department of Health and Environmental Control.
Federal water quality standards regulations require that States and authorized Indian Tribes specify appropriate water uses to be achieved and protected. Appropriate uses are identified by taking into consideration the use and value of the waterbody for public water supply, for protection of fish, shellfish, and wildlife, and for recreational, agricultural, industrial, and navigational purposes.
In SCDHEC's water quality standards regulations, the designated uses we protect are:
- Contact recreation (swimming or primary and boating/wading or secondary),
- Drinking water supply,
- Aquatic life uses, which include fishing, the survival and propagation of a balanced indigenous aquatic community (fresh and marine) of fauna and flora, shellfish harvesting, crabbing,
- Agricultural and industrial uses,
- All groundwaters in SC have a designated use of underground sources of drinking water.
Which waterbodies require a TMDL?
Waterbodies require TMDLs when the following pollution control requirements are not stringent enough to meet applicable water quality standards:
- Technology-based effluent limitations required by the Clean Water Act;
- More stringent effluent limitations required by either State or local authority; and
- Other pollution control requirements (e.g., best management practices) required by local, State or Federal authority are not stringent enough to implement any water quality standard applicable to such waters.
Usually, when these requirements are not met, the site becomes listed on the 303(d) list. Hence, the Clean Water Act requires development of a TMDL for all waters included on the 303(d) list.
How many TMDLS are currently developed?
Over 400 sites or stations are covered under a TMDL developed in South Carolina and approved by USEPA Region 4. Approximately 350 of these approved TMDLs are for fecal coliform bacteria. See the link below for the list of current approved TMDLs in South Carolina. The complete list of sites covered under TMDLs and whether the sites are meeting water quality standard for the pollutant of concern may be helpful to prospective permittees in finding out if a waterbody is impaired.
What TMDLs are currently being developed in South Carolina?
SCDHEC is currently developing TMDLs for sites that are impaired for fecal coliform bacteria in fresh waters, fecal coliform bacteria in shellfish harvesting waters, and nutrients in lakes.
Current List of TMDLs Under Development by SCDHEC to view a list of areas where these TMDLs are being developed. Please click at: Total Maximum Daily Loads (TMDL) for Impaired Waters in SC to view draft TMDLs available for public comment.
How are TMDLs Implemented?
After a TMDL has been approved, State and local water quality management plans should be updated and control measures implemented.
National Pollution Discharge Elimination Systems (NPDES) Permit limits based on TMDLs, known as water quality-based limits, must be issued for point sources, including MS4, construction, and industrial stormwater.
Nonpoint source controls may be established by implementing Best Management Practices (BMPs) through voluntary or mandatory programs for enforcement, technical assistance, financial assistance, education, training, technology transfer, and demonstration projects.
When allowing for nonpoint source controls, implementation plans should provide:
- A reasonable assurance that the controls will be implemented and maintained OR
- An effective monitoring program to demonstrate that nonpoint source reductions are taking place
In South Carolina, funding may be available for the implementation of TMDLs through Section 319 Grants administered by SCDHEC. These funds are only available for TMDL implementation activities not required under a permit. Learn more about the Section 319 Nonpoint Source grant program.
How is TMDL implementation evaluated?
Whenever a TMDL is being implemented, the following approaches are recommended as a way of evaluating the effectiveness and progress of TMDL implementation process:
- Monitor pollutant loadings.
- Track implementation and effectiveness of controls.
- Assess water quality trends in the waterbody.
- Reevaluate TMDL for attainment of water quality standards.
How does a TMDL implementation plan benefit citizens?
A TMDL is a road map that lets citizens know how much pollutant discharge is acceptable and reduces much of the uncertainty and ambiguity of water quality regulations. It also lets community member and regulated entities know what needs to be done inorder to improve and restore impaired water bodies. TMDLs are a valuable tool to quantify pollutant loading, identify sources and determine the actions needed to meet water quality standards and restore impaired water bodies. However, to be effective they must be implemented.
When a TMDL has been implemented, the local community becomes a better place to live because the water quality has improved. Swimming and other water-based recreation is safer, fishing is better and the water is cleaner. Landowners can take pride in addressing and solving resource issues at the local watershed level. If you are a landowner or any stakeholder interested in finding out more about TMDLs or how to implement one in your area, contact your Watershed Manager. Learn more about DHEC's watershed management efforts.
How should an NPDES permittee deal with a discharge to a waterbody for which there is a TMDL?
MS4 stands for the Municipal Separate Storm Sewer program, a permitting program that considers stormwater discharge from municipalities to be a point source. Operators of large, medium and regulated MS4s are required to obtain NPDES permit coverage in order to discharge pollutants into Waters of the State. These designations (large, medium, and small) are based on urbanized areas as determined by the latest census. There are also construction, industrial, and utilities stormwater discharger.
The TMDL must specify discharge conditions or requirements, generally expressed as a wasteload allocation, for all discharges, including MS4, of the pollutant of concern to the relevant waterbody. The allocation may be numeric or narrative (e.g. specific BMPS), and may take any reasonable form. The MS4 operator must incorporate the stipulated requirements into the stormwater management plan, and implement them accordingly to the maximum extent practicable. If the TMDL is subsequently revised, the operator must implement the new allocation.