Total Maximum Daily Loads (TMDLs)

 

Graphic showing a watershed - from rainfall to ground and surface water.

Section 303(d) of the federal Clean Water Act requires that states develop Total Maximum Daily Loads (TMDLs) for water bodies.  

 

TMDLs are calculations to determine the sum allowable load of a pollutant from all contributing point and nonpoint sources, that a waterbody can receive and still meet the applicable water quality standards.  

 

The calculation must include contributions from natural sources and have a margin of safety to ensure that the water body can be used for its designated beneficial use.

 

TMDLs must be developed for water bodies that do not meet the water quality standards, or might not meet water quality standards with the application of technology-based controls for point sources. In these cases, point sources of pollution would need additional water quality-based controls.

 

Once the state has developed a TMDL, we are required to public notice the TMDL and have it approved by the Environmental Protection Agency (EPA).

 

A more detailed explanation of how TMDLs are developed is available at this link. For additional  information about TMDLs, contact Kathleen Grigg by calling (605) 773-3351.

 


 

Information pertaining to nonpoint source TMDLs.

 


 

Every two years, the State of South Dakota is required to do an analysis of the impaired waterbodies throughout the state. This is assessed in the following current and archive Integrated Reports:

 

Integrated Reports