In 1973, the International Maritime Organization (IMO) adopted the International Convention for the Prevention of Pollution by Ships and
subsequently modified it by Protocol in 1978. The Convention is widely known as MARPOL 73/78. Its objective is to limit ship-borne pollution
by restricting operational pollution and reducing the possibility of accidental pollution. MARPOL specifies standards for stowing, handling,
shipping, and transferring pollutant cargoes, as well as standards for discharge of ship-generated operational wastes. Acceptance of the
convention by national government obliges them to make the requirements part of domestic law.
MARPOL 73/78 consists of six separate Annexes, each set out regulations covering the various sources of ship-generated pollution. Annex I
and II are mandatory for all signatory nations to MARPOL while Annexes III, IV, V and VI are optional.
Currently, the U.S. is signatory to Annexes I, II, III, V and VI. Annexes I, II, V and VI have been incorporated into U.S. law by the Act to
Prevent Pollution from Ships (APPS) and implemented within 33 USC 1901 and 33 CFR 151. The U.S. incorporates Annex III by the Hazardous Materials
Transportation Act (HMTA) implemented within 46 USC 2101 and 49 CFR 171 -174 and 176. Although the U.S. has not ratified Annex IV, the U.S. has
equivalent regulations for the treatment and discharge standards of shipboard sewage – the Federal Water Pollution Control Act (FWPCA) as
amended by the Clean Water Act and implemented by 33 USC 1251 and 33 CFR 159.
The table below indicates each Annex by pollution source, its title, U.S. signatory status and implementing legislation, law and/or regulations
and applicable Coast Guard guidance. A brief discussion of the major provisions of each MARPOL Annex follows.