Audit, Compliance and Risk Blog

EPA and the Corps of Engineers Finish Redefining “Waters of the United States”

Posted by Jon Elliott on Wed, Mar 18, 2020

LakeOn January 23, 2020 the Environmental Protection Agency (EPA) and the U.S. Army Corps of Engineers (Corps) finalized revisions to narrow their joint regulatory definitions of “waters of the United States”, applying authority under the Clean Water Act (CWA). The agencies characterize this narrowing as an increase in certainty for stakeholders, accomplished by eliminating some of the site-specific discretion that the 2015 rules provided to permit writers.

This marks the latest step in a cycle of rulemakings that began during the Obama administration in 2015, when the same agencies adopted revisions to the same rules expanding their definitions in order to interpret and apply then-recent decisions by the US Supreme Court.

Punctuated by litigation and the transition to the Trump administration, the past five years of regulatory back-and-forth have included several steps: the 2015 rules (I summarized them, and litigation leading up to them here); the Trump-era EPA’s 2017 proposal to roll back those 2015 revisions here); and the 2018 proposal of these rules here). Readers should note that a separate action in 2019 rescinded the 2015 rules and temporarily readopted pre-2015 definitions pending this latest action (this rulemaking notes that 6 legal challenges to the 2019 rules are pending).

What are “Waters of the United States”?

The outer edges of EPA and Corps CWA jurisdiction over waterways and wet areas have never been clear. These ambiguities were emphasized by Supreme Court Justice Kennedy’s use of “significant nexus” phrase in the 2006 Rapanos v. United States case, which pushed limits outward from clearly CWA-covered waters in ways that were intended to require case-specific analysis. The 2015 rules incorporated these expanded ambiguities in ways that expanded protected areas (particularly wetlands) but introduced further complexity in ways that opponents characterized as regulatory over-reach.

The new EPA and Corps definitions are designed to reverse this expansion and provide the clearest possible nationwide guidance. These definitions include significant editorial changes from the 2018 proposal, but continue to formalize and narrow terminology in order to formalize and narrow CWA jurisdictional authority. They continue to include relatively permanent flowing and standing waterbodies that are “navigable waters” in their own right, plus waters or wetlands with specific surface water connection to such waters. As part of this effort, the rules are built around new formal definitions of jurisdictional and non-jurisdictional waters.

  • What are “Jurisdictional Waters”?

The rules extend CWA jurisdiction to “waters of the United States” defined as:

    • The territorial seas, and waters which are currently used, or were used in the past, or may be susceptible to use in interstate or foreign commerce, including waters which are subject to the ebb and flow of the tide;

    • Tributaries;

    • Lakes and ponds, and impoundments of jurisdictional waters; and

    • Adjacent wetlands.

The first item attaches to waters that are actually “navigable” – transforming a word that had become an ambiguous term of art in CWA discussions into a narrower and more formal one. The other three items attempt to require direct connection to such waters in order to provide CWA jurisdiction.

  • What are “Non-Jurisdictional Waters”?

Rather than leave practitioners to assume that waters that aren’t “jurisdictional” are probably “non-jurisdictional,” the rules also provide a list of waters that are not subject to CWA jurisdiction. These consist of the following:

    • Waters or water features that are not identified in [the list of jurisdictional waters];

    • Groundwater, including groundwater drained through subsurface drainage systems;

    • Ephemeral features, including ephemeral streams, swales, gullies, rills, and pools;

    • Diffuse stormwater run-off and directional sheet flow over upland;

    • Ditches that are not [navigable waters or tributaries], and those portions of ditches constructed in [wetlands that do not meet the definition of jurisdictional wetlands];

    • Prior converted cropland;

    • Artificially irrigated areas, including fields flooded for agricultural production, that would revert to upland should application of irrigation water to that area cease;

    • Artificial lakes and ponds, including water storage reservoirs and farm, irrigation, stock watering, and log cleaning ponds, constructed or excavated in upland or in non-jurisdictional waters, so long as those artificial lakes and ponds are not impoundments that meet the definition of jurisdictional waters];

    • Water-filled depressions constructed or excavated in upland or in non-jurisdictional waters incidental to mining or construction activity, and pits excavated in upland or in non-jurisdictional waters for the purpose of obtaining fill, sand, or gravel;

    • Stormwater control features constructed or excavated in upland or in non-jurisdictional waters to convey, treat, infiltrate, or store stormwater run-off;

    • Groundwater recharge, water reuse, and wastewater recycling structures, including detention, retention, and infiltration basins and ponds, constructed or excavated in upland or in non-jurisdictional waters; and

    • Waste treatment systems.

The new rules also include 15 definitions of terms that appear in these lists, including adjacent wetlands; ephemeral, intermittent, and perennial; prior converted cropland; and tidal waters and waters subject to the ebb and flow of the tide.

Now What?

Landowners, developers and regulators will now set about interpreting and applying these new definitions. It’s also easy to anticipate another round of litigation, which certainly will extend until after the November election which could set off a further round of revisionism if a new President is elected.

Meanwhile, readers should keep in mind that these new federal terms do not preempt states’ authority to regulate waters that are not “waters of the United States” but which a state may consider to be “waters of [the state].” Some states, such as California, assert regulatory authority over a wide variety of waters and lands that EPA and the Corps have just removed from federal authority.

Self-Assessment Checklist

Does my organization routinely discharge wastewaters:

  • Into a natural water body?

  • Into an artificial conveyance (ditch, storm sewer, etc.)?

  • Into a sanitary sewer system?

Does my organization operate a facility where rainwater or snowmelt might flow:

  • Into a natural water body?

  • Into an artificial conveyance (ditch, storm sewer, etc.)?

Is my organization undertaking a construction or other project that disturbs a waterway, or disturbs soil or rock that might contaminate runoff into a waterway?

Has my organization evaluated the receiving waters to determine whether they qualify as “waters of the United States” subject to CWA requirements?

  • Under the previous definitions?

  • Under the newly adopted definitions?

Has my organization evaluated requirements under state laws in each state in which activities may affect water bodies or wetlands?

Where Can I Go For More Information?

  • EPA webpage for rulemaking and new rule 

  • Step Two” webpage, including latest rule 

  • Step One” webpage (replacement of 2015 rules with pre-2015 rules pending further rulemaking) 

Specialty Technical Publishers (STP) provides a variety of single-law and multi-law services, intended to facilitate clients’ understanding of and compliance with requirements. 

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About the Author

Jon Elliott is President of Touchstone Environmental and has been a major contributor to STP’s product range for over 30 years. 

Mr. Elliott has a diverse educational background. In addition to his Juris Doctor (University of California, Boalt Hall School of Law, 1981), he holds a Master of Public Policy (Goldman School of Public Policy [GSPP], UC Berkeley, 1980), and a Bachelor of Science in Mechanical Engineering (Princeton University, 1977).

Mr. Elliott is active in professional and community organizations. In addition, he is a past chairman of the Board of Directors of the GSPP Alumni Association, and past member of the Executive Committee of the State Bar of California's Environmental Law Section (including past chair of its Legislative Committee).

You may contact Mr. Elliott directly at:


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Tags: Business & Legal, Environmental risks, Environmental, EPA, clean water