Introduction to TMDLs
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- TMDL Definition
- Overview of Current Total Maximum Daily Load --TMDL--Program and Regulations
- Water Environment Federation's Information for Third Parties Interested in Developing TMDLs
- National Corn Growers Association Clean Water Act and the TMDL Program: An Introduction and Basic Desk Reference for Corn Growers (PDF) , Jan. 2007 (49 pp, 541K, About PDF)
- National Association of Counties (NACo) Introductory Information on TMDLs
- County Water Quality Issue Brief: Total Maximum Daily Loads (TMDLs) -- A Watershed Planning Tool For Counties
- Presentations on TMDLs from NACo Annual Conference, August 2006
- Audio version of Sept. 28, 2005 Webcast Seminar on "The ABCs of TMDLs for Stakeholders"
- TMDLs and Agriculture in the West (PDF) (2 pp, 198K, About PDF). Trifold flyer prepared by EPA Region 9. (EPA 909-F-03-003).
TMDL Definition -- What is a total maximum daily load (TMDL)?
A TMDL or Total Maximum Daily Load is a calculation of the maximum amount of a pollutant that a waterbody can receive and still meet water quality standards, and an allocation of that amount to the pollutant's sources.
Water quality standards are set by States, Territories, and Tribes. They identify the uses for each waterbody, for example, drinking water supply, contact recreation (swimming), and aquatic life support (fishing), and the scientific criteria to support that use.
A TMDL is the sum of the allowable loads of a single pollutant from all contributing point and nonpoint sources. The calculation must include a margin of safety to ensure that the waterbody can be used for the purposes the State has designated. The calculation must also account for seasonal variation in water quality.
The Clean Water Act, section 303, establishes the water quality standards and TMDL programs.