Definitions for "Total Maximum Daily Load"
A TMDL specifies the maximum amount of a pollutant that a waterbody can receive and still meet water quality standards, and allocates pollutant loadings among point and nonpoint pollutant sources. By law, EPA must approve or disapprove lists and TMDLs established by states, territories, and authorized tribes.
the sum of (1) a waste load allocation (WLA), or that portion of a surface water's loading capacity that is allocated to an existing or future point source discharge; (2) a load allocation (LA), or that portion of the surface water's loading capacity that is due to either existing or future nonpoint source pollution or to natural background sources; and (3) a margin of safety (MS), or that portion of a surface water's loading capacity that is allocated to uncertainty.  See Clean Water Act.
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.