Revised Definition of "Waters of the United States"
Response to Comments Document
Section 13 - Relatively Permanent Standard
See the Introduction to this Response to Comments Document for a discussion of the U.S. Environmental
Protection Agency and the U.S. Department of the Army's (hereinafter, the agencies ) comment response
process and organization of the eighteen sections.
13 General Comments About the Relatively Permanent Standard 2
13.1 General Implementation of the Relatively Permanent Standard 6
13.2 The Relatively Permanent Standard for Tributaries 11
13.2.1 General comments about the relatively permanent standard for tributaries 11
13.2.2 Scope of the relatively permanent standard for tributaries 13
13.2.2.1 Approaches to seasonal flow 17
13.2.2.2 Approaches to flow sources 17
13.2.2.3 Approaches to flow classifications 19
13.2.3 Implementation of the relatively permanent standard for tributaries 23
13.3 The Relatively Permanent Standard for Adjacent Wetlands 25
13.4 The Relatively Permanent Standard for "Other Waters" 29
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13
General Comments About the Relatively Permanent Standard
Several commenters provided general input on whether the relatively permanent standard should be used
in the final rule.
Some commenters expressed support for the relatively permanent standard and claimed that the standard
serves the purposes of the Clean Water Act, is informed by Supreme Court decisions, and is scientifically
supported. Other commenters stated that the focus on permanent or relatively permanent connections
would limit, prevent, or mitigate adverse impacts to aquatic ecosystems, particularly in upland tributaries
and other features that connect to "waters of the United States," which were not addressed in the 2020
Navigable Waters Protection Rule (2020 NWPR).
Several commenters provided input regarding how the relatively permanent standard should be
implemented with consideration of the significant nexus standard.
A few commenters claimed that the relatively permanent standard may provide "a quicker
option" than the significant nexus standard. These commenters added that the relatively
permanent standard should only be used as an alternative to the significant nexus standard as long
as the final rule is clear that it represents a subset of the significant nexus standard, rather than a
separate standard.
One commenter recommended that the agencies should not expand the definition of relatively
permanent to the point where it would include waters that could not meet the significant nexus
standard as well.
Another commenter asserted that the relatively permanent standard should not be included as an
independent test in the final rule, and that it should never be used alone to determine that a
resource is non-jurisdictional, without also first applying the significant nexus test.
One commenter supported the use of the relatively permanent standard or the significant nexus
standard to define jurisdiction, asserting that this approach is both scientifically sound and
consistent with Supreme Court rulings.
Another commenter supported the use of the relatively permanent standard in concert with the
significant nexus standard. The commenter asserted that this combination was important because
intermittent and ephemeral streams and wetlands may not be protected solely through a relatively
permanent standard.
One commenter asserted that the agencies should reject the use of the significant nexus standard
completely and only maintain the relatively permanent standard instead.
A few commenters objected to the relatively permanent standard, as proposed.
One commenter asserted that the interpretation of the relatively permanent standard in the
proposed rule was inconsistent with the plurality's opinion in Rapanos1, which did not state that
all waters are required to have a "continuous surface connection."
One commenter asserted that "the 2017 rule" more appropriately and accurately defines relatively
permanent waters than the proposed rule.
Another commenter expressed that the agencies seem to be expanding the scope of the relatively
permanent standard with the intended application in the proposed rule.
1 Rapanos v. United States, 547 U.S. 715 (2006) ("Rapanos")
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Another commenter asserted that relatively permanent as interpreted in the proposed rule would
include all of Florida's urbanized areas, most of its agricultural lands, and even the rural areas
supporting smaller towns.
A few commenters stated support for the relatively permanent standard provided by the Rapanos
Guidance.2 One commenter asserted that the agencies have not justified why the current understanding of
relatively permanent in Rapanos Guidance should be replaced with more expansive alternatives and
therefore stated that the current approach to defining relatively permanent waters should be retained.
Agencies' Response: The agencies agree with the commenters who expressed support for
including the relatively permanent standard in the final rule and assert that federal
protection is appropriate where a water meets the relatively permanent standard. The
agencies also agree with those commenters who stated that the relatively permanent
standard is insufficient as the sole standard for geographic jurisdiction under the Clean
Water Act. The standard's apparent exclusion of major categories of waters from the
protections of the Clean Water Act, specifically with respect to tributaries that are not
relatively permanent and adjacent wetlands that do not have a continuous surface water
connection to such relatively permanent waters or to paragraph (a)(1) waters, is
inconsistent with the Act's text and objective. In addition, the relatively permanent
standard used alone runs counter to the science demonstrating how such waters can affect
the integrity of downstream waters, including traditional navigable waters, the territorial
seas, and interstate waters. The agencies also note that that phrase "waters of the United
States" is by its terms expansive and not expressly limited to relatively permanent, standing
or continuously flowing bodies of water or to wetlands with a continuous surface
connection. The imposition of such limitations would disregard the science demonstrating
the effects of upstream waters and wetlands on downstream paragraph (a)(1) waters.
Taking science into account, the agencies agree with Justice Kennedy that the Clean Water
Act intends to protect waters that do not meet the relatively permanent standard, where
such waters have a significant nexus to a paragraph (a)(1) water. Rapanos, 547 U.S. at 773-
74.
The agencies agree with the commenter who asserted that the proposed rule would protect
more waters than were protected under the 2020 NWPR but disagree with the commenter's
characterization that the proposed rule focused on permanent or relatively permanent
connections, as described further below.
The agencies agree that scientific evidence supports the conclusion that tributaries of
paragraph (a)(1) waters with relatively permanent, standing or continuously flowing water
perform important functions that either individually, or cumulatively with similarly
situated waters in the region, have significant effects on the chemical, physical, or biological
integrity of paragraph (a)(1) waters. The same is true of adjacent wetlands and relatively
permanent open waters with continuous surface connections to tributaries that meet the
relatively permanent standard. See Technical Support Document Section III.A., III.B, and
III.D. However, as discussed above, the relatively permanent standard excludes waters that
2 U.S. EPA & U.S. Army Corps of Engineers, Clean Water Act Jurisdiction Following the U.S. Supreme Court's
Decision in Rapanos v. United States & Carabell v. United States (June 5, 2007)
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properly fall within the Clean Water Act's protections. Thus, the agencies have concluded
that the relatively permanent standard provides important efficiencies and additional
clarity for regulators and the public by more readily identifying a subset of waters that will
virtually always significantly affect paragraph (a)(1) waters but, on its own, the standard is
inconsistent with the text of the statute and Supreme Court precedent and is insufficient to
advance the objective of the Clean Water Act. For further discussion on why the agencies
have determined that the relatively permanent standard is insufficient as the sole standard
for geographic jurisdiction under the Clean Water Act, see Section IV.A of the Preamble to
the Final Rule.
The agencies agree with those commenters who supported the use of both the relatively
permanent and significant nexus standards. Under the final rule, the agencies are
interpreting the term "waters of the United States" to include tributaries to traditional
navigable waters, the territorial seas, interstate waters, and paragraph (a)(2)
impoundments when the tributaries meet either the relatively permanent standard or the
significant nexus standard ("jurisdictional tributaries"); wetlands adjacent to paragraph
(a)(1) waters, wetlands adjacent to and with a continuous surface connection to relatively
permanent paragraph (a)(2) impoundments or to jurisdictional tributaries when the
jurisdictional tributaries meet the relatively permanent standard, and wetlands adjacent to
paragraph (a)(2) impoundments or jurisdictional tributaries when the wetlands meet the
significant nexus standard ("jurisdictional adjacent wetlands"); and intrastate lakes and
ponds, streams, or wetlands, not identified in paragraphs (a)(1) through (a)(4) that meet
either the relatively permanent standard or the significant nexus standard ("paragraph
(a)(5) waters"). The agencies have concluded that the significant nexus standard as
established in the final rule is consistent with the statutory text and legislative history,
advances the objective of the Clean Water Act, is informed by the scientific record and
Supreme Court case law, and appropriately considers the policies of the Act, and as
discussed above, the relatively permanent standard is included in the rule because it
provides important efficiencies and additional clarity for regulators and the public by more
readily identifying a subset of waters that will virtually always significantly affect
paragraph (a)(1) waters. Thus, the agencies have determined that together the relatively
permanent standard and the significant nexus standard as codified in the final rule give
effect to the Clean Water Act's broad terms and environmentally protective aim as well as
its limitations. For further discussion on why the agencies are incorporating both the
relatively permanent and significant nexus standards in the final rule, see Section IV.A of
the Preamble to the Final Rule.
Under the final rule, tributaries; adjacent wetlands; and intrastate lakes, as well as ponds,
streams, or wetlands not identified in paragraphs (a)(1) through (4) will be assessed under
the relatively permanent or significant nexus standards per paragraph (a)(3), (a)(4), or
(a)(5) of the final rule, respectively. The relatively permanent standard cannot be used alone
to determine that a water is non-jurisdictional. Rather, waters that do not meet the
relatively permanent standard must be assessed under the significant nexus standard for
tributaries, adjacent wetlands, and paragraph (a)(5) provisions of the final rule. For
example, if a tributary has flowing water year-round or continuously during certain times
of the year, the tributary would meet the relatively permanent standard per paragraph
(a)(3) of the final rule if it flows directly or indirectly through another water or waters to a
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paragraph (a)(1) water. Conversely, tributaries that do not meet the relatively permanent
standard will be assessed under the significant nexus standard and may be jurisdictional
when they, either alone or in combination with similarly situated waters in the region,
significantly affect the chemical, physical, or biological integrity of a paragraph (a)(1)
water. For further discussion about the way the two standards will be implemented in
determining the jurisdiction of tributaries, adjacent wetlands, and intrastate lakes, as well
as ponds, streams, or wetlands not identified in paragraphs (a)(1) through (4), see Section
IV.C of the Preamble to the Final Rule. See also agencies' response to comments on
Tributaries in Section 8, Wetlands and Adjacency in Section 10, Paragraph (a)(5) Waters in
Section 11, and the Significant Nexus Standard in Section 12.
The agencies acknowledge that some commenters expressed support for the relatively
permanent standard provided by the Rapanos Guidance. While the final rule is founded on,
and generally returns to, the longstanding and familiar pre-2015 regulatory regime, it does
not adopt that regime unchanged. As discussed in Final Rule Preamble Section IV.A, the
agencies in the final rule have revised the 1986 regulations to reflect the agencies'
determination of the statutory limits on the scope of the "waters of the United States"
informed by Supreme Court precedent, the best available science, and the agencies'
experience and technical expertise. Additionally, as compared to the pre-2015 regulations or
pre-2015 regulatory regime, the final rule reflects updates and advances in implementation
tools, resources, and scientific support; codifies exclusions for features that were generally
considered non-jurisdictional under the pre-2015 regulatory regime; and is streamlined and
restructured for clarity. As discussed in Sections IV.A, IV.B, and IV.C of the Preamble to
the Final Rule, the agencies view their interpretation of the relatively permanent standard
under the final rule as more consistent with the statute and case law, and more
implementable, than the approach taken in the Rapanos Guidance.
