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TMDL Basics

A Total Maximum Daily Load (TMDL) is the amount of a particular pollutant that a water body (stream or river segment, lake or estuary) can receive and still meet State water quality standards for that pollutant.

TMDLs must be developed for all water bodies identified as not meeting water quality standards and for which there are no ongoing actions to resolve the impairment. This “303(d) list” is a subset of the larger “305(b) list” of all impaired waters in Georgia, which is updated every two years by the Georgia EPD after public comment and approval by USEPA. The most current Georgia 305(b)/303(d) list has been published by EPD in the official 305(b) report entitled “Water Quality in Georgia 1998-1999”. Since only a small percentage of State waters have actually been monitored, the fact that a water body is not listed on the 305(b)/303(d) impaired waters list does not mean that it meets water quality standards. The 305(b) report does contain a list of waters that have been tested and found to meet the standards, however.

The schedule for development of TMDLs is based on certain priority ranking factors and, in some cases, court rulings on lawsuits filed by various environmental groups. A Consent Decree in the Georgia TMDL lawsuit (Sierra Club v. EPA & Hankinson) requires TMDLs to be developed for all waters on the current 303(d) list consistent with Georgia’s 5-year rotating basin management planning cycle. TMDLS are developed by the Georgia EPD Water Protection Branch or by the USEPA Region 4 Water Quality Planning and Assessment Branch if EPD fails to do so. A list of proposed and finalized TMDLs is posted on the USEPA Region 4 TMDL Web site at http://www.epa.gov/region4/water/tmdl/index.htm, but is not necessarily comprehensive. TMDL lists may also be posted on the Georgia EPD website at http://www.ganet.org/dnr/environ/, under Technical Guidance.

An impaired water body may have more than one pollutant not meeting water quality standards, and a TMDL must be developed for each of these pollutants. Computer modeling is used to develop each TMDL, which defines the current and proposed maximum allowable point source and nonpoint source pollutant loadings, as well as a margin of safety. The TMDL calculations may also identify the percent reduction in pollutant loadings needed to meet the water quality standards.

TMDL Implementation Plans

After a TMDL is finalized, an implementation plan must be developed for initiating local, regional and state actions that will reduce pollutant loads to levels established by the TMDL. The Georgia Consent Decree required the development of TMDL implementation plans for over 100 TMDLS already finalized by EPA and EPD, by April 19, 2001, and others will follow. An implementation plan must identify and allocate existing pollutant loadings as well as future loadings that may result from land use and other changes in the watershed. An implementation plan would typically be developed by a lead organization and include active involvement by local stakeholders and the general public. Stakeholders may be any person or group whose activities contribute to the pollutant loading or whose interests are affected by the TMDL. Stakeholders could include city and county governments, industrial wastewater and storm water dischargers, farmer and agricultural producers, commercial forestry operators, environmental groups, developers, various business interests and other parties. EPD is responsible for facilitating the TMDL implementation process. The EPD Water Protection Branch provided funding for the 16 Georgia Regional Development Centers (RDCs) to develop initial implementation plans for TMDLs across the State, mostly for fecal coliform bacteria.

Implementation plans must include projected dates for meeting water quality standards and would typically utilize existing environmental programs, as well as new initiatives. For example, enforcement of existing permits and local ordinances might be a critical need in some watersheds, so the implementation plan could include innovative ways to fund this effort. Implementation plans might also include more stringent wastewater or storm water discharge permit requirements, land use restrictions, sewer hookup moratoriums and other activities that could have a major impact on growth and development until water quality standards are attained. The TMDL regulations also require EPD to re-assess all National Pollutant Discharge Elimination System (NPDES) discharge permits impacting a water body, within 18 months of a TMDL being finalized for that water body. The Phase II storm water regulations also expand the authority of EPD to require new municipal and industrial storm water discharge permits in watersheds with TMDLs. EPD already requires watershed assessments and protection plans for any new or increased NPDES municipal wastewater discharge permits, in response to 303(d) and TMDL concerns. This requirement may be extended to all NPDES municipal wastewater discharge permits as they come up for renewal.

Whether the initial round of TMDL implementation plans can achieve the goal of returning impaired waters to compliance with water quality standards for their designated uses remains to be seen. However, given the continuing litigation over the development of TMDLs and their implementation plans in Georgia and across the nation, the process will probably not be quick or easy.

Sources: USEPA TMDL Web site at http://www.epa.gov/OWOW/tmdl/, USEPA Region 4 Web site at http://www.epa.gov/region4/tmdl/index.htm.

Other Resources: Georgia EPD Web site at http://www.georgianet.org/dnr/environ/ (click on Water Quality). Association of State and Interstate Water Pollution Control Administrators (ASIWPCA) at http://www.asiwpca.org/. Local Government Environmental Assistance Program (LGEAN) at http://www.lgean.org/

Videotapes: “Water Quality in Georgia – The Total Maximum Daily Load (TMDL) Program” by the Georgia Water Management Campaign. Call the Association County Commissioners of Georgia at 404-522-5022.

“Watershed Wisdom: Georgia’s TMDL Program” by the Georgia EPD. Call the EPD TMDL Coordinator at 404-675-1752.

Contacts: Georgia EPD Water Protection Branch TMDL Coordinator at 404-675-1752.
Watershed Planning and Monitoring Program at 404-675-6236. A complete copy of the Georgia EPD’s 1998-1999 Water Quality In Georgia Report may also be obtained by calling this number.