The Ebb and Flow of Waters of the United States: A Look at the Latest Revised Definition of WOTUS

The Ebb and Flow of Waters of the United States: A Look at the Latest Revised Definition of WOTUS

Since the 1985 Supreme Court case United States vs. Riverside Bayview Homes, the U.S. has struggled over how we define and regulate our waterways as well the marshes, swamps, and wetlands that are associated with them. On February 14, 2019, the US Environmental Protection Agency and US Department of the Army unveiled the latest chapter in this ever-evolving saga, publishing a new rule in the Federal Register defining what constitutes a Water of the US (WOTUS) subject to regulation under the Federal Clean Water Act (CWA).

This move is consistent with the February 2017 Executive Order 13778, “Restoring the Rule of Law, Federalism, and Economic Growth by Reviewing the ‘Waters of the United States’ Rule.” In contrast, it appears to be a strategic policy shift away from the 2015 Clean Water Rule, which was developed after extensive review of over 1,200 scientific papers and data, previous jurisdictional determinations, agency guidance and manuals, and federal and state reports on the hydrologic connectivity of aquatic ecosystems to downstream waterbodies. As of January 31, 2018, the 2015 rule would not be applicable until February 6, 2020. The newly proposed rule and its definitions of WOTUS would likely take affect prior to this time and would supersede the 2015 rule. 

From a practical standpoint, we need to understand that the critical parts of WOTUS are the categories of regulated waters and how they are defined. They form the underlying basis for the assessment and delineation of these environmental resources on the ground, and how potential landowner actions related to farming, building roads and shopping centers, or developing mineral resources would impact them. Typically, impacts to WOTUS are classified, quantified, and permitted under the Federal CWA and its associated state-level programs. The new rule proposes the following categories of WOTUS: Traditional navigable waters, including the territorial seas; tributaries of such waters; certain ditches; certain lakes and ponds; impoundments of otherwise jurisdictional waters; and wetlands adjacent to other jurisdictional waters. Each of these categories are further defined within the proposed rule. 

Changes to the definitions of three categories associated with this latest proposed WOTUS rule stick out to me as having the potential for comment or concern. 

  1. Tributaries: the new rule defines tributaries to include both perennial and intermittent streams in the definition while excluding ephemeral surface features that only flow in direct response to precipitation. Tributaries must be shown to have at least intermittent flow throughout portions of a typical year to be considered WOTUS and thus jurisdictional under the CWA. 
  2. Ditches: the new rule defines and clarifies that ditches must be constructed in WOTUS, have tributary characteristics, and carry perennial and/or intermittent flow to be considered jurisdictional. 
  3. Adjacent Wetlands: the new rule does not change the longstanding regulatory definition of what makes a wetland (hydrophytic vegetation, hydric soils, and wetland hydrology). However, the new rule does redefine what makes up the term “adjacent” in terms of how a wetland area will be regulated. This is a key point for the regulated public, the agencies, and wetland delineators across the country. For a wetland to be considered adjacent and thus a jurisdictional WOTUS, the wetland must abut or have a direct hydrologic surface connection to other WOTUS features in a typical year. Wetlands that lack a direct hydrologic surface connection to jurisdictional waters would not be considered adjacent and therefore would not be themselves WOTUS. Importantly, ephemeral surface connections as well as subsurface groundwater connections between wetlands and jurisdictional waters would not constitute a direct hydrologic surface connection per the new rule. 

There are many other changes or revisions to note in the proposed new rule as compared to the original CWA definitions and the 2015 rule, but without going into great detail there are a few interesting ones that I see as potentially affecting the regulated public moving forward. The new rule proposes to remove the category of “interstate waters, including interstate wetlands,” which was included in the 1986 regulations (33 CFR 328.3(a) [1] – [7]). For the first time, ditches and lakes and ponds have been officially proposed as new standalone categories of WOTUS. The new rule also proposes to eliminate the post-Rapanos decision case-by-case determination of WOTUS through a significant nexus evaluation, and instead establish clear categories of waters subject to federal jurisdiction. Finally, the new rule removes the distance thresholds used in the 2015 rule to define “neighboring” when considering wetland adjacency and specifically removes the ecological connectivity concept that was sometimes used to determine whether a wetland was adjacent to a WOTUS pre-2015. 

In summary, as a wetland ecologist and an environmental consultant, the inclusion of intermittent streams was significant because they are often the initial point of groundwater and surface water interaction within a watershed and they often harbor aquatic species. Conversely, the exclusion of ephemeral channels where there is not strong evidence of groundwater-driven base flow during a typical year supports common-sense regulation of surface water features in relation to development projects that require temporary or permanent alteration to these upland drainage features. 

The specific exclusion of adjacent wetlands that are separated by uplands, dikes or other features and that lack a direct surface hydrologic connection along with removal of any reference to ecological connectivity is somewhat concerning. Some wetlands are naturally isolated and are therefore automatically not WOTUS under this proposal. However, certain naturally occurring isolated wetlands harbor sensitive or endangered plant and animal species. If these wetland areas are not subject to a review under federal or state permit processes, then we may eventually be unaware of significant losses of rare native endemic species.

Additionally, the simple fact that a wetland is not does not abut or possess a direct surface hydrologic connection to other WOTUS does not negate that the wetland performs important functions and has values related to flood storage, water quality, groundwater recharge, and terrestrial and aquatic wildlife habitat. A common theme among water professionals right now is green infrastructure or low-impact development related to stormwater management, and wetland conservation and proper permitting procedure are integrally related to those concepts. 

As our country grapples with another series of rules and definitions related to WOTUS, it is critical that we consider all the future implications of our laws related to development in wetlands and waterways. Many countries around the world are facing clean water challenges, and it is our job to lead with thoughtful, responsible, and flexible policy surrounding how we define and regulate our waterways. We have many challenges that will face our future generations, let’s be sure that clean water for drinking, sanitation, recreation, and wildlife is adequately addressed by our actions now.


Senior Scientist
Ecological Services

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