reach a navigable water. See Brief of Dr. Gene Likens et al. as Amici
Curiae in Support of Respondent at 6-28, SWANCC, 531 U.S. 159 (No. 99-
1178) [hereinafter Scientists' Brief] (quoting Decision Document A.R.
15645-47); see also id. (``[The SWANCC site] holds enough water to fill
the Pentagon four feet deep. . . . Absent strict controls, this water
could easily end up directly or indirectly in the Fox River, . . .
which in turn flows into the navigable Illinois and Mississippi
Rivers.''); Rapanos, 547 U.S. at 749 (Scalia, J., plurality) (``[T]he
ponds at issue in SWANCC could . . . offer nesting, spawning, rearing
and resting sites for aquatic or land species, and serve as valuable
storage areas for storm and flood waters[.]'' (internal quotation marks
and citations omitted)). In fact, given this evidence, were the Corps
not to find jurisdiction over the SWANCC ponds under the 2015 Rule's
(a)(8) provision, the agencies are cognizant that the Corps could be
subject to allegations that such a finding would be an arbitrary and
capricious application of that provision. And yet, with this
information before it,\30\ the majority of the SWANCC Court concluded
that the nonnavigable, isolated, intrastate waters at issue in SWANCC
fell beyond the scope of federal CWA jurisdiction. See SWANCC, 531 U.S.
at 174 (``[W]e find nothing approaching a clear statement from Congress
that it intended Sec.  404(a) to reach an abandoned sand and gravel pit
such as we have here.'').
---------------------------------------------------------------------------

    \29\ The ``seasonally ponded, abandoned gravel mining
depressions located on the [SWANCC] project site,'' 531 U.S. at 164,
would not have been covered by the 2015 Rule's exclusion for water-
filled depressions created incidental to mining activity. See e.g.,
33 CFR 328.3(b)(4)(v). While the text of the 2015 Rule is not clear
on this point, the earlier regulatory preambles that this exclusion
is based on and the 2015 Rule Response to Comments (RTC) document
confirm that this exclusion ceases to apply if the mining activities
that created the waters are abandoned. See 53 FR 20764, 20765 (June
6, 1988) (``we generally do not consider the following waters to be
`waters of the United States' . . . [w]ater-filled depressions
created in dry land incidental to construction activity and pits
excavated in dry land for the purpose of obtaining fill, sand, or
gravel unless and until the construction or excavation operation is
abandoned and the resulting body of water meets the definition of
waters of the United States'') (emphasis added); see also 2015 Rule
RTC, Topic 7 at 209 (``The exclusion applies to pits excavated in
dry land for obtaining fill, sand, or gravel. The rule does not
change the agencies' existing practice that these features could be
found to be jurisdictional once the construction or mining activity
is completed or abandoned and the water feature remains.'').
    \30\ This information, along with other ecological functions of
isolated waters, was submitted to the SWANCC Court in amicus briefs
filed in support of the Corps by ecologists and several States. See
Scientists' Brief; Brief of the States of California et al. as Amici
Curiae in Support of Respondents, SWANCC, 531 U.S. 159 (No. 99-
1178). Additionally, in oral argument during SWANCC, U.S. Deputy
Solicitor General Wallace stated, ``The waters here . . . serve as
storage for what would otherwise be flood waters during periods of
heavy rain that would cause overflow. That was part of what the
Corps had to deal with in dealing with this [permit] application.''
Transcript of Oral Argument at 39, Solid Waste Agency of Northern
Cook County v. U.S. Army Corps of Engineers, 531 U.S. 159 (2001)
(No. 99-1187).
---------------------------------------------------------------------------

    The agencies have solicited comment on the proper scope and
interpretation of the SWANCC decision as part of their effort to
propose a revised definition of ``waters of the United States''
pursuant to Executive Order 13778. See 84 FR 4165. In that proposal,
the agencies noted that the Federal government historically has applied
a more narrow reading of SWANCC when determining jurisdiction over
individual water features,\31\ while simultaneously

applying a broader reading of Justice Kennedy's concurring opinion in
Rapanos. Id. at 4167, 4177. While the agencies consider comments as to
the appropriateness of that dichotomy as part of their separate
rulemaking, the agencies continue to agree with their express statement
in the 2008 Rapanos Guidance regarding the jurisdictional limitations
articulated in SWANCC as interpreted by Justice Kennedy:
---------------------------------------------------------------------------

    \31\ But see Transcript of Oral Argument at 41, Rapanos v.
United States and Carabell v. United States, 547 U.S. 715 (2006)
(Nos. 04-1034, 04-1384) where U.S. Solicitor General Clement stated
that after SWANCC ``the Corps and the EPA's view of wetlands would
cover about 80 percent of the wetlands in the country. And that
shows that the impact of this Court's decision in SWANCC was real
and substantial because about 20 percent of the Nation's wetlands
are isolated.'' (emphasis added).

    When applying the significant nexus standard to tributaries and
wetlands, it is important to apply it within the limits of
jurisdiction articulated in SWANCC. Justice Kennedy cites SWANCC
with approval and asserts that the significant nexus standard,
rather than being articulated for the first time in Rapanos, was
established in SWANCC. 126 S. Ct. at 2246 (describing SWANCC as
``interpreting the Act to require a significant nexus with navigable
waters''). It is clear, therefore, that Justice Kennedy did not
intend for the significant nexus standard to be applied in a manner
that would result in assertion of jurisdiction over waters that he
and the other justices determined were not jurisdictional in SWANCC.
Nothing in this guidance should be interpreted as providing
authority to assert jurisdiction over waters deemed non-
---------------------------------------------------------------------------
jurisdictional by SWANCC.

2008 Rapanos Guidance at 9 n.32.\32\ The agencies continue to utilize
the 2008 Rapanos Guidance in those States where the pre-2015
regulations are in place, and upon reconsideration reiterate and agree
``that Justice Kennedy did not intend for the significant nexus
standard to be applied in a manner that would result in assertion of
jurisdiction over waters that he and the other justices determined were
not jurisdictional in SWANCC.'' Id.
---------------------------------------------------------------------------

    \32\ The agencies also recognize that Justice Stevens
interpreted the SWANCC majority opinion to apply beyond the
Migratory Bird Rule and the specific ponds at issue in SWANCC,
stating the decision ``invalidates the 1986 migratory bird
regulation as well as the Corps' assertion of jurisdiction over all
waters except for actually navigable waters, their tributaries, and
wetlands adjacent to each.'' 531 U.S. at 176-77 (Stevens, J.,
dissenting) (emphasis added).
---------------------------------------------------------------------------

    In the 2015 Rule, and in particular the (a)(8) provision, the
agencies reinterpreted their understanding of the limits of
jurisdiction set by Justice Kennedy's significant nexus test as
described in the 2008 Rapanos Guidance. Thus, under the 2015 Rule's
(a)(8) category for waters subject to case-specific significant nexus
analyses, the 2015 Rule could have swept ``ponds that are not adjacent
to open water,'' 531 U.S. at 168, along with other non-adjacent waters
and wetlands into the scope of federal jurisdiction under the CWA. It
did so by applying the nine functions described at 80 FR 37067, only
one of which--provided its effect on the nearest primary water, either
alone or in combination with other similarly situated waters in the
watershed, was more than speculative or insubstantial--was necessary to
subject a non-adjacent water or wetland to federal jurisdiction under
the 2015 Rule. See id. at 37091. Under this formulation of the
significant nexus standard, the very ponds at issue in SWANCC would be
subject to federal review under the (a)(8) category of the 2015 Rule,
and, as described above, would almost certainly be found to have a
significant nexus under the 2015 Rule.
    Some commenters identified a narrow interpretation of SWANCC that
they suggested would not conflict with the 2015 Rule's (a)(8) category
of jurisdictional waters: While the SWANCC ponds may not be
jurisdictional based on the use of those waters as habitat for
migratory birds, they could be jurisdictional nonetheless if they
satisfy one of the functions listed at 80 FR 37067 (e.g., sediment
trapping, runoff storage). Similarly, noting that Justice Kennedy had
characterized the SWANCC ponds as ``bearing no evident connection to
navigable-in-fact waters,'' some commenters suggested that it would be
appropriate to assert federal jurisdiction over the SWANCC ponds if the
agencies established that such features satisfy the significant nexus
test and thus have an ``evident connection'' to downstream navigable
waters. Other commenters asserted that finding the SWANCC ponds
jurisdictional under the 2015 Rule would be inconsistent with Justice
Kennedy's understanding of the scope of federal jurisdiction under the
Act.
    As noted above, the agencies believe that Justice Kennedy did not
intend for the significant nexus standard to be applied in a manner
that would result in the assertion of jurisdiction over waters that he
and the other justices determined were not jurisdictional in SWANCC.
The text of SWANCC supports this interpretation. The SWANCC majority
specifically concluded that the ``text of the statute will not allow''
the assertion of CWA jurisdiction over the ponds at issue in that case.
531 U.S. at 168. Thus, the agencies could not develop a formulation of
a case-specific significant nexus test that the Supreme Court
specifically rejected.\33\
---------------------------------------------------------------------------

    \33\ These same defects apply to the 2015 Rule's (a)(7)
category. The preamble to the 2015 Rule stated, ``a water [or
wetland] that does not meet the definition of `adjacent waters' may
be determined to be a `water of the United States' on a case-
specific basis under paragraph (a)(8) of the rule,'' 80 FR 37080,
and the 2015 Rule subjected (a)(7) waters to the same case-specific
significant nexus analysis that it applied to (a)(8) waters, only
without the distance-based limitations used in the (a)(8) category.
See id. (``[W]aters may be determined to have a significant nexus on
a case-specific basis under paragraph (a)(7) or (a)(8).'') (emphasis
added).
---------------------------------------------------------------------------

    For these reasons, the agencies now find that the 2015 Rule
departed from and conflicted with the agencies' prior interpretation of
SWANCC without adequate notice and a reasoned explanation for the
change in interpretation. See FCC v. Fox Television Stations, Inc., 556
U.S. 502, 515-16 (2009) (``Fox''). In promulgating the 2015 Rule, the
agencies acknowledged potential differences between their legal
interpretations underlying the rule and the 2008 Rapanos Guidance. See,
e.g., Technical Support Document for the Clean Water Rule: Definition
of Waters of the United States at 79-83. The agencies failed to
identify or acknowledge, however, that the 2015 Rule could regulate
that which the Supreme Court rejected in SWANCC, a clear departure from
their opposite position in the 2008 Rapanos Guidance. In this regard,
the agencies recognize that their reinterpretation of Rapanos, SWANCC,
and Justice Kennedy's significant nexus test was inconsistent with
those cases.
    After reconsidering this issue, the agencies conclude that they
lack statutory authority to promulgate a rule that would result in
assertion of jurisdiction over waters that the Supreme Court determined
were not jurisdictional in SWANCC, and that Justice Kennedy did not
intend for the significant nexus standard he articulated in Rapanos to
be applied in such a manner. In finalizing the 2015 Rule, the agencies
therefore improperly departed from their prior position regarding this
key element of the 2008 Rapanos Guidance.
    In returning to an interpretation of Justice Kennedy's decision
that comports with the 2008 Rapanos Guidance, the agencies recognize
the SWANCC Court's admonition to avoid constructions of the statute
that raise significant constitutional questions related to the scope of
federal authority authorized therein. 531 U.S. at 174; see also Section
III.C.3, infra. By interpreting Justice Kennedy's significant nexus
standard to regulate the very same or similar waters the Supreme Court
ruled the text of the statute would not allow, the agencies pushed the
boundaries of statutory interpretation. The 2015 Rule also raised
questions regarding whether there is any meaning to the limits of

jurisdiction articulated by a unanimous Supreme Court in Riverside
Bayview, which found that ``[i]n determining the limits of [their]
power to regulate discharges under the Act,'' the agencies ``must
necessarily choose some point at which water ends and land begins.''
474 U.S. at 132 (``[B]etween open waters and dry land may lie shallows,
marshes, mudflats, swamps, bogs--in short, a huge array of areas that
are not wholly aquatic but nevertheless fall far short of being dry
land. Where on this continuum to find the limit of `waters' is far from
obvious.''). By allowing federal jurisdiction to reach certain isolated
ponds, such as those at issue in SWANCC, and certain physically remote
wetlands that ``do not implicate the boundary-drawing problem of
Riverside Bayview,'' the 2015 Rule asserted federal control over some
features that ``lack the necessary connection to covered waters . . .
described as a `significant nexus' in SWANCC[.]'' 547 U.S. at 742
(Scalia, J., plurality); \34\ see also Hawkes, 136 S. Ct. at 1817
(Kennedy, J., concurring) (``[T]he reach and systemic consequences of
the Clean Water Act remain a cause for concern.'' (emphasis added)).
---------------------------------------------------------------------------

