MARPOL & Pollution Prevention
Complete study guide for the USCG OUPV exam. Covers all six MARPOL Annexes, OPA 90, the Act to Prevent Pollution from Ships (APPS), Vessel Response Plans, spill reporting, and US Clean Water Act requirements.
MARPOL Overview
MARPOL — the International Convention for the Prevention of Pollution from Ships — is the primary international treaty governing marine pollution. Adopted in 1973 and modified by the 1978 Protocol (hence "MARPOL 73/78"), it sets minimum standards for discharges of oil, noxious liquids, packaged hazardous substances, sewage, garbage, and air pollutants.
MARPOL is enforced in US waters by the Act to Prevent Pollution from Ships (APPS), 33 U.S.C. 1901 et seq. APPS makes MARPOL requirements enforceable as US federal law with criminal and civil penalties. The USCG enforces APPS during port state control inspections.
MARPOL vs. US law: US regulations are sometimes stricter than MARPOL. For example, the Clean Water Act Section 311 and state no-discharge zones can apply tighter restrictions on sewage and oily water discharge than the minimum MARPOL thresholds. The rule is: always follow whichever standard is more protective.
Which vessels must comply with MARPOL?
- •All vessels flagged to MARPOL signatory states (includes US-flagged vessels worldwide)
- •Foreign vessels operating in US waters (port state control enforcement)
- •Fixed and floating platforms operate under modified rules
- •Warships and government non-commercial vessels are exempt but should comply as far as practicable
- •Annex-specific thresholds apply based on vessel size (gross tonnage) and type
The Six Annexes at a Glance
Annex I — Oil
Annex I is the most tested MARPOL topic on the OUPV exam. Know the 15 ppm rule, the oily water separator, the Oil Record Book, and the special area prohibition cold.
The 15 ppm Rule
No vessel may discharge oil or oily mixtures at a concentration exceeding 15 parts per million (ppm) into the sea outside of special areas. This applies to bilge water from the machinery space.
Annex I Special Areas (Zero Discharge)
Oily Water Separator (OWS)
The OWS is a gravity or coalescing separator that removes oil from bilge water to below 15 ppm before discharge. An oil content meter (OCM) continuously monitors the effluent. If the discharge exceeds 15 ppm, the OCM automatically diverts flow back to the bilge holding tank — the overboard valve must never be opened manually to bypass this.
Oil Record Book (ORB)
The ORB is a required log of all oil operations aboard the vessel. It has two parts: Part I (Machinery Space Operations) for all vessels 400 GT+, and Part II (Cargo/Ballast Operations) for oil tankers 150 GT+. Every entry must be in English, signed by the officer in charge of the operation, and countersigned by the master on each completed page.
| What Must Be Recorded | Notes |
|---|---|
| Ballasting / cleaning of fuel oil tanks | Date, tank ID, quantity, position at start and finish |
| Discharge of dirty ballast or cleaning water from fuel oil tanks | Include oil content meter readings |
| Collection, transfer, and disposal of oily residues (sludge) | Volume, method of disposal, port reception facility if used |
| Discharge overboard of bilge water | Position, ppm reading, OWS operating status |
| Condition of OWS and oil content meter | Malfunctions must be recorded and reported to COTP |
| Accidental or exceptional oil discharges | Circumstances, cause, actions taken, notification |
Annex II — Noxious Liquid Substances (NLS)
Annex II covers bulk liquid chemical cargoes carried by chemical tankers. Substances are categorized by their hazard to the marine environment, and discharge rules differ by category. The NLS Cargo Record Book is required (similar to the ORB for oil tankers).
| Category | Hazard Level | Pre-wash Required? |
|---|---|---|
| X | Major hazard — greatest harm to marine environment or human health | Mandatory pre-wash at sea |
| Y | Hazardous — harmful to marine resources or human health | May be required by P&A Manual |
| Z | Minor hazard — minor risk to marine environment | Generally not required |
| OS | Other Substances — minimal hazard, not regulated under Annex II for discharge | Not required |
Pre-Washing — The Key Concept
For Category X substances, the cargo tanks must be pre-washed at sea before the vessel enters any port. The pre-wash must be performed according to the ship's Procedures and Arrangements (P&A) Manual. All washings must be pumped to a port reception facility — they cannot be discharged overboard. A surveyor must certify the pre-wash is complete before the tank can receive a new cargo.
