Legal Alert: The Navigable Waters Protection Rule: Revised Definition of "Waters of the United States"

On April 21, 2020, the U.S. Environmental Protection Agency (EPA) and the U.S. Army Corps of Engineers (Army) jointly published their final rule redefining the regulatory definition of “waters of the United States” (WOTUS) under the federal Clean Water Act (CWA), which rule will be effective on June 22, 2020.  Both agencies announced issuance of the final “Navigable  Waters Protection Rule” (Rule) earlier this year.  As asserted in prior WOTUS rulemakings, both agencies state the Rule will increase the predictability and consistency in CWA programs by clarifying the scope of WOTUS.

This 2020 Rule replaces the October 22, 2019 WOTUS rule that repealed the 2015 WOTUS rule and consequently required reliance on the 1986 WOTUS rule and the 2008 Rapanos guidance (the Rapanos guidance become inoperative upon the effective date of the Rule).  These changes to the definition of WOTUS under the CWA have been prompted by various court decisions and different political perspectives.  This new Rule has already been legally challenged by various states and environmental interest groups, will be subject to years of litigation, and the Rule is likely to be subject to future modifications.

Overview of Final WOTUS Rule

The EPA and the Army issued the proposed WOTUS rule in December 2018, which created six categories of waterways subject to CWA jurisdiction. The proposed WOTUS rule garnered 620,000 comments and 6,200 recommendations. The final Rule creates four narrower categories of jurisdictional waters. Those waters are:

  • territorial seas and traditional navigable waters;
  • perennial and intermittent tributaries that contribute surface flow to navigable waters in a typical year based on a thirty-year period (excludes ephemeral streams that only have surface flow in direct response to precipitation);
  • certain lakes, ponds, and impoundments of jurisdictional waters when they contribute surface water flow to a traditional navigable water in a typical year either directly or through channelized non-jurisdictional surface waters; and
  • wetlands adjacent to other jurisdictional waters if they (a) abut, (b) are inundated by flooding from a jurisdictional water in a typical year, and (c) are separated from a jurisdictional water by an artificial barrier (e.g. dike) and the structure allows for a direct hydrologic surface connection. To be jurisdictional wetlands, they must satisfy the three wetland factors (possess necessary hydrology, hydrophytic vegetation, and hydric soils).

One important change in the Rule from the 2015 WOTUS rule is that ephemeral streams and wetlands that are not adjacent to jurisdictional waters are excluded from the definition of WOTUS. The Rule also narrowed the definition of key terms in the WOTUS rule such as “adjacent” and “tributary” to further limit federal CWA jurisdiction.  The Rule eliminated the “significant nexus” test in the 2015 WOTUS rule that was based on the 2006 U.S. Supreme Court decision in Rapanos v. United States

Non-jurisdictional Waters

The Rule excludes from WOTUS all waters not within the four defined categories above, and provides express exclusions from CWA jurisdiction for 12 specific types of waters, including groundwater, ephemeral waters, diffuse stormwater runoff, prior converted cropland, certain ditches, water  and waste treatment systems, artificially irrigated areas, certain artificial lakes and ponds, and water-filled depressions created by mining or construction activities.


The definition of WOTUS under the Rule is important since it affects the applicability of various CWA programs affecting water quality, pollutant discharge permits, and oil spill prevention and planning programs.  Various sources indicate the Rule reduces protection of approximately half of the Nation’s wetlands, and about twenty percent of its streams, and a much higher percentage of streams in the western U.S. that rely on rainfall for flow would be impacted by this Rule.

Over the years, as the definition of WOTUS has changed, many states have enacted statutes and adopted regulations regulating impacts to non-jurisdictional waters which may be important for landowners, farmers, developers, etc. to investigate before proceeding with impacts to waters excluded from regulation  under the WOTUS Rule.

A copy of the Federal Register notice issuing this Rule is available here.

Should you have any questions please contact Brian Babb at 513.579.6963.

KMK Law articles and blog posts are intended to bring attention to developments in the law and are not intended as legal advice for any particular client or any particular situation. The laws/regulations and interpretations thereof are evolving and subject to change. Although we will attempt to update articles/blog posts for material changes, the article/post may not reflect changes in laws/regulations or guidance issued after the date the article/post was published. Please consult with counsel of your choice regarding any specific questions you may have.


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