    \34\ While the agencies acknowledged being informed by the
Rapanos plurality in developing the 2015 Rule, see 80 FR 37061, the
regulation of non-adjacent waters as jurisdictional via the (a)(7)
and (a)(8) categories is inconsistent with that opinion. See
Rapanos, 547 U.S. at 742 (Scalia, J., plurality) (``[O]nly those
wetlands with a continuous surface connection to bodies that are
`waters of the United States' in their own right, so that there is
no clear demarcation between `waters' and wetlands, are `adjacent
to' such waters and covered by the Act.'' (emphasis omitted)); see
also id. at 748 (``If isolated permanent and seasonal ponds of
varying size and depth, which, after all, might at least be
described as `waters' in their own right--did not constitute `waters
of the United States,' a fortiori, isolated swampy lands do not
constitute `waters of the United States.' '') (original emphasis)
(internal quotation marks and citations omitted).
---------------------------------------------------------------------------

    Given the 2015 Rule permitted federal jurisdiction over certain
physically disconnected waters and wetlands like those at issue in
SWANCC--either categorically as ``adjacent'' waters or on a case-
specific basis according to an expanded significant nexus test--the
agencies now conclude for this and other reasons that the 2015 Rule
exceeded the agencies' statutory authority as interpreted in SWANCC and
Justice Kennedy's concurrence in Rapanos. The agencies may not exceed
the authority of the statutes they are charged with administering, see
5 U.S.C. 706(2)(C) (prohibiting agency actions ``in excess of statutory
jurisdiction, authority, or limitations''), and must avoid
interpretations of the statutes they administer that push
constitutional boundaries. See Section III.C.3, supra. In contrast to
the 2008 Rapanos Guidance, the 2015 Rule failed to respect the limits
of the significant nexus standard established in SWANCC and the
foundation for Justice Kennedy's significant nexus standard in Rapanos.
For these reasons, the agencies repeal the 2015 Rule.
b. The 2015 Rule's Interpretation and Application of the Significant
Nexus Standard Did Not Respect the Limits of Federal Jurisdiction
Reflected in Justice Kennedy's Opinion in Rapanos
    In the SNPRM, the agencies ``propose[d] to conclude that the 2015
Rule exceeded the agencies' authority under the CWA'' by adopting an
``expansive'' interpretation of Justice Kennedy's significant nexus
standard that was ``inconsistent with important aspects of that
opinion'' and resulted in a rule that ``cover[ed] waters outside the
scope of the Act.'' 83 FR 32228, 32240. The agencies have considered
the many comments received discussing these issues and now conclude
that, in contrast to the limiting nature of the significant nexus
standard first described in SWANCC and elaborated on by Justice Kennedy
in Rapanos, the agencies' interpretation of the significant nexus
standard in the 2015 Rule was overly expansive and did not comport with
or respect the limits of jurisdiction reflected in the CWA and
decisions of the Supreme Court.
    The agencies' broader interpretation of the significant nexus
standard served as a fundamental basis of the 2015 Rule and informed
the development of the definitions of the categorically jurisdictional
and case-specific waters under the rule. See 80 FR 37060 (``The key to
the agencies' interpretation of the CWA is the significant nexus
standard, as established and refined in Supreme Court opinions.''). In
applying this broad standard, the agencies established an expansive
definition of jurisdictional ``tributaries,'' which in turn provided
for per se jurisdictional ``adjacent'' (including ``neighboring'')
waters and wetlands within specific distance and geographic limits of
those tributaries and from which even farther-reaching case-specific
significant nexus analyses could be conducted for isolated waters and
wetlands not already meeting the broad jurisdictional-by-rule
definitions. The result was a compounding of errors that subjected the
vast majority of water features in the United States to the
jurisdictional purview of the Federal government.\35\ This outcome is
incompatible with the significant nexus standard and the limits of
jurisdiction described in SWANCC and by Justice Kennedy in Rapanos.
---------------------------------------------------------------------------

    \35\ The agencies noted in 2015 ``that the vast majority of the
nation's water features are located within 4,000 feet of a covered
tributary, traditional navigable water, interstate water, or
territorial sea.'' 2015 Rule Economic Analysis at 11.
---------------------------------------------------------------------------

    To be sure, the agencies enjoy discretion in setting the
jurisdictional limits of the Act. See Rapanos, 547 U.S. at 758
(Roberts, C.J., concurring); but see id. at 757 (noting that the Corps'
``boundless view'' of its authority in SWANCC ``was inconsistent with
the limiting terms Congress had used in the Act''). However, that
discretion is not unbridled. It must remain within the confines of the
Act's text and the Supreme Court's interpretations of the outer bounds
of jurisdiction. The agencies exercised this discretion in an
impermissible manner in 2015 by codifying a regulatory test for
jurisdiction that exceeded the agencies' authority under the Act.
Whereas ``the significant-nexus test itself prevents problematic
applications of the statute,'' 547 U.S. at 783 (Kennedy, J.,
concurring) (emphasis added), the 2015 Rule misapplied the standard to
create them.
i. The 2015 Rule's Definition of ``Significant Nexus'' Was Inconsistent
With the Limiting Nature of Justice Kennedy's Significant Nexus
Standard
    In Rapanos, Justice Kennedy found that adjacent ``wetlands possess
the requisite nexus, and thus come within the statutory phrase
`navigable waters,' if the wetlands, either alone or in combination
with similarly situated lands in the region, significantly affect the
chemical, physical, and biological integrity of other covered waters
more readily understood as `navigable.' '' Id. at 780 (Kennedy, J.,
concurring). Justice Kennedy articulated this significant nexus
standard to limit federal jurisdiction under the CWA to avoid
``problematic'' or ``unreasonable'' applications of the statute arising
from the breadth of the Corps' then-existing standard for tributaries.
See id. at 783, 782. Pursuant to Justice Kennedy's opinion, if a water
lacks a ``significant nexus,'' it is not jurisdictional under the Act.
See id. at 767.
    After reviewing the public comments received on this rulemaking,
the agencies conclude that the 2015 Rule's definition of ``significant
nexus'' was inconsistent with the limiting nature of Justice Kennedy's
significant nexus standard, resulting in a definition of ``waters of
the United States'' that exceeded the scope of federal jurisdiction
under the Act. In particular, the agencies now find that the 2015

Rule's interpretation of the phrase ``similarly situated lands in the
region'' contravened the limiting principles inherent in Justice
Kennedy's articulation of the significant nexus test. The significant
change in the agencies' understanding of the meaning of Justice
Kennedy's opinion and reasons for reinterpreting it was not explained
and led to a compounding of errors in the agencies' misapplication of
the significant nexus test.
    Justice Kennedy did not expressly define the phrase ``similarly
situated lands in the region.'' His opinion, nevertheless, provides
indications of the intended meaning of this phrase. The agencies
expressed their understanding of this phrase in the 2008 Rapanos
Guidance (at 8), stating that the phrase includes a tributary and all
wetlands adjacent to that tributary. The guidance describes a
``tributary'' as ``the entire reach of the stream that is of the same
order (i.e., from the point of confluence, where two lower order
streams meet to form the tributary, downstream to the point such
tributary enters a higher order stream).'' Id. at 10. Thus, under the
agencies' 2008 guidance:

    [W]here evaluating significant nexus for an adjacent wetland,
the agencies will consider the flow characteristics and functions
performed by the tributary to which the wetland is adjacent along
with the functions performed by the wetland and all other wetlands
adjacent to that tributary. This approach reflects the agencies'
interpretation of Justice Kennedy's term ``similarly situated'' to
include all wetlands adjacent to the same tributary. . . .
Interpreting the phrase ``similarly situated'' to include all
wetlands adjacent to the same tributary is reasonable because such
wetlands are physically located in a like manner (i.e., lying
adjacent to the same tributary).

Id.
    In the 2015 Rule, the agencies reinterpreted the phrase ``similarly
situated lands in the region'' by defining ``(1) which waters are
`similarly situated,' and thus should be analyzed in combination, in
(2) the `region,' for purposes of a significant nexus analysis.'' 80 FR
37065. This approach departed from the agencies' interpretation in the
2008 Rapanos Guidance by splitting the phrase into two separate,
expansive concepts (``similarly situated'' and ``in the region''). The
agencies considered waters to be ``similarly situated'' in the 2015
Rule when they ``function alike and are sufficiently close to function
together in affecting downstream waters.'' 80 FR 37106. The preamble of
the 2015 Rule further explained the concept of ``sufficiently close'':

    Similarly situated waters can be identified as sufficiently
close together for purposes of this paragraph of the regulation when
they are within a contiguous area of land with relatively
homogeneous soils, vegetation, and landform (e.g., plain, mountain,
valley, etc.). In general, it would be inappropriate, for example,
to consider waters as ``similarly situated'' under paragraph (a)(8)
if these waters are located in different landforms, have different
elevation profiles, or have different soil and vegetation
characteristics, unless the waters perform similar functions and are
located sufficiently close to a ``water of the United States'' to
allow them to consistently and collectively function together to
affect a traditional navigable water, interstate water, or the
territorial seas. In determining whether waters under paragraph
(a)(8) are sufficiently close to each other the agencies will also
consider hydrologic connectivity to each other or a jurisdictional
water.

80 FR 37092 (emphasis added). The 2015 Rule preamble also established
that ``under paragraph (a)(8), waters do not need to be of the same
type (as they do in paragraph (a)(7)) to be considered similarly
situated. As described above, waters are similarly situated under
paragraph (a)(8) where they perform similar functions or are located
sufficiently close to each other, regardless of type.'' Id. (emphasis
added). The agencies explained that this interpretation was based in
part on ``one of the main conclusions of the [Connectivity Report] . .
. that the incremental contributions of individual streams and wetlands
are cumulative across entire watersheds, and their effects on
downstream waters should be evaluated within the context of other
streams and wetlands in that watershed.'' Id. at 37066. The agencies
then defined ``in the region'' within the 2015 Rule's regulatory
definition of ``significant nexus'' to mean ``the watershed that drains
to the nearest'' primary water (i.e., categories (a)(1)-(3)).\36\
---------------------------------------------------------------------------

    \36\ The preamble of the 2015 Rule, however, created an
exception for the codified definition of ``in the region'' in the
Arid West in ``situations where the single point of entry watershed
is very large.'' See 80 FR 37092 (``[In those situations] it may be
reasonable to evaluate all similarly situated waters in a smaller
watershed. Under those circumstances, the agencies may demarcate
adjoining catchments surrounding the water to be evaluated that,
together, are generally no smaller than a typical 10-digit
hydrologic unit code (HUC-10) watershed in the same area. The area
identified by this combination of catchments would be the `region'
used for conducting a significant nexus evaluation under paragraphs
(a)(7) or (a)(8) under those situations. The basis for such an
approach in very large single point of entry watersheds in the arid
West should be documented in the jurisdictional determination.'').
The agencies now conclude that this exception, included in the final
rule preamble without adequate notice, was at odds with the
regulatory text of the 2015 Rule and created further confusion as to
the application of the 2015 Rule's ``significant nexus'' test and
the scope of aggregation for purposes of a significant nexus inquiry
under the rule.
---------------------------------------------------------------------------

    The agencies acknowledged this change in position from the 2008
Rapanos Guidance by explaining: ``The functions of the contributing
waters are inextricably linked and have a cumulative effect on the
integrity of the downstream traditional navigable water, interstate
water, or the territorial sea. For these reasons, it is more
appropriate to conduct a significant nexus analysis at the watershed
scale than to focus on a specific site, such as an individual stream
segment.'' Id. at 37066. As expressed in the 2008 Rapanos Guidance, the
agencies previously understood the phrase ``similarly situated lands in
the region'' to include all wetlands adjacent to the same tributary.
The 2008 Rapanos Guidance states that ``[a] tributary . . . is the
entire reach of the stream that is of the same order[.]'' 2008 Rapanos
Guidance at 10.
    The 2015 Rule also departed from the 2008 Rapanos Guidance by
applying the concept of ``similarly situated lands in the region'' to
other waters, not only wetlands, across the entire watershed of the
nearest primary water. See id. at 37066 (``A single point of entry
watershed is the drainage basin within whose boundaries all
precipitation ultimately flows to the nearest single traditional
navigable water, interstate water, or the territorial sea. . . . The
watershed includes all streams, wetlands, lakes, and open waters within
its boundaries.''). In essence, the agencies determined that not only
do ``wetlands possess the requisite nexus . . . if the wetlands, either
alone or in combination with similarly situated lands in the region,
significantly affect the chemical, physical, and biological integrity
of other covered waters more readily understood as `navigable,' '' 547
U.S. at 780 (Kennedy, J., concurring) (emphasis added), but also
``[tributaries] possess the requisite nexus, and thus come within the
statutory phrase `navigable waters,' if the [tributaries], either alone
or in combination with similarly situated [tributaries] in the region,
significantly affect the chemical, physical, and biological integrity
of other covered waters more readily understood as `navigable.' '' 80
FR 37068 (``[W]aters meeting the definition of `tributary' in a single
point of entry watershed are similarly situated and have a significant
nexus because they significantly affect the chemical, physical, or
biological integrity of traditional navigable waters, interstate
waters, and the territorial seas.'').