Annex III — Harmful Substances in Packaged Form
Annex III governs the transport of harmful substances in packaged form — that is, in drums, containers, portable tanks, freight containers, or other packages. The key reference document is the International Maritime Dangerous Goods (IMDG) Code.
IMDG Code Requirements
- •Marking: Each package must bear the proper shipping name of the substance
- •Labeling: Hazard labels (diamonds) indicating hazard class must be affixed
- •Placarding: Cargo transport units (containers, tanks) must display placards
- •Documentation: Dangerous goods declaration must accompany the cargo
- •Stowage: Segregation requirements based on compatibility of hazard classes
Jettisoning Prohibited
Annex III prohibits the jettisoning of harmful substances in packaged form at sea except where necessary for the safety of the ship or to save life.
Marine Pollutants
Substances identified as marine pollutants in the IMDG Code must be marked with the marine pollutant mark (stylized fish and tree) on their packages and containers.
Annex IV — Sewage
MARPOL Annex IV regulates the discharge of sewage from ships. In the United States, the Clean Water Act also imposes requirements — sometimes stricter — through the Marine Sanitation Device (MSD) regulations at 33 CFR Part 159.
Marine Sanitation Device (MSD) Types
Maceration + chlorination (or equivalent). Treats and discharges continuously.
3 nm from nearest land (comminuted, disinfected)
Approved by USCG for underway discharge at 3 nm
Biological + chemical treatment to secondary treatment standards.
3 nm from nearest land
Higher treatment standard; meets secondary treatment quality
No treatment — stores sewage on board until discharged to a pump-out facility.
12 nm from nearest land (if pumped overboard)
Required in No Discharge Zones (NDZ); pump-out at marina or facility
Discharge Distance Summary
No Discharge Zones (NDZ)
The EPA and states can designate No Discharge Zones where no overboard discharge of sewage — even treated sewage — is permitted. NDZs include many popular coastal areas, lakes, and inland waterways. Check NOAA charts and EPA NDZ maps before operating. Vessels in an NDZ must use a Type III holding tank and pump out at a marina or reception facility.
Annex V — Garbage
MARPOL Annex V was significantly amended in 2013. The most important change: plastics are now prohibited from discharge anywhere at sea — no exceptions. A vessel 12 meters or more in length must display placards notifying passengers and crew of the garbage discharge regulations.
| Garbage Type | Outside Special Areas | Inside Special Areas |
|---|---|---|
| Plastics (all) | PROHIBITED | PROHIBITED |
| Food waste | 12 nm+ | Not permitted |
| Cargo residues (non-hazardous) | 12 nm+ | Not permitted |
| Cleaning agents / additives | Not harmful only | Not permitted |
| Carcasses of animals | As far from land as possible | Not permitted |
| Paper, rags, glass, metal, crockery | 12 nm+ | Not permitted |
| Operational waste (non-plastic) | 12 nm+ | Not permitted |
| Fishing gear (lost overboard) | Report required | Report required |
Garbage Management Plan (GMP)
Required on vessels 100 GT and above, and vessels certified to carry 15 or more persons. The GMP must include:
- •Procedures for collecting, storing, processing, and disposing of garbage
- •Designation of the person responsible for carrying out the plan
- •Written in the working language of the crew
Garbage Record Book
Required on vessels 400 GT and above, and vessels certified to carry 15+ persons. Must record:
- •Each discharge to sea or reception facility
- •Date, time, position, estimated amount and category
- •Retained on board for 2 years after last entry
Annex V Special Areas (Most Restrictive)
In special areas, the only garbage that may be discharged is food waste at least 12 nm from nearest land. All other garbage must be retained. Special areas under Annex V include:
Annex VI — Air Pollution
MARPOL Annex VI regulates air emissions from ships, primarily sulfur oxides (SOx), nitrogen oxides (NOx), and ozone-depleting substances. The International Air Pollution Prevention (IAPP) Certificate is required for vessels 400 GT and above (and new ships 400 GT+).
Sulfur Limits
The North American ECA extends 200 nautical miles from the US and Canadian coastlines (Atlantic, Pacific, and Gulf coasts) and applies to vessels operating within that zone.
