A key component of the federal effluent limitation requirements are the total maximum daily load (TMDL) provisions under Section 303(d) of the CWA. TMDLs are the amount of pollutant, or property of a pollutant, from point, nonpoint, and natural background sources, that may be discharged to receiving water that is water quality-limited. Any pollutant loading above the TMDL results in violation of an applicable water quality standard.
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