    As a result of the agencies' reinterpretation of a Supreme Court
Justice's opinion referencing ``similarly situated lands in the
region,'' the 2015 Rule broadened the scope of aggregation for
determining jurisdiction in a ``significant nexus'' analysis relative
to the 2008 Rapanos Guidance, which more closely aligned with what
Justice Kennedy intended for that test. In the SNPRM, the agencies
solicited comment on whether the 2015 Rule's approach to the phrase
``similarly situated lands in the region'' relied on the scientific
literature ``without due regard for the restraints imposed by the
statute and case law.'' 83 FR 32240. Multiple commenters expressed
concern that the 2015 Rule's interpretation of the phrase was
inconsistent with Justice Kennedy's opinion. In particular, these
commenters suggested that the 2015 Rule's approach of aggregating the
contributions of all streams or all wetlands within an entire watershed
impermissibly lowered the bar for establishing a significant nexus.
Other commenters asserted that the 2015 Rule's approach was consistent
with Justice Kennedy's opinion because the agencies found, in reliance
on the Connectivity Report, that waters aggregated at a watershed scale
have a connection to and impact downstream traditional navigable
waters.
    The agencies now conclude that applying Justice Kennedy's concept
of ``similarly situated lands in the region'' to encompass all
``tributaries'' as broadly defined in the 2015 Rule and potentially all
wetlands in a single point of entry watershed of the nearest primary
water resulted in a regulatory definition that expanded federal
jurisdiction to cover waters outside the scope of the Act, and thus
exceeded the agencies' statutory authority. The agencies' analytical
failure occurred in the first instance in the transition between the
proposed and final versions of the 2015 Rule. For example, potential
inclusion of all of the wetlands or waters in the watershed of the
nearest primary water under the final 2015 Rule significantly expanded
the scope of aggregation that determined jurisdiction in a
``significant nexus'' analysis from the focus in the proposed rule on
waters ``located sufficiently close together or sufficiently close to a
`water of the United States' so that they can be evaluated as a single
landscape unit.'' 79 FR 22263. The proposed rule adhered more closely
to the agencies' position on aggregation in the 2008 Rapanos Guidance
in that wetlands adjacent to the same tributary reach are inherently
located closer together and closer to a ``water of the United States''
than are all non-adjacent wetlands across an entire single point of
entry watershed. But in finalizing the 2015 Rule, the agencies viewed
the scientific literature through a broader lens relative to the
proposed rule. See, e.g., 80 FR 37094. This broader lens, as discussed
in the following subsections, resulted in the per se regulation of a
more expansive class of (a)(5) ``tributaries,'' including categorical
jurisdiction over ephemeral ``tributaries,'' the per se regulation of a
broader range of waters (not just wetlands) considered ``adjacent''
under the (a)(6) category, and case-specific inclusion of waters (not
just wetlands) that are not ``adjacent'' to other waters but
nonetheless could be regulated as ``waters of the United States''
according to the rule's (a)(7) and (a)(8) categories.
    The agencies adopted this broader aggregation approach without
proper analysis of whether this approach was consistent with the
statutory limits in the CWA's text and the limits included in Justice
Kennedy's opinion in Rapanos. As explained in Section III.B, Justice
Kennedy articulated the significant nexus standard to limit federal
jurisdiction under the CWA to avoid ``unreasonable'' assertions of
jurisdiction arising from the breadth of the Corps' then-existing
standard for tributaries. As evidenced by the discussion in his
concurrence, Justice Kennedy intended his significant nexus standard to
be a limiting test, cabining the potential overreach of federal CWA
jurisdiction. The agencies now believe that interpreting ``similarly
situated lands in the region'' to encompass all ``tributaries'' as
broadly defined in the 2015 Rule and potentially all wetlands in a
``watershed that drains to the nearest'' primary water was inconsistent
with the application of Justice Kennedy's significant nexus test as a
limiting standard.
    For example, the agencies should have considered whether the
aggregated landscape approach swept certain isolated ponds, such as
those at issue in SWANCC, into federal jurisdiction. See Section
III.C.1.a, supra. The SWANCC Court concluded that ``the text of the
statute will not allow'' the Corps to regulate ``ponds that are not
adjacent to open water.'' SWANCC, 531 U.S. at 168. And in Rapanos,
Justice Kennedy even questioned the dissent's conclusion ``that the
ambiguity in the phrase `navigable waters' allows the Corps to construe
the statute as reaching all `non-isolated wetlands[.]' '' 547 U.S. at
780 (emphasis added) (stating that this position ``seems incorrect'').
Similarly, Justice Kennedy did not subscribe to the Rapanos dissent's
position that ``would permit federal regulation whenever wetlands lie
alongside a ditch or drain, however remote and insubstantial, that
eventually may flow into traditional navigable waters.'' Id. at 778.
``The deference owed to the Corps' interpretation of the statute,''
Justice Kennedy wrote, ``does not extend so far.'' Id. at 778-79.
    The 2015 Rule also permitted the agencies to find a ``significant
nexus'' based on ``just one function,'' 80 FR 37068, such as
``provision of life cycle dependent aquatic habitat'' for species found
in primary waters. Id. at 37106. For an effect to be significant, the
rule required that it must be more than speculative or insubstantial.
Id. The rule allowed for jurisdiction when a water significantly
affects ``aquatic habitats through wind- and animal-mediated
dispersal'' of ``[a]nimals and other organisms,'' id. at 37072,
including when ``[p]lants and invertebrates'' `` `hitchik[e]' on
waterfowl'' ``to and from prairie potholes'' anywhere across an entire
watershed. Connectivity Report at 5-5. Yet if, as the SWANCC Court
held, the use of isolated ponds by migratory birds themselves was an
insufficient basis upon which to establish jurisdiction, it cannot
stand to reason that the seeds and critters clinging to their feathers
can constitute a ``significant nexus.'' See 547 U.S. at 749 (Scalia,
J., plurality) (``This [strictly ecological] reasoning would swiftly
overwhelm SWANCC altogether[.]'').
    Several federal courts have now questioned the 2015 Rule's
interpretation of Justice Kennedy's significant nexus standard in
Rapanos. The U.S. District Court for the District of North Dakota found
``[t]he Rule . . . likely fails to meet [Justice Kennedy's significant
nexus] standard'' and ``allows EPA regulation of waters that do not
bear any effect on the `chemical, physical, and biological integrity'
of any navigable-in-fact water.'' North Dakota v. EPA, 127 F. Supp. 3d
1047, 1056 (D.N.D. 2015). Likewise, the Sixth Circuit stated in
response to petitioners' ``claim that the [2015] Rule's treatment of
tributaries, `adjacent waters,' and waters having a `significant nexus'
to navigable waters is at odds with the Supreme Court's ruling in
Rapanos'' that ``[e]ven assuming, for present purposes, as the parties
do, that Justice Kennedy's opinion in Rapanos represents the best
instruction on the permissible parameters of `waters of the United
States' as used in the Clean Water Act, it is far from clear that the
new Rule's distance limitations are harmonious with the instruction.''
In re EPA, 803 F.3d at 807 & n.3 (noting that

``[t]here are real questions regarding the collective meaning of the
[Supreme] Court's fragmented opinions in Rapanos''). The agencies
recognize these deficiencies in the 2015 Rule and agree with the
concerns raised by these courts.
    As explained in the following sections, the agencies find that the
application of an overly broad significant nexus standard in the 2015
Rule resulted in a regulatory definition of ``waters of the United
States'' that did not comport with Justice Kennedy's understanding of
the limits of federal CWA jurisdiction and exceeded the agencies'
statutory authority. Moreover, the agencies find that while Justice
Kennedy noted ``the significant-nexus test itself prevents problematic
applications of the statute,'' 547 U.S. at 783 (Kennedy, J.,
concurring), including asserting jurisdiction over waters or wetlands
like those at issue in SWANCC having ``little or no connection'' to
navigable waters, id. at 767, the 2015 Rule's broad significant nexus
standard would have led to similar unreasonable applications of the CWA
that the SWANCC Court and Justice Kennedy both sought to prevent. See
Section III.C.3, infra.
ii. The 2015 Rule's Definition of (a)(5) Waters Exceeded the Scope of
CWA Jurisdiction Envisioned in Justice Kennedy's Significant Nexus Test
    The agencies' misinterpretation of Justice Kennedy's significant
nexus standard resulted in the categorical assertion of per se
jurisdiction over an expansive ``tributary'' network. The 2015 Rule
defined ``tributary'' as a water that contributes flow, either directly
or through another water, to a primary water and that is characterized
by the presence of the ``physical indicators'' of a bed and banks and
an ordinary high water mark. ``These physical indicators demonstrate
there is volume, frequency, and duration of flow sufficient to create a
bed and banks and an ordinary high water mark, and thus to qualify as a
tributary.'' 80 FR 37105. The 2015 Rule's ``tributary'' definition
included channels that flow ``only in response to precipitation
events,'' id. at 37076-77, and features that may be dry for months or
many years \37\ as long as they contribute flow, however minimal,
infrequent, or indirect to a primary water, and exhibit physical
indicators of a bed, bank, and an ordinary high water mark.
---------------------------------------------------------------------------

    \37\ A study by the U.S. Army Corps of Engineers in the Arid
West, for example, revealed flood recurrence intervals for the field
ordinary high water mark ranged from <1 to 15.5 years. See U.S. Army
Corps of Engineers Engineer Research and Development Centers. ERDC/
CRREL TR-11-12. Ordinary High Flows and the Stage-Discharge
Relationship in the Arid West Region. Curtis, K.E., R.W. Lichvar,
L.E. Dixon. (July 2011) at Table 4, available at http://www.spk.usace.army.mil/Portals/12/documents/regulatory/pdf/TR11-12_gage.pdf (hereafter, ``Ordinary High Flows in the Arid West'').
---------------------------------------------------------------------------