In response to the reference to a 2017 rule, the agencies note that they did not promulgate a
definition of "waters of the United States" in 2017. However, in developing the final rule,
the agencies thoroughly considered alternatives to this rule, and have concluded that this
final rule best accomplishes the agencies' goals to promulgate a rule that advances the
objective of the Clean Water Act, is consistent with Supreme Court decisions, is informed
by the best available science, and promptly and durably restores vital protections to the
nation's waters. See Section IV.B of the Preamble to the Final Rule for further discussion of
the agencies' grounds for concluding that none of the agencies' previous rulemakings are
suitable alternatives to the final rule.
The agencies disagree with the commenter who asserted that the proposed rule's approach
to the relatively permanent standard was inconsistent with the plurality's opinion in
Rapanos, and who asserted that the plurality opinion did not state that all waters are
required to have a continuous surface connection. To be clear, in the final rule the agencies
are exercising the authority granted to them by Congress to construe and implement the
Clean Water Act and to interpret an ambiguous term and its statutory definition. While the
agencies' interpretation of the statute is informed by Supreme Court decisions, including
Rapanos, it is not an interpretation of the multiple opinions in Rapanos. See Final Rule
Preamble Section IV.A.1. The agencies note that the rule does not require that all waters
have a continuous surface connection. Rather, under the final rule, a continuous surface
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connection is only required for adjacent wetlands and paragraph (a)(5) waters to meet the
relatively permanent standard. As discussed in Section IV.C of the Preamble to the Final
Rule, the agencies have determined that this approach is consistent with the plurality's
opinion in Rapanos, which concluded, "relatively permanent, standing or continuously
flowing bodies of water," 547 U.S. at 739, that are connected to traditional navigable waters,
id. at 742, and waters with a "continuous surface connection" to such waterbodies, id.,
(Scalia, J., plurality opinion), are "waters of the United States" under the relatively
permanent standard.
As described in Section IV.A of the Preamble to the Final Rule, the agencies are finalizing a
definition of "waters of the United States" that is within the agencies' authority under the
Act; that advances the objective of the Clean Water Act; that establishes limitations that are
consistent with the statutory text, supported by the scientific record, and informed by
relevant Supreme Court decisions; and is both familiar and implementable. Further, the
agencies disagree that the final rule generally represents an expansion beyond the pre-2015
regulatory regime. Rather, as discussed in Section V.A of the Preamble to the Final Rule,
the agencies expect that there will be a slight and unquantifiable increase in waters being
found to be jurisdictional under the final rule in comparison to the pre-2015 regulatory
regime. Indeed, as discussed in Section V.A of the Preamble to the Final Rule, this final rule
is generally comparable in scope to the pre-2015 regulatory regime that the agencies are
currently implementing.
In response to commenters who asserted that the relatively the permanent standard would
include all of Florida's urbanized areas, most of its agricultural lands, and even the rural
areas supporting smaller towns, the agencies are not aware of any basis for this assertion
but note that determinations regarding the jurisdictional status of any specific water are
outside the scope of this rulemaking. The agencies will assess jurisdiction under the final
rule on a case-specific basis.
For further discussion on the final rule's incorporation of the relatively permanent
standard, see Sections IV.A, IV.B, and IV.C of the Preamble to the Final Rule.
13.1 General Implementation of the Relatively Permanent Standard
Several commenters provided general input regarding implementation of the relatively permanent
standard. A few commenters claimed that the proposed rule did not define "relatively permanent." As
such, one commenter asserted that it is unclear how the agencies will implement the standard or
determine what constitutes a continuous surface connection. Further, one commenter claimed that without
a definition for the relatively permanent standard, the agencies would be given too much discretion and
there would be more potential for inconsistent application. One commenter asserted that the agencies
present the relatively permanent standard differently in different sections of the proposed rule, which
makes its application unclear. Another commenter asserted that the agencies should remove the term
"relatively" from relatively permanent standard because they felt the word itself added uncertainty to the
proposed rule.
A few commenters proposed specific recommendations for implementation of the relatively permanent
standard and continuous surface connection requirement.
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One commenter claimed that the final rule should more clearly define the concept of a continuous
surface connection. The commenter asserted that without a clear definition, "waters of the United
States" could include all upstream resources. The commenter further claimed that within this
definition, there needs to be a clear separation from conveyance systems and treatment systems
constructed in uplands.
Another commenter asserted that the qualification of "either directly or indirectly" was missing
from the continuous surface waters connection description.
One commenter asserted that the agencies should not include guidance on the application of the
relatively permanent standard with respect to specific features (e.g., ditches, culverts, pipes, or
swales), but should clarify that the relatively permanent standard should only be used when those
specific features maintain a continuous surface connection or the qualification of those specific
features is exceptionally intuitive. The commenter claimed that in all other cases, the significant
nexus standard should be used.
One commenter expressed concern that areas of land or other features that provide for a
continuous surface connection between a lake or wetland and a main body of water may itself be
considered jurisdictional. This commenter recommended that the agencies define and determine
whether and how jurisdiction may or may not extend to seasonal water features.
Some commenters provided feedback on how the relatively permanent standard should be implemented,
specifically with regard to how precipitation and other climate information will be considered in the final
rule.
A few commenters expressed concern that the agencies were proposing to change the
methodology from using 30-year averages for determining trends in rainfall patterns to using
short-term averages.
One commenter requested that the agencies reconsider using the typical year concept to assist
with determinations, using the rolling 30-year record for precipitation data.
One commenter expressed support for using the Antecedent Precipitation Tool and requested that
the agencies provide training to state and federal staff on how to use the tool.
Another commenter requested that the agencies clearly define how the typical year concept will
be determined in the final rule.
One commenter asserted that the proposed rule did not make clear what constitutes relative
permanence given the changing climate.
Agencies' Response: In the proposed rule, the agencies sought comment on alternative
options for interpreting the relatively permanent standard for tributaries, adjacent
wetlands, and waters evaluated under paragraph (a)(5) of the final rule. As described in
Sections IV.C.4, IV.C.5, and IV.C.6 of the Preamble to the Final Rule, the agencies have
considered public comments on the relatively permanent standard and provided clarity
regarding how the agencies intend to implement the relatively permeant standard for each
of these categories of waters, including the continuous surface connection requirement for
adjacent wetlands and waters evaluated under paragraph (a)(5).
The "relatively permanent standard" refers to the test to identify relatively permanent,
standing or continuously flowing waters connected to paragraph (a)(1) waters, and waters
with a continuous surface connection to such relatively permanent waters or to traditional
navigable waters, the territorial seas, or interstate waters. Under the final rule, the
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relatively permanent standard encompasses surface waters that have flowing or standing
water year-round or continuously during certain times of the year. Relatively permanent
waters do not include surface waters with flowing or standing water for only a short
duration in direct response to precipitation. See Final Rule Preamble Sections IV.C.4.c.ii
and IV.C.6.c.ii for additional information on how the agencies will identify relatively
permanent tributaries and paragraph (a)(5) waters, respectively. Further, under the
relatively permanent standard, adjacent wetlands or paragraph (a)(5) waters meet the
continuous surface connection requirement if they physically abut, or touch, a requisite
jurisdictional water, or if they are connected to these waters by a discrete feature like a
ditch, swale, pipe, or culvert. A natural berm, bank, dune, or similar natural landform
between an adjacent wetland or a paragraph (a)(5) water and a relatively permanent water
does not sever a continuous surface connection to the extent it provides evidence of a
continuous surface connection. A continuous surface connection does not require a constant
hydrologic connection. Rather, the agencies will identify a continuous surface connection
consistent with theRapanos plurality opinion, which indicates that the continuous surface
connection standard is a "physical connection requirement." 547 U.S. at 754; see also
Rapanos Guidance at 6. See Final Rule Preamble Section IV.C.5.c.ii and Section IV.C.6.c.ii
for additional discussion. See also the agencies' response to comments below, in Sections
13.2,13.3, and 13.4.
The agencies are not promulgating distinct definitions of "relatively permanent standard"
or "continuous surface connection" under the final rule. Rather, the agencies have
incorporated the standard into the text of the regulation and explained directly and
specifically in the preamble the way the relatively permanent standard should be
implemented for tributaries, adjacent wetlands, and waters evaluated under paragraph
(a)(5) of the final rule, including how the continuous surface connection requirement should
be implemented for waters evaluated under paragraph (a)(5), as well as adjacent wetlands.
The agencies disagree that, without a definition for the relatively permanent standard or
continuous surface connection, the agencies would be given too much discretion and there
would be more potential for inconsistent application of the final rule. The agencies'
approach to implementation of the relatively permanent and significant nexus standards is
broadly consistent with the pre-2015 regulatory regime, but the agencies have clarified and
refined both the regulatory text and the guidance on how the agencies intend to implement
these standards in order to promote consistent Clean Water Act protections for waters. The
clarifications in the final rule, including the addition of exclusions that codify longstanding
practice, and review of the advancements in implementation resources, tools, and scientific
support address many of the concerns raised in the past about timeliness and consistency of
jurisdictional determinations under the Clean Water Act. See Final Rule Preamble Section
IV.C.7 and IV.G.
The agencies have decided not to include the phrase "either directly or indirectly" in the
description of the continuous surface connection. The agencies agree that wetlands may be
connected to relatively permanent waters directly or indirectly through a discrete feature
like a non-jurisdictional ditch, swale, pipe, or culvert, which can serve as a physical
connection that maintains a continuous surface connection between an adjacent wetland
and a relatively permanent water. See Final Rule Preamble Section IV.C.5 and IV.C.6 for
the agencies' rationale regarding their interpretation of continuous surface connection in
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the final rule. The agencies disagree with the commenter who asserted that the agencies
should not include guidance on specific features that maintain a continuous surface
connection. The agencies have added guidance on such features in the final rule to provide
clarity and regulatory certainty, as described above. The agencies acknowledge commenters
who expressed concern that features maintaining a continuous surface connection may be
considered jurisdictional. However, the final rule preamble does not state that such features
are automatically jurisdictional, and the preamble also clarifies that features maintaining a
continuous surface connection may be non-jurisdictional.
The agencies recognize that some commenters supported the "typical year" approach, a
concept fundamental to many of the 2020 NWPR's definitions. 85 FR 22273. The concept of
"typical year conditions," including precipitation normalcy, may be relevant to ensuring
that certain surface water connections in natural streams are not being observed under
conditions that are unusually wet or dry. In terms of implementation, the concept of
precipitation normalcy is valid in certain contexts, such as to inform determinations as to
the presence of a wetland. However, the typical year analysis proved difficult to implement
and yielded arbitrary and potentially outdated results. For example, a recent study by the
U.S. Army Corps of Engineers (Corps) found that precipitation normalcy (as calculated
based on the methodology described in the preamble to the 2020 NWPR) was neither a
reliable predictor of streamflow normalcy, nor was it a precise predictor of streamflow
percentiles, in an analysis of watersheds across the United States.3 Moreover, it is not
required by the plurality opinion in Rapanos, which simply required a "connection]" to
paragraph (a)(1) waters. See Section IV.B.3 of the Preamble to the Final Rule and Section
II.B.4 of the Technical Support Document for additional discussion regarding the
implementation challenges of the "typical year" concept. Thus, under the final rule, the
agencies have not retained the 2020 NWPR's requirement that tributaries, or other
relatively permanent waters, contribute surface water flow to a paragraph (a)(1) water in a
"typical year." Similarly, the final rule does not require that waters assessed under
paragraph (a)(5) of the final rule or adjacent wetlands maintain a continuous surface
connection to a relatively permanent water at least once in a typical year.
