MARPOL Discharge Regulations: Annex I, II, and V Under 33 CFR Part 151
TL;DR — Plastic discharge is prohibited everywhere, at all times, from all U.S.-flagged and U.S.-waters vessels; special areas impose stricter restrictions on oil and garbage discharges, and the Antarctic area carries the most absolute prohibitions of any designated zone. 33 CFR §151.51 33 CFR §151.13
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What the Rule Says
Purpose and Scope
33 CFR Part 151 implements the Act to Prevent Pollution from Ships (APPS, 33 U.S.C. 1901–1911) and Annexes I, II, and V of MARPOL 73/78. It also implements the Antarctic Science, Tourism, and Conservation Act of 1996 and the Protocol on Environmental Protection to the Antarctic Treaty. 33 CFR §151.01
The subpart applies to each ship that must comply with Annex I, II, or V of MARPOL 73/78 unless otherwise indicated. 33 CFR §151.03
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Key Definitions You Must Know Cold
Garbage means all kinds of food wastes, domestic wastes and operational wastes, all plastics, cargo residues, cooking oil, fishing gear, and animal carcasses generated during the normal operation of the ship and liable to be disposed of continuously or periodically — except substances defined or listed in other MARPOL Annexes. Garbage does not include fresh fish and parts thereof generated as a result of fishing activities undertaken during the voyage, or from aquaculture transport activities. 33 CFR §151.05
Plastics means all garbage that consists of or includes plastic in any form, including synthetic ropes, synthetic fishing nets, plastic garbage bags, and incinerator ashes from plastic products. 33 CFR §151.05
Graywater means drainage from dishwater, shower, laundry, bath, and washbasin drains. It does not include drainage from toilets, urinals, hospitals, animal spaces, or cargo spaces. 33 CFR §151.05
Oily mixture means a mixture, in any form, with any oil content. This includes slops from bilges, slops from oil cargoes, oil residue (sludge), and oily ballast water from cargo or fuel oil tanks. 33 CFR §151.05
Oil means petroleum whether in solid, semi-solid, emulsified, or liquid form, including crude oil, fuel oil, sludge, oil refuse, oil residue, and refined products. Oil does not include animal and vegetable based oil or NLSs designated under Annex II. 33 CFR §151.05
Oil residue (sludge) means the residual waste oil products generated during normal ship operations, such as those resulting from purification of fuel or lubricating oil, separated waste oil from filtering equipment, waste oil from drip trays, and waste hydraulic and lubricating oils. 33 CFR §151.05
Special area means a sea area where, for recognized technical reasons relating to its oceanographical and ecological condition and the particular character of traffic, the adoption of special mandatory methods for the prevention of sea pollution by oil, NLSs, or garbage is required. 33 CFR §151.05
Antarctic area means the area south of 60 degrees south latitude. 33 CFR §151.05
En route means that the ship is underway at sea on a course or courses, including deviation from the shortest direct route, which as far as practicable for navigational purposes will cause any discharge to be spread over as great an area of the sea as is reasonable and practicable. 33 CFR §151.05
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Annex I Special Areas — Oil Discharge (33 CFR §151.13)
The Annex I special areas are: Mediterranean Sea, Baltic Sea, Black Sea, Red Sea, Gulfs area, Gulf of Aden, Antarctic area, North West European waters, Oman area of the Arabian Sea, and Southern South African Waters. Discharge restrictions are currently effective in the Mediterranean Sea, Baltic Sea, Black Sea, and the Antarctic area. 33 CFR §151.13
Within a special area:
- A ship of 400 gross tons or over, and any oil tanker, may not discharge oil or oily mixture. 33 CFR §151.13
- In the Antarctic area, discharge of oil or oily mixture from any ship is prohibited — there is no gross tonnage threshold. 33 CFR §151.13
- A ship of less than 400 gross tons (other than an oil tanker) may discharge within a special area only if the oil content of the effluent without dilution does not exceed 15 ppm. 33 CFR §151.13
- All ships operating in the Antarctic area must have on board a tank or tanks of sufficient capacity to retain all oily mixtures while operating in the area, with arrangements made to discharge oily mixtures at a reception facility outside the Antarctic area. 33 CFR §151.13
