The Environmental Protection Agency (EPA) and the U.S. Army Corps of Engineers (the “Corps”) (together the “Agencies”) have continued working on a proposed rule to revise the definition of “waters of the United States” (WOTUS) under the Clean Water Act (CWA or Act), which will soon move to the next stage of agency consideration.[1] The outcome of these rulemaking efforts will impact countless regulated parties, from solar developers to manufacturers, and heavily regulated industry.

While federal jurisdiction under the CWA is established by the scope of the WOTUS definition, it is not actually defined in the Act. How the phrase is interpreted can affect a multitude of regulatory issues, such as: (1) the applicability of water quality standards; (2) total maximum daily loads; (3) dredge and fill permit requirements; (4) state and tribal water quality certification programs; (5) and National Pollutant Discharge Elimination System (NPDES) permit requirements. The proposed rule to redefine WOTUS is in part a response to President Biden’s Executive Order 13990, 86 Fed. Reg. 7037 (Jan. 25, 2021), which tasked federal agencies with the review of certain regulations for conformance with the administration’s priorities and objectives, including regarding the reach of federal jurisdiction over the nation’s waters and implementation of existing CWA programs (i.e., Sections 303, 311, 401, 402, and 404).[2] This continued effort to implement the Biden administration’s policy preferences also comes in the wake of legal decisions setting aside previous CWA rulemaking efforts and current legal challenges. Most recently, on January 24, the Supreme Court granted certiorari in Michael Sackett et al. v. EPA et al., (Case No. 21-454), to determine if the Ninth Circuit used the right test to determine whether wetlands are subject to federal jurisdiction under the CWA.

WOTUS and Uncertainty

The CWA charges environmental regulators, such as the EPA, the Corps, and states that have been delegated federal permitting authority, with the responsibility of regulating the discharge of pollutants into waters of the United States or “WOTUS.” Key programs of the CWA impacted by the scope of WOTUS include CWA Section 404 “dredge and fill” permits issued by the Corps. Development and construction projects have long grappled with the reach of WOTUS over, for example, wetlands, ephemeral streams, and other similar water features. Proposed projects typically seek a jurisdictional determination from the Corps to determine whether there are WOTUS features that may be affected by the project’s design. If the Corps determines that a proposed project cannot avoid and will disturb WOTUS, the proponent must obtain a 404 permit prior to development and may need to mitigate impacts. Further, project proponents and landowners who discover after-the-fact that they have mistakenly filled “jurisdictional” wetlands may be subject to enforcement action and required to restore the area.

Another major program affected by the scope of WOTUS is CWA Section 402, the NPDES permit program, which allows for the discharge of pollutants from a point source into WOTUS. Many states have EPA-approved NPDES state permitting programs and serve as the primary permitting authority. Regardless of the permitting authority, the Supreme Court’s recent decision in County of Maui, Hawaii v. Hawaii Wildlife Fund, 140 S. Ct. 1462, 1476 (2020) (Maui), which held that discharges to groundwater that eventually reach WOTUS by means of a “functional equivalent” of a direct discharge are subject to the NPDES permitting program, has only added to the importance of, among other things, determining whether a permit is even needed for historically exempt discharges now potentially covered by Maui.

Yet, despite the critical importance of knowing what WOTUS is under the CWA’s programs, the scope of WOTUS has had a tumultuous history because of obscure or fluctuating agency definitions. As EPA Administrator Michael S. Regan stated: “In recent years, the only constant with WOTUS has been change, creating a whiplash in how to best protect our waters in communities across America.”[3]

The Future of WOTUS

The Agencies’ current proposed rule is the latest chapter in the challenge to interpret WOTUS, and would define “waters of the United States” as follows:

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

The Agencies further argue that their proposed “relatively permanent standard” and the “significant nexus standard” are supported by congressional intent, the objective of the CWA, the scientific record, decades of experience implementing prior standards, and the U.S. Supreme Court’s decisions in United States v. Riverside Bayview Homes, 474 U.S. 121, 132 (1985), Solid Waste Agency of Northern Cook County v. U.S. Army Corps of Engineers, 531 U.S. 159 (2001), Rapanos v. United States, 547 U.S. 715 (2006), and Maui.[5] The relatively permanent standard would apply to “waters that are relatively permanent, standing or continuously flowing and waters with a continuous surface connection to such waters.”[6]

The “significant nexus standard” would apply to waters that “either alone or in combination with similarly situated waters in the region, significantly affect the chemical, physical, or biological integrity of traditional navigable waters, interstate waters, or the territorial seas (the ‘foundational waters’).” The practical effect of this latter standard, if adopted, is that it will likely re-initiate litigation over whether certain waters are considered jurisdictional because of a hydrological connection to traditional navigable waters, interstate waters, or the territorial seas.

Although the Agencies’ aim was to rectify the uncertainty surrounding the WOTUS definition, there is likely to be substantial debate surrounding the proposed rule. Indeed, numerous organizations have already submitted comments on the proposal, and many more are expected to do so over the coming days.[7] Moreover, it is likely that this proposed rule is only the first step of a two-part initiative to revamp the WOTUS definition. The Agencies stated that they will, “consider changes through a second rulemaking that they anticipate proposing in the future, which would build upon the foundation of this proposed rule.”[8] There has been little indication, however, of whether the second rulemaking would limit or expand the scope of federal jurisdiction. This lack of clarity leaves many stakeholders without predictable and ascertainable guidelines to follow in planning for future development.

Given the broad reach of the proposed WOTUS definition, and the number of affected stakeholders, if the proposed rule is finalized there will likely be challenges to its scope. It is unlikely that the upcoming Supreme Court change would greatly impact any success or failure rate of such a challenge. However, the midterm elections later this year may change the political debate and the potential trajectory of agency thinking on the rule.

Comments on the proposed WOTUS rule must be received on or before February 7.[9] After the close of the comment period, the Agencies are expected to consider and respond to all public comments before promulgating a final rule.



[1] 86 Fed. Reg. 69,372 (Dec. 7, 2021).

[2] 86 Fed. Reg. at 69,373.

[3] EPA and Army Take Action to Provide Certainty for the Definition of WOTUS, U.S. Envtl. Protection Agency (Nov. 18, 2021),

[4] 86 Fed. Reg. at 69,373.

[5] Id. at 69,374.

[6] Id. at 69,373.

[7] See Revised Definition of “Waters of the United States”, Comments,

[8] 86 Fed. Reg. at 69,374.

[9] Id. at 69,372.