The agencies disagree with the commenter who requested that the agencies reconsider using
the typical year concept to assist with determinations using the rolling 30-year record for
precipitation data. As discussed in Section IV.B.3 of the Preamble to the Final Rule, the
agencies have concluded that the 30-year precipitation record required by 2020 NWPR's
"typical year" definition did not allow the agencies flexibility to consider other time
intervals when appropriate to reflect effects of a rapidly changing climate, including
positive trends in temperature, increasing storm events, and extended droughts. For
additional discussion regarding why the agencies are not including the "typical year"
concept in the final rule, see Section IV.B.3 of the Preamble to the Final Rule. See also the
agencies' response to comments in Section 4.2.
3 Sparrow, K.H, Gutenson, J.L., Wahl, M.D. and Cotterman, K.A. 2022. Evaluation of Climatic and Hydroclimatic
Resources to Support the US Army Corps of Engineers Regulatory Program. Engineer Research and Development
Center (U.S.) Technical Report no. ERDC/CHL TR-22-19.
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While the final rule does not retain the 2020 NWPR's "typical year concept," under
longstanding practice since Rapanos, the agencies consider the effects of climatic conditions,
such as drought, when assessing the flow regime of tributaries. Specifically, the agencies
have substantial experience using visual hydrologic observations, field data and indicators,
and remote tools, as well as evaluating whether such evidence reflects regular flow
conditions characteristic of the waterbody in question when determining the relative
permanence of tributaries. For example, as discussed in Section IV.C.4.c.ii of the Preamble
to the Final Rule, the agencies have used Streamflow Duration Assessment Methods
(SDAMs), which are rapid, field-based assessment methods that rely on physical and/or
biological field indicators of stream flow duration and can be used to assist in determining
whether tributaries are "relatively permanent." Because SDAMs use indicators that are
robust as to seasonal and short-term climatic variability, these methods can be applied in a
single site visit to distinguish streamflow duration when a channel is flowing or in the
absence of flow and, in combination with best professional judgment, during abbreviated
periods of time when current conditions are wetter or drier than normal. The agencies will
continue to use their experience and expertise, as well as the many other available tools and
sources of information, to help complete jurisdictional determinations for relatively
permanent waters, as described further in the Preamble to the Final Rule in Section IV.C
and Section IV.G.
In response to the commenter that expressed support for the use of the Antecedent
Precipitation Tool (APT), the agencies acknowledge that automated tools will continue to be
important for supporting jurisdictional decision-making. The APT is one example of a tool
that can be used to determine precipitation normalcy. The APT is a desktop tool developed
by the Corps and is commonly used by the agencies to help determine whether field data
collection and other site-specific observations occurred under normal climatic conditions. In
addition to providing a standardized methodology to evaluate normal precipitation
conditions ("precipitation normalcy"), the APT can also be used to assess the presence of
drought conditions, as well as the approximate dates of the wet and dry seasons for a given
location. As discussed in Section IV.B.3 of the Preamble to the Final Rule, precipitation
data are often not useful in providing evidence as to whether a surface water connection
exists in a typical year, as required by the 2020 NWPR. However, the agencies have long
used the methods employed in the APT to provide evidence that wetland delineations are
made under normal circumstances or to account for abnormalities during interpretation of
data, and automated tools like the APT will also continue to be important for supporting
jurisdictional decision-making. Additional information on the APT is available on EPA's
"waters of the United States" website (https://www.epa.gov/wotus/antecedent-precipitation-
tool-apt). Supporting documentation, including a Technical and User Guide and step-by-
step instructions for running an analysis, is available on the APT Help Page located on the
APT user interface. The agencies may consider the development of additional support
materials or trainings over time to facilitate use of the APT. For further discussion on use of
the APT, see Section IV.G of the Preamble to the Final Rule. See also Section IV.C of the
Preamble to the Final Rule for additional discussion on the other tools and resources that
the agencies will use to implement the relatively permanent standard under paragraphs
(a)(3), (a)(4), and (a)(5) of the final rule, including other tools and datasets for assessing
climatic conditions.
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13.2 The Relatively Permanent Standard for Tributaries
13.2.1 General comments about the relatively permanent standard for tributaries
A few commenters expressed concerns regarding the approach to tributaries under the relatively
permanent standard in the proposed rule. For example, one commenter claimed that the proposed rule
would categorically assert jurisdiction over relatively permanent waters to include intermittent tributaries,
which the commenter claimed was done without regard to whether those features significantly affect
downstream traditional navigable waters. A few commenters asserted that the relatively permanent
standard, as defined in the proposed rule, would mean that more ephemeral features are likely to be
jurisdictional tributaries. As such, one commenter claimed that this may trigger additional regulatory
requirements. Another commenter claimed that the agencies were asserting jurisdiction over relatively
permanent tributaries based on indirect connections to a traditional navigable water, which they asserted
would not satisfy the plurality's test in Rapanos.
Some commenters stated that flow regime should not be used to establish jurisdictional status, with one
commenter asserting that the proposed rule would not confirm protections for upstream tributaries under
the relatively permanent standard. Another commenter argued that all tributaries, regardless of stream
flow, affect the health of downstream waters and should be protected. One commenter stated that
restricting protections based on regularity of flow is legally and scientifically baseless. Another
commenter asserted that the proposed rule ignored the importance of volume, duration, and frequency of
flow related to ephemerals, particularly in the arid West. One commenter stated that a flow-based
approach is inconsistent with the Clean Water Act, since intermittent streams and shallow subsurface
flows should be included as "waters of the United States" under Part 328(a)(3)(ii) due to impact on
downstream waters and under Part 120(a)(5)(ii) and (g) due to hydrological connections.
Agencies' Response: The "relatively permanent standard" refers to the test to identify
relatively permanent, standing or continuously flowing waters connected to paragraph
(a)(1) waters, and waters with a continuous surface connection to such relatively permanent
waters or to traditional navigable waters, the territorial seas, or interstate waters. The final
rule establishes that the relatively permanent standard encompasses tributaries that have
flowing or standing water year-round or continuously during certain times of the year.
Relatively permanent waters do not include tributaries with flowing or standing surface
water for only a short duration in direct response to precipitation. Rather than
distinguishing between relatively permanent and non-relatively permanent waters with the
terms "perennial," "intermittent," and "ephemeral," the agencies have decided to explain
directly the way that the relatively permanent standard should be implemented. As
discussed in Section IV.C.4 of the Preamble to the Final Rule, the approach in the final rule
would encompass tributaries considered relatively permanent under the 2020 NWPR, as
well as those considered relatively permanent under the Rapanos Guidance, providing
continuity in approach for the regulated community and other stakeholders.
The agencies disagree with commenters who asserted that the final rule would categorically
assert jurisdiction over tributaries with certain flow regimes without regard to whether
those tributaries significantly affect traditional navigable waters, the territorial seas, or
interstate waters. The agencies are not categorically including or excluding streams as
jurisdictional based on their flow regime in the final rule. Streams that are tributaries,
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regardless of their flow regime, will be assessed under the relatively permanent or
significant nexus standard per paragraph (a)(3) of the final rule, and streams that are not
tributaries will be assessed under the relatively permanent or significant nexus standard
per paragraph (a)(5). See Section III.A of the Technical Support Document for more
information on the agencies' rationale for the scope of tributaries covered by the final rule.
Furthermore, regarding tributaries that meet the relatively permanent standard, scientific
evidence supports the conclusion that tributaries of paragraph (a)(1) waters with relatively
permanent, standing or continuously flowing water perform important functions that either
individually, or cumulatively with similarly situated waters in the region, have significant
effects on the chemical, physical, or biological integrity of paragraph (a)(1) waters. See
Technical Support Document Section III.A., III.B, and III.D.
The agencies recognize that the final rule's approach to the relatively permanent standard
has the potential to result in certain tributaries being jurisdictional under the relatively
permanent standard that may have been considered jurisdictional under the pre-2015
regulatory regime following a significant nexus analysis. However, the agencies have
decided to implement this approach because it is consistent with the Rapanos plurality
opinion, it reflects and accommodates regional differences in hydrology and water
management, and it can be implemented using available, easily accessible tools.
The agencies disagree that the final rule generally represents an expansion beyond the pre-
2015 regulatory regime; rather, the agencies expect that there will be a slight and
unquantifiable increase in waters being found to be jurisdictional under the final rule in
comparison to the pre-2015 regulatory regime. Indeed, as discussed in Section V.A of the
Preamble to the Final Rule, this final rule is generally comparable in scope to the pre-2015
regulatory regime that the agencies are currently implementing. In particular, the agencies
disagree that the final rule would result in more than a de minimis increase in tributaries
with non-perennial flow regimes being jurisdictional or trigger additional regulatory
requirements. While analyses under the relatively permanent and significant nexus
standards will be slightly different under the final rule compared to pre-2015 practice, it is
expected that those slight differences will not have substantive effects to indirect monetary
or temporal costs. See the agencies' response to comments in Section 17. For further
discussion on how the two standards will be implemented in determining the jurisdiction of
tributaries, see Section IV.C.4 of the Preamble to the Final Rule. For additional discussion
of the costs associated with implementation of the final rule, see the Economic Analysis for
the Final Rule.
The agencies acknowledge that the relatively permanent standard on its own does not
provide sufficient protections for all upstream tributaries and agree with the general
statements that a flow-based approach to protections is not sufficient to protect the health
of downstream waters. While the relatively permanent standard is administratively useful
as it more readily identifies a subset of waters that will nearly always significantly affect
paragraph (a)(1) waters, on its own, it is inconsistent with the text of the statute and
Supreme Court precedent and is insufficient to advance the objective of the Clean Water
Act.
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The agencies disagree with the commenter who asserted that the proposed rule ignored the
importance of volume, duration, and frequency of flow related to ephemeral streams,
particularly in the arid West. The proposed rule did not restrict jurisdiction over
tributaries based solely on the regularity of flow, nor does the final rule. Rather, under the
final rule, tributaries may be jurisdictional where they meet either the relatively permanent
standard or the significant nexus standard. In conducting a significant nexus analysis under
the final rule, the agencies will consider a number of factors, including hydrologic factors
such as the frequency, duration, magnitude, timing, and rate of hydrologic connections,
including shallow subsurface flow. For a more detailed discussion of the functions and
factors that the agencies will consider in conducting a significant nexus analysis for non-
relatively permanent tributaries, see Section IV.C.4 and Section IV.C.9 of the Preamble to
the Final Rule. See also the agencies' response to comments on Tributaries in Section 8 and
the Significant Nexus Standard in Section 12.