    Coupling the 2015 Rule's expansive definition of ``significant
nexus'' with the findings of the Connectivity Report, the agencies
concluded at that time that features meeting the rule's ``tributary''
definition ``provide many common vital functions important to the
chemical, physical, and biological integrity of downstream waters'' and
``function together to affect downstream waters'' such that all
features that satisfied the ``tributary'' definition could be
considered ``similarly situated'' and thus assessed together in a
significant nexus analysis. 80 FR 37066. Because of this aggregate
approach, the agencies found that all (a)(5) ``tributaries'' could be
considered categorically jurisdictional because any covered tributary,
either alone or when considered in combination with other covered
tributaries in the watershed, had a significant nexus to primary
waters. 80 FR 37058.
    Though some commenters found that the agencies properly relied on
the 2015 Rule's scientific record to conclude that features meeting the
``tributary'' definition possess the requisite significant nexus and
are thus categorically jurisdictional, other commenters expressed
concern with the agencies' categorical assertion of jurisdiction over
covered tributaries. These commenters suggested that the rule's
``tributary'' definition was too broad and would extend federal
jurisdiction to features with remote proximity and tenuous connections
to traditional navigable waters, contrary to the limits of CWA
authority recognized in Justice Kennedy's Rapanos concurrence.
    The agencies now conclude that the 2015 Rule's ``tributary''
definition exceeded the jurisdictional limits envisioned in Justice
Kennedy's significant nexus standard. Under the 2015 Rule's definition
of ``tributary,'' the agencies determined that the mere contribution of
flow to primary waters--however minimal, infrequent, or indirect--and
the presence of ``physical indicators'' of a bed and banks and an
ordinary high water mark were sufficient to support the categorical
assertion of jurisdiction over features (including individual features)
meeting the definition of ``tributary'' because the agencies determined
that such features, in the aggregate, would possess a significant nexus
to navigable waters. See 80 FR 37076. Yet, Justice Kennedy found that
``[a]bsent some measure of the significance of the connection for
downstream water quality,'' a ``mere hydrologic connection'' is ``too
uncertain'' and ``should not suffice in all cases'' as ``the connection
may be too insubstantial . . . to establish the required nexus'' with
``navigable waters as traditionally understood.'' 547 U.S. at 784-85
(Kennedy, J., concurring). Moreover, while Justice Kennedy questioned
jurisdiction over features with ``[t]he merest trickle [even] if
continuous'' as potentially lacking a significant nexus to navigable
waters, id. at 769, the 2015 Rule's definition of ``tributary''
categorically includes the merest trickle--whether continuous or
discontinuous--so long as it contributes flow at some unspecified time,
directly or indirectly, to downstream navigable-in-fact waters, has the
requisite physical indicators, and is not covered by an exclusion. Such
an interpretation of ``tributary'' is, at the very least, in
significant tension with Justice Kennedy's standard.
    The agencies also conclude that the categorical assertion of
jurisdiction over features meeting the 2015 Rule's ``tributary''
definition, particularly ephemeral features, was inconsistent with
Justice Kennedy's significant nexus standard. Because ephemeral streams
were not categorically jurisdictional under the pre-2015 regulations as
informed by the agencies' applicable guidance, see 2008 Rapanos
Guidance at 7 (`` `[R]elatively permanent' waters do not include
ephemeral tributaries which flow only in response to precipitation. . .
. CWA jurisdiction over these waters will be evaluated under the
significant nexus standard[.]''), the 2015 Rule's ``tributary''
definition expanded the scope of federal CWA jurisdiction over such
features without subjecting them to a case-specific significant nexus
evaluation. The agencies expect that the extent of this change might
have been greater in portions of the country where non-relatively
permanent (i.e., non-seasonal intermittent and ephemeral) streams are
more prevalent (e.g., the arid West), relative to other parts of the
country. The agencies now conclude that this change in the scope of
federal CWA jurisdiction due to the categorical inclusion of ephemeral
streams meeting the rule's ``tributary'' definition encroached too far
into the realm of traditional State land use authority by asserting per
se federal control over certain waters more appropriately left to the
jurisdiction of the States, such as

ephemeral streams distant or far-removed from navigable-in-fact waters.
This intrusion into State authority does not align with Justice
Kennedy's significant nexus standard, as it gives rise to the type of
federalism concerns and ``problematic applications of the statute''
that Justice Kennedy's significant nexus test was intended to prevent.
See 547 U.S. at 783 (Kennedy, J., concurring) (``[T]he significant-
nexus test itself prevents problematic applications of the
statute[.]''). Though the agencies had found it appropriate to
categorically include (a)(5) ``tributaries'' due to the ``science-based
conclusion'' that such waters, either individually or collectively,
possess the requisite significant nexus, the agencies now find that
this approach was flawed, as the agencies relied on scientific
information about the aggregate effects of (a)(5) ``tributaries''
without due regard for the limits on federal CWA jurisdiction reflected
in Justice Kennedy's Rapanos concurrence. See 80 FR 37079; 2015 Rule
Response to Comments--Topic 8: Tributaries at 140; see also Section
III.C.1.d, infra.
    The agencies' concerns regarding the breadth of the 2015 Rule's
``tributary'' definition are echoed in the U.S. District Court for the
Southern District of Georgia's remand order. Georgia v. Wheeler, No.
2:15-cv-079, 2019 WL 3949922 (S.D. Ga. Aug. 21, 2019). There, the court
found that the categorical assertion of jurisdiction over features
meeting the 2015 Rule's ``tributary'' standard ``is an impermissible
construction of the CWA,'' as it could cover waters that lack the
requisite significant nexus, particularly in the Arid West. Id. at *13-
15.
    The agencies also conclude that the 2015 Rule's ``tributary''
definition failed to properly account for Justice Kennedy's concerns,
explained in Rapanos, regarding the use of a broad ``tributary''
standard as the ``determinative measure'' of whether adjacent wetlands
possess the requisite significant nexus. 547 U.S. at 781. Before
Rapanos, the Corps deemed a water a jurisdictional tributary if it fed
into a traditional navigable water (or a tributary thereof) and
possessed ``an ordinary high-water mark,'' defined as a ``line on the
shore established by the fluctuations of water and indicated by
[certain] physical characteristics.'' Id. Justice Kennedy found that
this tributary concept ``may well provide a reasonable measure of
whether specific minor tributaries bear a sufficient nexus with other
regulated waters to constitute `navigable waters' under the Act'' if it
``is subject to reasonably consistent application.'' Id. (citing a 2004
GAO Report ``noting variation in results among Corps district
offices''). ``Yet,'' as Justice Kennedy stated, ``the breadth of this
standard--which seems to leave wide room for regulation of drains,
ditches, and streams remote from any navigable-in-fact water and
carrying only minor volumes towards it--precludes its adoption as the
determinative measure of whether adjacent wetlands are likely to play
an important role in the integrity of an aquatic system comprising
navigable waters as traditionally understood.'' Id. ``[M]ere adjacency
to a tributary of this sort is insufficient; a similar ditch could just
as well be located many miles from any navigable-in-fact water and
carry only insubstantial flow towards it. A more specific inquiry,
based on the significant-nexus standard, is therefore necessary.'' Id.
at 786. Justice Kennedy's discussion focused on adjacent wetlands
because the facts of Rapanos presented the question of jurisdiction
over wetlands. However, his concern that the agencies' ``tributary''
definition giving rise to the Rapanos dispute may be overly expansive--
such that federal jurisdiction over wetlands adjacent to those
tributaries may exceed the scope of the CWA--is relevant to the
agencies' consideration of the ``tributary'' definition in the 2015
Rule.
    Justice Kennedy stated that ``[t]hrough regulations or
adjudication, the Corps may choose to identify categories of
tributaries that, due to their volume of flow (either annually or on
average), their proximity to navigable waters, or other relevant
considerations, are significant enough that wetlands adjacent to them
are likely, in the majority of cases, to perform important functions
for an aquatic system incorporating navigable waters,'' id. at 780-81,
but the 2015 Rule did not properly consider those factors. Under the
2015 Rule, many minor ditches and ephemeral ``tributaries'' would be
considered ``navigable waters'' categorically, regardless of their
distance to traditional navigable waters or whether the downstream
water quality effects of such individual features are ``speculative or
insubstantial.'' 547 U.S. at 780 (Kennedy, J., concurring). As such,
the agencies conclude that the 2015 Rule's ``tributary'' definition
would have swept in ``drains, ditches, and streams remote from any
navigable-in-fact water and carrying only minor water volumes towards
it'' such that it could not be ``the determinative measure of whether
adjacent wetlands [to such features] are likely to play an important
role in the integrity of an aquatic system.'' See id. at 781 (Kennedy,
J., concurring); see also id. at 738 (plurality).\38\
---------------------------------------------------------------------------

    \38\ Courts that have considered the merits of challenges to the
2015 Rule at the preliminary injunction stage similarly observed
that the rule may conflict with Justice Kennedy's opinion in
Rapanos, particularly the rule's definition of ``tributary.'' The
District of North Dakota found that the definitions in the 2015 Rule
raise ``precisely the concern Justice Kennedy had in Rapanos, and
indeed the general definition of tributary [in the 2015 Rule] is
strikingly similar'' to the standard for tributaries that concerned
Justice Kennedy in Rapanos. North Dakota, 127 F. Supp. 3d at 1056.
The Southern District of Georgia also found that ``[t]he same fatal
defects that plagued the definition of tributaries in Rapanos plague
the [2015 Rule] here.'' Georgia v. Wheeler, No. 2:15-cv-079, 2019 WL
3949922, at *16 (S.D. Ga. Aug. 21, 2019).
---------------------------------------------------------------------------

    The agencies now conclude that the 2015 Rule inappropriately
established per se jurisdiction over features that Justice Kennedy
characterized as ``drains, ditches, and streams remote from any
navigable-in-fact water and carrying only minor water volumes toward
it.'' Id. at 781 (Kennedy, J., concurring). The rule then used those
``tributaries'' as the starting point from which to establish its
category of jurisdictional-by-rule ``adjacent'' and ``neighboring''
waters and wetlands and the baseline from which to extend distance
limits of up to 4,000 feet to determine the jurisdictional status of
those waters and wetlands based on a case-specific significant nexus
test. In doing so (as described in the next two subsections), the
agencies now find that they compounded their error and cast an even
wider net of federal jurisdiction in contravention of Justice Kennedy's
concurrence in Rapanos.
iii. The 2015 Rule's Definition of (a)(6) Waters Exceeded the Scope of
CWA Jurisdiction Envisioned in Justice Kennedy's Significant Nexus Test
    Under category (a)(6), the 2015 Rule asserted jurisdiction-by-rule
over ``all waters adjacent to a water identified in paragraphs (a)(1)
through (5) of this section, including wetlands, ponds, lakes, oxbows,
impoundments, and similar waters.'' 80 FR 37104. The agencies did not
expressly amend the longstanding definition of ``adjacent'' (defined as
``bordering, contiguous, or neighboring''), but effectively broadened
the definition by adding a definition of ``neighboring'' that impacted
the interpretation of ``adjacent.'' The 2015 Rule defined
``neighboring'' to encompass all waters located within 100 feet of the
ordinary high water mark of a category (1) through (5) ``jurisdictional
by rule'' water; all waters located within the 100-year floodplain of a
category (1) through (5) ``jurisdictional by rule'' water and not more
than 1,500 feet from the ordinary high water mark of such