NOx Emission Tiers
| Tier | Applies To | NOx Limit |
|---|---|---|
| Tier I | Ships built 2000–2010 | 17 g/kWh (at 130 rpm) |
| Tier II | Ships built 2011 and after | 14.4 g/kWh (at 130 rpm) |
| Tier III | Ships built 2016+ (in ECAs only) | 3.4 g/kWh (at 130 rpm) |
IAPP Certificate
The International Air Pollution Prevention (IAPP) Certificate is required for vessels 400 GT and above. It certifies that the vessel's engines comply with the applicable NOx Tier and that the vessel's fuel meets the applicable sulfur limits. Issued by the flag state or a recognized organization.
Ozone-Depleting Substances
Annex VI prohibits deliberate emissions of ozone-depleting substances (ODS) such as halons and CFCs. An Ozone-Depleting Substances Record Book is required on vessels with ODS-containing systems (older fire suppression and refrigeration equipment). New installations of ODS are prohibited.
OPA 90 — Oil Pollution Act of 1990
OPA 90 is the cornerstone of US oil spill prevention and response law. It was enacted in the wake of the Exxon Valdez disaster and fundamentally restructured US policy on vessel and facility oil spill liability, response planning, and financial responsibility.
Certificate of Financial Responsibility (COFR)
The COFR is a USCG-issued certificate proving the vessel owner can pay for oil spill cleanup up to the OPA 90 liability limits. Without a valid COFR, a vessel cannot legally operate in US waters.
APPS — Act to Prevent Pollution from Ships
The Act to Prevent Pollution from Ships (APPS), 33 U.S.C. 1901-1915, is the US implementing legislation for MARPOL. It makes MARPOL's requirements enforceable as US federal law and establishes civil and criminal penalties for violations.
Civil Penalties
Civil penalties can be assessed by the USCG through an administrative process. Each day a violation continues is a separate violation.
Criminal Penalties
For knowing violations, individuals face up to 6 years imprisonment. Corporations face unlimited fines. The USCG frequently prosecutes false ORB entries as a knowing violation.
What APPS Enforces
Vessel Response Plans (VRP)
Under OPA 90 and 33 CFR Part 155, certain vessels must have a USCG-approved Vessel Response Plan (VRP) on board at all times. The VRP describes how the vessel owner will respond to a worst-case oil discharge scenario.
Vessels Required to Have a VRP
Required Elements of a VRP
The Qualified Individual (QI)
The Qualified Individual is a specific person named in the VRP who has full authority to activate and direct the spill response. The QI must be reachable 24 hours a day, 7 days a week. When a spill occurs, the first call is to the National Response Center (NRC) at 1-800-424-8802, and then to the QI.
Spill Response — Immediate Actions
When an oil or hazardous substance spill occurs, the sequence of immediate actions is critical. The reporting obligation is immediate — there is no threshold below which reporting is not required if a sheen is visible.
NRC Reporting — What to Report
National Response Center: 1-800-424-8802 (24 hours)
Failure to report is a separate federal offense under the Clean Water Act and APPS — penalties up to $25,000 per day.
US Clean Water Act — Section 311 & SPCC
The Clean Water Act (CWA) Section 311 is the primary US statute governing oil and hazardous substance spills into navigable waters. It predates MARPOL and OPA 90, and remains in force alongside those laws.
CWA Section 311 Key Provisions
- •Prohibits discharge of oil or hazardous substances in harmful quantities into US navigable waters or the EEZ
- •Any discharge that causes a visible sheen is considered harmful and must be reported
- •Applies to vessels, onshore facilities, and offshore facilities
- •Establishes the National Contingency Plan (NCP) as the framework for federal response
- •Civil penalties up to $25,000 per day; criminal penalties for knowing violations
SPCC Plans
Spill Prevention, Control, and Countermeasure (SPCC) plans are required by 40 CFR Part 112 for facilities (including some floating facilities and marinas) that store oil above certain thresholds. SPCC plans are an EPA (not USCG) requirement.
Stormwater
CWA also regulates stormwater discharges from vessels and facilities. Industrial facilities and construction sites near waterways must obtain National Pollutant Discharge Elimination System (NPDES) permits for stormwater runoff containing pollutants.
Interaction of Environmental Laws
| Law | Administering Agency | Primary Focus |
|---|---|---|
| MARPOL 73/78 | IMO / Flag State / USCG (port state) | International minimum standards for vessel pollution |
| APPS (33 U.S.C. 1901) | USCG | US implementing law for MARPOL; criminal and civil penalties |
| OPA 90 | USCG / EPA | Oil spill liability, COFR, VRPs, double hull, financial responsibility |
| CWA Section 311 | EPA / USCG | Oil and hazardous substance discharges into US navigable waters |
| CERCLA (Superfund) | EPA | Hazardous substance cleanup liability for land and water sites |
Practice Problems with Solutions
These questions mirror the style and difficulty of MARPOL and pollution prevention questions on the USCG OUPV exam. Work through each question before revealing the answer.
