I n November 2011 the Environmental Protection Agency (EPA) proposed two Clean Water Act permits to regulate certain types of discharges from vessels into U.S. waters. The proposed permits would replace a single permit issued by EPA in 2008 that was due to expire in December 2013. As proposed, the two permits would apply to approximately 71,000 large domestic and foreign vessels and perhaps as many as 138,000 small vessels. This universe of regulated entities is diverse as well as large, consisting of tankers, freighters, barges, cruise ships and other passenger vessels, and commercial fishing vessels. Their regulated discharges are similarly diverse, including among other pollutants non-native aquatic nuisance species (ANS), nutrients, pathogens, oil and grease, metals, and toxic chemical compounds that can have a broad array of effects on aquatic species and human health, many of which can be harmful. Developing and administering a regulatory program covering sources so numerous and different from one another is more complicated than for other currently regulated sources. Because the sources themselves are mobile and move between jurisdictions, the traditional mechanism of regulating through state-issued permits is problematic. Many regulated vessels are small entities; thus, the economic impacts of regulatory requirements are an important consideration. Identifying technology-based treatment systems and management practices that can control vessel discharges effectively and economically presents many challenges. The two permits proposed by EPA in 2011 included one (draft VGP) for large vessels to replace the 2008 VGP, and one for smaller vessels covered by a congressionally enacted temporary moratorium (draft sVGP). On March 28, 2013, EPA issued a final version of the VGP for large vessels. It became effective on December 19, 2013. The permit for smaller vessels was issued on September 10, 2014; it was scheduled to become effective on December 19, 2014, but Congress passed a three-year extension as part of P.L. 113-281 . This report is an overview of the revised VGP for large vessels and two key issues: inclusion of numeric performance standards to limit ballast water discharges from vessels, and controversies about the role of states in regulating vessel discharges. It also reviews the final sVGP for small vessels and Congress's recent interest in these issues. The Clean Water Act (CWA) prohibits the discharge of pollutants from a point source into the navigable waters of the United States without a permit. Vessels are defined in the statute as point sources. In 1973, EPA promulgated a regulation that excluded discharges incidental to the normal operation of vessels (including ballast water, but not including vessel sewage discharges, which are regulated under CWA Section 312) from CWA permitting requirements. This long-standing regulation was challenged in federal district court by environmental advocacy groups who wanted EPA to address ballast water as a source of ANS in U.S. waters. In 2005 the court found that Congress had directly expressed its intention that discharges from vessels be regulated under the CWA, and that the 1973 regulation contradicted that intention. In September 2006 the court issued a final order vacating (revoking) the regulatory exclusion as of September 30, 2008, and remanding the ruling to EPA for further proceedings. The Ninth Circuit U.S. Court of Appeals upheld the district court's ruling on July 23, 2008. On June 17, 2008, EPA proposed two CWA general permits in response to the court's 2006 order, one applicable to commercial vessels and one applicable to small recreational vessels. CWA permits are either individual permits issued to specific facilities or general permits. Both types of permit are issued for a specific period of time (not to exceed five years), after which the permit must be renewed. A general permit covers multiple facilities within a specific category having common elements, such as similar types of operations that discharge the same types of wastes. Because of the large number of potential sources of vessels, EPA believed that it made administrative sense to use general permits, rather than individual permits. In August 2008, the federal district court agreed to EPA's request to delay vacating the regulatory exemption for three months, to ensure that permits could be issued before the exemption was eliminated. EPA finalized a Vessel General Permit for vessels subject to a permit requirement on December 18, 2008. The permit became effective on December 19, 2008. However, on the same day, the federal district court granted an EPA motion to delay vacating the existing regulatory exclusion until February 6, 2009. Thus, the effective date remained December 19, 2008, but regulated sources were not required to comply with terms of the permit until February 6, 2009. In July 2008, Congress enacted two bills to exempt discharges incidental to the normal operation of certain types of vessels from CWA permitting, thus restricting the