Exception for processed bilge water — the prohibition on ships of 400 GT or over does not apply to processed bilge water from machinery space bilges if all of the following conditions are met: (1) bilge water does not originate from cargo pump room bilges; (2) bilge water is not mixed with oil cargo residues; (3) the ship is proceeding en route; (4) oil content of the effluent without dilution does not exceed 15 ppm; (5) oily-water separating equipment complying with 33 CFR Part 155 is in operation; and (6) the separating equipment is equipped with a device that stops discharge automatically when oil content exceeds 15 ppm. 33 CFR §151.13
No discharge into the sea shall contain chemicals or other substances introduced for the purpose of circumventing the discharge conditions. 33 CFR §151.13
Oily mixtures that cannot be lawfully discharged shall be retained on board or discharged to reception facilities. 33 CFR §151.13
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Annex II Special Areas — Noxious Liquid Substances (33 CFR §151.32)
The Annex II special areas are the Baltic Sea area, the Black Sea area, and the Antarctic area. Discharges into the sea of NLSs or mixtures containing such substances are prohibited in the Antarctic area. 33 CFR §151.32
Discharge restrictions for the Baltic Sea and Black Sea areas under Annex II will enter into effect when each bordering MARPOL party has certified that reception facilities are available and the IMO has established an effective date. 33 CFR §151.32
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Annex V Special Areas — Garbage (33 CFR §151.53)
The Annex V special areas are: Mediterranean Sea, Baltic Sea, Black Sea, Red Sea, Gulfs area, North Sea, Antarctic area, and the Wider Caribbean Region (including the Gulf of Mexico and the Caribbean Sea). 33 CFR §151.53
Discharge restrictions are currently in effect in the Wider Caribbean Region, the Mediterranean Sea, the Baltic Sea, the North Sea, the Gulfs, and the Antarctic special areas. 33 CFR §151.53
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Applicability of Annex V Requirements (33 CFR §151.51)
Sections 151.51 through 151.77 apply to:
- Any ship of U.S. registry or nationality, or operated under U.S. authority — including recreational vessels and uninspected vessels — wherever located; and
- Any ship operated under the authority of a country other than the United States while in the navigable waters or the Exclusive Economic Zone (EEZ) of the United States. 33 CFR §151.51
Warships, naval auxiliaries, and other government ships engaged in noncommercial service are exempt. 33 CFR §151.51
The EEZ extends from the baseline of the territorial sea seaward 200 miles. 33 CFR §151.51
Recordkeeping (§151.55) applies to: manned oceangoing ships of 400 GT and above (U.S. or foreign in U.S. waters/EEZ); manned fixed or floating drilling rigs or platforms subject to U.S. jurisdiction; and manned ships certified to carry 15 or more persons engaged in international voyages. 33 CFR §151.51
Garbage Management Plans (§151.57) apply to: manned oceangoing U.S. ships of 40 feet or more in length that are engaged in commerce or equipped with a galley and berthing; manned U.S. drilling rigs or platforms; and manned foreign ships of 100 GT or more in U.S. navigable waters or EEZ. 33 CFR §151.51
Placards (§151.59) apply to: manned U.S. ships 26 feet or more in length; manned floating drilling rigs in transit subject to U.S. jurisdiction; and manned foreign ships of 40 feet or more in U.S. navigable waters or EEZ. 33 CFR §151.51
Uninspected vessels must meet the garbage discharge, waste management plan, and placard requirements of 33 CFR Part 151 applicable to the vessel. 46 CFR §25.50-1
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Why It Matters on the Exam
Exam questions on MARPOL cluster around four themes:
1. What can be discharged, where, and under what conditions — particularly the 15 ppm threshold for oil, the absolute prohibition on plastics, and the heightened restrictions in special areas. 2. Which vessels are subject to which requirements — the gross tonnage and length thresholds for recordkeeping, garbage management plans, and placards are frequently tested. 3. Definitions — examiners test whether candidates can distinguish garbage from graywater, oil from NLS, and oily mixture from clean ballast. 4. Antarctic area rules — the Antarctic area is the most restrictive zone and appears disproportionately often in exam questions because its rules apply to any ship regardless of tonnage.