1A vessel is operating in the Baltic Sea. Can the crew discharge oily water that tests at 12 ppm through the oily water separator?
No. Although 12 ppm is below the global 15 ppm limit, the Baltic Sea is a MARPOL Annex I special area. In special areas, zero discharge of oily water is permitted — all oily bilge water must be retained on board and discharged to a port reception facility. The oily water separator cannot be used to discharge overboard in special areas regardless of the ppm reading.
2A fishing vessel is 40 feet long and operating 8 miles offshore. A crew member wants to throw a plastic bag of garbage overboard. Is this permitted?
No. Plastics are prohibited from discharge anywhere at sea under MARPOL Annex V — there is no distance exception for plastics. The prohibition applies regardless of vessel size, distance offshore, or whether the vessel is inside or outside a special area. The plastic bag must be retained on board and disposed of at a port reception facility.
3A small passenger vessel operating on US inland waters has a Type I MSD. The vessel is 2.5 nautical miles from shore. Can sewage be discharged overboard?
No. A Type I MSD (comminuted and disinfected sewage) requires the vessel to be at least 3 nautical miles from the nearest land to discharge. At 2.5 miles, the vessel is within the 3 nm limit. Additionally, if the vessel is operating in a designated No Discharge Zone (NDZ), no overboard discharge is permitted regardless of MSD type or distance — the holding tank must be used and pumped out at a facility.
4A vessel's chief engineer made a false entry in the Oil Record Book to conceal an illegal overboard discharge. What law is violated and what are the potential penalties?
This violates the Act to Prevent Pollution from Ships (APPS), 33 U.S.C. 1908, which implements MARPOL in the United States. APPS penalties include fines up to $25,000 per day of violation and/or up to 6 years imprisonment for knowing violations. The illegal discharge itself also violates the Clean Water Act Section 311 and MARPOL Annex I. The USCG takes false ORB entries extremely seriously — this is one of the most prosecuted maritime crimes.
5A tanker vessel over 300 gross tons wants to transit US waters. What document must it carry to demonstrate financial responsibility for oil spill liability?
The vessel must carry a Certificate of Financial Responsibility (COFR) issued under OPA 90. The COFR is issued by the US Coast Guard after the vessel demonstrates it can meet the financial liability limits set by OPA 90. Without a valid COFR, the vessel cannot operate in US waters. The COFR must be kept on board and produced on demand to USCG officers.
6A vessel is burning bunker fuel with 0.45% sulfur content while transiting the North American Emission Control Area. Is this compliant with MARPOL Annex VI?
No. Within the North American ECA (which extends 200 nautical miles from the US and Canadian coastline), the sulfur limit for fuel oil is 0.10% m/m under MARPOL Annex VI. Burning fuel with 0.45% sulfur in an ECA violates Annex VI. Compliance options include switching to fuel with less than or equal to 0.10% sulfur before entering the ECA, or using an approved exhaust gas cleaning system (scrubber) that achieves equivalent emissions.
7What category of noxious liquid substance (NLS) under MARPOL Annex II requires pre-washing of cargo tanks before a vessel enters port, regardless of where in the world the vessel is?
Category X substances (formerly Category A) require mandatory pre-washing of cargo tanks at sea before the vessel proceeds to port. Category X substances are those that pose the greatest hazard to the marine environment. The pre-wash must be performed in accordance with the procedures in the ship's Procedures and Arrangements (P&A) Manual, and the washings must be discharged to a port reception facility. Only after the surveyor confirms the pre-wash can the tank be further cleaned.