The agencies disagree with the commenter who asserted that indirect connections would not
satisfy the plurality's test in Rapanos. As discussed in Section IV.C.4 of the Preamble to the
Final Rule, there is no text in the Clean Water Act supporting limits on tributaries to those
with direct connections to paragraph (a)(1) waters, and the agencies have never interpreted
the Act to cover only such tributaries. Moreover, the science is clear that the chemical,
physical, and biological integrity of paragraph (a)(1) waters depends on the many
tributaries, including headwater streams, that feed such waters. It would be impossible to
restore and maintain the chemical, physical, and biological integrity as required by the
Clean Water Act with a definition of "waters of the United States" that included solely the
last tributary that flows "directly" into a paragraph (a)(1) water. Thus, a tributary for
purposes of the final rule includes rivers, streams, lakes, ponds, and impoundments that
flow directly or indirectly through another water or waters to a downstream paragraph
(a)(1) water, or a paragraph (a)(2) impoundment. See Section IV.C.4 of the Preamble to the
Final Rule for further discussion on how contribution of flow from tributaries is established
in the final rule. See also the agencies' response to comments on Tributaries in Section 8.
13.2.2 Scope of the relatively permanent standard for tributaries
Some commenters proposed their own definitions or provided specific suggestions for "relatively
permanent" as it pertains to the duration of relatively permanent flow for tributaries.
A few commenters recommended that relatively permanent be defined as waters with a
continuous hydrologic connection to a traditional navigable water for the entire calendar year.
One commenter asserted that relatively permanent flow should have an obvious definition of
constant presence or flow of water except under unusual circumstances such as drought
conditions.
Another commenter proposed that relatively permanent should be defined as waters that are
present throughout the year except for infrequent periods of severe drought and have an
indistinguishable surface connection with interstate waters that are navigable-in-fact and currently
used or susceptible to use in interstate or foreign commerce, including territorial seas.
Another commenter recommended that relatively permanent be defined as waters with continuous
flow for 290 days.
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A few commenters asserted that jurisdictional relatively permanent waters do not need continuous
flow and the relatively permanent standard should include waters which contain continuous flow
during some months of the year and no flow during dry months.
A couple of commenters proposed that relatively permanent be defined as waters that flow for at
least three contiguous months per year, except during periods of extreme drought or precipitation
according to United States Geological Survey (USGS) standards. In particular, one commenter
asserted that this definition would exclude dry washes, arroyos, and similar ephemeral and
intermittent features.
One commenter recommended that the agencies include intermittent waters as relatively
permanent provided they have a continuous hydrologic connection to a traditionally navigable
water for a minimum of 90 consecutive days within the calendar year.
Another commenter claimed that it would be unreasonable for the agencies to claim jurisdiction
over a waterbody that flows less than 90 days per year. The commenter asserted that their state,
Wyoming, is generally a semi-arid region that has many ephemeral drainages that only flow in
response to precipitation events and are not associated with any navigable waters.
One commenter recommended that the final rule should include a stream as jurisdictional under
the relatively permanent standard only if it flows three or more months of a normal year and
contains multiple indicators of an ordinary high water mark (OHWM).
Agencies' Response: The agencies acknowledge commenters who provided
recommendations regarding the scope of relatively permanent tributaries. The "relatively
permanent standard" refers to the test to identify relatively permanent, standing or
continuously flowing waters connected to paragraph (a)(1) waters, and waters with a
continuous surface connection to such relatively permanent waters or to traditional
navigable waters, the territorial seas, or interstate waters. The final rule establishes that the
relatively permanent standard encompasses tributaries that have flowing or standing water
year-round or continuously during certain times of the year. Relatively permanent waters
do not include surface waters with flowing or standing water for only a short duration in
direct response to precipitation. Rather than distinguishing between relatively permanent
and non-relatively permanent waters with the terms "perennial," "intermittent," and
"ephemeral," the agencies have decided to explain directly the way that the relatively
permanent standard should be implemented. As discussed in Section IV.C.4 of the
Preamble to the Final Rule, the approach in the final rule would encompass tributaries
considered relatively permanent under the 2020 NWPR, as well as those considered
relatively permanent under the Rapanos Guidance, providing continuity in approach for
the regulated community and other stakeholders. The agencies have decided to implement
this approach because it is consistent with the Rapanos plurality opinion, it reflects and
accommodates regional differences in hydrology and water management, and it can be
implemented using available, easily accessible tools. For further discussion and rationale on
the final rule's approach to the relatively permanent standard for tributaries, see Section
IV.C.4 of the Preamble to the Final Rule.
The agencies disagree with commenters who asserted that jurisdiction of relatively
permanent tributaries should be limited to only those tributaries that flow perennially, or
year-round, except under times of drought. To be clear, in the final rule the agencies are
exercising the authority granted to them by Congress to construe and implement the Clean
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Water Act and to interpret an ambiguous term and its statutory definition. While the
agencies' interpretation of the statute is informed by Supreme Court decisions, including
Rapanos, it is not an interpretation of the multiple opinions in Rapanos. See Final Rule
Preamble Section IV.A.1. The agencies have determined that the final rule's approach to
the relatively permanent standard is consistent with the Rapanos plurality opinion which
noted that its reference to "relatively permanent" waters did not necessarily exclude
"seasonal rivers, which contain continuous flow during some months of the year but no flow
during dry months." 547 U.S. at 732 n.5 (emphasis in original). For additional discussion on
why the final rule's approach is consistent with the Rapanos plurality opinion, see Section
IV.C.4 of the Preamble to the Final Rule. See also the agencies' response to comments on
Legal Arguments in Section 2.
The agencies acknowledge commenters who provided recommendations regarding a
specific flow duration for water features to qualify as "relatively permanent." Consistent
with the proposal, the final rule does not establish a specific duration of flow (e.g., a number
of days, weeks, or months) that constitutes relatively permanent flow. The agencies decided
not to establish a minimum duration because flow duration varies extensively by region
based upon climate, hydrology, topography, soils, and other conditions, and establishing a
uniform number equally applicable across the country would not be scientifically sound.
The agencies acknowledge that an approach utilizing a specific duration would provide for
enhanced national consistency, but it would also undermine the regionalized
implementation of relatively permanent tributaries as provided for under the final rule.
Additionally, the agencies have determined that a specific flow duration requirement would
be challenging to implement, as it would often be infeasible for the regulated community or
agency staff to determine whether a stream ordinarily flows for a precise number of days or
weeks per year. For further discussion on why the agencies are not establishing a specific
duration of flow, see Section IV.C.4 of the Preamble to the Final Rule.
The agencies disagree with those commenters who asserted that the relatively permanent
standard should require tributaries to have a continuous hydrologic connection with
interstate waters that are navigable-in-fact. The final rule retains the longstanding
categorical protections for interstate waters, regardless of their navigability, that were
established by the earliest predecessors to the 1972 Clean Water Act and remained in place
except during the time period the 2020 NWPR was in effect. As described in Section IV.C.2
of the Preamble to the Final Rule, because the Clean Water Act unambiguously includes
interstate waters, they are fundamental to the Act in the same manner as the traditional
navigable waters and the territorial seas. Therefore, the final rule, like the 1986 regulations,
provides Clean Water Act protections for interstate waters in the same manner as for
traditional navigable waters and the territorial seas, and the following waters that meet the
relatively permanent standard or significant nexus standard based on their connection to
interstate waters are "waters of the United States": tributaries to interstate waters,
wetlands adjacent to interstate waters or to their jurisdictional tributaries, and paragraph
(a)(5) waters. For further discussion on why the final rule treats interstate waters in the
same manner as the traditional navigable waters and the territorial seas, see Section IV.C.2
of the Preamble to the Final Rule. See also the agencies' response to comments on interstate
waters in Section 6.
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The agencies disagree with those commenters who recommended that the relatively
permanent standard require tributaries to maintain consistent flow to a downstream
paragraph (a)(1) water. Under the final rule, tributaries are required to flow directly or
indirectly through another water or waters to certain downstream waters. A tributary may
contribute flow through a number of downstream waters or features, including both non-
jurisdictional features, such as a ditch excluded under paragraph (b) of the final rule, and
jurisdictional waters that are not tributaries, such as an adjacent wetland. However, the
tributary must be part of a tributary system that eventually flows to a paragraph (a)(1)
water. Therefore, under the final rule a relatively permanent tributary may flow through
another stream that flows infrequently, and only in direct response to precipitation, and the
presence of that stream is sufficient to demonstrate that the tributary flows to a paragraph
(a)(1) water. The agencies also disagree with those commenters who recommended that the
relatively permanent standard require tributaries to maintain a continuous or
indistinguishable surface connection to paragraph (a)(1) waters. For further discussion on
why the final rule does not require tributaries to maintain a continuous or indistinguishable
surface connection to paragraph (a)(1) waters, see Section IV.C.4 of the Preamble to the
Final Rule. See also the agencies' response to comments on Tributaries in Section 8.
In reference to the commenter recommending that relatively permanent tributaries exhibit
multiple indicators of an OHWM, the agencies note that the OHWM, a term unchanged
since 1977, defines the lateral limits of jurisdiction in non-tidal "waters of the United
States," provided the limits of jurisdiction are not extended by adjacent wetlands. See 41
FR 37144 (July 19,1977); 33 CFR 323.3(c) (1978). As described in Section IV.C.4 of the
Preamble to the Final Rule, tributaries typically have at least one indicator of an OHWM
and, consistent with pre-2015 practice, physical OHWM characteristics are used to identify
waterbodies including streams, lakes, ponds, and ditches that are present on the landscape.
To be a jurisdictional tributary under this provision of the rule, the tributary must meet
either the relatively permanent standard or the significant nexus standard. For additional
discussion on the use of an OHWM in identifying tributaries under the final rule, see
Section IV.C.4 of the Preamble to the Final Rule. See also the agencies' response to
comments on Tributaries in Section 8.
The agencies agree with commenters who asserted that relatively permanent flow need not
be present during drought conditions. As discussed above in the agencies' response to
comments in Section 13.1, under longstanding practice sineeRapanos, the agencies consider
the effects of climatic conditions such as drought when assessing the flow regime of
tributaries, and will continue to use this experience and expertise, as well as the many tools
and available sources of information, to help make jurisdictional determinations for
relatively permanent waters assessed under variable climate conditions. However, the
agencies disagree with those commenters who recommended that the relatively permanent
standard require tributaries to have relatively permanent flow in a "typical year," or to
contribute surface water flow downstream in a typical year. For additional discussion
regarding why the agencies are not including the "typical year" concept in the final rule, see
Section IV.B.3 in the Preamble to the Final Rule. See also the agencies' response to
comments in Section 4.2. See Section IV.C and Section IV.G of the Preamble to the Final
Rule, where the agencies have described a number of tools and resources that can be used
when evaluating naturally variable flow conditions.
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13.2.2.1 Approaches to seasonal flow
Some commenters provided recommendations regarding how the proposed rule approached seasonal
flow.
