New Year, New Definition of Waters of the United States

Graphic of USGS topography map symbols for wetlands

On December 30, the Biden Administration released a pre-publication version of their final Rule re-defining ‘Waters of the United States’ (WOTUS). Last year alone, the government reviewed 20,000 applications that essentially ask ‘Is this a water?’ While it might seem obvious what a water or wetland or stream is, the sheer number of applications gives a sense of the complexity of that question, not to mention the high stakes - it could either be $0 to develop a project or much more. So while WOTUS is a jargon-y term, what it really means is how much of US wetlands, streams, rivers, and lakes are protected.

How WOTUS is defined not only has huge implications for the protection of aquatic resources (and the valuable services they provide like flood mitigation and water quality), but underpins the restoration economy - a little-known sector estimated to directly employ 126,000 and generate $9.5 billion in sales annually, as well as providing significant indirect jobs and economic output (95,000 jobs, and $15 billion, respectively).

The definition of WOTUS has changed multiple times over the half century of implementation of the Clean Water Act. The most durable definition arose after the Rapanos v. United States Supreme Court case and has been implemented for 45+ years. This WOTUS definition - referred to alternately as ‘post-Rapanos’, ‘1986 regulations’, and ‘pre-2015 regulations’ - notably adopted two tests for determining if a water was WOTUS: 

  1. Is the wetland or stream ‘relatively permanent’ and/or 

  2. Does it “significantly affect the chemical, physical, or biological integrity” of waters (aka does it have a ‘significant nexus’ (scroll down for definitions). 

Subsequently, the Obama administration adopted the 2015 Clean Water Rule that expanded the scope of WOTUS, the Trump administration shrank protections under its Navigable Waters Protection Rule (NWPR)*, the Biden administration repealed the NWPR and is now largely going back to the 1986 regulations, with minor changes. 

*To see just how much the NWPR Shrank Protections, scroll down to the bottom of the post

The New Rule’s Definitions of ‘Relatively Permanent’ and ‘Significant

  • The “relatively permanent standard” means relatively permanent, standing or continuously flowing waters connected to paragraph (a)(1) waters [traditionally navigable waters, territorial seas, and interstate waters], and waters with a continuous surface connection to such relatively permanent waters or to paragraph (a)(1) waters.

  • The “significant nexus standard” means waters that, either alone or in combination with similarly situated waters in the region, significantly affect the chemical, physical, or biological integrity of traditional navigable waters, the territorial seas, or interstate waters. 

  • Significantly affect” means a material influence on the chemical, physical, or biological integrity of waters identified in paragraph (a)(1) of this section. To determine whether waters, either alone or in combination with similarly situated waters in the region, have a material influence on the chemical, physical, or biological integrity of waters identified in paragraph (a)(1) of this section, the functions identified in paragraph (c)(6)(i) of this section will be assessed and the factors identified in paragraph (c)(6)(ii) of this section will be considered:  

    • (i) Functions to be assessed: (A) Contribution of flow; (B) Trapping, transformation, filtering, and transport of materials (including nutrients, sediment, and other pollutants); (C) Retention and attenuation of floodwaters and runoff; (D) Modulation of temperature in waters identified in paragraph (a)(1) of this section; or (E) Provision of habitat and food resources for aquatic species located in waters identified in paragraph (a)(1) of this section; 

    • (ii) Factors to be considered: (A) The distance from a water identified in paragraph (a)(1) of this section; (B) Hydrologic factors, such as the frequency, duration, magnitude, timing, and rate of hydrologic connections, including shallow subsurface flow; (C) The size, density, or number of waters that have been determined to be similarly situated; (D) Landscape position and geomorphology; and (E) Climatological variables such as temperature, rainfall, and snowpack.

Table 1. Summary of Differences

The source for this table comes from the EPA’s December 2022 Economic Analysis for the Final “Revised Definition of ‘Waters of the United States’ Rule” unless otherwise noted.  

