From Ecological Function to Plain Meaning: What Sackett Signals for Environmental Policy

Environmental regulation is in a period of unusual uncertainty. Longstanding rules are being reconsidered, agencies are adjusting to new limits on their authority, and courts are taking a closer look at the words Congress actually used. For businesses, regulators, consultants, and environmental advocates, it can be difficult to know which direction the law is moving.

One of the clearest examples is the changing definition of “waters of the United States,” or WOTUS. But its history, including the Supreme Court’s 2023 decision in Sackett v. EPA, may also offer broader clues about what lies ahead.

WOTUS determines the geographic reach of the Clean Water Act. Yet Congress never clearly explained where those waters begin and end. Does the term encompass only rivers, lakes, and streams? What about wetlands, seasonal channels, drainage ditches, or land that affects downstream waters without visibly touching them? Because the phrase is open to interpretation, courts and agencies have repeatedly redefined its reach. WOTUS is therefore more than a technical jurisdictional issue. It also reflects the values shaping environmental law at a particular moment.

Those values matter because legal decisions are never based on text and science alone. Beneath them are judgments about which risks deserve priority, how much uncertainty society will tolerate, and whether the environment should be protected primarily for its own sake or for the benefits it provides to people. Understanding those values can help explain not only why a decision was made, but also anticipate how future environmental disputes may be resolved.

From Human Use to Ecological Connection

Federal water law did not begin as an effort to protect nature for its own sake. For much of American history, people harmed by pollution relied on nuisance lawsuits. Pollution became a legal issue when it damaged someone’s health, property, or livelihood. The environment received protection primarily because of its value to people.

Early federal law reflected the same outlook. The Rivers and Harbors Act of 1899 focused on keeping navigable waters open for transportation and commerce. The federal interest was not in protecting aquatic ecosystems broadly, but in ensuring that waterways remained useful for navigation and trade. Put simply, water was protected because it was useful for commerce.

The Clean Water Act of 1972 reflected a broader vision. Its stated goal was to restore and maintain the “chemical, physical, and biological integrity” of the nation’s waters. It also defined “pollutant” broadly enough to include ordinary materials such as rock, sand, and cellar dirt. Together, these provisions reflected a growing recognition that protecting water quality required looking beyond traditional navigable waters and considering the broader systems that influence them.

Wetlands became one of the clearest examples of this shift. Although they may not resemble rivers or lakes, wetlands can store floodwaters, filter pollutants, recharge groundwater, and influence the health of downstream waters. The question increasingly became not simply whether an area looked like a “water,” but whether it functioned as part of a connected aquatic system.

That understanding became central to the “significant nexus” test articulated by Justice Kennedy in Rapanos v. United States. Under that approach, wetlands could be federally regulated if, alone or in combination with similarly situated lands, they significantly affected the chemical, physical, or biological integrity of downstream navigable waters, even if they lacked a continuous surface connection.

Sackett Returns to Plain Meaning

Sackett asked a different question.

The case concerned whether wetlands on an Idaho property fell within the Clean Water Act’s definition of “waters of the United States.” More broadly, the Court had to decide whether federal jurisdiction over wetlands should depend on their ecological relationship to nearby waters or on the ordinary meaning of the statutory text.

The majority began with the ordinary meaning of the word “waters.” In everyday speech, the Court reasoned, “waters” refers to recognizable geographic features such as streams, rivers, lakes, and oceans. People do not ordinarily describe land, even wet land, as “waters.” From that starting point, wetlands generally qualify as WOTUS only when they have a continuous surface connection to a covered water, making it difficult to determine where the water ends and the wetland begins.

That shift is more significant than it may first appear.

Under the significant-nexus approach, jurisdiction depended largely on what a wetland did—that is, its role within a connected aquatic system. Under Sackett, it depends more heavily on what the area is, as understood through the ordinary meaning of the statute and its physical characteristics. The inquiry shifted from ecological function to statutory meaning.

The majority did not say that separated wetlands lack ecological value. Instead, it concluded that ecological importance cannot expand the reach of statutory language that does not clearly authorize regulation. The decision signaled that, for the majority, ecological importance alone cannot extend federal jurisdiction beyond what the ordinary meaning of the statutory text will bear.

What Values Did Sackett Elevate?

Viewed through an ethical lens, Sackett reflects more than a narrower definition of WOTUS. It signals a renewed emphasis on values that more closely resemble the historical foundations of federal water law. Before the modern environmental era, federal authority over water was largely justified by its direct importance to navigation, commerce, and other human uses. While the Clean Water Act expanded that vision to recognize ecological integrity, Sackett places greater weight on textual clarity, predictable jurisdictional boundaries, property rights, and limits on agency authority.

To be clear, debates over textualism, plain meaning, and legislative purpose are nothing new. They have shaped Supreme Court jurisprudence for generations. What is notable about Sackett is not that the Court embraced textualism, but that it chose to resolve an environmental dispute by giving greater weight to the ordinary meaning of the statutory text than to evolving ecological science.

Viewed through the constitutive–contextual value spectrum described in my earlier work, the decision reflects movement toward a more constitutive approach to interpretation—particularly one that prioritizes the enacted language itself over broader contextual considerations, including evolving scientific understanding. Whether that trend continues remains to be seen, but if it does, it may influence far more than the definition of WOTUS.

What May Come Next

Understanding the values underlying legal decisions can help us anticipate where environmental law is headed. No two statutes are identical, and Sackett does not dictate how every environmental law will be interpreted. But interpretive values often carry across cases. Courts and agencies that emphasize ordinary meaning, clear congressional authorization, and administrable legal boundaries in one context may be inclined to apply those same principles elsewhere.

Recent developments under the Endangered Species Act suggest that this trend may already be underway. In July 2026, the U.S. Fish and Wildlife Service and NOAA Fisheries issued a final rule rescinding the longstanding regulatory definition of “harm.” For decades, that definition interpreted the ESA’s prohibition on the “take” of listed species to include significant habitat modification that actually killed or injured wildlife, reflecting a broader understanding of ecological interconnectedness.

In rescinding the definition, the Services concluded that it did not reflect the best reading of the statutory text. They reasoned that “take,” understood in its ordinary sense and in the context of the surrounding statutory terms, is directed primarily toward actions against individual animals rather than indirect effects arising from habitat modification. The final rule therefore returns to the statutory text without adopting a replacement regulatory definition of “harm.”

Whether that interpretation ultimately survives judicial review remains to be seen. Nevertheless, the reasoning is notable. Like Sackett, the rule gives greater weight to the ordinary meaning of statutory language than to later interpretations that expanded the practical reach of environmental regulation through ecological interconnectedness.

If this interpretive approach continues, older environmental statutes may increasingly be read according to the ordinary meaning of the words Congress enacted rather than through evolving scientific understanding or decades of agency interpretation. Ecological science will remain indispensable for understanding environmental impacts, but it may play a smaller role in defining the outer limits of federal regulatory authority.

For environmental professionals, the lesson is not to abandon ecological science, but to recognize that scientific evidence alone may no longer carry the same legal weight when defining the limits of federal authority. Increasingly, persuasive environmental arguments may need to pair sound science with careful attention to statutory text, legislative authority, and direct human consequences such as drinking water, flood protection, infrastructure resilience, public health, and economic impacts.

The changing definition of WOTUS therefore represents more than a jurisdictional debate. It reflects a broader shift in how environmental laws are being interpreted.

Whether this marks a lasting change remains to be seen. But if Sackett and the recent ESA rule are any indication, the next chapter of environmental law may be shaped as much by how courts and agencies interpret statutory language as by the science underlying the regulations themselves.