Revised Definitions of WOTUS

Just weeks ago on Valentine’s Day, February 14th, 2019, the US Environmental Protection Agency (USEPA) and the US Army Corps of Engineers (USACE) (collectively known as “the agencies”) responded to President Trump’s 2017 Executive Order (Restoring the Rule of Law, Federalism, and Economic Growth by Reviewing the ‘Waters of the United States’ Rule), which in part called for the revision of the 2015 Clean Water Rule (we covered this in 2017). What changes were made to the WOTUS definitions?

What are Waters of the United States (WOTUS)?

The Tennessee River. Photo by Jeff Gunn (retrieved from Wikipedia).

The Tennessee River. Photo by Jeff Gunn (retrieved from Wikipedia).


Waters of the United States (WOTUS) is the term given to rivers, lakes, streams, and several other types of water features intended to be protected from pollution. Traditionally, the definition includes all waters that have been or currently are used for interstate or foreign commerce, including those subject to the ebb and flow of the tide. We’ll explain this further below (Revisions to Waters Types).


Isolated wetlands lost protection following the SWANCC case.

Isolated wetlands lost protection following the SWANCC case.

Certain wetlands were considered jurisdictional following the Rapanos case, where there was a significant nexus.

Certain wetlands were considered jurisdictional following the Rapanos case, where there was a significant nexus.

The history of the Clean Water Act of 1972 is complex, and we encourage our readers to click here to learn more. Although there are many court cases, we would like to point to SWANCC (2001) and Rapanos (2006) v. the USACE. These are widely known Supreme Court cases that laid the groundwork for defining and regulating WOTUS, as they apply to the decisions environmental consultants make daily. In the years following following the Rapanos case, the number of lawsuits that challenged the WOTUS definitions increased. In response, the Obama Administration and USEPA began work on the Clean Water Rule in 2011, which became effective in 2015.

Under the Clean Water Rule, the agencies proposed to establish categorical “bright lines” that provided predictability for regulators and the regulated community. Figure 1 illustrates examples of these categories.

Figure 1. Examples of the jurisdictional categories under the Clean Water Rule. Source:  Friends of the Rappahannock .

Figure 1. Examples of the jurisdictional categories under the Clean Water Rule. Source: Friends of the Rappahannock.

The 2015 Rule was published to clarify water resource management under the Clean Water Act (1972) and to more consistently define protection of potential WOTUS. It clearly outlined the nine steps necessary to define WOTUS via the “significant nexus” test. The Rule, while fully supported by many environmental groups, was immediately viewed as over-reach of executive power by many Republicans and farm states. In fact, thirteen states sued to prevent the Rule’s implementation, and after a series of litigation, the Trump Administration in 2017 announced its interest in rescinding and revising the Rule.

Revisions to Waters Categories

The agencies published the Revised Definition of ‘‘Waters of the United States’’ on February 14th, 2019. In what follows, we list the categories and an explanation of the changes (and copy much of the language directly from the Federal Register to maintain the intent of the proposed rules). Also note that the significant nexus test is proposed to be eliminated.

A. Traditional Navigable Waters and Territorial Seas (subject to additional clarification; otherwise no change)


B. Interstate Waters. The agencies found that this regulation is a relic of the original Water Pollution Control Act (WPCA, 1948). The revised definition therefore proposes to remove interstate waters and interstate wetlands as a separate category of WOTUS.

C. Impoundments (no change)


D. Tributaries (rivers, streams, or naturally occurring surface water, etc). There has been some confusion about the jurisdictional status of a tributary, as it flows through artificial or natural breaks.

In the revised definition, whether or not a tributary is named or visible on a topographic map, it remains a jurisdictional feature, even if it flows into an excluded ditch or a waste treatment system, if those excluded features convey perennial or intermittent flow to a tributary downstream. Additionally, a tributary remains jurisdictional if it flows through a culvert, dam, or other similar artificial break. If the feature flows through a debris pile, boulder field, or similar natural break, it remains jurisdictional as long as the break conveys perennial or intermittent flow to a tributary or other jurisdictional water at the downstream end of the break.

To clarify the definition of temporal flow, the following definitions apply:

  • Perennial. Where surface water is flowing continuously year-round during a typical year;

  • Intermittent.Where surface water is flowing continuously during certain times of a typical year, rather than in direct response to precipitation; and

  • Ephemeral. Surface water flowing or pooling only in direct response to precipitation, such as rain or snow fall.

