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EPA and US Army Corps of Engineers release a new “Waters of the US” rule (again) for the last time (….maybe).

By Nat Morse


On January 18, 2023, the United States EPA and United States Army Corps of Engineers (“USACE”) published the latest iteration of the “Water of the United States” (“WOTUS”) rule, called the “Revised Definition of ‘Waters of the United States’” (the “2023 WOTUS Rule”)[1].

This sounds familiar; what happened to the last WOTUS rule?

Ever since the 2001 SWANCC v. USACE Supreme Court decision, [2] the definition of a “water of the US” under the Clean Water Act and, as a result, the scope of federal jurisdiction over the nation’s waters, has been under constant revision. Both the Obama and Trump administrations released rules (in 2015 and 2020, respectively) designed to clarify the extent of the jurisdiction based on different opinions in the 2006 Rapanos United States Supreme Court decision.[3] However, both rules were subject to legal challenges and different courts stayed each of the rules. This led to a patchwork of regulation and substantial confusion about Clean Water Act enforcement.

The dispute about the rules centered on how one defines WOTUS and, therefore, the jurisdiction of the nation’s waters under the Clean Water Act. There is little controversy about the jurisdiction of certain categories of waters (e.g., traditional navigable waters, territorial seas, and interstate waters). Instead, the controversy has primarily focused on either 1) the jurisdictional classification of “adjacent” wetlands and ephemeral streams, or 2) the exclusions of engineered or highly-modified water systems (such as roadside ditches or irrigation canals). This 2023 WOTUS Rule is designed to establish a “durable” WOTUS definition, which the Biden administration hopes will definitively settle a decades long controversy over which waterbodies are subject to regulation under the federal Clean Water Act.

What is in this 2023 WOTUS rule, and how does it differ from prior rules?

This new 2023 WOTUS Rule is based on the pre-2015 guidance from USEPA and the USACE with modifications designed to directly address the concerns raised in the 2015 (Obama-era) and 2020 (Trump-era) rules and from the various legal challenges to those rules. As a result, the 2023 rule is an attempt to codify the pre-2015 regulatory regime, with some minor additions, exclusions, and clarifying definitions.

Under the new rule, the following types of waters are WOTUS and subject to federal jurisdiction:

  1. traditional navigable waters, interstate waters, and the territorial seas, and their adjacent wetlands
  2. most impoundments of “waters of the United States”;
  3. tributaries to traditional navigable waters, interstate waters, the territorial seas, and impoundments, that meet either the relatively permanent standard or the significant nexus standard;
  4. wetlands adjacent to impoundments and tributaries, that meet either the relatively permanent standard or the significant nexus standard; and
  5. “other waters” that meet either the relatively permanent standard or the significant nexus standard.[4]

The 2023 WOTUS Rule also codifies certain exclusions that categorically are not considered WOTUS. The list of exclusions is more limited than the list included in the 2020 Trump-era rule but includes wastewater treatment systems (such as treatment ponds or lagoons), prior converted cropland, artificial lakes or ponds, swimming pools, and certain ditches (including some roadside ditches), along with other categories. Notably, the categorically-excluded ditches are limited to those “excavated wholly in and draining only dry land and that do not carry a relatively permanent flow of water.” Thus, there is not a broad categorical exclusion for all ditches. As a result, some ditches (including some roadside ditches) could still be considered WOTUS if they satisfy other criteria as set out in the rule.

The most notable addition to the 2023 WOTUS Rule is the addition of both the “significant nexus” and the “relatively permanent” tests for determining if a stream or wetland should be considered a WOTUS and, therefore, subject to federal jurisdiction under the Clean Water Act. In the “significant nexus” test, which Justice Kennedy championed in his concurring opinion in Rapanos, the USACE must determine whether a significant nexus exists between the water in question (such as a wetland or ephemeral stream) and a jurisdictional water based on whether the potentially jurisdictional water “significantly affect[s] the chemical, physical, and biological integrity” of jurisdictional waters.[5] In contrast, the “relatively permanent” test, which Justice Scalia outlined in his plurality opinion in Rapanos, explains that federal jurisdiction extends to “relatively permanent, standing or continuously flowing bodies of water,” connected to traditional navigable waters, and extends to wetlands with a “continuous surface connection[.]”[6]

In a further effort to provide concrete guidance and to reduce confusion about the application of the significant nexus test, the Rule also includes a definition for “significantly affect.” That definition includes the factors to consider and functions to assess when applying the significant nexus test.[7] Such a definition was missing from the Obama-era rule. The Rule also strikes a middle ground for waters that are categorically excluded, with a more extensive list of exclusions than the Obama-era rule but less extensive than the Trump-era rule.

