What is TMDL?
Ok, so what is a Total Maximum Daily Load (TMDL)? It is the amount of a pollutant that a water body can assimilate without having a deleterious effect on its designated beneficial use. As a practical matter, this assessment is generally accomplished by comparing test results for a specific water body with the US Environmental Protection Agency’s (EPA) Maximum Contaminant Levels for each element. So, for example, mercury, arsenic, and lead may be below the threshold while copper can exceed this level. If the results are higher than acceptable limits, then the local governing body will write a “proposed” TMDL and pass it along to the State Water Resources Control Board who then gives it to the Federal EPA. If all agree along the line, then that particular part of the water body will be listed for that particular TMDL (element, compound, condition) and a time table established to try and rectify the matter. As one could expect, this business gets complicated quickly.
(Total Maximum Daily Load) A TMDL is a technical analysis that determines the maximum loading of the pollutant of concern a water body can receive and still both attain and maintain its water quality standards, and allocates this allowable loading to pollutant sources in the watershed. Upon approval by the Commission, this technical analysis must be submitted to EPA for review and approval. TMDL stands for Total Maximum Daily Loads. These projects evaluate stream and lake segments, ultimately determining the amount of pollutant which can be contributed by both point and non-point sources. The TMDL Program works to improve water quality in impaired or threatened water bodies in Texas. The program is authorized by and created to fulfill the requirements of Section 303(d) of the federal Clean Water Act. The goal of a TMDL is to restore the full use of a water body that has limited quality in relation to one or more of its uses.