One commenter proposed that relatively permanent be defined as waters that flow at least
seasonally during the year and are not only driven by precipitation.
Another commenter proposed that relatively permanent be defined as waters that have flow at
least seasonally during the years when precipitation falls within statistical norms.
Some commenters expressed concern regarding the way the proposed rule approached seasonal
flow. For example, multiple commenters asserted that the proposed rule did not provide any
scientific or legal justification for interpreting seasonal flow to mean three months.
A few commenters also asserted that the proposed rule's approach to seasonal flow could
unlawfully include ephemeral features that flow during a season, but not necessarily for three
months, as well as many intermittent features.
One commenter claimed that the "at least seasonal flow" requirement in the proposed rule does
not meet the plurality's standard.
Agencies' Response: The agencies acknowledge commenters who requested that the
agencies interpret relatively permanent tributaries to include those that flow year-round or
at least seasonally (e.g., typically three months), consistent with the approach in the
Rapanos Guidance. The agencies note that while the final rule encompasses tributaries that
are "relatively permanent" under the Rapanos Guidance, the agencies have decided not to
use the term "seasonal" from the Rapanos Guidance in the final rule for several reasons.
First, the agencies have determined that directly describing the scenarios in which waters
would be "relatively permanent" is clearer than using the term "seasonal," the meaning of
which can vary and could be misunderstood to establish a specific required flow duration.
Additionally, the phrase "relatively permanent flow" is also intended to encompass
tributaries in which extended periods of standing or continuously flowing water are not
linked to naturally recurring annual or seasonal cycles (e.g., tributaries in which flow is
driven more by various water management regimes and practices), as well as tributaries in
regions where the timing of relatively permanent flow is highly variable from year to year.
For further discussion on why the agencies are not using the term "seasonal" to describe
relatively permanent waters, see Section IV.C.4 of the Preamble to the Final Rule.
13.2.2.2 Approaches to flow sources
Several commenters provided input on the way water sources should be used to determine relatively
permanent waters in the final rule.
A few commenters recommended that the agencies should not specify which water sources may
contribute to intermittent tributaries under the relatively permanent standard.
One commenter claimed that the agencies should establish that the relatively permanent standard
applies when the flows exist during certain times of the year without the need to clarify or
identify the sources of intermittent flow.
Another commenter asserted that the final rule must not require that waters be fed by any
particular source in order to satisfy the relatively permanent standard. This commenter claimed
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that such a requirement has no basis in Justice Scalia's plurality opinion, which focuses on the
frequency of flow rather than its source. This commenter also claimed that such a requirement has
no basis in science or the significant nexus test, which recognize that relatively permanent
streams significantly affect downstream waters regardless of the source of water that feeds the
stream.
One commenter recommended that intermittent flow should be determined based on flows
associated with the natural hydrologic cycle. This commenter provided suggestions for water
sources that should not be considered in making flow determinations, including flows from dry
weather urban runoff off, including landscape irrigation runoff, potable water discharges, and
swimming pool discharges, effluent from wastewater treatment plants, and water rights transfers
imported from outside of the tributary's region. This commenter asserted that making a
determination based on effluent dependent or out-of-watershed flows would result in regulatory
uncertainty.
One commenter expressed support for an exclusion clearly stating that effluent from wastewater
treatment plants should not be considered when determining whether a flow regime is relatively
permanent.
Another commenter recommended that intermittent flow should be included in the relatively
permanent standard based on regionally specific interpretations of flow sources.
Agencies' Response: The agencies acknowledge commenters who provided
recommendations regarding the appropriate flow sources for relatively permanent flow.
Under the final rule, implementation of the relatively permanent standard for tributaries
does not require that relatively permanent flow originate from any particular source.
Rather, the final rule establishes that the relatively permanent standard applies to
tributaries without the need to identify a specific source of flow. The agencies agree with the
commenter who asserted that requiring relatively permanent flow to originate from any
particular source has no basis in the Clean Water Act, Justice Scalia's plurality opinion in
Rapanos, nor does it have any scientific basis. As discussed in Section IV.C.4 of the
Preamble to the Final Rule, the agencies have concluded that the final rule's approach is
consistent with the plurality opinion in Rapanos, which lays out the relatively permanent
standard and does not require that relatively permanent waters originate from any
particular source. See e.g., 547 U.S. at 739. The final rule's approach is also science-based,
as the source of a tributary's flow does not influence whether it has an effect on
downstream waters, including paragraph (a)(1) waters. For further discussion on how the
final rule's approach to the relatively permanent standard accounts for regional variation
in sources of relatively permanent flow, see Section IV.C.4 of the Preamble to the Final
Rule.
For the reasons described above, the agencies disagree with the commenters who asserted
that effluent from wastewater treatment plants should not be considered when determining
relatively permanent flow, or that relatively permanent flow should be based only on
natural hydrologic sources. The agencies' longstanding interpretation of the Clean Water
Act includes tributaries that are natural, modified, or constructed waters, and the agencies
are not changing this interpretation. Therefore, under the final rule, waterbodies that have
been physically or hydrologically modified, including effluent-dependent streams or
streams that flow in response to water transfers, may be jurisdictional as relatively
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permanent tributaries under paragraph (a)(3) of the final rule if they have flowing water
year-round or continuously during certain times of the year. Relatively permanent waters
do not include tributaries with flowing or standing water for only a short duration in direct
response to precipitation.
The agencies also disagree with commenters who asserted that consideration of both
natural and artificial sources of flow would result in regulatory uncertainty. Requiring that
relatively permanent flow originate solely from a natural source could present unnecessary
implementation challenges to the agencies and the regulated public, as it could be difficult
to differentiate between natural and artificial sources of flow. In addition, as discussed
above, this approach has no basis in science or in the Clean Water Act. For additional
discussion about why the agencies are not requiring that flow originate from any particular
hydrologic source, see Section IV.C.4 of the Preamble to the Final Rule.
13.2.2.3 Approaches to flow classifications
Several commenters provided input on specific flow classifications under the relatively permanent
standard for tributaries. For example:
Some commenters stated that jurisdiction should be limited to perennial waters only, stating that
this approach would be consistent with Justice Scalia's plurality opinion in Rapanos and would
provide clarity and certainty for federal and state regulators as well as the regulated public.
Some commenters stated that waters must have consistent flow into traditional navigable waters
to be considered jurisdictional tributaries. One commenter stated that they support that "relatively
permanent, continuously flowing waters that contribute surface water flow in a typical year to
navigable-in-fact waters" (perennial waters) are jurisdictional.
A few commenters asserted that the final rule should not interpret relatively permanent to include
all perennial and intermittent tributaries. In particular, one commenter proposed that the agencies
use the significant nexus standard to categorically evaluate intermittent tributaries instead of the
relatively permanent standard.
A few commenters did not support including intermittent flow in the definition of "waters of the
United States."
Another commenter asserted that intermittent flow should not be included in the relatively
permanent standard.
Several commenters recommended that the final rule should only apply the relatively permanent
standard to perennial and intermittent waters. In particular, a few commenters recommended that
the relatively permanent standard should only include intermittent waters with significant flows at
least three months of the year.
One commenter asserted that the agencies should clarify that intermittent streams under the
relatively permanent standard may flow less than three months each year.
Several commenters supported implementation of the relatively permanent standard consistent
with the pre-2015 regulatory regime. Some commenters asserted that the agencies should use past
precedent when considering protection of intermittent and perennial streams and wetlands to
ensure waters with impacts on drinking water supplies are appropriately regulated.
One commenter asserted that the relatively permanent standard should protect all intermittent and
perennial streams. Therefore, the commenter claimed, the agencies should reject the Rapanos
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Guidance, which they asserted only protected an undefined subset of perennial and intermittent
streams.
One commenter stated that the rule and associated guidance should recognize that relatively
permanent flow includes perennial and intermittent flow and that neither need be present during
drought conditions.
A few commenters proposed that the agencies should not use the 2020 NWPR approach to
intermittent to implement the relatively permanent test because they asserted that the 2020
NWPR approach to intermittent was not based solely on the relatively permanent standard.
A few commenters expressed concerns about the way intermittent waters in particular would be included
under the relatively permanent standard in the final rule. For example, one commenter recommended that
the agencies carefully define intermittent waters and asserted that these waters should rarely be
jurisdictional according to the relatively permanent standard. Another commenter asserted that applying
the relatively permanent standard to intermittent waters would be problematic. The commenter raised
concerns regarding mapping of streams in the National Wetlands Inventory, which they stated does not
accurately capture intermittent and ephemeral streams.
A few commenters proposed that the agencies should include ephemeral, intermittent, and perennial
waters as relatively permanent in the final rule. In particular, one commenter specifically opposed any
approach whereby ephemeral features would not be considered relatively permanent while intermittent
and perennial waters would be relatively permanent. In addition, one commenter claimed that protecting
ephemeral, intermittent, and perennial waters in Colorado would include headwater streams and
connected wetlands, which they asserted are important for downstream communities, the environment,
and the economy.
A few commenters asserted that the agencies should provide clarity about flow regimes for perennial,
intermittent, and ephemeral flows. One commenter asserted that the proposed rule does not make any real
distinction between permanent, intermittent, and ephemeral flows.
Some commenters requested that the agencies provide definitions of the terms "perennial," "intermittent,"
and "ephemeral," stating that doing so would benefit implementation of the rule by establishing concise
and comprehensible definitions. The commenters further requested that the definitions should recognize
the importance of ephemeral and non-adjacent wetlands to the protection of foundational waters.4 In
referencing the need for these definitions, one commenter additionally recommended providing detailed
guidance documents and examples that have been problematic in the past, to help generate a rule that is
predictable and consistent.
Several commenters provided their own definitions or specific suggestions for definitions for "perennial,"
"intermittent," and "ephemeral" in the context of the relatively permanent standard.
4 In the proposed rule, the term "foundational waters" was used to refer to traditional navigable waters, the territorial
seas, and interstate waters. In this response to comments, the agencies will preserve the use of the term
"foundational waters" as used by commenters; however, responses will use "traditional navigable waters, the
territorial seas, and interstate waters" or "paragraph (a)(1) waters," as the final rule does not use the term
"foundational waters."
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One commenter proposed that "perennial" includes surface waters flowing year-round that result
from surface water and/or groundwater inflow that may be supplemented by precipitation. The
commenter proposed that "intermittent" includes surface waters flowing continuously for a
specific time that the responsible regional EPA and Regional Corps Engineer office determine
appropriate; that results from regionally specific, high-volume runoff events due to snowpack
melt, snow accumulation melt, retained stormwater, or other regionally specific events; and that
does not occur solely due to one rainfall or snowfall event. The commenter proposed that
"ephemeral" includes surface water flowing or pooling solely due to precipitation.