water; all waters located within 1,500 feet of the high tide line of a
category (1) though (3) ``jurisdictional by rule'' water; and all
waters within 1,500 feet of the ordinary high water mark of the Great
Lakes. 80 FR 37105. The entire water was considered neighboring if any
portion of it lies within one of these zones. See id. The agencies'
2014 proposed rule did not include these distance limitations on the
definition of ``adjacent'' or ``neighboring.''
    The agencies received many comments on the NPRM and SNPRM
discussing the 2015 Rule's approach to ``adjacent'' waters. Many
commenters asserted that the rule's definition of ``adjacent'' waters
could cover waters adjacent to remote tributaries, resulting in the
assertion of jurisdiction over the same type of waters that Justice
Kennedy suggested did not fall within the scope of CWA jurisdiction.
Other commenters stated that the 2015 Rule's ``adjacent'' waters
definition was consistent with Justice Kennedy's significant nexus
standard because they stated that the scientific record for the 2015
Rule supported the agencies' finding at that time that such waters had
a significant nexus to downstream navigable-in-fact waters. After
considering the public comments, the agencies now find that the 2015
Rule's treatment of ``adjacent'' exceeded the agencies' statutory
authority and ran afoul of Justice Kennedy's significant nexus test in
Rapanos.
    As a threshold matter, because the definition of (a)(6) waters in
the 2015 Rule was keyed to waters ``adjacent'' to (a)(1) through (a)(5)
waters, the definition of (a)(6) waters rests on tenuous jurisdictional
footing for the reasons discussed in the (a)(5) ``tributaries'' section
above. In addition, the rule's definition of (a)(6) waters did not
comport with Justice Kennedy's significant nexus test.
    In Rapanos, Justice Kennedy's analysis of the agencies'
jurisdictional test clearly distinguished between ``wetlands adjacent
to navigable-in-fact waters,'' which can be regulated based on
adjacency alone, and wetlands adjacent ``to nonnavigable tributaries,''
for which ``the Corps must establish a significant nexus on a case-by-
case basis'' should it seek to regulate them, ``[a]bsent more specific
regulations.'' 547 U.S. at 782 (Kennedy, J., concurring). Justice
Kennedy found this individualized significant nexus determination
``necessary to avoid unreasonable applications of the statute'' in the
face of ``the potential overbreadth of the Corps' regulations.'' Id.
Specifically, Justice Kennedy expressed concern that the breadth of the
Corps' then-existing tributary standard ``precludes its adoption as the
determinative measure of whether adjacent wetlands are likely to play
an important role in the integrity of an aquatic system comprising
navigable waters as traditionally understood.'' Id. at 781.
    The agencies now conclude that the 2015 Rule did just that--adopted
a categorically jurisdictional rule for all adjacent wetlands (and
waters) tied to a similarly broad ``tributary'' standard that did not
adequately respond to Justice Kennedy's concerns about ``insubstantial
flow'' and remoteness. Id. at 786. The agencies now find that the 2015
Rule codified the very test that Justice Kennedy rejected and for which
the dissenting Justices in Rapanos advocated. Justice Stevens, writing
for himself and three other Justices in dissent, did not share Justice
Kennedy's concerns with the breadth of the Corps' then-existing
tributary standard and with it serving as the basis for determining
adjacency. Indeed, Justice Stevens would have held that the significant
nexus test ``is categorically satisfied as to wetlands adjacent to
navigable waters or their tributaries'' because ``it [is] clear that
wetlands adjacent to tributaries of navigable waters generally have a
`significant nexus' with the traditionally navigable waters
downstream.'' 547 U.S. at 807 (Stevens, J., dissenting) (emphasis
added). Although the agencies sought to implement the significant nexus
test articulated by Justice Kennedy in Rapanos when finalizing the 2015
Rule, the agencies now conclude that by failing to address Justice
Kennedy's concerns as to the breadth of the ``tributary'' definition to
which the ``adjacent'' definition was tied, the agencies erroneously
adopted and codified a test more like Justice Stevens's categorical
test for adjacent waters under the guise of promulgating ``more
specific regulations.'' Id. at 782 (Kennedy, J., concurring).
    In remanding the 2015 Rule to the agencies, the U.S. District Court
for the Southern District of Georgia also found that the rule's
``adjacent'' waters definition relied on an impermissibly broad
``tributary'' standard. Georgia v. Wheeler, No. 2:15-cv-079, 2019 WL
3949922, at *15-17 (S.D. Ga. Aug. 21, 2019). There, the court explained
that though the 2015 Rule's ``tributary'' definition contained the
additional requirement of a bed and banks, the rule's definition was
``functionally the same as the definition in Rapanos,'' as the court
found ``no evidence demonstrating how the addition of bed and banks . .
. does anything to further limit the definition of tributaries so as to
alleviate Justice Kennedy's concerns of over-breadth in Rapanos.'' Id.
at *16-17. The court held that as a result, the ``adjacent'' waters
provision ``could include `remote' waters . . . that have only a
`speculative or insubstantial' effect on the quality of navigable in
fact waters,'' contrary to the significant nexus standard in Justice
Kennedy's opinion. Id. (quoting Rapanos, 547 U.S. at 778-81 (Kennedy,
J., concurring)).
    Upon further reflection, including consideration of arguments made
in the subsequent litigation expressing certain concerns that litigants
were unable to make during the notice and comment period, as well as
the decisions of those courts that have preliminarily or finally
reviewed the 2015 Rule, the agencies now believe that Justice Kennedy
would not have endorsed the agencies' approach in the 2015 Rule, just
as he did not join the dissenting Justices in Rapanos. For the agencies
to conclude otherwise in the 2015 Rule was an error, requiring its
repeal.
    In addition, the agencies find that the 2015 Rule's definition of
``adjacent'' also exceeded the agencies' authority to regulate
``navigable waters'' under the CWA. Under the 2015 Rule, the agencies
determined that all waters and wetlands meeting the ``adjacent''
definition categorically possessed a significant nexus, either alone or
in combination with similarly situated waters, and thus were
jurisdictional. 80 FR 37058. The agencies justified this approach
through heavy reliance on the findings of the Connectivity Report, see
80 FR 37066, and a reinterpretation of the phrase ``similarly situated
lands in the region.'' See Section III.C.1.b.i, supra. Under the 2008
Rapanos Guidance, which the agencies now believe hews closer to Justice
Kennedy's opinion in that case, only wetlands adjacent to the ``reach
of the stream that is of the same order'' of a non-navigable tributary
that is not relatively permanent or wetlands adjacent to but that do
not directly abut a relatively permanent non-navigable tributary were
aggregated for the purposes of a significant nexus analysis. 2008
Rapanos Guidance at 1. In contrast, under the 2015 Rule, these same
wetlands were per se jurisdictional as ``adjacent waters.'' The 2015
Rule also expanded the scope of aggregation for its case-specific
significant nexus analysis to non-adjacent wetlands and waters alone or
in combination with similarly situated wetlands and waters across an
entire single point of entry watershed that drains to the nearest
primary water. The agencies now conclude that this approach was
inconsistent with the

agencies' CWA authority as envisioned by Justice Kennedy's concurring
opinion in Rapanos.
    While the 2015 Rule asserted categorical jurisdiction over ``all
waters [and wetlands] located within 100 feet of the ordinary high
water mark'' of even the most remote and minor channel meeting the
rule's definition of ``tributary,'' Justice Kennedy stated that ``[t]he
deference owed to the Corps' interpretation of the statute does not
extend'' to ``wetlands'' that ``lie alongside a ditch or drain, however
remote or insubstantial, that eventually may flow into traditional
navigable waters.'' Rapanos, 547 U.S. at 778-79 (Kennedy, J.,
concurring). Justice Kennedy also stated that ``[t]he Corps' theory of
jurisdiction'' in Rapanos and Carabell--that being ``adjacency to
tributaries, however remote and insubstantial''--``raises concerns.''
Id. at 780. In fact, Justice Kennedy took issue with the dissent's
conclusion in Rapanos that ``the ambiguity in the phrase `navigable
waters' allows the Corps to construe the statute as reaching all `non-
isolated wetlands,' '' noting that this position ``seems incorrect.''
Id. Further, with respect to wetlands adjacent to nonnavigable
tributaries, Justice Kennedy determined that ``mere adjacency . . . is
insufficient. A more specific inquiry, based on the significant-nexus
standard, is . . . necessary.'' Id. at 786; see also id. at 774 (``As
Riverside Bayview recognizes, the Corps' adjacency standard is
reasonable in some of its applications.'') (emphasis added). Yet, under
the 2015 Rule's expansive ``adjacent'' waters definition, the agencies
established that adjacency alone was sufficient and reasonable in all
of its applications--including situations where any portion of a
physically disconnected wetland lay within 100 feet of a remote drain
meeting the rule's broad ``tributary'' definition.
    The agencies also find that the 2015 Rule's per se coverage under
the definition of ``adjacent'' of all waters and wetlands located
within the 100-year floodplain and within 1,500 feet of the ordinary
high water mark of a primary water, jurisdictional impoundment, or
tributary was not consistent with the limits of federal jurisdiction
under the CWA as interpreted by Justice Kennedy. Pursuant to that
provision, the rule extended federal jurisdiction to certain isolated
ponds, wetlands, and ditches categorically simply because they might
have a hydrologic connection with such waters during a storm event with
a low probability of occurring in any given year. The agencies now
conclude that this categorical inclusion was inconsistent with Justice
Kennedy's significant nexus standard in Rapanos, which requires beyond
``speculat[ion]'' that a water or wetland ``significantly affect[s] the
chemical, physical, and biological integrity of other covered waters
more readily understood as `navigable.' '' Id. at 780. Indeed, Justice
Kennedy stated that a ``mere hydrologic connection should not suffice
in all cases'' because it ``may be too insubstantial for the hydrologic
linkage to establish the required nexus with navigable waters as
traditionally understood.'' Id. at 784-85 (emphasis added). As applied
to the facts of Carabell, Justice Kennedy believed that ``possible
flooding'' was an unduly speculative basis for a jurisdictional
connection between wetlands and other jurisdictional waters. Id. at 786
(Kennedy, J., concurring). The Rapanos plurality similarly questioned
the Corps' broad interpretation of its regulatory authority to include
wetlands `` `adjacent' to covered waters . . . if they lie within the
100-year floodplain of a body of water.'' Id. at 728 (Scalia, J.,
plurality) (internal quotation marks and citations omitted). Thus, the
agencies find that a once in a 100-year hydrologic connection between
otherwise physically disconnected waters, which satisfied the
definition of ``neighboring'' in the 2015 Rule, is too insubstantial to
justify a categorical finding of a ``significant nexus'' with
navigable-in-fact waters under Rapanos. See also Georgia v. Wheeler,
No. 2:15-cv-079, 2019 WL 3949922, at *18 (S.D. Ga. Aug. 21, 2019)
(finding that the 2015 Rule failed to show that the majority of waters
within the 100-year floodplain have a significant nexus to navigable
waters). To be sure, certain waters that meet the definition of
``neighboring'' in the 2015 Rule would meet Justice Kennedy's
``significant nexus'' test; however, other features that would not meet
Justice Kennedy's test would nonetheless meet the definition of
``neighboring'' in the 2015 Rule and thus be jurisdictional per se.
    The agencies therefore find that their interpretation of
``adjacent'' and ``neighboring'' exceeded the limits of federal CWA
jurisdiction described by Justice Kennedy and ignored his intention
that the significant nexus test be used to prevent categorical
assertion of jurisdiction over all wetlands adjacent to all
tributaries, broadly defined. The 2015 Rule misconstrued Justice
Kennedy's significant nexus standard to do exactly the opposite--permit
categorical assertion of jurisdiction over all wetlands and waters
``adjacent'' or ``neighboring'' all ``tributaries.'' For the foregoing
reasons, the agencies conclude that the 2015 Rule's definition of
(a)(6) waters exceeded their statutory authority.
iv. The 2015 Rule's Inclusion of (a)(7) and (a)(8) Waters That Could Be
Jurisdictional Under a Case-Specific Significant Nexus Analysis
Exceeded the Scope of CWA Jurisdiction Envisioned in Justice Kennedy's
Significant Nexus Test
    The 2015 Rule established two types of jurisdictional waters
``found after a case-specific analysis to have a significant nexus to
traditional navigable waters, interstate waters, or the territorial
seas, either alone or in combination with similarly situated waters in
the region.'' 80 FR 37058. The first category, (a)(7) waters, consists
of five specific types of waters in specific regions of the country:
Prairie potholes, Carolina and Delmarva bays, pocosins, western vernal
pools in California, and Texas coastal prairie wetlands. Id. at 37105.
The second category, (a)(8) waters, consists of all waters located
within the 100-year floodplain of any category (1) through (3)
``jurisdictional by rule'' water and all waters located within 4,000
feet of the high tide line or ordinary high water mark of any category
(1) through (5) ``jurisdictional by rule'' water. Id. The rule
established no distance limitation for the (a)(7) waters, id. at 37093,
and the distance-based limitations for the (a)(8) waters were adopted
without adequate notice in violation of the APA. See Texas v. EPA, No.
3:15-cv-162, 2019 WL 2272464, at *5 (S.D. Tex. May 28, 2019).\39\
---------------------------------------------------------------------------

    \39\ The agencies also note that the distance limitations in the
2015 Rule were included without sufficient record support.
---------------------------------------------------------------------------

