In the United States, several federal agencies and laws have some jurisdiction over pollution from ships in U.S. waters. States and local government agencies also have responsibilities for ship-related pollution in some situations.

International laws and regulations

MARPOL 73/78 (the "International Convention for the Prevention of Pollution From Ships") is one of the most important treaties regulating pollution from ships. Six Annexes of the Convention cover the various sources of pollution from ships and provide an overarching framework for international objectives. In the U.S., the Convention is implemented through the Act to Prevent Pollution from Ships (APPS).Act to Prevent Pollution from Ships, . Under the provisions of the Convention, the United States can take direct enforcement action under U.S. laws against foreign-flagged ships when pollution discharge incidents occur within U.S. jurisdiction. When incidents occur outside U.S. jurisdiction or jurisdiction cannot be determined, the United States refers cases to flag states, in accordance with MARPOL. These procedures require substantial coordination between the Coast Guard, the State Department, and other flag states, and the response rate from flag states has been poor.U.S. Government Accountability Office, Washington, D.C. (2000). "Progress Made to Reduce Marine Pollution by Cruise Ships, but Important Issues Remain." Report to Congressional Requesters. Report No. RCED-00-48. Different regulations apply to vessels, depending on the individual state.ANCO Maritime Activities Ltd., Piraeus, Greece (2011-04-11). "Update to USCG requirements."

Federal laws and regulations In the United States, several federal agencies have some jurisdiction over ships in U.S. waters, but no one agency is responsible for or coordinates all of the relevant government functions. The U.S. Coast Guard and Environmental Protection Agency (EPA) have principal regulatory and standard-setting responsibilities, and the Department of Justice prosecutes violations of federal laws. EPA and the Department of Defense (DOD) began jointly issuing Uniform National Discharge Standards ("UNDS") for armed forces vessels in 2017.DOD and EPA (2017-01-11). "Uniform National Discharge Standards for Vessels of the Armed Forces-Phase II Batch One." Final rule. Federal Register, .

In addition, the Department of State represents the United States at meetings of the IMO and in international treaty negotiations and is responsible for pursuing foreign-flag violations. Other federal agencies have limited roles and responsibilities. For example, the National Oceanic and Atmospheric Administration (NOAA, Department of Commerce) works with the Coast Guard and EPA to report on the effects of marine debris. The Animal and Plant Health Inspection Service (APHIS) is responsible for ensuring quarantine inspection and disposal of food-contaminated garbage. In some cases, states and localities have responsibilities as well.

Vessels General Permit EPA issued its most recent Vessels General Permit, under the National Pollutant Discharge Elimination System (NPDES), a Clean Water Act (CWA) program, in 2013. The permit applies to large commercial vessels ( in length or greater) (except fishing vessels) and regulates 26 specific types of vessel discharges: Deck Washdown and Runoff and Above Water Line Hull Cleaning Bilge water/Oily Water Separator Effluent Ballast water Anti-fouling Hull Coatings/Hull Coating Leachate Aqueous film forming foam (AFFF) Boiler/Economizer Blowdown Cathodic protection Chain Locker Effluent Controllable Pitch Propeller and Thruster Hydraulic Fluid and other Oil Sea Interfaces including Lubrication Discharges from Paddle Wheel Propulsion, Stern Tubes, Thruster Bearings, Stabilizers, Rudder Bearings, Azimuth Thrusters, and Propulsion Pod Lubrication, and Wire Rope and Mechanica l #Equipment Subject to Immersion] Distillation and Reverse Osmosis Brine Elevator Pit Effluent Firemain Systems Freshwater Layup Gas Turbine Washwater Graywater (except certain commercial vessels operating in the Great Lakes) Motor Gasoline and Compensating Discharge Non-Oily Machinery Wastewater Refrigeration and Air Condensate Discharge Seawater Cooling Overboard Discharge (Including Non-Contact Engine Cooling Water; Hydraulic System Cooling Water, Refrigeration Cooling Water) Seawater Piping Biofouling Prevention Boat Engine Wet Exhaust Sonar Dome Discharge Underwater Ship Husbandry Welldeck Discharges Graywater Mixed with Sewage from Vessels Exhaust Gas Scrubber Washwater Discharge.U.S. Environmental Protection Agency (EPA), Washington, D.C. (2013-04-12). "Final National Pollutant Discharge Elimination System (NPDES) General Permit for Discharges Incidental to the Normal Operation of a Vessel." Federal Register. 78 FR 21938.

In 2016 EPA estimated that approximately 69,000 vessels, both domestic and foreign flagged, were covered by the VGP.

EPA issued its Small Vessels General Permit (sVGP) for smaller commercial vessels in 2014, however this permit only applied to ballast water.EPA (2014-09-10). Final National Pollutant Discharge Elimination System (NPDES) Small Vessel General Permit for Discharges Incidental to the Normal Operation of Vessels Less Than 79 Feet. Federal Register. . In 2018 Congress repealed the sVGP under the Vessel Incidental Discharge Act. As of 2023 small vessels are subject to the ballast water requirements of the VGP, Coast Guard regulations, and applicable state and local government requirements.