population of vessels subject to EPA regulation. The first measure, P.L. 110-288 , the Clean Boating Act of 2008, exempted discharges incidental to the normal operation of recreational vessels of all sizes from CWA permitting requirements. The legislation directed EPA and the Coast Guard to create a regulatory regime under new CWA Section 312(o); EPA is currently developing regulations for recreational vessels, as required by the legislation. The second measure, P.L. 110-299 , provided a two-year moratorium on CWA permitting for certain discharges from commercial fishing vessels of all sizes and non-recreational vessels less than 79 feet in length. This moratorium has been extended three times. First, it was extended to December 18, 2013, by P.L. 111-215 . During the moratorium, EPA was directed to study the discharges from these vessels and submit a report to Congress. The 112 th Congress extended the permit moratorium for one more year, until December 18, 2014, in P.L. 112-213 . And in the 113 th Congress, legislation providing an additional three-year extension, until December 18, 2017, was enacted as part of a Coast Guard reauthorization bill ( S. 2444 / P.L. 113-281 ). Ballast water discharges from vessels less than 79 feet in length are not affected by the moratorium (although EPA believes that few of these smaller vessels use or discharge ballast water) and are required to be authorized by permits. (See " Small Vessel Permit Moratorium " for discussion of legislation.) However, P.L. 110-288 and P.L. 110-299 did not exempt or provide a permitting moratorium for all discharges from all types of vessels. Thus, the Vessel General Permit (VGP) finalized by EPA in December 2008 gave permit coverage to an estimated 72,000 vessels larger than 79 feet in length used in a transportation capacity that were not affected by the moratorium in P.L. 110-299 , including tankers, freighters, barges, and cruise ships, and it also applied to ballast water discharges from vessels covered by the moratorium. It applied to pollutant discharges, including ballast water, that are incidental to the normal operation from non-recreational vessels that are 79 feet or more in length, and to ballast water discharges from commercial vessels of less than 79 feet and commercial fishing vessels of any length. Geographically, it applied to discharges into waters of the United States in all states and territories, extending to 3 miles from the baseline (i.e., shoreline). In the 2008 permit, EPA identified 26 types of waste streams or discharge types from the normal operation of covered vessels (some are not applicable to all vessel types). The types of pollutant discharges subject to the permit included ANS (also known as invasive species), nutrients, pathogens, oil and grease, metals, and pollutants with toxic effects. The CWA requires that all point source discharges must meet effluent limitations representing applicable levels of technology-based control. Under the 2008 VGP, EPA concluded that, based on available information, it was not practicable to derive numeric effluent limits to achieve technology-based controls for many of the discharge types regulated under the permit. Thus, most discharges covered by the 2008 VGP were controlled by specific best management practices (BMPs), many of which were already in use. Some vessel categories, such as cruise ships, were subject to more detailed requirements for discharges such as graywater (water from showers, baths, sinks, and laundry facilities) and pool and spa water. Monitoring, recordkeeping, and reporting requirements applied, as well. Procedurally, vessels larger than 79 feet or more than 300 gross tons (an estimated 50,000 domestic and foreign vessels) were required to submit a Notice of Intent (NOI) to be covered by the permit. Smaller regulated vessels were automatically covered. There were no permit fees. Projected industry compliance costs (including paperwork requirements) ranged from a low of $8.9 million to $23.0 million annually; they varied based on assumptions of vessel populations affected and the number of instances in which incremental costs would be incurred. In anticipation of the expiration of the 2008 VGP on December 18, 2013, in November 2011, EPA proposed two Vessel General Permits, one for large vessels (draft VGP) to replace the 2008 VGP, and one for smaller vessels to authorize discharges from vessels covered by the congressionally enacted temporary moratorium (draft sVGP). Both draft permits proposed to regulate discharges from 26 types of waste streams (like the 2008 VGP), plus an additional waste stream category—fish hold effluent. Pollutants in these waste streams can include ANS, nutrients, pathogens, oil and grease, metals, and toxic chemical compounds. Both draft permits largely retained the 2008 permit's approach of relying on specific behaviors or BMP techniques to control most regulated discharges, as EPA again concluded that it is infeasible to develop numeric effluent limits for most controlled discharges covered by the permit.