    The 2015 Rule defined ``significant nexus'' to mean a water,
including wetlands, that either alone or in combination with other
similarly situated waters in the region, significantly affects the
chemical, physical, or biological integrity of a primary water. 80 FR
37106. Under the 2015 Rule, to determine whether a water, alone or in
combination with similarly situated waters across a watershed, had a
``significant nexus,'' the agencies considered nine functions such as
sediment trapping, runoff storage, provision of life cycle dependent
aquatic habitat, among others. Id. Under the rule, it was sufficient
for determining whether a water has a significant nexus if any single
function performed by the water, alone or together with similarly
situated

waters in the watershed of the nearest primary water, contributed
significantly to the chemical, physical, or biological integrity of the
nearest primary water. Id.
    The agencies conclude that the 2015 Rule's categories of (a)(7) and
(a)(8) waters exceeded the agencies' CWA authority for several
independent reasons. As described in Section III.C.1.a, certain waters
that fall within the scope of category (a)(8) are beyond the limits of
federal authority. By establishing a jurisdictional category for (a)(8)
waters to which the 2015 Rule's case-specific significant nexus test
applied, the rule would have swept certain ``ponds that are not
adjacent to open water''--like those isolated ponds and mudflats at
issue in SWANCC--into the federal regulatory net despite the SWANCC
Court's conclusion that ``the text of the statute will not allow
this.'' 531 U.S. at 168. Moreover, like the agencies' interpretation of
(a)(6) ``adjacent'' waters in the 2015 Rule, the baseline for
determining if a water was subject to a case-specific significant nexus
analysis under the 2015 Rule's (a)(8) category was established, among
other means, according to specified distances keyed to the definition
of (a)(5) ``tributaries.'' The agencies established a distance up to
4,000 feet from the ordinary high water mark of even the most remote
and insubstantial ``tributary'' within which all waters and wetlands
would be subject to a case-specific significant nexus analysis based in
large part on the expanded aggregation theory discussed in Section
III.C.1.b.i.\40\
---------------------------------------------------------------------------

    \40\ The 2015 Rule placed no distance limits on the scope of a
significant nexus inquiry for waters within the 100-year floodplain
of a primary water. See 80 FR 37088.
---------------------------------------------------------------------------

    Further, while the 2008 Rapanos Guidance (at 1) limited the case-
specific significant nexus inquiry to (1) non-navigable tributaries
that are not relatively permanent, (2) wetlands adjacent to non-
navigable tributaries that are not relatively permanent, and (3)
wetlands adjacent to but that do not directly abut a relatively
permanent nonnavigable tributary, the 2015 Rule asserted jurisdiction
over such tributaries and adjacent wetlands categorically and then
expanded the scope of the case-specific significant nexus test to non-
adjacent waters and wetlands alone or in combination with ``similarly
situated'' waters and wetlands anywhere within the same single point of
entry watershed. In other words, the (a)(7) and (a)(8) categories were
designed to capture waters that fall outside the 2015 Rule's broad
``adjacent'' waters (a)(6) category. See 80 FR 37080. Given the
agencies' conclusion that the categorical assertion of jurisdiction
over features meeting the 2015 Rule's definitions of ``tributary'' and
``adjacent'' contravened the limits of federal jurisdiction reflected
in Justice Kennedy's opinion, it necessarily follows that the 2015
Rule's (a)(7) and (a)(8) categories--which apply to certain waters
located outside the scope of those jurisdictional-by-rule categories--
similarly exceeded the scope of the agencies' statutory authority. See
Georgia v. Wheeler, No. 2:15-cv-079, 2019 WL 3949922, at *20 (S.D. Ga.
Aug. 21, 2019) (finding that the 2015 Rule's (a)(8) provision would
``extend federal jurisdiction beyond the limits allowed under the
CWA''). For example, because of the expansive significant nexus test in
the 2015 Rule coupled with the breadth of certain key concepts and
terms (e.g., ``tributaries,'' ``adjacent,'' and ``neighboring'')
relative to the prior regulatory regime, the agencies now conclude that
the 2015 Rule's (a)(7) and (a)(8) categories would have permitted
federal jurisdiction over waters and wetlands appearing ``little more
related to navigable-in-fact waters than were the isolated ponds held
to fall beyond the Act's scope in SWANCC.'' 547 U.S. at 781-82
(Kennedy, J., concurring).
    Relying on the concurring opinion of Justice Kennedy,\41\ the 2015
Rule misapplied the significant nexus standard to subject similarly-
situated waters (including small streams, ephemeral ``tributaries,''
non-adjacent wetlands, and small lakes and ponds) across entire
watersheds that were not already jurisdictional categorically under
another provision of the 2015 Rule to federal purview. Indeed, taken
together, the enumeration of the nine functions relevant to the
``significant nexus'' analysis and the more expansive interpretation of
``similarly situated'' and ``in the region'' in the 2015 Rule meant
that the vast majority of water features in the United States would be
per se jurisdictional or could come within the jurisdictional purview
of the Federal government pursuant to the rule's (a)(7) and (a)(8)
provisions for case-specific waters.\42\ As discussed in Section
III.C.1.b.i, such a result is inconsistent with the limiting nature of
Justice Kennedy's significant nexus test.
---------------------------------------------------------------------------

    \41\ The agencies note that they requested comment on the
appropriate scope and application of Justice Kennedy's concurring
opinion as part of their proposed new definition of ``waters of the
United States,'' including whether it is the controlling opinion
from Rapanos, the application of the significant nexus standard to
tributaries in addition to adjacent wetlands, and related topics.
See 84 FR 4167, 4177. The agencies are evaluating comments submitted
in response to that request and need not take positions on those
questions to support or resolve the issues raised in this
rulemaking.
    \42\ The agencies noted in 2015 ``that the vast majority of the
nation's water features are located within 4,000 feet of a covered
tributary, traditional navigable water, interstate water, or
territorial sea.'' 2015 Rule Economic Analysis at 11. As such, the
agencies' attempts to mitigate the expansive reach of (a)(8) waters
through this distance limitation was illusory.
---------------------------------------------------------------------------

    Justice Kennedy also stated that ``[a]bsent more specific
regulations . . . the Corps must establish a significant nexus on a
case-by-case basis when it seeks to regulate wetlands based on
adjacency to nonnavigable tributaries. Given the potential overbreadth
of the Corps' regulations, this showing is necessary to avoid
unreasonable applications of the statute.'' Id. at 782 (emphasis
added). In the 2015 Rule, the agencies provided more specific
regulations for ``tributaries'' and ``adjacent'' waters and wetlands,
both of which were based upon their misinterpretation of Justice
Kennedy's significant nexus standard. But the agencies then applied
their overbroad interpretation of significant nexus to the evaluation
of (a)(7) and (a)(8) waters on case-specific basis. The agencies are
concerned that there is nothing in Justice Kennedy's concurring opinion
in Rapanos that indicates he envisioned a case-specific approach to
establish adjacency-based jurisdiction after more specific regulations
have been established that purported to establish the categorical
limits of adjacency. And while the 2015 Rule preamble properly
characterized Justice Kennedy's acknowledgment that ``the agencies
could establish more specific regulations or establish a significant
nexus on a case-by-case basis,'' 80 FR 37058 (emphasis added), the 2015
Rule nevertheless ``continue[d] to assess significant nexus on a case-
specific basis'' for (a)(7) and (a)(8) waters. Id.
    The 2015 Rule also established different scopes of inquiry for
determining whether an (a)(7) or (a)(8) water has a significant nexus
to a primary water. ``For practical administrative purposes, the rule
[did] not require evaluation of all similarly situated waters under
paragraph (a)(7) or (a)(8) when concluding that those waters have a
significant nexus'' to a primary water. 80 FR at 37094. ``When a subset
of similarly situated waters provides a sufficient science-based
justification to conclude presence of a significant nexus, for
efficiency purposes a significant nexus analysis need not unnecessarily
require time and resources to locate and analyze all

similarly situated waters in the entire point of entry watershed.'' Id.
In contrast, ``[a] conclusion that significant nexus is lacking may not
be based on consideration of a subset of similarly situated waters
because under the significant nexus standard the inquiry is how the
similarly situated waters in combination affect the integrity of the
downstream water.'' Id. (emphasis added). In other words, under the
2015 Rule, a significant nexus inquiry for (a)(7) and (a)(8) waters may
be inconclusive until all similarly situated waters across the entire
single point of entry watershed are analyzed and it is determined that
such features do not have a significant nexus, when considered in
combination, to the nearest downstream primary water. The agencies are
concerned that the potential requirement for an analysis of all broadly
defined ``similarly situated waters in the region'' until the agencies
can determine that a feature does not possess a significant nexus to a
primary water ``raise[s] troubling questions regarding the Government's
power to cast doubt on the full use and enjoyment of private property
throughout the Nation.'' Hawkes, 136 S. Ct. 1807, 1812, 1816-17
(Kennedy, J., concurring). As a result, the agencies are concerned that
the 2015 Rule potentially leaves ``people in the dark,'' Sessions v.
Dimaya, No. 15-1498, 2018 U.S. LEXIS 2497, at *39, 42-43 (S. Ct. Apr.
17, 2018) (Gorsuch, J., concurring in part and concurring in judgment),
about the jurisdictional status of individual isolated ponds and
wetlands within their property boundaries until every last similarly
situated feature within the watershed boundary of the nearest primary
water is analyzed by the Federal government. The agencies find that
these concerns provide further support for the agencies' decision to
repeal the 2015 Rule.
    In summary, the agencies conclude that the significant nexus test
articulated in the 2015 Rule and the systemic problems associated with
its use to justify the definition of ``tributary'' (which formed the
baseline from which to extend the limits of ``adjacent'' waters and the
scope of case-specific significant nexus analyses) resulted in a
definition of ``waters of the United States'' that failed to respect
the limits of the ``significant nexus'' standard articulated in SWANCC
and Justice Kennedy's Rapanos concurrence. The agencies' conclusion is
also supported by reasoning that has been adopted by various district
courts reviewing requests for preliminary injunctions of the 2015 Rule
and ruling on the merits of the 2015 Rule. The U.S. District Court for
the District of North Dakota, for example, found that ``[t]he Rule . .
. likely fails to meet [Justice Kennedy's significant nexus] standard''
and ``allows EPA regulation of waters that do not bear any effect on
the `chemical, physical, and biological integrity' of any navigable-in-
fact water.'' North Dakota v. EPA, 127 F. Supp. 3d 1047, 1056 (D.N.D.
2015). And the U.S. District Court for the Southern District of Georgia
found that multiple provisions in the 2015 Rule were inconsistent with
Justice Kennedy's significant nexus standard, including the rule's
``tributary'' definition, which the court held extended federal CWA
jurisdiction ``well beyond what is allowed under Justice Kennedy's
interpretation of the CWA,'' and the rule's ``adjacent'' waters
provision, which the court found ``could include `remote' waters . . .
that have only a `speculative or insubstantial' effect on the quality
of navigable in fact waters.'' Georgia v. Wheeler, No. 2:15-cv-079,
2019 WL 3949922, at *14, 17 (S.D. Ga. Aug. 21, 2019) (quoting Rapanos,
547 U.S. at 778-81 (Kennedy, J., concurring)). Further, as discussed in
Section III.C.3, the agencies find that the 2015 Rule leads to similar
unreasonable applications of the CWA that SWANCC and Justice Kennedy
both sought to prevent. The agencies now conclude that the 2015 Rule
was flawed due to the systemic misapplication of the significant nexus
standard, and the agencies therefore repeal the 2015 Rule in its
entirety to ``avoid the significant constitutional and federalism
questions'' it raises. 531 U.S. at 174.
c. The 2015 Rule's Expansive Interpretation of the Significant Nexus
Standard Failed To Give the Word ``Navigable'' in the CWA Sufficient
Effect
    By applying an expansive interpretation of the significant nexus
standard within the definitions and treatment of ``tributaries,''
``adjacent'' waters, and waters subject to a case-specific
``significant nexus'' test, the agencies now believe and conclude that
the 2015 Rule did not give the word ``navigable'' within the phrase
``navigable waters'' sufficient effect. The CWA grants the agencies
jurisdiction over ``navigable waters,'' 33 U.S.C. 1311(a), defined as
``the waters of the United States.'' Id. at 1362(7). ``Congress'
separate definitional use of the phrase `waters of the United States'
[does not] constitute[ ] a basis for reading the term `navigable
waters' out of the statute.'' SWANCC, 531 U.S. at 172. Indeed,
navigability was ``what Congress had in mind as its authority for
enacting the CWA.'' Id.
    As described in Section III.B.1, Congress intended to assert
federal authority over more than just waters traditionally understood
as navigable but rooted that authority in ``its commerce power over
navigation.'' Id. at 168 n.3. Therefore, there must necessarily be a
limit to that authority and to what waters are subject to federal
jurisdiction. See, e.g., 547 U.S. at 779 (Kennedy, J., concurring)
(``[T]he word `navigable' in the Act must be given some effect.''); see
also id. at 734 (Scalia, J., plurality) (``As we noted in SWANCC, the
traditional term `navigable waters'--even though defined as `the waters
of the United States'--carries some of its original substance: `[I]t is
one thing to give a word limited effect and quite another to give it no
effect whatever.' 531 U.S., at 172.'').
    The agencies find that in defining ``tributary,'' ``adjacent,''
``neighboring,'' and ``significant nexus'' broadly so as to sweep
within federal jurisdiction many ephemeral ``tributaries'' as defined
in the 2015 Rule, certain remote ditches, and certain isolated ponds
and wetlands that, like the isolated ponds and mudflats at issue in
SWANCC, ``bear[ ] no evident connection to navigable-in-fact waters,''
547 U.S. at 779 (Kennedy, J., concurring), the 2015 Rule did not give
sufficient effect to the term ``navigable'' in the CWA. See South
Carolina v. Catawba Indian Tribe, 476 U.S. 498, 510 n.22 (1986) (``It
is our duty to give effect, if possible, to every clause and word of a
statute[.]'' (quoting United States v. Menasche, 348 U.S. 528, 538-39
(1955)) (internal quotations omitted)). Many commenters expressed a
similar concern. Other commenters asserted that the 2015 Rule did give
sufficient effect to the term ``navigable.''
    Justice Kennedy's concurring opinion in Rapanos, which the 2015
Rule sought to implement, recognized it is a ``central requirement'' of
the Act that ``the word `navigable' in `navigable waters' be given some
importance.'' 547 U.S at 778 (Kennedy, J., concurring). If the word
``navigable'' has any meaning, the CWA cannot be interpreted to
``permit federal regulation whenever wetlands lie along a ditch or
drain, however remote and insubstantial, that eventually may flow into
traditional navigable waters.'' Id. at 778-79 (Kennedy, J.,
concurring). Yet the agencies find that the 2015 Rule did just that in
certain cases, including sweeping the SWANCC ponds and similarly-
situated waters within federal purview. See Section III.C.1.a, supra.
The agencies conclude, therefore, that the 2015 Rule did not give
sufficient effect to the word ``navigable'' in the

