Emerging Issues: Total Maximum Daily Loads

The Clean Water Act (CWA) requires states, territories, and authorized tribes to develop lists of impaired waters-waters that do not meet established water quality standards. The law requires that these jurisdictions establish priority rankings and develop Total Maximum Daily Loads (TMDL) for these waters. A TMDL is the allowable load of a pollutant from all contributing point sources (e.g., industrial and sewage treatment plants) or nonpoint sources (e.g., runoff containing natural and human-made pollutants). The calculation must include a margin of safety and account for seasonal variation in water quality.

These TDML "pollution budgets" are effective planning tools that help states and the public determine what is necessary to restore water quality in their streams, lakes, and rivers. The public process for their development ensures that all interested parties can participate in developing sound implementable TMDLs.

EPA encourages the development of watershed-based TMDLs where such efforts will yield efficiencies in planning and carrying out water quality restoration. It is not uncommon for dredging projects in estuaries and rivers to involve handling sediment or pollutants in sediment that may be an issue for the larger watershed. In these circumstances, the involvement of dredging stakeholders in the development of relevant watershed TDMLs could facilitate more appropriate restoration plans, as well as contribute to the control of upstream pollutants that would otherwise subsequently need to be dredged.

For more information, please see EPA's TMDL Web site.