Type of Water CoveredChange from Previous Rule(s)
Traditional Navigable Waters, Territorial Seas, Interstate Waters1986 Rule: The categories of waters are grouped together in the new Rule but the protections are the same.

2020 NWPR: The new Rule adds protections back. The 2020 NWPR did not include interstate waters (unless they met another jurisdictional category),and exclusions could apply to traditional navigable waters and territorial seas: “If the water meets any of the exclusions, the water is excluded even if the water satisfies on or more conditions to be a [jurisdictional] water” (2020 NWPR).
Impoundments1986 Rule: The only difference is that impoundments of intrastate waters would have to meet either the relatively permanent or significant nexus test (see below).

2020 NWPR: No practicable difference, although the 2020 NWPR created a category for lakes, ponds, and impoundments whereas the new Rule has a specific category for impoundments (lakes and ponds are either covered under ‘traditional navigable waters’, ‘impoundments’, or ‘intrastate lakes and ponds’). The 2020 NWPR also did not have covered impoundments of tributaries that did not contribute surface water flow to a traditional navigable water.
Tributaries1986 Rule: The new Rule is consistent but has a somewhat different standard for determining if the tributary is ‘relatively permanent’ or has ‘significant nexus’ (see below).

2020 NWPR
: The new Rule provides more protections with regards to the ‘relatively permanent’ standard (see below). The 2020 NWPR also excluded ephemeral waters and did not protect interstate waters not connected to a traditional navigable water or territorial sea.
Adjacent Wetlands1986 Rule: No practicable difference.

2020 NWPR: The new Rule adds protections back. The 2020 NWPR only covered wetlands that touch or have a regular surface water connection to other jurisdictional waters.
Intrastate Waters not Covered by Other Categories1986 Rule: The new Rule is similar but adopts the relatively permanent or significant nexus standards, whereas the 1986 Rule had an interstate commerce test.

2020 NWPR: The new Rule adds protections bank, although in practice the agencies believe changes in jurisdiction will be de minimis. The NWPR did not have this category of waters and would have excluded these waters if they did not fall in other categories of waters (e.g., in lakes, ponds, and impoundments).
Exclusions to WOTUS1986 Rule: The new Rule is consistent but adds some categories of excluded waters mentioned in the 1986 Rule preamble that were not in the Rule itself and adds two additional categories from guidance that the EPA/Corps published after the Rapanos v. United States Supreme Court decision. The new Rule also clarifies the prior converted cropland exclusion from the 1986 Rule.

2020 NWPR: the new Rule’s exclusions are generally consistent with 2020 NWPR exclusions with a few exceptions: the 2020 NWPR excluded groundwater and diffuse stormwater runoff and direction sheet flow; excluded waters not otherwise included in their definition of WOTUS; and allowed exclusions to apply to traditional navigable waters and territorial seas.
* Must be either
‘Relatively permanent’1986 Rule: The new Rule is consistent but has a somewhat different definition. In the new rule, the “relatively permanent standard encompasses surface waters that have flowing or standing water year-round or continuously during certain times of the year, whereas under pre-2015 practice tributaries are considered relatively permanent if they typically flow year-round or have continuous flow at least seasonally (e.g., typically three months).”

2020 NWPR: The new Rule adds protections back. The 2020 NWPR only protected perennial or intermittent tributaries if they contributed surface water flow to a traditional navigable water or the territorial seas in a ‘typical year’… and excluded ephemeral waters. The 2020 NWPR rule also only covered adjacent wetlands that had a regular surface water connection to [or touched] jurisdictional waters.
Significantly affect the chemical, physical, or biological integrity of abovementioned WOTUS1986 Rule: The new Rule “adds specific factors and functions to consider as part of the significant nexus analysis.” The new Rule also changes the area to analyze whether waters ‘in combination with similarly situated waters in the region’ significantly affect WOTUS. The new area of analysis (‘region’) is the “catchment that drains to and includes the tributary [or wetland] of interest. Catchments will be delineated from the downstream-most point of the tributary reach of interest and include the land uphill that drains to that point. It is expected that this will slightly increase the number of tributaries that are found to be jurisdictional” as compared to the 1986 Rule.