Vessel Incidental Discharge Act The Vessel Incidental Discharge Act (VIDA), approved in 2018, requires EPA to develop new performance standards for vessel discharges, and generally requires that the new standards be at least as stringent as the 2013 VGP.United States. Vessel Incidental Discharge Act. (Title IX of the Frank LoBiondo Coast Guard Authorization Act of 2018.) Approved 2018-12-04. On October 9, 2024 EPA published final VIDA implementation regulations.EPA (2024-10-09). "Vessel Incidental Discharge National Standards of Performance." Final rule. Federal Register, VIDA also requires that the Coast Guard issue regulations for compliance and enforcement of the EPA standards. Until these new Coast Guard regulations are promulgated, the existing EPA discharge permits and Coast Guard regulations remain in effect.

Sewage Commercial vessels discharging sewage, except fishing vessels, are subject to the VGP or other requirements for small vessels. Recreational vessels are exempt from the permit requirements, but vessel operators must implement Best Management Practices to control their discharges.Clean Water Act sec. 402(r), . This provision was added by the Clean Boating Act of 2008, , July 29, 2008.

Marine sanitation devices Section 312 of the CWA prohibits the dumping of untreated or inadequately treated sewage from vessels into the navigable waters of the United States (defined as within of shore). This prohibition is implemented jointly by EPA and the Coast Guard. Commercial and recreational vessels with installed toilets are required to have marine sanitation devices (MSDs), which are designed to prevent the discharge of untreated sewage. EPA is responsible for developing performance standards for MSDs, and the Coast Guard is responsible for MSD design and operation regulations and for certifying MSD compliance with the EPA rules. MSDs are designed either to hold sewage for shore-based disposal or to treat sewage prior to discharge.

The Coast Guard regulations cover three types of MSDs.U.S. Coast Guard, Washington, D.C. "Marine Sanitation Devices." Code of Federal Regulations, . Large vessels use either Type II or Type III MSDs. In Type II MSDs, the waste is either chemically or biologically treated prior to discharge and must meet limits of no more than 200 fecal coliforms per 100 milliliters and no more than 150 milligrams per liter of suspended solids. Type III MSDs store wastes and do not treat them; the waste is pumped out later and treated in an onshore system or discharged outside U.S. waters. Type I MSDs use chemicals to disinfect the raw sewage prior to discharge and must meet a performance standard for fecal coliform bacteria of not greater than 1,000 per 100 milliliters and no visible floating solids. Type I MSDs are generally only found on recreational vessels or others under in length. The regulations, which have not been revised since 1976, do not require ship operators to sample, monitor, or report on their effluent discharges.

Critics point out a number of deficiencies with this regulatory structure as it affects large vessels. First, the MSD regulations only cover discharges of bacterial contaminants and suspended solids, while the NPDES permit program for other point sources typically regulates many more pollutants such as chemicals, pesticides, heavy metals, oil, and grease that may be released by large vessels as well as land-based sources. Second, sources subject to NPDES permits must comply with sampling, monitoring, recordkeeping, and reporting requirements, which do not exist in the MSD rules.

In addition, the Coast Guard, responsible for inspecting vessels for compliance with the MSD rules, has been heavily criticized for poor enforcement of Section 312 requirements. In its 2000 report, the Government Accountability Office (GAO) said that Coast Guard inspectors "rarely have time during scheduled ship examinations to inspect sewage treatment equipment or filter systems to see if they are working properly and filtering out potentially harmful contaminants." GAO reported that a number of factors limit the ability of Coast Guard inspectors to detect violations of environmental law and rules, including the inspectors' focus on safety, the large size of some ships, limited time and staff for inspections, and the lack of an element of surprise concerning inspections. The Coast Guard carries out a wide range of responsibilities that encompass both homeland security (ports, waterways, and coastal security, defense readiness, drug and migrant interdiction) and non-homeland security (search and rescue, marine environmental protection, fisheries enforcement, aids to navigation). Since the September 11 terrorist attacks on the United States, the Coast Guard has focused more of its resources on homeland security activities. One likely result is that less of the Coast Guard's time and attention are available for vessel inspections for MSD or other environmental compliance.

Annex IV of MARPOL was drafted to regulate sewage discharges from vessels. It has entered into force internationally and would apply to ships that are flagged in ratifying countries, but because the United States has not ratified Annex IV, it is not mandatory that ships follow it when in U.S. waters. However, its requirements are minimal, even compared with U.S. rules for MSDs. Annex IV requires that vessels be equipped with a certified sewage treatment system or holding tank, but it prescribes no specific performance standards. Within three miles (5 km) of shore, Annex IV requires that sewage discharges be treated by a certified MSD prior to discharge. Between three and from shore, sewage discharges must be treated by no less than maceration or chlorination; sewage discharges beyond from shore are unrestricted. Vessels are permitted to meet alternative, less stringent requirements when they are in the jurisdiction of countries where less stringent requirements apply. In U.S. waters, vessels must comply with the regulations implementing Section 312 of the Clean Water Act.