Another commenter provided recommendations for the definitions of "perennial," "intermittent,"
and "ephemeral" based on flow characteristics. The commenter proposed that "perennial"
includes waters with year-round continuous surface water flow, even in dry years or years of
drought, and the commenter asserted that waters should display clear physical flow evidence. The
commenter recommended that this could be based on historical data. The commenter asserted that
current flow data must support continuous surface water flow despite fluctuating water elevations
or flow discharge rates. The commenter also proposed that "intermittent" includes waters that
have surface flow that varies dependent on weather, season, climate, and display clear physical
flow evidence. The commenter asserted that this intermittent flow may be year-round and
continuous, or may flow only during the regional wet and rainy season, or may flow normally
except in those years of drought or extremely dry conditions. The commenter suggested that
historical context may be used in this determination. The commenter stated that flow may stem
from seasonally wet months, connections to a water table, snowmelt where the region receives
normally large quantities of snowfall to influence local and regional hydrology, or any other
regionally-appropriate morphological observation. The commenter further proposed that
"ephemeral" includes waters with flow dependent on short-duration events, such as precipitation
or snow-melting.
Another commenter asserted that the agencies should use the 2020 NWPR definitions for
"perennial," "intermittent," and "ephemeral" but that there should be exceptions allowing for
changes due to drought conditions which would prevent continuous or seasonal flow during a
particular year.
One commenter asserted that the agencies should define "perennial," "intermittent," and
"ephemeral" and that the agencies use the definitions that appeared in the most recent 2017
Issuance and Reissuance of Nationwide Permits.
Another commenter requested that the agencies define "ephemeral stream" and "intermittent
stream" based on the longstanding Corps definition.
Another commenter recommended that the agencies take an approach similar to that of the Rhode
Island Freshwater Wetlands Rules and Regulations for defining relatively permanent. The
commenter stated that Rhode Island differentiates flowing bodies of water into three categories:
Rivers, Streams and Intermittent Streams, and Areas Subject to Storm Flowage (which the
commenter stated are analogous to ephemeral streams). The commenter further asserted that the
agencies should conduct site visits to support their jurisdictional determinations.
One commenter asserted that the agencies should clarify that flow is not considered "intermittent"
if it exists only in response to precipitation.
Another commenter recommended that intermittent flow should include tributaries with flow for
at least three months.
One commenter stated that there is a category of streams that is in between "intermittent" and
"ephemeral," which flow less than seasonally, yet more than in response to direct precipitation
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(e.g., flows for one month of the year). This commenter stated that if the agencies define the
terms "perennial," "intermittent," or "ephemeral," then the definition of "ephemeral" should
encompass these sub-seasonal streams, or there should be a new category for such streams.
Once commenter stated that if the agencies determine that flow classification definitions are necessary or
useful, the definitions should reflect the usage of these terms by the scientific community and should be
derived in consideration of the different climatic, hydrologic, and geomorphic features in regions
throughout the country.
Another commenter asserted that the agencies should maintain a general interpretation of relatively
permanent flow with perennial, intermittent, and ephemeral flow classifications including physical flow
characteristics in the definitions. The commenter claimed that this would provide enough flexibility for
regional districts to use historical observations and data from the EPA, Corps, and National Resources
Conservation Service (NRCS), or other university or published studies, to discern typical flow
characteristics.
A few commenters recommended that the agencies not define the terms "perennial," "intermittent," and
"ephemeral." In particular, one commenter asserted that not defining these terms would support
regionalized approaches to determining "waters of the United States." Another commenter recommended
that definitions for "perennial," "intermittent," and "ephemeral" should not be used in the final rule
because the terms are difficult to define and require the establishment of methods to define flow. One
commenter asserted that the definition for perennial streams in the 2020 NWPR failed to recognize that
even perennial streams can lack continuous flow year-round during drought conditions. One commenter
expressed concern that the agencies are seeking public comment on contentious topics, such as whether to
define the terms "intermittently," "ephemerally," or "periodically." Another commenter asserted that the
agencies do not need to define flow classifications in the final rule as some states and tribes have these
definitions in their own regulations.
Agencies' Response: In the proposed rule, the agencies sought comment on alternate
approaches to interpreting the phrase "relatively permanent waters," including an
approach that would use the terms "perennial" and "intermittent." The agencies also
sought comment on whether these flow regime classifications should be defined in the final
rule and, if so, whether the agencies should use the same definitions for these terms as the
2020 NWPR. After considering all of the comments received, the agencies have decided to
explain directly the way that the relatively permanent standard should be implemented,
rather than defining the phrase with these terms. Although the approach in the final rule
would encompass tributaries that were jurisdictional under the 2020 NWPR, the agencies
have determined that adding these terms to the final rule could cause confusion and
uncertainty, as evidenced by the variety of comments proposing definitions for "perennial"
and "intermittent." For further explanation on why the agencies have decided not to
describe relatively permanent waters using these terms, see Section IV.C.4 of the Preamble
to the Final Rule. For the agencies' response to comments on the general scope of relatively
permanent tributaries in the final rule, see Sections 13.1 and 13.2.2 above.
The agencies agree with the general statements provided by commenters that tributaries of
various flow regimes provide functions that are important for downstream communities,
the environment, and the economy. The final rule establishes that the relatively permanent
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standard encompasses tributaries that have flowing water year-round or continuously
during certain times of the year. Relatively permanent waters do not include tributaries
with flowing or standing water for only a short duration in direct response to precipitation.
As discussed in the agencies' response to comments in Section 13, the agencies recognize
that the relatively permanent standard excludes many waters that properly fall within the
Clean Water Act's protections, including many headwater tributaries. Under the final rule,
tributaries may be jurisdictional where they meet either the relatively permanent standard
or the significant nexus standard. In conducting a significant nexus analysis under the final
rule, the agencies will consider a number of functions and factors to determine whether a
tributary and its adjacent wetlands, either alone or in combination with similarly situated
waters in the region, have a material influence on the chemical, physical, or biological
integrity of a paragraph (a)(1) water. For a discussion of the functions and factors that the
agencies will consider in conducting a significant nexus analysis for non-relatively
permanent tributaries, see Section IV.C.4 and Section IV.C.9 of the Preamble to the Final
Rule. See also the agencies' response to comments in on Tributaries in Section 8 and the
Significant Nexus Standard in Section 12.
13.2.3 Implementation of the relatively permanent standard for tributaries
Some commenters requested that the agencies provide clarification regarding implementation of specific
aspects of the relatively permanent standard.
One commenter asserted that the agencies should clarify if relatively permanent flow will include
continuous flow of water or if it refers to a historic natural drainage pathway similar to those
delineated on the USGS quad maps.
One commenter urged the agencies to clarify how landowners should distinguish between streams
that are intermittent and streams that form in response to rainfall.
One commenter asserted that to the extent that the agencies conclude that an erosional feature is
not considered intermittent if it exists only in direct response to precipitation in arid systems,
clarification at the regional level would be useful.
Some commenters expressed concern regarding the need to distinguish between relatively permanent and
non-relatively permeant flow, particularly in regions where streamflow is highly variable, and in light of
climate change. One commenter opposed approaches that require site-specific determinations, asserting
that the proposed rule indicates significant uncertainty in determinations for perennial/intermittent
classifications due to the climate variations common throughout the Great Plains. The commenter stated
that the complexities make cost-effective, timely, and predictable jurisdictional determinations difficult,
imposing significant costs and uncertainties on citizens, and privileging those with resources to engage
experts and exposing those lacking such resources to federal enforcement. Another commenter urged the
agencies not to distinguish between ephemeral and intermittent streams by providing definitions of the
terms, asserting that in the arid Southwest, the distinctions are difficult and meaningless since the
variables that determine whether a streamor portion of a streamis ephemeral or intermittent are
myriad and erratic (including precipitation, evaporation, infiltration, and snowpack). They also stated that
extreme conditions such as drought are becoming more typical, and that climate change will shift stream
flow categorizations over time. One commenter noted that flow regime distinctions in the arid Southwest
are very challenging, especially with respect to intermittent versus ephemeral because the relevant
variables (precipitation, infiltration, evaporation, diversion, etc.) can fluctuate season-to-season, year-to-
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year, and decade-to-decade. The commenter provided examples and argued that there is no "typical" year.
Another commenter stated that climate change will create challenges for any rule based on flow volume,
since perennial streams may become intermittent or ephemeral. The commenter claimed that as a result,
any approach that relies on past precipitation averages will result in determinations that quickly become
outdated or incorrect.
Several commenters provided feedback regarding how relatively permanent flow might be considered in
light of climate change. In particular, one commenter asserted that when the relatively permanent standard
of flow is utilized instead of applying a significant nexus test, changing climate and hydrologic conditions
should be considered. Another commenter claimed that it would be inappropriate for the agencies to
consider potential future climate change effects when determining the permanence of a water feature. The
commenter asserted that evaluation of a water feature's relative permanence should be limited to currently
existing conditions only. One commenter asserted that while the preamble acknowledges that changes in
flow in tributaries caused by climate change will also be relevant to the relatively permanent standard,
there is no explanation as to how such changes will affect "relative" permanence.
Agencies' Response: The agencies recognize that flow regimes are naturally dynamic and
variable, and that the flow permanence of certain streams may fluctuate over time.
However, the agencies note that this was equally true under the 2020 NWPR, as well as the
pre-2015 regulatory regime, the latter of which applied different tests for jurisdictional
determinations of certain waters based upon flow permanence according to the Rapanos
Guidance. The agencies do not conclude that this natural variability presents any new
implementation challenges for the final rule. Following current agency practice,
determinations of relative permanence under the final rule will consider all relevant sources
of information, including remote tools, on-site observations, and other applicable data. In
the Preamble to the Final Rule in Sections IV.C.4 and IV.G, the agencies have described a
number of tools and resources that can be used for evaluating naturally variable flow
conditions. The agencies will continue to use their professional judgment to make accurate
determinations of jurisdiction based on the best available data.
The agencies also recognize that climate change and other anthropogenic modifications will
lead to changes in the relative permanence of tributaries (See Section II.C of the Technical
Support Document), and the agencies' current practices and guidance acknowledge that
stream flow can and does change over time. Consistent with longstanding practice, when the
agencies assess whether or not a water meets the definition of a "water of the United
States," they do not assess future conditions based on potential climatic changes. See also
Final Rule Preamble Section IV.C.9.c.ii for a discussion of how the agencies can consider a
changing climate under the significant nexus standard consistent with the best available
science. For further discussion on why the final rule's approach to the relatively permanent
standard does not rely on the use of a specific precipitation record when assessing a
tributary's flow regime, see Section IV.B.3 of the Preamble to the Final Rule. See also the
agencies' response to comments in Section 4.2 and Section 13.1.
The agencies acknowledge that some commenters opposed an approach to the relatively
permanent standard that requires case-specific determinations. However, as discussed in
Final Rule Preamble Section IV.A.3, the agencies have determined that fact-based
standards for determining Clean Water Act jurisdiction are reasonable. All definitions of
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"waters of the United States," including the pre-2015 regulatory regime, the 2015 Clean
Water Rule, and the 2020 NWPR have required some level of case-specific analysis. The
agencies have authority to determine which tributaries and their adjacent wetlands are
jurisdictional either through regulations or adjudication. See 547 U.S. at 780-81. This final
rule continues the use of case-specific jurisdictional tests, but also provides needed clarity
by establishing regulations that include definitions of key terms and specific exclusions.