Quick Reference — Numbers to Memorize
| Number | What It Means |
|---|---|
| 15 ppm | Maximum oil concentration for overboard discharge (outside special areas) |
| 0.50% | Global sulfur cap for fuel oil (IMO 2020) |
| 0.10% | Sulfur limit in Emission Control Areas (ECAs) |
| 3 nm | Minimum distance for Type I/II MSD sewage discharge |
| 12 nm | Minimum distance for untreated (Type III) sewage discharge overboard |
| 4 knots | Minimum speed for untreated sewage discharge |
| 12 nm | Minimum distance for Annex I oily water discharge (400 GT+) |
| 200 nm | Extent of North American ECA from US/Canadian coast |
| $25,000 | Maximum civil penalty per day under APPS |
| 300 GT | Threshold for COFR requirement under OPA 90 |
| 400 GT | Threshold for ORB (Part I) and IAPP Certificate requirements |
| 100 GT / 15 persons | Thresholds triggering Garbage Management Plan requirement |
| 3 years | Retention period for Oil Record Book after last entry |
| 2 years | Retention period for Garbage Record Book after last entry |
| 1-800-424-8802 | National Response Center (NRC) — call immediately for any spill |
Frequently Asked Questions
What is the 15 ppm rule under MARPOL Annex I?
MARPOL Annex I prohibits the discharge of oil or oily mixtures exceeding 15 parts per million (ppm) into the sea. Vessels must use an approved oily water separator (OWS) that continuously monitors the discharge and automatically stops flow if the 15 ppm limit is exceeded. In special areas (such as the Mediterranean, Baltic, and Arctic), no discharge of oily water is permitted at all — all oily water must be retained on board and discharged to a port reception facility.
What must be recorded in the Oil Record Book (ORB)?
The Oil Record Book (ORB) must record every oil transfer, ballasting and cleaning of fuel oil tanks, disposal of oily bilge water, and any accidental or emergency discharge of oil. Entries must be made in English and signed by the officer in charge of each operation. The master must also sign each completed page. The ORB must be retained on board for three years after the last entry and must be produced to USCG officers on demand. False entries in the ORB are a federal crime with severe penalties.
How far offshore can you discharge treated sewage under MARPOL Annex IV?
Under MARPOL Annex IV, vessels may discharge sewage that has been comminuted and disinfected (Type I or II MSD) at least 3 nautical miles from the nearest land. Untreated sewage (no MSD or Type III holding tank) may only be discharged at least 12 nautical miles from the nearest land, and the vessel must be underway at a speed of at least 4 knots. No discharge of any sewage is permitted in special areas such as the Baltic Sea.
What garbage can never be discharged overboard under MARPOL Annex V?
Under MARPOL Annex V (as amended in 2013), plastics of any kind are prohibited from discharge anywhere at sea — no exceptions. This includes synthetic ropes, fishing nets, plastic garbage bags, and incinerator ash from plastic products. Food waste, paper, rags, glass, metal, and crockery have distance-from-shore restrictions that vary by whether the vessel is inside or outside special areas. A vessel 12 meters or longer in length must display placards notifying crew and passengers of the garbage discharge rules.
What is OPA 90 and who is the responsible party?
The Oil Pollution Act of 1990 (OPA 90) was enacted after the Exxon Valdez disaster. It establishes strict liability for oil spills in US waters and the Exclusive Economic Zone (EEZ). The 'responsible party' is the vessel owner, operator, or demise charterer. OPA 90 requires vessels over 300 gross tons (and certain smaller vessels) operating in US waters to maintain a Certificate of Financial Responsibility (COFR) demonstrating the ability to pay for oil spill cleanup, up to the liability limits. The limits are based on vessel size but can be exceeded if gross negligence or willful misconduct is proved.
What are the MARPOL Annex VI sulfur limits?
MARPOL Annex VI sets a global sulfur cap of 0.50% m/m (mass by mass) in fuel oil, effective January 1, 2020. In Emission Control Areas (ECAs) — which include the North American ECA, US Caribbean ECA, Baltic Sea, and North Sea — the sulfur limit is much stricter at 0.10% m/m. Vessels can comply by using low-sulfur fuel, switching to LNG, or using an approved exhaust gas cleaning system (scrubber). The International Air Pollution Prevention (IAPP) Certificate is required under Annex VI.
When must you report an oil spill to the Coast Guard?
Any discharge of oil or hazardous substance into US navigable waters, adjoining shorelines, or the EEZ must be immediately reported to the National Response Center (NRC) at 1-800-424-8802. There is no minimum quantity — any sheen on the water requires reporting. The report must include: location, source, size of slick, type of oil, actions taken, and contact information. Failure to report is a federal crime under the Clean Water Act and APPS, with penalties up to $25,000 per day of violation.
Lock in MARPOL and pollution prevention
1,628+ practice questions cover MARPOL, OPA 90, APPS, and spill response. Detailed answer explanations for every question. Track your weak areas by topic. Don't sit for the exam until you're consistently scoring 80%+.
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