The Total Maximum Daily Load (TMDL) Program is a Federal program authorized under the Clean Water Act to address waters that are not meeting water quality standards. A TMDL is a calculation of the maximum amount of a pollutant that a waterbody can receive and still meet water quality standards. The TMDL is then used to establish limits on sources of the pollutant which are classified as either point sources (waste load allocation), and non point sources (load allocation). The TMDL must account for seasonal variation in water quality and include a margin of safety to ensure that the TMDL allocations will adequate to protect the body of water. The Modeling and Assessment Branch of the Division of Water Resources publishes the 303(d) list and develops TMDLs based on EPA guidance.
Please visit EPA's Introduction to TMDLs for more information on the TMDL development process.
Addressing Point Sources:
Addressing Non-Point Sources:
The TMDL load allocation is calculated for all non-point sources that are contributing to the pollution. Depending on the sources identified in the TMDL, the load allocation may apply to septic tanks, fertilizer runoff from agricultural and residential areas, or sediment runoff from new construction sites. Unlike point sources, the TMDL does not have authority in most cases to force a reduction of pollutants from non-point sources.
TMDLs are usually only effective at addressing non point sources when enough interest is present from the community, local governments, or water quality advocacy groups, to implement the TMDL.
Funding is available to public and non-profit organizations through the NC Nonpoint Source 319 Grant Program to help address nonpoint source concerns identified in TMDLs.
Anyone whose interests may be affected by a TMDL project should be involved. Examples of participants include permitted wastewater dischargers, municipal and county governments, agricultural producers and groups, environmental and recreational groups, or other water users. State and federal agencies, as well as experts from universities, should also participate to provide technical and scientific support.
The TMDL process is an excellent opportunity for you to get involved in improving water quality in your local watershed. As a resident, you have unique insights into the conditions that influence water quality in your area. Your local expertise is needed to identify site-specific problems, target them for water quality cleanup, and help determine what measures will be most effective.
Public participation is an integral part of the TMDL process. In fact it is a required part of the process. Here are a few of the ways you can get involved:
One way to be involved is to read the North Carolina 303(d) List; identify waters in your area that are listed; find out what is being done, when, and what help is needed; and spread the word in your community.