Ultimately, the 2023 WOTUS Rule still fails to include a scientifically-justified bright-line rule, which can be broadly and easily applied to demarcate jurisdictional waters and obviate the need for any case-by-case evaluations. Although such a bright line rule, arguably, does not exist, the lack of such a rule was the main challenge to both prior rules.

Is this 2023 WOTUS rule actually durable?

Although the Biden administration spent considerable effort to address deficiencies in the prior rules, there is little doubt that opponents will challenge the 2023 WOTUS Rule. In fact, two separate lawsuits were filed the same day the Rule was published—one suit by various industry groups, including the American Farm Bureau Federation, the American Petroleum Institute, and other groups; the other suit by the Texas Attorney General. Moreover, the validity of the 2023 WOTUS Rule will also hinge on the United States Supreme Court’s handling of the matter in the Sackett v. EPA case, which heard oral arguments earlier this term.

Whether these legal suits are successful or how the Supreme Court considers the rule depend on various factors. Many of those factors are outside the scope of this alert, but we can address some of the substantive concerns with the Rule.

One main concern opponents have already raised about the Rule (and previous iterations) is that it fails to provide an easily interpreted, unambiguous standard upon which landowners can rely. In developing this iteration of the Rule, USEPA and USACE incorporated both tests identified in the Rapanos decision (the significant nexus and the relatively permanent tests, as explained above). While this inclusion would appear to address substantive criticism about prior versions of the rule, the preamble to the Rule also acknowledges that the inclusion of the relatively permanent test is functionally symbolic. [8] Thus, in reality, the significant nexus test will actually control whether a water is jurisdictional or not. As a result, a substantial factor in determining whether the 2023 WOTUS Rule is durable or not will depend on how well the rule addresses the concerns the courts had in the Obama-era’s rule first incorporating the significant nexus test. This will hinge in large part on the Rule’s definition of “significantly affect” and the rule’s guidance in that definition to evaluate whether or not the test is met.

Ultimately, however, the review of the actual text of the rule may only be one factor. The Supreme Court’s handling of the issue in the Sackett case and the lower courts’ review of the rule from the other challenges will also depend, at least in part, on larger issues. This could include larger, macro-level political considerations. But, particularly at the Supreme Court, it might also depend on the Justices’ opinions on the appropriate level of agency deference. Therefore, it is very difficult to assess the actual durability of the 2023 WOTUS Rule.


The 2023 WOTUS Rule has already been challenged in the federal court system. Although the new Rule incorporates improvements from prior rules and, therefore, should be more durable than the previous rules, the success of those legal challenges is difficult to predict.

One thing that is known is that the limits of state jurisdiction can extend beyond the federal jurisdiction. For instance, Ohio’s jurisdiction currently extends beyond the federal limits, to waters such as isolated wetlands. Therefore, it is important for landowners, developers, and anyone else considering impacts to waters to consider permitting requirements under both state and federal jurisdiction.

If you have any questions about state or federal permitting under the Clean Water Act or Ohio laws, reach out to Nat Morse, Kristin Watt, or your Vorys attorney.



[1] 88 Fed. Reg. 3004-3144 (Jan. 18, 2023).

[2] Solid Waste Agency of Northern Cook County v. U.S. Army Corps of Eng’rs, 531 U.S. 159 (2001).

[3] Rapanos v. United States. 547 U.S. 715 (2006)

[4] 88 Fed. Reg. at 3005-6.

[5] Rapanos at 780.

[6] Id. at 739, 742.

[7] See also 88 Fed. Reg. at 3119-3121.

[8] See 88 Fed. Reg. at 3034 (“The relatively permanent standard is administratively useful as it more readily identifies a subset of waters that will virtually always significantly affect paragraph (a)(1) waters, but standing alone the standard is insufficient to meet the objective of the Clean Water Act.”)

Tags: WOTUS, Clean Water Act, USEPA, USACE

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