Clean Water Act Section 303(d): Impaired Waters and Total Maximum Daily Loads (TMDLs)

Section 303(d) of the Clean Water Act authorizes EPA to assist states, territories and authorized Tribes in listing impaired waters and developing Total Maximum Daily Loads (TMDLs) for these waterbodies. A TMDL establishes the maximum amount of a pollutant allowed in a waterbody and serves as the starting point or planning tool for restoring water quality.