National Pollutant Discharge Elimination System (NPDES)


Incidental Discharge Permitting

Section 402 (PDF)(8 pp, 165 KB, About PDF) of the Clean Water Act (CWA) establishes authority for the NPDES permitting program to regulate discharges incidental to the normal operation of a commercial (i.e., non-military, non-recreational) vessel when operating as a means of transportation (i.e., “incidental discharges”). This includes a broad range of incidental discharges such as ballast water, bilgewater, graywater (e.g., water from sinks, showers), and deck washdown and runoff.  EPA controls these incidental discharges primarily through two NPDES general permits: the Vessel General Permit (VGP) and the Small Vessel General Permit (sVGP).

Information on the regulation and control of other types of vessel discharges, such as the control of sewage under Section 312 of the CWA, is at EPA’s Vessel Discharges web area.