phrase ``navigable waters'' in a manner consistent with SWANCC, Justice
Kennedy's concurring opinion in Rapanos, or the text of the CWA.
d. Because the 2015 Rule Misinterpreted the Significant Nexus Standard,
it Misapplied the Findings of the Connectivity Report To Assert
Jurisdiction Over Waters Beyond the Limits of Federal Authority
    The 2015 Rule relied on a scientific literature review--the
Connectivity Report--to support exerting federal jurisdiction over
certain waters. See 80 FR 37065 (``[T]he agencies interpret the scope
of `waters of the United States' protected under the CWA based on the
information and conclusions in the [Connectivity] Report.''). The
report notes that connectivity ``occur[s] on a continuum or gradient
from highly connected to highly isolated,'' and ``[t]hese variations in
the degree of connectivity are a critical consideration to the
ecological integrity and sustainability of downstream waters.'' Id. at
37057. The conclusions in this report, while informative, cannot be
dispositive in interpreting the statutory reach of ``waters of the
United States.'' The definition of ``waters of the United States'' must
be grounded in a legal analysis of the limits on CWA jurisdiction that
Congress intended by use of the term ``navigable waters,'' and a
faithful understanding and application of the limits expressed in
Supreme Court opinions interpreting that term.
    In its review of a draft version of the Connectivity Report, EPA's
Science Advisory Board (``SAB'') noted, ``[s]patial proximity is one
important determinant of the magnitude, frequency and duration of
connections between wetlands and streams that will ultimately influence
the fluxes of water, materials and biota between wetlands and
downstream waters.'' \43\ ``Wetlands that are situated alongside rivers
and their tributaries are likely to be connected to those waters
through the exchange of water, biota and chemicals. As the distance
between a wetland and a flowing water system increases, these
connections become less obvious.'' \44\ The Connectivity Report also
recognizes that ``areas that are closer to rivers and streams have a
higher probability of being connected than areas farther away.''
Connectivity Report at ES-4.
---------------------------------------------------------------------------

    \43\ Science Advisory Board, U.S. EPA. Review of the EPA Water
Body Connectivity Report at 60 (Oct. 17, 2014).
    \44\ Id. at 55.
---------------------------------------------------------------------------

    Yet, as the SAB observed, ``[t]he Report is a science, not policy,
document that was written to summarize the current understanding of
connectivity or isolation of streams and wetlands relative to large
water bodies such as rivers, lakes, estuaries, and oceans.'' \45\ ``The
SAB also recommended that the agencies clarify in the preamble to the
final rule that `significant nexus' is a legal term, not a scientific
one.'' 80 FR 37065. And in issuing the 2015 Rule, the agencies stated,
``the science does not provide a precise point along the continuum at
which waters provide only speculative or insubstantial functions to
downstream waters.'' Id. at 37090. Although the agencies acknowledged
that science cannot dictate where to draw the line of federal
jurisdiction, see, e.g., 80 FR 37060, notwithstanding that qualifier,
the agencies relied on the Connectivity Report extensively in
establishing the 2015 Rule's definition of ``waters of the United
States.'' See id. at 37057 (``The [Connectivity] Report provides much
of the technical basis for [the] rule.'').
---------------------------------------------------------------------------

    \45\ Id. at 2.
---------------------------------------------------------------------------

    In promulgating the 2015 Rule, the agencies stated that the science
documented in the Connectivity Report showed that Justice Kennedy's
significant nexus standard was satisfied by the rule's expansive
definition of ``water of the United States.'' See, e.g., 80 FR 37058
(`` `[T]ributaries' and `adjacent' waters, are jurisdictional by rule,
as defined, because the science confirms that they have a significant
nexus to traditional navigable waters, interstate waters, or
territorial seas.'' (emphasis added)). Yet, as described previously,
the definition failed to properly implement the fundamental limits of
Justice Kennedy's test. In doing so the agencies focused too heavily on
the nexus component of the significant nexus test to define the scope
of CWA jurisdiction without appropriate regard to the significance of
that nexus. While this approach and the Connectivity Report correctly
recognize that upstream waters are connected to downstream waters, the
agencies now find that the approach failed to acknowledge that
``[a]bsent some measure of the significance of the connection for
downstream water quality, this standard [is] too uncertain'' and ``mere
hydrologic connection should not suffice in all cases; the connection
may be too insubstantial for the hydrologic linkage to establish the
required nexus with navigable waters as traditionally understood.''
Rapanos, 547 U.S. at 784-85 (Kennedy, J., concurring). By adopting an
aggregated watershed-scale approach to CWA jurisdiction, as further
described in Section III.C.1.b.i, the 2015 Rule interpreted too broadly
a key element of Justice Kennedy's significant nexus standard and
greatly increased the scope of federal regulation.
    A number of commenters expressed the view that the agencies relied
too heavily on scientific principles in interpreting ``significant
nexus'' in the 2015 Rule and did not adequately consider the legal
constraints on federal jurisdiction inherent in the CWA's statutory
text and Supreme Court precedent. Commenters noted that the
Connectivity Report did not provide the agencies with any ``bright
lines'' as to where federal CWA jurisdiction begins and ends and that
the report did not provide any guidance on how to apply Justice
Kennedy's significant nexus test to a waterbody. Other commenters
suggested that the agencies appropriately relied on the Connectivity
Report and the SAB's review of its findings in developing the 2015
Rule's significant nexus standard. Several commenters, in fact, argued
that the science underlying the Connectivity Report should drive the
limits of federal jurisdiction under the CWA.
    The agencies conclude that in establishing the limits of federal
regulatory authority under the CWA in the 2015 Rule, the agencies
placed too much emphasis on the information and conclusions of the
Connectivity Report at the expense of the limits on federal
jurisdiction reflected in the statutory text and decisions of the
Supreme Court. According to the 2015 Rule, the Connectivity Report and
the SAB review confirmed that:

    Tributary streams, including perennial, intermittent, and
ephemeral streams, are chemically, physically, and biologically
connected to downstream waters, and influence the integrity of
downstream waters. Wetlands and open waters in floodplains and
riparian areas are chemically, physically, and biologically
connected with downstream waters and influence the ecological
integrity of such waters. Non-floodplain wetlands and open waters
provide many functions that benefit downstream water quality and
ecological integrity, but their effects on downstream waters are
difficult to assess based solely on the available science.

80 FR 37057. Thus, despite Justice Kennedy's description of the extent
of ``[t]he deference owed the Corps' interpretation of the statute,''
547 U.S. at 778-79 (Kennedy, J., concurring), the agencies concluded
that the Connectivity Report supported a ``tributary'' definition that
included certain ``remote and insubstantial'' channels ``that
eventually may flow into traditional navigable waters,'' id. at 778, an
``adjacent'' waters definition that

included all ``wetlands [and waters that] lie alongside'' such
channels, id., and a case-specific significant nexus test that applied
to non-adjacent waters and wetlands, either alone or in combination,
within 4,000 feet of those channels. These aspects of the 2015 Rule, at
a minimum, created substantial tension with Justice Kennedy's opinion
in Rapanos.
    Of particular concern to the agencies today is the 2015 Rule's
broad application of Justice Kennedy's phrase ``similarly situated
lands in the region.'' As discussed in Section III.C.1.b.i, the
agencies took an expansive reading of this phrase, in part based on
``one of the main conclusions of the [Connectivity Report] . . . that
the incremental contributions of individual streams and wetlands are
cumulative across entire watersheds, and their effects on downstream
waters should be evaluated within the context of other streams and
wetlands in that watershed.'' 80 FR 37066. Yet, Justice Kennedy
observed in Rapanos that what constitutes a ``significant nexus'' is
not a solely scientific question and that it cannot be determined by
environmental effects alone. See, e.g., 547 U.S. at 777-78 (noting that
although ``[s]cientific evidence indicates that wetlands play a
critical role in controlling and filtering runoff . . . environmental
concerns provide no reason to disregard limits in the statutory text''
(citations omitted) (emphasis added)); see also Rodriguez v. United
States, 480 U.S. 522 (1987) (``[N]o legislation pursues its purposes at
all costs.''). The 2015 Rule's treatment of the phrase ``similarly
situated'' to mean ``waters that function alike and are sufficiently
close to function together in affecting downstream waters'' and ``in
the region'' to mean ``the watershed that drains to the nearest''
primary water together expanded the potential jurisdictional purview of
the Federal government to include the vast majority of the nation's
waters and contravened the limiting nature of Justice Kennedy's
description of the significant nexus standard. As a consequence, the
2015 Rule's aggregation method for purposes of its significant nexus
inquiry ``raise[d] significant constitutional questions'' similar to
the Corps' assertion of jurisdiction over the abandoned ponds at issue
in SWANCC. See Section III.C.3, infra (addressing these constitutional
questions in further detail).
    The agencies also find that the 2015 Rule placed insufficient
weight on the direction of the Court in Riverside Bayview regarding the
limits of federal jurisdiction and instead relied heavily on the
Connectivity Report to support its assertion of jurisdiction.\46\ The
2015 Rule stated, ``it is the agencies' task to determine where along
[the] gradient [of connectivity] to draw lines of jurisdiction under
the CWA,'' 80 FR 37057, yet in establishing those lines, the agencies
did not appropriately consider the Riverside Bayview Court's discussion
regarding the limits of jurisdiction lying within the ``continuum'' or
``transition'' ``between open waters and dry land.'' 474 U.S. at 132.
Instead, the agencies appeared to follow the advice of the SAB \47\ and
issued a definition of ``waters of the United States'' that went far
beyond that continuum to reach physically disconnected waters and
wetlands under categories (a)(7) and (a)(8).
---------------------------------------------------------------------------

