On September 4, 2026, EPA published a proposed rule to revise the regulatory definition of “discharge of a pollutant” to accurately implement the statutory exclusion of vessels and other floating craft that add pollutants in the contiguous zone or the ocean. 91 Fed. Reg. 56819 (Sept. 4, 2026). As a result, such discharges would be expressly excluded from the regulatory definitions of “discharge of a pollutant” and “discharge” and would not be subject to National Pollutant Discharge Elimination System (NPDES) program requirements. While this proposal might catch the attention of the operators of certain maritime vessels or platforms, such as Mobile Offshore Drilling Units (MODUs), that are sometimes treated as a vessel and sometimes as a point source, it is important to note that EPA’s proposed rule states that the “primarily potentially affected operations” are offshore seafood harvesting and processing from vessels that discharge in the contiguous zone or the ocean, and that offshore oil and gas production entities are unlikely to be affected.
The Clean Water Act (CWA) generally prohibits discharges into navigable waters, the contiguous zone, and the ocean without first obtaining an NPDES permit. “Discharge of a pollutant” or “discharge” is defined differently based on the geographic location of the receiving water. For waters of the contiguous zone or the ocean, CWA § 502(12)(B) defines “discharge of a pollutant” as “any addition of any pollutant to waters of the contiguous zone or the ocean from any point source other than a vessel or other floating craft.” Thus, additions of pollutants from a vessel or other floating craft into waters of the contiguous zone or ocean are expressly excluded from this definition and not within the scope of the NPDES permitting program.
However, the current regulatory definition of “discharge of a pollutant” in 40 C.F.R. § 122.2 appears to narrow the statutory exclusion provided by CWA § 502(12) by limiting its application to a vessel or other floating craft in the contiguous zone or ocean that “is being used as a means of transportation.” Similarly, 40 C.F.R. § 122.3(a) provides that a vessel or other floating craft that adds pollutants to the waters of the contiguous zone or ocean is not excluded from NPDES permit requirements when it is operating in any additional capacity “other than as a means of transportation.”
As such, EPA is proposing to clarify that NPDES permitting “does not apply to pollutant additions from certain vessel offshore operations in the contiguous zone and ocean.” In particular, the proposal, if finalized, “would provide that, in either the contiguous zone or the ocean, a vessel or other floating craft that is not secured to the seabed does not require NPDES permit authorization to add pollutants to such waters.” EPA is also proposing to add an explanatory phrase that a point source is “secured” when “it is either permanently attached to the seabed or is a buoyant facility substantially moored to the seabed, such that it cannot be moved without special effort through an undertaking from outside and separate from the facility, to change the location of the facility, or it is a mobile offshore drilling unit engaged in drilling operations.”
As a result, most entities, such as ocean placer mining (exclusively in waters of the United States), offshore oil and gas production (secured via risers), and most offshore aquaculture (net pens secured), are unlikely to be affected. Rather, the primarily potentially affected operations, according to EPA, are offshore seafood harvesting and processing from vessels that discharge in the contiguous zone or the ocean.
Regardless, EPA’s proposed rule cautions that dumping and other activities by vessels into either the contiguous zone or the ocean “may be subject to other statutory or regulatory requirements imposed by other statutes such as the Marine Protection, Research, and Sanctuaries Act (MPRSA), the Oil Pollution Control Act of 1990 (OPA), and the Vessel Incidental Discharge Act (VIDA).”
Comments on the proposed rule are due by October 19, 2026.
Liskow will continue to monitor for updates regarding EPA’s proposed rule. For further questions regarding this topic, contact Liskow attorneys Greg Johnson, Clare Bienvenu, Emily von Qualen, and Colin North.
The effect of these changes would be that the addition of pollutants by a vessel or other floating craft in the contiguous zone or the ocean that is not secured to the seabed would not be a discharge and would not require CWA NPDES permit authorization to add pollutants to those waters.