Know that the Antarctic area is defined as south of 60° south latitude. 33 CFR §151.05 Know that in the Antarctic area, oil or oily mixture discharge from any ship is prohibited, NLS discharge is prohibited, and all oily mixtures must be retained on board for discharge at a reception facility outside the area. 33 CFR §151.13 33 CFR §151.32
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Common Pitfalls
Pitfall 1 — Confusing graywater with sewage. Graywater is drainage from dishwater, shower, laundry, bath, and washbasin drains. It does not include drainage from toilets, urinals, hospitals, animal spaces, or cargo spaces. 33 CFR §151.05 Candidates who conflate graywater with sewage will misapply the applicable annex.
Pitfall 2 — Assuming the 400 GT threshold applies in the Antarctic area. For Annex I, the 400 GT threshold applies in other special areas, but in the Antarctic area the prohibition on oil or oily mixture discharge applies to any ship. 33 CFR §151.13
Pitfall 3 — Treating fresh fish as garbage. Garbage does not include fresh fish and parts thereof generated as a result of fishing activities undertaken during the voyage. 33 CFR §151.05 A fishing vessel's fresh catch is not subject to garbage discharge restrictions.
Pitfall 4 — Misidentifying which special areas have active discharge restrictions. For Annex I, restrictions are effective in the Mediterranean Sea, Baltic Sea, Black Sea, and Antarctic area — not yet in the Red Sea, Gulfs, Gulf of Aden, Oman area, or Southern South African Waters. 33 CFR §151.13 For Annex V, restrictions are in effect in the Wider Caribbean Region, Mediterranean Sea, Baltic Sea, North Sea, Gulfs, and Antarctic special areas. 33 CFR §151.53
Pitfall 5 — Forgetting that incinerator ash from plastic products is itself plastic. The definition of "all plastics" expressly includes incinerator ashes from plastic products. 33 CFR §151.05 Burning plastic and then discharging the ash overboard does not circumvent the prohibition.
Pitfall 6 — Overlooking the placard threshold for U.S. vessels. Placards are required on manned U.S. ships 26 feet or more in length — a lower threshold than the 40-foot length trigger for garbage management plans. 33 CFR §151.51
Pitfall 7 — Assuming uninspected vessels are exempt. Every uninspected vessel must meet the garbage discharge, waste management plan, and placard requirements of 33 CFR Part 151 applicable to that vessel. 46 CFR §25.50-1
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Quick Check
Q1 — What is the oil content limit for processed bilge water discharged from machinery space bilges within an Annex I special area (other than the Antarctic area) by a ship of 400 GT or over?
15 ppm, without dilution. The ship must also be proceeding en route, the bilge water must not originate from cargo pump room bilges, it must not be mixed with oil cargo residues, oily-water separating equipment complying with 33 CFR Part 155 must be in operation, and that equipment must be fitted with an automatic shutoff device. 33 CFR §151.13
Q2 — A 28-foot manned U.S. recreational vessel is operating on the Gulf of Mexico. Is it required to carry a MARPOL garbage placard?
Yes. The placard requirement under §151.59 applies to manned U.S. ships 26 feet or more in length. At 28 feet, this vessel meets the threshold. 33 CFR §151.51
Q3 — A commercial fishing vessel hauls in a catch and generates fish offal during the voyage. Is that offal "garbage" under 33 CFR §151.05?
No. Garbage does not include fresh fish and parts thereof generated as a result of fishing activities undertaken during the voyage. 33 CFR §151.05
Q4 — A vessel is operating in the Antarctic area and has oily bilge water on board. What must the vessel do with it?
The vessel must retain all oily mixtures on board in a tank or tanks of sufficient capacity and make arrangements to discharge those oily mixtures at a reception facility outside the Antarctic area. Discharge of oil or oily mixture from any ship in the Antarctic area is prohibited regardless of gross tonnage. [33 CFR §151.13](cite://33-cfr-151