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Will SCOTUS upend new Waters of the US Rule?

On January 18, 2023, the U.S. Army Corps of Engineers and Environmental Protection Agency (EPA) published the latest Waters of the United States (WOTUS) rule covering all Clean Water Act (CWA) programs and adopting the two conflicting tests from the Supreme Court’s 2006 Rapanos opinion (88 Fed. Reg. 3004 (Jan. 18, 2023) Effective March 20, the new rule is the latest in a string of guidance and rules issued under the Bush, Obama and Trump Administrations. However, the pending Sackett case in the Supreme Court could upend their efforts.

In developing the rule, the agencies drew upon extensive scientific evidence and experience in setting out 5 categories of regulated waters and wetlands covering:

  1. Traditionally navigable waters (TNWs) (waters presently or in the past used in interstate or foreign commerce and all interstate waters and wetlands)

  2. Impoundments

  3. Tributaries that are either relatively standing or continuously flowing or that significantly affect the chemical, physical or biological integrity of a downstream TNW, either alone or in combination with similarly situated waters in the region

  4. Adjacent wetlands that meet either the continually flowing or significant nexus tests

  5. Intrastate lakes, ponds, streams and wetlands that meet either test.

The final rule does not define or quantify “continuous flow” but merely states that it includes features with flowing or standing waters year-round or continuously during certain times of the year. It appears to include flow that is more than ephemeral and suggests that multiple storm events in succession could be enough.

The final rule defines “significantly affect” as “a material influence” on the chemical, physical or biological integrity of downstream TNWs. The rule then lists specific factors and functions that should be assessed in determining “significantly affect.”


  • Distance from a downstream TNW

  • Hydrologic factors such as the frequency, duration, magnitude, timing and rate of hydrologic connections including shallow subsurface flow

  • The size, density or number of similarly situation waters

  • Landscape position

  • Climatological variables such as temperature, rainfall and snowpack


  • Contribution of flow

  • Trapping, transformation, filtering and transport of materials such as sediment

  • Retention and attenuation of floodwaters and runoff

  • Modulation of temperature

  • Provision of habitat and foods resources for aquatic species located in the downstream TNW

The final rule excludes the following:

  • Waste treatment systems

  • Prior converted cropland

  • Ditches excavated wholly in and draining only dry land and do not carry relatively permanent flow

  • Artificially irrigated areas, reflecting or swimming pools of ornamental waters

  • Water filled depressions and pits excavated on dry land for the purpose of obtaining sand or gravel. The exclusion is lost once the activity is abandoned and wetlands return.

The agencies assert the rule will be “durable” and provide clarity on the geographic scope of federally regulated waters and wetlands by adopting both tests. Opponents of the rule argue that a landowner will be at the mercy of a Corps or EPA regulator because the rule essentially creates a presumption of CWA jurisdiction that may be impossible to overcome. Companies that require permits decry the new rule will result in increased mitigation and permitting costs and delays for many critically important activities such as major infrastructure and energy transmission projects.

However, the Supreme Court’s pending Sackett case argued on October 3, 2022 could provide clarity. The Court accepted this case to review whether the significant nexus test was the proper test for determining CWA jurisdiction. The tone of oral arguments in the case appear to lean towards a rejection of the significant nexus test and adoption of a much more limiting test, perhaps similar to justice Scalia’s “continuous surface connection” test from Rapanos.

Should the Court reject the “significant nexus” test, much of the recently issued rule will have to be redone. Hopefully, the result will be clearer statement on the reach of the CWA. In the meantime, permit applicants should carefully review the new WOTUS definition to determine how the expanded scope of waters may impact federal jurisdiction for their projects. Bottom line: Stay tuned!

Lawrence R. Liebesman, Esq.

Senior Advisor

A nationally recognized environmental lawyer with more than 40 years of experience, including 11 years at the U.S. Justice Department, Larry specializes in federal Clean Water and Endangered Species Acts and the National Environmental Policy Act (NEPA).


The views expressed here are those of the author and do not necessarily reflect the views of Dawson & Associates.


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