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National Pollutant Discharge Elimination System (NPDES)

National Pretreatment Program Implementation

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Local municipalities are mostly responsible for implementing and enforcing the national pretreatment program requirements. The general pretreatment regulations at 40 CFR Part 403.8(a) require certain POTWs to establish a local pretreatment program to control discharges from nondomestic sources and to prevent pass through and interference at the treatment plant. There are approximately 1,600 POTWs that have local programs.
In a traditional pretreatment program, EPA approves a state’s NPDES authority to regulate the pretreatment program. Requirements for states to obtain NPDES state pretreatment authority are outlined in 40 CFR 403.10(3 pp, 188 K) — 36 states are authorized to act as the approval authorityHelpapproval authorityThe director in an NPDES Authorized State with an approved state pretreatment program, or the appropriate EPA regional administrator in a non-NPDES Authorized State or NPDES state without an approved state pretreatment program. [40 CFR 403.3(c)] for POTWs in their states.

The state includes conditions outlining pretreatment implementation requirements in NPDES permits issued to POTWs. For states not authorized to implement the pretreatment program, EPA serves as the approval authority. 

A POTW with an approved local pretreatment program is called the control authorityHelpcontrol authorityThe POTW, in the case of a POTW with an approved pretreatment program, or the Approval Authority, in the case of a POTW without an approved pretreatment program. [paraphrased from 40 CFR 403.3(f)] which regulates nondomestic facilities discharging to its system.

For the 40 CFR 403.10(e) (PDF) (3 pp, 188 K) states (Alabama, Connecticut, Mississippi, Nebraska, and Vermont), the state serves as the control authority.
An industrial user (IU)Helpindustrial userA source of indirect discharge. [40 CFR 403.3(j)] is a nondomestic source of indirect discharge into a POTW. An IU must comply with all applicable federal, state, and local pretreatment standards and requirements. Some federal requirements apply to all IUs and other requirements apply only to specific types of IUs. These federal requirements apply regardless of whether the IU has a control mechanism (e.g., permit or discharge authorization) from its control authority.