EPA Re-Defines “Waterways” in New Rule Following Sackett v. EPA

EPA Re-Defines “Waterways” in New Rule Following Sackett v. EPA

Amanda Lane

Associate Editor

Loyola University Chicago School of Law, JD 2025

The U.S. Environmental Protection Agency (EPA) and Department of the Army (together, Agencies) issued an amended final rule in August of 2023 revising the definition of “waters of the United States” following the Supreme Court decision in Sackett v. Environmental Protection Agency in May. The conforming rule became effective in September. Sackett, and the resulting EPA final rule, may be one of the most significant water-related regulatory shifts in recent memory as it dramatically weakens the Clean Water Act (CWA). Now, under the new definition of “waters of the United States”, some US waterways are protected while others are not. Environmental protection organizations are sounding the alarms.

History of WOTUS and the Clean Water Act

“Waters of the United States” (WOTUS) is a threshold term in the CWA. It establishes the geographic scope of federal jurisdiction under the CWA, and grants the EPA and the U.S. Army Corps of Engineers (Corps) regulatory implementation. Amended and expanded most recently in 1972, the CWA prohibits the discharge of pollutants from a point source into “navigable waters” unless otherwise authorized under the Act. Since 1972, the CWA has played an essential role in protecting the nation’s diverse array of aquatic environments from pollution and protecting waterways for wildlife and for (human) recreation, like fishing and swimming. The CWA also protects the integrity and safety of drinking water for millions of Americans.

To achieve these ends, the CWA imposes regulatory requirements upon both public and private actions that affect waterways. For example, public and private actors are required under the Act to apply for a Corps permit to use fill material in waterways. A different section of the Act includes provisions for oil spill prevention and response. Another section regulates state and Tribal water quality certifications. Permits issued under the CWA are federal actions and thus trigger the requirements under the National Environmental Policy Act (NEPA) and other federal regulations like the Endangered Species Act (ESA) and the National Historic Preservation Act (NHPA). Therefore, a determination that an activity triggers regulatory jurisdiction under the CWA can result in delays and expense from complying with the additional federal requirements.

“Navigable waters” is defined under the CWA as “the waters of the United States, including the territorial seas”. The CWA does not define “waters of the United States”, however. Historically, though, the United States Congress, the EPA, and the Corps have defined WOTUS through regulations and programmatic activities to include a variety of aquatic ecosystems and watersheds: streams, wetlands, small ponds, marshes, swamps, and other waterways. Since 1972, WOTUS have comprised all the relevant parts of an aquatic ecosystem, even if the waterways are not necessarily connected to a tributary system on the surface. That means that navigable waters have also included tributaries and adjacent wetlands that did not have to be navigable but must have a connection to interstate or foreign commerce.   


Since its passage in 1972, the CWA has prompted a few noteworthy Supreme Court decisions attempting to define WOTUS. The most notable was Rapanos v. United States in 2006. There, the petitioner sought to fill in three wetland areas on his property in order to build a shopping center but did so without the required permit under the CWA. In a 5-4 decision for the petitioners, Justice Kennedy wrote a concurring opinion maintaining that the connections between wetlands and other bodies of water do not necessarily have to be visible – continuous and on the surface – but could be measured in other ways. The essential question in Justice Kennedy’s test was whether a given wetland shared a “significant nexus” with another, adjacent body of water that is already protected. That is, if the potential polluting or destroying of certain wetlands would affect the physical, chemical, or biological health of a second body of water already protected under the CWA, then both deserved the same level of protection.

This differed from Justice Scalia’s test, where waters meriting protection under the CWA had to be navigable waters (like rivers, lakes, or basically anything that can accommodate a boat), regularly flowing tributaries of those waters, or wetlands, so long as those wetlands had a continuous surface connection to a body of water that was already protected under the CWA.

Advocates for a narrower view of WOTUS argue Justice Scalia’s test should govern, while many environmental protection organizations, lower courts, and the Bush, Obama, and Biden administrations have advocated for Justice Kennedy’s broader test.

Enter Sackett. There, the petitioners attempted to fill in an adjacent wetland without the requisite CWA permits. Although the Court was unanimous in holding that the specific wetlands in the case did not qualify for protection, the Justices split in their opinions on why. Justice Alito, following the late Justice Scalia’s definition of WOTUS, argued that any wetland that does not connect at its surface to another body of water that is protected under the CWA does not merit the same degree of protection. Justice Kavanaugh disagreed and took issue with the plurality’s “rewriting of adjacent to mean adjoining.” Justice Kagan argued that in ordinary language, “adjacent” not only means when something is touching, but also when it is nearby. Conflating the two terms, the Justices argued, may “leave long-regulated and long-accepted-to-be-regulable wetlands suddenly beyond the scope of the agencies’ regulatory authority.”

The Final Amended Rule and Implications

The final amended rule now eliminates the “significant nexus” test when identifying waterways that may be federally protected under the CWA. Following the Sackett decision and the EPA and Corps’ revised final rule, the CWA now extends only to 1) relatively permanent bodies of water (tributaries like streams and rivers) connected to navigable waters, the territorial seas, or interstate waters, and 2) wetlands that have a continuous surface connections with those waters.

Further, the adjacency test propounded by Justice Alito means that interstate wetlands do not fall within the interstate waters category in (1) above unless they are “adjacent” to other CWA waters (i.e. they have a continuous surface connection).

What the Sackett rule and the now revised final EPA rule fail to account for is the environmental and hydrological reality of water systems, which may be inextricably connected to each other via subsurface or underground systems. Further, many wetlands would have “continuous surface connections” and thus be WOTUS under the new rules but for man-made features like dikes or roads. Even natural features like river berms or beach dunes may mean the difference between federal protection and not if they interrupt the continuous surface connection of waterways.

Arguing the minute differences between “adjacent” and not belies the essential importance of aquatic ecosystems in the United States. The EPA describes the nation’s wetlands as “among the most productive ecosystems in the world, comparable to rainforests and coral reefs.” By regulating water flow, wetlands dramatically lessen the impact of both floods and droughts. They provide habitat for numerous fish, bird, mammal, insect, reptile, and amphibian species. All while storing massive amounts of carbon in their vegetation. These reasons make safeguarding wetlands a valuable natural climate change solution.