Implementation of the final rule will be aided by improved and increased scientific and
technical information and tools that both the agencies and the public can use to determine
whether waters are "waters of the United States." The clarifications in the final rule,
including the addition of exclusions that codify longstanding practice, and review of the
advancements in implementation resources, tools, and scientific support address many of
the concerns raised in the past about timeliness and consistency of jurisdictional
determinations under the Clean Water Act. See Final Rule Preamble Section IV.G.
In reference to the commenter regarding the jurisdictional status of erosional features and
clarification at the regional level, the agencies have clarified in the final rule that swales and
erosional features (e.g., gullies, small washes) characterized by low volume, infrequent, or
short duration flow are not tributaries and are not jurisdictional. As described in Section
IV.C.4 of the Preamble to the Final Rule, streams are waterbodies that are typically
characterized by the presence of a channel and an OHWM. In contrast, erosional features
like gullies and rills are typically more deeply incised than streams and lack an OHWM.
Similarly, swales do not have an OHWM and typically lack a more defined channel than a
stream exhibits. Field indicators, remote sensing, and mapping information can help
identify an OHWM, and the Corps continues to improve such regulatory practices across
the country through ongoing research and the development of regional and national
OHWM delineation procedures. For example, the Corps has developed field indicators to
help field staff identify the OHWM in common stream types in the arid West. Under the
final rule, streams that are tributaries, regardless of their flow regime, will be assessed
under the relatively permanent or significant nexus standard per paragraph (a)(3) of the
final rule, and streams that are not tributaries will be assessed under the relatively
permanent or significant nexus standard per paragraph (a)(5) of the final rule. For
additional discussion about how to distinguish between tributaries, erosional features, and
swales, and how to identify tributaries based on an OHWM, see Sections IV.C.4 and IV.C.7
of the Preamble to the Final Rule; see also Sections IILA.v and IV.A.ii of the Technical
Support Document. For additional discussion on implementation of the relatively
permanent and significant nexus standards for purposes of determining jurisdiction over
tributaries, see Section IV.C.4.C of the Preamble to the Final Rule.
13.3 The Relatively Permanent Standard for Adjacent Wetlands
Several commenters provided input as to how the relatively permanent standard should be implemented
for adjacent wetlands.
One commenter expressed concern that under the proposed rule, the agencies could determine a
water meets the relatively permanent standard for adjacent wetlands, but not the significant nexus
standard, and therefore may not be considered jurisdictional. This commenter recommended that
the agencies should clarify in the final rule that the relatively permanent standard cannot be used
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on its own to determine that wetlands that are adjacent to relatively permanent waters are non-
jurisdictional.
A few commenters provided feedback regarding how a continuous surface connection would be
considered in the proposed rule. In particular, one commenter supported the agencies' position
that a continuous surface connection does not require surface water to be continuously present
between the wetland and the tributary and may be satisfied when the space between the two is
inundated or saturated by surface or ground water at a frequency and duration sufficient to
support a prevalence of vegetation typically adapted for life in saturated soil conditions.
However, the commenter expressed concern that the proposed rule preamble describes the
relatively permanent standard as requiring a "continuous surface water connection" rather than a
"continuous surface connection."
One commenter asserted support for a connection between wetlands and ephemeral waters as
requirement for adjacency, and the commenter asserted that such connections demonstrate a
potential significant effect on the chemical, physical, and biological integrity of foundational
waters.
One commenter claimed that adjacent wetlands should be considered relatively permanent only if
there is a surface water that is continuously present between the wetland and the tributary.
Another commenter opposed the interpretation that the continuous surface connection
requirement could be satisfied by other physical connections, rather than requiring a constant
hydrologic connection.
A commenter recommended that the agencies interpret and implement the relatively permanent
standard for adjacent wetlands in accordance with the 2008 Rapanos Guidance. The commenter
stated that adjacent wetlands should satisfy the continuous surface connection requirement only if
"the wetland directly abuts the [relatively permanent] tributary (e.g., they are not separated by
uplands, aberm, dike, or similar feature)."
One commenter asserted that the agencies should further define the relatively permanent standard
and limit its application to wetlands adjacent to non-navigable tributaries of traditional navigable
waters. The commenter claimed that the agencies were erroneously conflating the jurisdictional
test for "wetlands adjacent to non-navigable tributaries of traditionally navigable waters" with the
jurisdictional test for all waters in the proposed definition for relatively permanent standard. The
commenter asserted that the relatively permanent standard is appropriate as one of many bases for
protecting wetlands adjacent to non-navigable tributaries of traditional navigable waters, but it
should not be used as a bar to asserting CWA jurisdiction over all wetlands or as a jurisdictional
limit on any waters.
One commenter asked the agencies to clarify that a "continuous surface connection" does not
require water to be observed on the ground surface, but rather a hydrologic connectivity must be
observable, whether that be wetland conditions or evidence of surface flow.
Another commenter claimed that the agencies should provide guidance regarding how the
relatively permanent standard would be applied to specific features that serve as a physical
connection between a wetland and a relatively permanent water. The commenter claimed that
short-term flow due to flooding could provide false-positive indicators of flow between a
relatively permanent water and a wetland. The commenter recommended that guidance should
note this possibility for field interpretations for any sort of connection.
Another commenter claimed that the agencies should clarify in the final rule that the connection
between a wetland and a stream or other water may occur through a jurisdictional or non-
jurisdictional feature, whether natural or man-made.
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Agencies' Response: The final rule defines "waters of the United States" to include: (1)
wetlands adjacent to traditional navigable waters, the territorial seas, and interstate waters;
(2) wetlands adjacent to and with a continuous surface connection to relatively permanent
paragraph (a)(2) impoundments or jurisdictional tributaries when the jurisdictional
tributaries meet the relatively permanent standard; and (3) wetlands adjacent to paragraph
(a)(2) impoundments or jurisdictional tributaries when the wetlands meet the significant
nexus standard. In the final rule, the agencies have amended the regulatory text from the
proposed rule to be clearer that a wetland adjacent to but lacking a continuous surface
connection to a tributary that is relatively permanent must be assessed under the significant
nexus standard. For example, if a wetland is "neighboring" to a relatively permanent
tributary, and thus "adjacent," but lacks a continuous surface connection to that tributary,
the wetland would need to be assessed under the significant nexus standard in order to
determine its jurisdictional status. Thus, under the final rule, the relatively permanent
standard cannot be used alone to determine that wetlands that are adjacent to relatively
permanent waters are non-jurisdictional; rather, an adjacent wetland that does not meet
the relatively permeant standard must be assessed under the significant nexus standard.
This is consistent with pre-2015 practice under the Rapanos Guidance for wetlands adjacent
to relatively permanent tributaries and was the agencies' intent under the proposed rule
language. SeeRapanos Guidance at 8; 86 FR 69423 ("Wetlands adjacent to relatively
permanent tributaries but that lack a continuous surface connection to such waters would
then be assessed under the significant nexus [standard], along with the tributary."). For
further discussion on how the two standards will be implemented in determining the
jurisdiction of adjacent wetlands, see Section IV.C.5 of the Preamble to the Final Rule.
In the proposed rule, the agencies sought comment on alternative options for interpreting
the continuous surface connection requirement under the relatively permanent standard.
As described in Section IV.C.5 of the Preamble to the Final Rule, the agencies have
considered public comments on the continuous surface connection requirement for adjacent
wetlands and provided clarity regarding how the agencies intend to implement that
requirement. In the final rule, under the relatively permanent standard for adjacent
wetlands, wetlands meet the continuous surface connection requirement if they physically
abut, or touch, a relatively permanent paragraph (a)(2) impoundment or a jurisdictional
tributary when the jurisdictional tributary meets the relatively permanent standard, or if
the wetlands are connected to these waters by a discrete feature like a non-jurisdictional
ditch, swale, pipe, or culvert. A natural berm, bank, dune, or similar natural landform
between an adjacent wetland and a relatively permanent water does not sever a continuous
surface connection to the extent it provides evidence of a continuous surface connection. In
the final rule, the agencies also clarify that a continuous surface connection does not require
continuous presence of surface water between the adjacent wetland and relatively
permanent paragraph (a)(2) impoundment or jurisdictional tributary when the
jurisdictional tributary meets the relatively permanent standard, and the agencies continue
this longstanding approach in this rule. Rather, the agencies will identify a continuous
surface connection consistent with the Rapanos plurality opinion, which indicates that the
continuous surface connection requirement is a "physical connection requirement." 547
U.S. at 754; see also Rapanos Guidance at 6.
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As with any final regulation, the agencies will consider developing new guidance to facilitate
implementation of the final rule should questions arise in the field regarding application of
the continuous surface connection requirement, including guidance regarding how the
relatively permanent standard would be applied to specific features that serve as a physical
connection between a wetland and a relatively permanent water. Nevertheless, the agencies
conclude that the final rule, together with the preamble and existing tools, provides
sufficient clarity to allow consistent implementation of the final rule.
The agencies disagree with commenters who asserted that the relatively permanent
standard should require surface water to be continuously present between the wetland and
the tributary. The agencies have clarified in the final rule that a continuous surface
connection can be present, for example, when a wetland physically abuts another
jurisdictional water, even if surface water is not continuously present between the two.
Requiring a continuous surface water connection, as suggested by some commenters, would
effectively limit Clean Water Act protection of wetlands to areas that are inundated
throughout the year. But many wetlands have surface water only seasonally or
intermittently, while others do not express water at the surface (i.e., have saturated soils),
and no scientific or regulatory definition of wetlands demands year-round surface water.
This approach to continuous surface connection is supported by the scientific literature,
case law, and the agencies' technical expertise and experience. See Final Rule Preamble
Section IV.C.5.C for additional discussion.
The agencies agree with commenters who stated that the continuous surface connection
between a wetland and relatively permanent water may occur through a non-jurisdictional
feature, whether natural or man-made. In the final rule, the agencies clarify that adjacent
wetlands may meet the continuous surface connection requirement if they are connected to
relatively permanent waters by a discrete feature like a non-jurisdictional ditch, swale, pipe,
or culvert. This is because a ditch or other such feature can serve as a physical connection
that maintains a continuous surface connection between an adjacent wetland and a
relatively permanent water. The agencies have determined that this approach to the
continuous surface connection is supported by the scientific literature, case law, and the
agencies' technical expertise and experience. See United States v. Cundiff, 555 F.3d 200, 213.
In reference to the commenter who supported the "connection between wetlands and
ephemeral waters as justification for adjacency," the agencies note that the presence of an
ephemeral water does not change the approach described above for identifying
jurisdictional wetlands. See Section IV.C.5 of the Preamble to the Final Rule for additional
discussion on wetland adjacency.