When a tributary runs through a wetland (known as a run-of-stream), the tributary would remain jurisdictional even though it may be difficult to identify channelized flow through the wetland. Wetlands adjacent to and/or abutting a tributary would also be considered jurisdictional (see G).

When a perennial or intermittent stream flows through an excluded ditch, the non-jurisdictional ditch would not sever jurisdiction, as long as the ditch conveys perennial or intermittent flow to tributaries or other jurisdictional waters at the downstream end of the ditch.

E. Ditches (now defined as “artificial channels used to convey water”). This is a new provision added to provide regulatory clarity and predictability to, for example, farmers and ranchers. The revised definition proposes to enumerate the categories of ditches that would be WOTUS.

“Very basically, if an artificial channel used to convey water satisfies any of the earlier rulings proposed in the regulation, they will be considered WOTUS.”


F. Lakes and Ponds. Lakes and ponds are considered jurisdictional in three instances:

  • Lakes and ponds would be jurisdictional as an (a)(1) water (traditional navigable water), as well as an (a)(4) water (impoundment);

  • Lakes and ponds that contribute perennial or intermittent flow to an (a)(1) water in a typical year through an (a)(2)–(6) water (interstate waters, territorial seas, impoundments, tributaries, and waters adjacent) would also be considered waters of the United States; and

  • Waters that are flooded by an (a)(1)–(5) water in a typical year would be waters of the United States. These lakes and ponds would receive flood waters from (a)(1)– (5) waters via over-topping in a typical year.

G. Wetlands. This is another new category added to the rule for clarification.

Under this rule, wetlands are “those areas that are inundated or saturated by surface or ground water at a frequency and duration sufficient to support, and that under normal circumstances do support, a prevalence of vegetation typically adapted for life in saturated soil conditions.”

All wetlands adjacent to traditional navigable waters (including the territorial seas, tributaries to those waters, jurisdictional ditches, jurisdictional lakes and ponds, and impoundments of otherwise jurisdictional waters) are jurisdictional under the revised definition.

The revised definition also clarified language concerning the location of wetlands and other jurisdictional features:

  • Adjacent. Wetlands that abut or have a direct hydrologic surface connection to other WOTUS;

  • Abutting. Wetlands that touch WOTUS at either a point or side; and

  • Direct hydrologic surface connection. This occurs as a result of inundation from a jurisdictional water to a wetland or by perennial or intermittent flow between a wetland and a jurisdictional water.

What is Not Included as WOTUS?


There are some notable exceptions to the WOTUS definitions, including:

  • Ephemeral channels (in-part);

  • Groundwater drained through subsurface drainage systems;

  • Certain ditches;

  • Prior converted cropland;

  • Artificially irrigated areas that would revert to upland if artificial irrigation ceases;

  • Certain artificial lakes and ponds constructed in upland;

  • Water-filled depressions created in upland incidental to mining or construction activity;

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

  • Wastewater recycling structures constructed in upland; and

  • Waste treatment systems. In addition, the agencies are proposing to clarify and define the terms ‘‘prior converted cropland’’ and ‘‘waste treatment system’’ to improve regulatory predictability and clarity.

Other Notable Developments


As the agencies reached out to the general public, States, and Tribes to amend this rule, they discovered that States maintained a high degree of familiarity with waters within their borders. They also found that most States maintained systems to appropriately map aquatic resources. Several States and stakeholders indicated that maps could increase certainty regarding which waters are jurisdictional or not.

In response, the agencies are “interested in advancing the development of state-of-the-art geospatial data tools through Federal, State and tribal partnerships to provide an enhanced, publicly-accessible platform for critical CWA information, such as the location of federally jurisdictional waters, the applicability of State and tribal water quality standards, permitted facility locations, impaired waters, and other important features.”

The USACE and USEPA are soliciting comments as to how they could establish an approach to authorize States, Tribes, and Federal agencies to establish geospatial datasets of what is considered a WOTUS, as well as waters that the agencies propose to exclude.

What are the Next Steps?

Do you think the new rule provides enough protection for WOTUS? The public will have sixty (60) days from the date of the filing of the revisions to comment on the proposed definition (until April 15th, 2019). You can submit a formal comment about the revised definitions.

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