Improving Water Quality in Impaired Waterbodies Pending the Establishment of a TMDL Listing Impaired Waterbodies and Establishing TMDLs Improving Water Quality in Impaired Waterbodies Pending the Establishment of a TMDL Listing Impaired Waterbodies and Establishing TMDLs States and Territories identify impaired waterbodies, those not meeting water quality standards. Lists of these waterbodies are provided to the public and EPA every two years.
States then establish TMDLs for waterbodies on the list.
TMDLs specify the reductions needed to meet water quality standards and allocate those reductions among the sources in the watershed. TMDLs can take up to 15 years to establish. These permits contain enforceable limitations and requirements that ensure that water quality standards will be met. Dischargers who will be required to obtain these offsets are large new dischargers and large existing dischargers undergoing a significant expansion. Offsets must be obtained before the discharger begins discharging.