The Clean Water Act constitutes the basis of United States legislation responsible for keeping the nation’s water supply clean and safe. It establishes general guidelines for the discharge of pollutants into US waters, as well as directives for measuring and assessing the quality of those waters. Enforced by the Environmental Protection Agency (EPA) and the Army Corps of Engineers, the act allows for the development of pollution control programs and industry pollution standards, essential methods of maintaining a clean water supply for US citizens.

On May 25, the Supreme Court severely limited its abilities to do just that.

Their decision arose from Sackett v. Environmental Protection Agency, in which homeowners Michael and Chantall Sackett disagreed with the EPA’s definition of the waters regulated by the Clean Water Act. The act prohibits the discharge of pollutants into all “waters of the United States, including the territorial seas” and specifically includes “wetlands adjacent” to these waters. The Sacketts had planned to build their new home on a lot just thirty feet away from a small tributary that fed into a creek, which in turn fed into Priest Lake, Idaho. However, shortly after they began construction, the EPA informed them that their lot contained wetlands that fell under the Clean Water Act’s jurisdiction, and that they could not build their house there. The question for the justices was: What defines the “waters of the United States” that can be regulated under the Clean Water Act?

In a 5-4 decision, the Court delineated the act’s regulation authority to waters that have “a continuous surface connection” to larger, navigable bodies of water. According to the majority opinion written by Justice Samuel Alito, the Sacketts’ lot did not fall under this narrow definition, as the wetlands on their property were decisively separate from the tributary. Thus, they were free to continue constructing their home and continue backfilling the lot with dirt and rocks. 

The Court’s interpretation of “adjacent” wetlands to mean “adjoining” wetlands makes little sense from a hydrological perspective. Waterways need not have direct, contiguous connections in order to influence one another. Even if no clear nexus exists between a wetland and a nearby waterway, patterns of surface runoff and groundwater flow mean that wastewater and other pollutants dumped in wetlands will undoubtedly end up in nearby streams, lakes, and rivers, potentially even penetrating underground aquifers. Prohibiting the direct dumping of pollutants into a major waterway, yet simultaneously allowing such dumping in wetlands that eventually flow there, is effectively useless. It leaves vital sources of drinking water, irrigation, and habitat vulnerable to now-legal contamination. 

In his dissent, Justice Brett Kavanaugh points out a similar weakness of Alito’s opinion. Kavanaugh refers to the extensive levee system surrounding the Mississippi River, the second-longest river in the United States, writing, “The presence of those levees would seemingly preclude Clean Water Act coverage of adjacent wetlands on the other side of the levees, even though the adjacent wetlands are often an important part of the flood-control project”. The Court’s majority interpretation of the Clean Water Act is clearly counterproductive; while the law was originally devised to protect and preserve essential waterways, it may now do the opposite. And it seems to overlook the fact that wetlands are some of the most productive aquatic ecosystems on Earth, harboring a diverse ecosystem and moderating the climate. They contribute greatly to primary productivity (the conversion of chemical energy to biological energy at the base of the food chain) and can help reduce downstream soil erosion by slowing water flow. If hundreds of wetlands now fall beyond the scope of the Clean Water Act, there is no way of guaranteeing the long-term continuity of their numerous natural roles — which range from flood protection to wildlife habitat.

Alito’s definition of adjacent is also shaky, and leaves room for numerous technicalities. Though he accounts for temporary discontinuities between wetlands and waterways due to low tides or droughts, there still remains a plethora of unanswered questions about how his test will be used in practice. Kavanaugh raises several: 

[H]ow difficult does it have to be to discern the boundary between a water and a wetland for the wetland to be covered by the Clean Water Act? How does that test apply to the many kinds of wetlands that typically do not have a surface water connection to a covered water year-round—for example, wetlands and waters that are connected for much of the year but not in the summer when they dry up to some extent? How “temporary” do “interruptions in surface connection” have to be for wetlands to still be covered? How does the test operate in areas where storms, floods, and erosion frequently shift or breach natural river berms? Can a continuous surface connection be established by a ditch, swale, pipe, or culvert?

Furthermore, Justice Elena Kagan argues that Alito’s opinion ignores the ordinary meaning of “adjacent”. “In ordinary language, one thing is adjacent to another not only when it is touching, but also when it is nearby,” she writes. “So, for example, one house is adjacent to another even when a stretch of grass and a picket fence separate the two.” For almost fifty years, the EPA has recognized that wetlands come within the act even if they are only separated by a small manmade or natural barrier. Sackett v. EPA reveals the Court both abandoning precedent and, as Kagan states, “altering—more precisely, narrowing the scope of—the statute Congress drafted”. If the Clean Water Act cannot protect wetlands and other bodies of water near major waterways, it cannot protect those waterways at all.