Biden-Harris Administration Plans to Revise ‘Waters of the United States’ Definition

June 15, 2021

In a move that is expected to expand the reach of the Clean Water Act, the US Environmental Protection Agency and the Army Corps of Engineers announced their intent to revise the definition of “waters of the United States”—a key threshold for the Clean Water Act’s application.

The US Environmental Protection Agency (EPA) and the Army Corps of Engineers (Corps) issued a June 9 press release announcing their intent to redefine “waters of the United States” under the Clean Water Act, shifting away from a Trump-era rule that had defined “waters of the United States” narrowly. The agencies signaled their intent to proceed in two steps—first repealing the Trump-era rule, and then undertaking an additional rulemaking to promulgate a new, more expansive definition of “waters of the United States.”

Various interest groups have already weighed in strongly in response to the announcement, including industry stakeholders that are concerned with a potential expansion of the act and environmental groups that believe the agencies are not moving fast enough. Any rule the agencies promulgate therefore is almost certain to result in litigation and further scrutiny by federal courts.


The Clean Water Act applies to “navigable waters,” which is in turn defined by the statute to include “waters of the United States.” Because of the importance of that threshold applicability issue, EPA and the Corps have long wrestled with how to delineate which waters are waters of the United States. And in recent years, the issue has become a political football, shifting back and forth with changes in administration.

The difficulty of defining waters of the United States is encapsulated by the US Supreme Court’s 2006 decision in Rapanos v. United States. That 4-1-4 split decision created a standard that lower courts have struggled to apply and EPA and the Corps have endeavored to further define. In Rapanos, five Supreme Court justices agreed to overturn the agencies’ finding that certain wetlands were covered by the Clean Water Act, but they did not agree about why. Justice Scalia’s plurality held that there must be a “continuous surface connection” to a traditionally navigable water, while Justice Kennedy’s concurrence required only a “significant nexus,” which allowed broader consideration of hydrologic and ecological factors. Lower courts have typically understood Justice Kennedy’s test as controlling because it was the narrowest grounds for overturning the agencies’ interpretation of the act.

In 2015, the Obama administration promulgated a rule that it characterized as designed to further define the “significant nexus” standard and establish certain “bright line” categories of waters that are always covered by the Clean Water Act. That rule defined “significant nexus” broadly, which, in combination with other tweaks to the agencies’ preexisting definition of waters of the United States, represented an expansion of the act’s reach.

The Trump administration then reversed course dramatically. In 2017, President Donald Trump issued an executive order directing EPA and the Corps to repeal the 2015 rule and then issue a revised regulation. EPA and the Corps followed that two-step process, ultimately issuing a final regulation in September 2019 that eliminated the agencies’ use of the “significant nexus” test in favor of Justice Scalia’s “continuous surface connection” standard and made other changes that contracted the scope of the act. Those changes collectively rendered the jurisdiction of the Clean Water Act narrower than not just the Obama-era rule but also the pre-2015 standards originally implemented by the Bush administration.


President Joseph Biden issued an executive order in early 2020 directing EPA and the Corps to review the Trump-era rule. On June 9, 2021, the agencies announced the results of that review and outlined their plans to issue a revised definition. The agencies’ review found that “nearly every one of over 1,500 streams assessed has been found to be non-jurisdictional” under the Trump-era rule and identified “333 projects that would have required Section 404 permitting prior to the [Trump-era rule], but no longer do.” The agencies further found that the limited jurisdiction of the Clean Water Act was contributing to significant environmental degradation.

In light of those findings, the agencies outlined their plan to repeal and replace the Trump-era rule through a process similar to the one used by the prior administration. First, the agencies will repeal the Trump-era rule and revert to the agencies’ pre-2015 regulations and guidance. Then, they will undertake a separate process to issue a new rule further defining waters of the United States.

The agencies’ announcement highlighted four considerations that will influence that rulemaking process:

  • “Protecting water resources and our communities consistent with the Clean Water Act”
  • “The latest science and the effects of climate change on our waters”
  • “Emphasizing a rule with a practical implementation approach for state and Tribal partners”
  • “Reflecting the experience of and input received from landowners, the agricultural community that fuels and feeds the world, states, Tribes, local governments, community organizations, environmental groups, and disadvantaged communities with environmental justice concerns”

The agencies also highlighted that they will take into account the “experience of implementing” each of the Bush-era, Obama-era, and Trump-era regulations.

On the same day, the US Department of Justice (DOJ) filed a motion in litigation in the US District Court for the District of Massachusetts requesting remand of the Trump-era rule to the agencies. If successful, the motion will have the effect of ending that litigation and sending the rule back to the agencies. But the DOJ notably did not seek vacatur of the Trump-era rule, so it will remain in place until the agencies repeal it.


When EPA and the Corps issue a revised definition of waters of the United States, it is expected to expand the scope of the Clean Water Act at least beyond both the Trump-era rule and, perhaps, the Bush-era rule. A more expansive application of the Clean Water Act is in line with the overarching emphasis of the Biden-Harris administration on enhancing environmental protections, and the priorities listed in the agencies’ announcement further suggest that the agencies are likely to take an expansive view.” The agencies could, however, take some lessons from criticism of the Obama-era rule to avoid provisions of that rule that proved particularly controversial.

Given the agencies’ plans to repeal the Trump-era rule and then later proceed with a new rulemaking, it is likely that the new rule will not be in place for a number of months and potentially into 2022. In the time between the repeal of the Trump-era rule and the agencies’ new rule, EPA and the Corps will determine what waters are covered by the Clean Water Act according to the agencies’ pre-2015 regulations and guidance.

When the agencies issue a notice of proposed rulemaking for a revised definition of waters of the United States, they undoubtedly will receive a large number of comments from interested stakeholders on both sides of the issue. And when a final rule is promulgated, it is almost certain to be subject to legal challenges. Those legal challenges could result in appellate decisions that provide further clarity on the scope of the Clean Water Act, including a potential return visit to the Supreme Court.


If you have any questions or would like more information on the issues discussed in this LawFlash, please contact any of the following Morgan Lewis lawyers:

Washington, DC
Duke K. McCall, III
Douglas Hastings
Drew Clearly Jordan

San Francisco
Ella Foley Gannon

Los Angeles
James Dragna
Rick Rothman

John McGahren
Stephanie R. Feingold
Christopher McAuliffe

Summer associate Alyssa Huang contributed to this LawFlash.