The agencies recognize that some commenters expressed support for implementing the
relatively permanent standard for adjacent wetlands in accordance with the 2008 Rapanos
Guidance. In developing the final rule, the agencies thoroughly considered alternatives to
the relatively permanent standard approach taken in this rule, including the 2008 Rapanos
Guidance. While the final rule is founded on, and generally returns to, the longstanding and
familiar pre-2015 regulatory regime, it does not adopt that regime unchanged. As discussed
in Final Rule Preamble Section IV.A, the agencies in the final rule have revised the 1986
regulations to reflect the agencies' determination of the statutory limits on the scope of the
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"waters of the United States," as informed by Supreme Court precedent, the best available
science, and the agencies' experience and technical expertise. Additionally, as compared to
the pre-2015 regulations or pre-2015 regulatory regime, the final rule reflects updates and
advances in implementation tools, resources, and scientific support; codifies exclusions for
features that were generally considered non-jurisdictional under the pre-2015 regulatory
regime; and is streamlined and restructured for clarity. Though the agencies are not relying
on theRapanos Guidance for purposes of implementing the final rule, many aspects of the
final rule, including implementation-related issues, are consistent with or similar to the
approaches taken in the Rapanos Guidance. See Section IV.C.5 of the Preamble to the Final
Rule for further discussion of the final rule's approach to relatively permanent standard for
adjacent wetlands.
13.4 The Relatively Permanent Standard for "Other Waters"
Several commenters provided recommendations for how the agencies should implement the relatively
permanent standard for the paragraph (a)(3) "other waters" category in the proposed rule.
One commenter recommended that the final rule include relatively permanent criteria for "other
waters," particularly waters that are in close proximity to larger wetlands and maintain seasonal
hydrological connections through groundwater discharge or diffuse surface flows. The
commenter further recommended that this approach should also apply to isolated depressional
wetlands that receive seasonal flooding from larger, permanent or semi-permanent waterbodies as
well as headwater seeps and wetlands, due to the importance of seasonal hydrologic connectivity,
with measurable seasonal non-channel flows and nutrient transfers.
Another commenter supported application of the relatively permanent standard to "other waters"
but indicated that it should not exclude important waters for protection, such as wetlands with a
hydrological connection via flooding. This commenter further stated that such wetlands should be
jurisdictional without the need for "a complex significance review."
One commenter recommended that the agencies should not assess non-tributary open waters
under the relatively permanent standard and should not require that these waters have a
continuous surface water connection to a relatively permanent tributary to be considered
jurisdictional. This commenter argued that "isolated" wetlands and similar open waters are
critical to the health of our downstream waters and such an approach would ignore the statutory
obligation to protect the chemical and biological integrity of the nation's waters.
One commenter recommended that the agencies should not apply the relatively permanent
standard to "other waters" because it would be duplicative. The commenter asserted that "other
waters" that meet the relatively permanent standard as described in the proposed rule would
always meet the jurisdictional criteria for another rule category.
One commenter supported the application of the relatively permanent standard to non-tributary
open waters with a connection to a stream on public lands. The commenter generally questioned
whether this approach would be unduly burdensome if applied to private landowners.
Agencies' Response: Paragraph (a)(5) of the final rule defines "waters of the United States"
to include "intrastate lakes and ponds, streams, or wetlands not identified in paragraphs
(a)(1) through (a)(4)" that meet either the relatively permanent standard or the significant
nexus standard. Under the final rule, waters assessed under paragraph (a)(5) meet the
relatively permanent standard if they are relatively permanent, standing or continuously
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flowing bodies of water with a continuous surface connection to a paragraph (a)(1) water or
relatively permanent tributary. Waters assessed under paragraph (a)(5) meet the significant
nexus standard if they significantly affect the chemical, physical, or biological integrity of a
traditional navigable water, the territorial seas, or a interstate water. See Section IV.C.6.C
of the Final Rule Preamble for further discussion on implementation of these standards for
paragraph (a)(5) waters.
The agencies agree with those commenters recognizing the importance of certain intrastate
lakes and ponds, streams, or wetlands not identified in paragraphs (a)(1) through (4) to
maintaining the integrity of paragraph (a)(1) waters. The scientific literature unequivocally
demonstrates that wetlands and open waters in riparian areas and floodplains are
chemically, physically, and biologically integrated with rivers via functions that improve
water quality in paragraph (a)(1) waters. Wetlands and open waters in non-floodplain
landscape settings can also provide numerous functions that benefit the chemical, physical,
and biological integrity of larger downstream waters, including the paragraph (a)(1) waters,
particularly when analyzed in the aggregate. This diverse group of features, including many
prairie potholes, vernal pools, and playa lakes, can be connected to downstream waters
through surface water, shallow subsurface water, and groundwater flows and through
biological and chemical connections. See Technical Support Document Sections I, III.B, and
III.D. The final rule provides for case-specific analysis of waters not addressed by any other
provision of the definition to determine whether they are "waters of the United States"
under the relatively permanent or significant nexus standards.
Under the final rule, the agencies intend to identify relatively permanent waters under
paragraph (a)(5) using a similar approach to the one described for relatively permanent
tributaries in Section IV.C.4.c.ii of the Preamble to the Final Rule. The agencies also intend
to identify a continuous surface connection between waters assessed under paragraph (a)(5)
and a paragraph (a)(1) water or a tributary that is relatively permanent using the approach
described for adjacent wetlands in section IV.C.5.C of the Preamble to the Final Rule
(although waters assessed under paragraph (a)(5) are not subject to the adjacency
requirement for jurisdictional adjacent wetlands). There must be a continuous surface
connection on the landscape for waters assessed under paragraph (a)(5) to be jurisdictional
under the relatively permanent standard. Relatively permanent waters under paragraph
(a)(5) do not include features with flowing or standing water for only a short duration in
direct response to precipitation. However, a continuous surface connection does not require
a constant hydrologic connection. Waters assessed under paragraph (a)(5) can meet the
continuous surface connection requirement if they are connected to a paragraph (a)(1)
water or a tributary that is relatively permanent by a discrete feature like a non-
jurisdictional ditch, swale, pipe, or culvert. Similarly, a natural berm, bank, dune, or
similar natural landform between a water assessed under paragraph (a)(5) and a paragraph
(a)(1) water or a tributary that is relatively permanent does not sever a continuous surface
connection to the extent it provides evidence of a continuous surface connection. The
agencies have decided to implement this approach because it is consistent with theRapanos
plurality opinion, it reflects and accommodates regional differences in hydrology and water
management, and it can be implemented using available, easily accessible tools. See Section
IV.C.6.C of the Preamble to the Final Rule for further discussion of implementation of the
relatively permanent standard for paragraph (a)(5) waters.
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Under the final rule, waters evaluated under paragraph (a)(5) that do not meet the
relatively permanent standard may be jurisdictional under the significant nexus standard if
they significantly affect the chemical, physical, or biological integrity of a traditional
navigable water, the territorial seas, or a interstate water. The agencies acknowledge that
the need for case-specific analyses will continue under the final rule for certain
jurisdictional determinations, potentially raising some timeliness and consistency issues that
the agencies' rules in 2015 and 2020 were designed, in part, to reduce. Yet, as discussed in
Final Rule Preamble Section IV.A.3, the agencies find that fact-based standards for
determining Clean Water Act jurisdiction are appropriate and not unique to the definition
of "waters of the United States." The agencies have provided more clarity in the final rule
by: adding limitations to the scope of the definition to the rule text; adding a definition of
"significantly affect" that identifies the functions and factors to be evaluated as part of a
significant nexus analysis; adding exclusions to the rule; restructuring and streamlining the
1986 regulations; and drawing on more than a decade of post-Rapanos implementation
experience to provide additional implementation guidance and resources. These
improvements, taken together, substantially reduce any inefficiencies that may be presented
by the rule's case-specific approach. The agencies have established a definition of
"significantly affect" in the final rule, provided additional guidance on applying the
significant nexus standard, and identified implementation tools and resources that will
work together to provide clarity and further consistency in implementing the significant
nexus standard. See Final Rule Preamble Section IV.C.9 and IV.G. The agencies have
concluded that these actions, along with the agencies' experience making determinations
under the significant nexus standard, will increase the clarity and consistency of
determinations of jurisdiction.
The agencies disagree with the commenter who asserted that assessing non-tributary open
waters under the relatively permanent standard would ignore the statutory obligation to
protect the chemical and biological integrity of the nation's waters. Under the final rule,
waters evaluated under paragraph (a)(5) are not required to have a continuous surface
connection to a relatively permanent tributary to be jurisdictional. Rather, as described
above, waters evaluated under paragraph (a)(5) that do not have a continuous surface
connection to a relatively permanent water may be jurisdictional under the significant
nexus standard if they significantly affect the chemical, physical, or biological integrity of a
traditional navigable water, the territorial seas, or an interstate water. As discussed in
section IV.A of the Final Rule Preamble, the agencies have concluded that the significant
nexus standard is consistent with the statutory text and legislative history, advances the
objective of the Clean Water Act, is informed by the scientific record and Supreme Court
case law, and appropriately considers the policies of the Act. The relatively permanent
standard is included in the rule because it provides important efficiencies and additional
clarity for regulators and the public by more readily identifying a subset of waters that will
virtually always significantly affect paragraph (a)(1) waters. For further discussion about
the implementation of the significant nexus standard for paragraph (a)(5) waters, see
Section IV.C.6.C of the Preamble to the Final Rule.
The agencies disagree with commenters who asserted that applying the relatively
permanent standard to the paragraph (a)(5) waters would be duplicative, or that paragraph
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(a)(5) waters that meet the relatively permanent standard would always meet the
jurisdictional criteria for another category of water under the rule. Under the final rule,
certain aquatic resources that do not meet the requirements for tributaries or adjacent
wetlands could be jurisdictional as paragraph (a)(5) waters under the relatively permanent
standard. For example, lakes and ponds that are not connected to a tributary system but
are relatively permanent waters and have a continuous surface connection to a paragraph
(a)(1) water or a tributary that is relatively permanent, could be jurisdictional as paragraph
(a)(5) waters. To illustrate, a relatively permanent lake that is located near a tributary that
meets the relatively permanent standard, but is separated by a natural berm, to the extent
the berm provides evidence of a continuous surface connection, is jurisdictional as a
paragraph (a)(5) water under the relatively permanent standard. See section IV.C.4.c.ii of
the Final Rule Preamble. Similarly, a relatively permanent oxbow pond located near a
traditional navigable water and connected to that traditional navigable water via a swale
that provides a continuous surface connection between the pond and the traditional
navigable water is jurisdictional as a paragraph (a)(5) water under the relatively permanent
standard. For further discussion about the implementation of the relatively permanent
standard for paragraph (a)(5) waters, see Section IV.C.6.C of the Preamble to the Final
Rule.
The agencies disagree with commenters who asserted that application of the relatively
permanent standard to paragraph (a)(5) waters, including non-tributary open waters,
would be unduly burdensome to private landowners. The agencies' regulations have long
authorized the assertion of jurisdiction on a case-specific basis over waters that do not fall
within the other jurisdictional provisions. As discussed in Final Rule Preamble Section V.A,
the final rule will establish a regime that is generally comparable to current practice and is
expected to generate de minimis costs and benefits as compared to the pre-2015 regulatory
regime that the agencies are currently implementing.
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