USGS Technical Assistance for TMDLs

	What's New :
	-The USGS Role in TMDL Assessments -PowerPoint Presentation on USGS TMDL-related projects or assistance: Part 1, Part 2, Part 3 (divided into 3 parts for faster downloading), presented at the TMDL Science Issues Conference. -USGS: A Resource for TMDL Activities Handout

Water is one of our most precious natural resources.  We often take it for granted until it is threatened by problems with water quantity or quality.  Quantity issues are addressed on other U.S. Geological Survey pages for ground water and surface water.  The wide range of monitoring, assessment, and research activities conducted by the USGS to help understand and protect the quality of our water resources is described on these pages. Studies are often done in collaboration with other Federal, State, Tribal, and local agencies. The results of these activities and studies can be used to assist management authorities with development of Total Maximum Daily Loads (TMDLs).

A TMDL 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 caluclation must also account for seasonable variation in water quality. The Clean Water Act, section 303, establishes the water-quality standards and TMDL programs.

If you would like information on how to develop a partnership with the USGS, or about information available related to TMDLs or TMDL development, please contact your USGS State Representative.

USGS National TMDL Assistance

Other TMDL Links

Return to Office of Water Quality page