2020 NWPR: The 2020 NWPR removed the significant nexus standard.

What Else is in the Rule?

The new Rule itself is 5 pages long (p.505-509), with a lengthy preamble (450 pages) laying out the case law for the decision to continue with 45-year interpretation of WOTUS. The preamble’s constant reference to case law is likely written to inform the Supreme Court’s upcoming decision on Sackett v. EPA (see our summary of the October 2022 oral arguments here). Although SCOTUS was not happy with the existing tests for determining WOTUS, the new Rule sticks to its guns. SCOTUS was also not happy that an average landowner couldn’t determine whether they have WOTUS on their property, and guess what… the preamble includes a step by step guide for landowners (p.462-478).

This has the Supreme Court written all over it… They are trying to explain themselves to keep out of trouble… The way they wrote this is probably the safest thing to do because they have been sued on this nonstop the past 10 years” (Mark Ryan, a former EPA lawyer, in Greenwire, 1/3/2002).

The new Rule has a detailed explanation about each of the elements of the Rule and what was considered, including court cases, public comments, experience from implementation, scientific analysis and more (Section IV.C. of the preamble, p.225-478). Within this section, there is guidance for regulatory staff on implementation. For example, there is background and guidance on how to identify a jurisdictional tributary (p.286-293), what an ‘adjacent’ wetland means (Section IV.C.5, p.323-330), how to determine if flow is ‘relatively permanent’ (mentioned within the context of specific types of waters - e.g., p.330-337 for adjacent wetlands), and if there is a ‘significant nexus’ (p.449-460 for general information, and mentioned within the context of specific types of waters). 

What Happens Next?

The new Rule is scheduled to go into effect 90 days from publication in the Federal Register. Sometime early this year, the Supreme Court will issue their decision on Sackett v. EPA. The oral arguments suggested the Justices were not about to throw out the entire definition of WOTUS but they were not happy with the way it was currently interpreted, particularly the ‘significant nexus’ test. We will have to await their final decision to see whether the Court gives deference to this new Rule or throws a new spin that will leave lawyers, the regulated and the restoration economy spinning to understand implications for the interpretation of WOTUS. Ryan noted: “There will be a court challenge, there always is… The upcoming Sackett decision will tell us how durable it is. Or not” (Greenwire, 1/3/2023). We will keep up with developments.
 

Want to know more about WOTUS in SCOTUS? Read background here, our summary of the Supreme Court’s oral arguments from Sackett v. EPA, and perspectives from the restoration economy community.


WOTUS Resources


Bonus: Just How Much Did the Trump-Era NWPR Shrink Protections?

One of the things that caught our attention while reviewing the new Rule was that the Economic Analysis (EPA 2022) included an analysis of jurisdictional determinations (JDs) under different definitions of WOTUS as an indication of the scope of protection afforded by these definitions (Table A-2, p.131-132). JDs are decisions about whether a water is included in the jurisdiction of the Clean Water Act. The analysis found the following changes between the NWPR and 1986 regulations:

  • A 78% reduction in how many lacustrine JD’s were determined to be jurisdictional (lakeshores and deepwater habitats of a lake)

  • A 65% reduction for riparian JDs (streamside habitats)

  • A 53% reduction for riverine JDs

  • A 34% reduction for palustrine JDs (non-tidal wetlands) 

With regards to the second bullet, 0 of the 12,518 of the ephemeral streams assessed under NWPR were considered WOTUS. Another interesting fact: about the same amount of ephemeral streams were assessed for JDs under NWPR (a 13-month period), as during the entire use of the 1986 definition of WOTUS (roughly a 40-year period). It’s as if there were a mad rush to get a certificate that “this is not WOTUS” while you still could during the Trump Administration.


The Restoration Economy Center, housed in the national nonprofit Environmental Policy Innovation Center (EPIC), aims to increase the scale and speed of high-quality, equitable restoration outcomes through policy change. Join our newsletter list to make sure you are notified when new reports are published.

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