    \46\ The agencies also note that the 2015 Rule was remanded back
to the agencies because the final Connectivity Report, which served
as the scientific foundation for the rule, was not made available to
the public for review and comment. See Texas v. EPA, No. 3:15-cv-
162, 2019 WL 2272464 (S.D. Tex. May 28, 2019).
    \47\ See, e.g., 80 FR 37064, citing SAB Consideration of the
Adequacy of the Scientific and Technical Basis of the EPA's Proposed
Rule titled ``Definition of Waters of the United States under the
Clean Water Act,'' U.S. EPA (2014) (In promulgating the 2015 Rule,
the agencies noted that the SAB ``expressed support for the proposed
rule's . . . inclusion of `other waters' on a case-specific basis''
and that the SAB ``found it `appropriate to define `other waters' as
waters of the United States on a case-by-case basis, either alone or
in combination with similarly situated waters in the same region.'
'').
---------------------------------------------------------------------------

2. The 2015 Rule Did Not Adequately Consider and Accord Due Weight to
Clean Water Act Section 101(b)
    When Congress passed the CWA in 1972, it established the objective
``to restore and maintain the chemical, physical, and biological
integrity of the Nation's waters.'' 33 U.S.C. 1251(a). In order to meet
that objective, Congress provided a major role for the States in
implementing the CWA and recognized the importance of preserving the
States' independent authority and responsibility in this area. See 33
U.S.C 1251(b) and 1370. As the Supreme Court has explained, the ``Clean
Water Act anticipates a partnership between the States and the Federal
Government, animated by a shared objective: `to restore and maintain
the chemical, physical, and biological integrity of the Nation's
waters.' '' Arkansas v. Oklahoma, 503 U.S. 91, 101 (1992) (emphasis
added).
    The CWA balances the traditional power of States to regulate land
and water resources within their borders with the need for federal
water quality regulation to protect the ``navigable waters'' defined as
``the waters of the United States, including the territorial seas.'' 33
U.S.C. 1362(7). Section 101(b) of the Act establishes ``the policy of
the Congress to recognize, preserve, and protect the primary
responsibilities and rights of States to prevent, reduce, and eliminate
pollution'' and ``to plan the development and use . . . of land and
water resources . . . . '' Id. at 1251(b). Congress also declared as a
national policy that States manage the major construction grant program
and implement the core permitting programs authorized by the statute,
among other responsibilities. Id. The policy statement of 101(b) ``was
included in the Act as enacted in 1972 . . . prior to the addition of
the optional state administration program in the 1977 amendments. Thus,
the policy plainly referred to something beyond the subsequently added
state administration program of 33 U.S.C. 1344(g)-(l).'' 547 U.S. at
737 (Scalia, J., plurality) (citations omitted). Congress further added
that ``[e]xcept as expressly provided in this [Act], nothing in this
Act shall . . . be construed as impairing or in any manner affecting
any right or jurisdiction of the States with respect to the waters
(including boundary waters) of such States.'' 33 U.S.C. 1370. The court
in Georgia v. Wheeler also recognized the important balance between
States and the Federal government that Congress prescribed in the CWA,
explaining that ``[w]hile the CWA allows the federal government to
regulate certain waters for the purposes of protecting the chemical,
physical, and biological integrity of the nation's waters, Congress
also included within that statute a provision which states that the
policy of Congress is to `recognize, preserve, and protect the primary
responsibilities and rights of States to prevent, reduce, and eliminate
pollution, to plan the development and use (including restoration,
preservation, and enhancement) of land and water resources.' '' Georgia
v. Wheeler, No. 2:15-cv-079, 2019 WL 3949922, at *22 (S.D. Ga. Aug. 21,
2019) (internal citation omitted).
    The agencies must develop regulatory programs designed to ensure
that the full statute is implemented as Congress intended. See, e.g.,
Hibbs v. Winn, 542 U.S. 88, 101 (2004) (``A statute should be construed
so that effect is given to all its provisions, so that no part will be
inoperative or superfluous, void or insignificant''). This includes
pursuing the overall ``objective'' of the CWA to ``restore and maintain
the chemical, physical, and biological integrity of the Nation's
waters,'' 33 U.S.C. 1251(a), while implementing the specific ``policy''
directives from Congress to preserve state authority over their own

land and water resources. See id. at 1251(b); see also Webster's II,
New Riverside University Dictionary (1994) (defining ``policy'' as a
``plan or course of action, as of a government[,] designed to influence
and determine decisions and actions;'' an ``objective'' is ``something
worked toward or aspired to: Goal''). The agencies therefore must
recognize a distinction between the specific word choices of Congress,
including the need to develop regulatory programs that aim to
accomplish the objective of the Act while implementing the specific
policy directives of Congress. See Section III.B.1 for additional
discussion of this language in the CWA.
    In promulgating the 2015 Rule, the agencies conclude that they did
not adequately consider and accord due weight to the policy directive
of the Congress in section 101(b) of the Act. The 2015 Rule
acknowledged the language contained in section 101(b) and the vital
role States and Tribes play in the implementation and enforcement of
the Act, 80 FR 37059, but it did not appropriately recognize the
important policy of 101(b) to preserve the traditional power of States
to regulate land and water resources within their borders or the
utility and independent significance of the Act's non-regulatory
programs.\48\ In fact, the agencies failed to adequately acknowledge
the meaning of perhaps the most important verb in 101(b), the direction
to ``preserve'' existing State authority. That is, Congress recognized
existing State authorities at the time it enacted the 1972 CWA
amendments and directed the agencies to preserve and protect those
authorities, which includes the authority to regulate certain waters as
the States deem appropriate, without mandates from the Federal
government. It is true that the agencies noted that ``States and
federally-recognized tribes, consistent with the CWA, retain full
authority to implement their own programs to more broadly and more
fully protect the waters in their jurisdiction,'' id. at 37060, but the
agencies did not include a discussion in the 2015 Rule preamble of the
meaning and importance of section 101(b) in guiding the choices the
agencies make in setting the outer bounds of CWA jurisdiction. Instead
of considering this aspect of the 101(b) congressional policy
directive, the agencies reduced the number of waters subject solely to
State jurisdiction by broadening their interpretation of ``waters of
the United States.'' Several commenters offered interpretations of
section 101(b) of the Act similar to the interpretation that the
agencies offered in the 2015 Rule and asserted that the import of
section 101(b) is Congress' policy that States implement the Act and
have authority to impose conditions that are more stringent than the
conditions the agencies impose under the Act. As described above,
however, the policy directive from Congress in section 101(b) is not so
limited.
---------------------------------------------------------------------------

    \48\ The majority of the agencies' discussion of section 101(b)
in the preamble to the final 2015 Rule focused on the ``particular
importance'' of States and Tribes administering the CWA permitting
programs. 80 FR 37059.
---------------------------------------------------------------------------

    The agencies now conclude that, at a minimum, the 2015 Rule's case-
specific significant nexus provisions stretched the bounds of federal
jurisdiction to cover certain waters that more appropriately reside in
the sole jurisdiction of States. In describing those provisions, the
agencies stated that ``the 100-year floodplain and 4,000 foot
boundaries in the rule will sufficiently capture for analysis those
waters that are important to protect to achieve the goals of the Clean
Water Act.'' 80 FR 37090; see also id. at 37091 (``[P]roviding for
case-specific significant nexus analysis for waters that are not
adjacent but within the 4,000 foot distance limit, as well as those
within the 100-year floodplain of a traditional navigable water,
interstate water, or the territorial seas . . . will ensure protection
of the important waters whose protection will advance the goals of the
Clean Water Act . . . .'') (emphasis added). Such statements--and
indeed naming the 2015 Rule the ``Clean Water Rule''--imply that waters
that are not ``waters of the United States'' (i.e., the subset of the
``Nation's waters'' subject solely to State and tribal authority) are
not important to protect to meet the objective of the Act. In other
words, when they finalized the 2015 Rule, the agencies believed the
rule's definition of ``waters of the United States'' covered all waters
necessary for regulation under the CWA in order to meet the objective
of the Act in section 101(a), and in turn neglected to incorporate the
policy of the Congress in section 101(b). And as the plurality warned
in Rapanos, ``the expansive theory [of jurisdiction] advanced by the
Corps, rather than `preserv[ing] the primary rights and
responsibilities of the States,' would have brought virtually all
`plan[ning of] the development and use . . . of land and water
resources' by the States under federal control.'' Rapanos, 547 U.S. at
737 (Scalia, J., plurality). The 2015 Rule generated the same result,
and the agencies now conclude that its definition was ``therefore an
unlikely reading of the phrase `the waters of the United States.''' Id.
The agencies' conclusion is consistent with the court's holding in
Georgia v. Wheeler that the 2015 Rule inappropriately encroached on
traditional state power. The court in that case found that the 2015
Rule increased the scope of federal jurisdiction ``to a significant
degree'' and that this ``significant increase in jurisdiction takes
land and water falling traditionally under the states' authority and
transfers them to federal authority.'' Georgia v. Wheeler, No. 2:15-cv-
079, 2019 WL 3949922, at *23 (S.D. Ga. Aug. 21, 2019) (footnote
omitted).
    Several commenters criticized the agencies for not articulating the
precise limits that the agencies understand section 101(b) to impose.
The agencies are not concluding in this rulemaking that section 101(b)
of the Act establishes a precise line between waters that are subject
to Federal and State regulation, on the one hand, and subject to State
regulation only, on the other. Instead, they find that the 2015 Rule
failed to adequately consider and accord due weight to the policy
directive in section 101(b) and, as a result, asserted jurisdiction
over certain waters that are more appropriately left solely in the
jurisdiction of States. For example, as described in Section
III.C.1.b.iii, the 2015 Rule's definition of ``adjacent'' established
per se coverage of all waters and wetlands within the 100-year
floodplain and within 1,500 feet of the ordinary high water mark of a
primary water, jurisdictional impoundment, or tributary. As a result,
the rule extended federal jurisdiction to certain isolated ponds,
wetlands, and ditches categorically simply because they might have a
hydrologic connection with such waters only during an infrequent storm
event. Further, the agencies find that the policy directive from the
Congress in section 101(b) indicates that certain types of isolated
waters are more appropriately left solely under the jurisdiction of
States, including those waters the Supreme Court found beyond the
statute's reach in SWANCC and Rapanos. Leaving these types of waters in
the sole jurisdiction of States will give due regard to the CWA's
numerous non-regulatory programs designed to protect and restore the
Nation's waters, not just its navigable waters, the utility of which
would be diminished if the ``vast majority'' \49\ of the Nation's
waters are subject to federal purview under the 2015 Rule.
---------------------------------------------------------------------------

    \49\ 2015 Rule Economic Analysis at 11.
---------------------------------------------------------------------------

    Finally, the 2015 Rule upset the Federal-State balance of the Act
by

``mistaken[ly] . . . assum[ing] . . . that whatever might appear to
further the statute's primary objective must be the law.'' Henson v.
Santander Consumer USA Inc., 137 S. Ct. 1718, 1725 (2017); see also
Rapanos, 547 U.S. at 755-56 (Scalia, J., plurality) (``[C]lean water is
not the only purpose of the statute. So is the preservation of primary
State responsibility for ordinary land-use decisions. 33 U.S.C.
1251(b).'') (original emphasis). Several commenters emphasized the
importance of the objective in section 101(a) to ``restore and maintain
the chemical, physical, and biological integrity of the Nation's
waters'' and asserted that the policy directive in section 101(b) does
not supersede that objective. The agencies recognize the importance of
the objective in section 101(a), but they also must recognize the
specific policy directives from Congress in section 101(b).\50\ As the
Supreme Court has explained, ``an administrative agency's power to
regulate in the public interest must always be grounded in a valid
grant of authority from Congress,'' and ``in [its] anxiety to
effectuate the congressional purpose,'' an agency ``must take care not
to extend the scope of the statute beyond the point where Congress
indicated it would stop.'' See FDA v. Brown & Williamson Tobacco Corp.,
529 U.S. 120, 161 (2000) (citations omitted).
---------------------------------------------------------------------------

    \50\ See, e.g., Transcript of Oral Argument at 58, Rapanos v.
United States and Carabell v. United States, 547 U.S. 715 (2006)
(Nos. 04-1034, 04-1384). (Quoting Justice Kennedy, ``[T]he Congress
in 1972 . . . said it's a statement of policy to reserve to the
States the power and the responsibility to plan land use and water
resources. And under your definition, I just see that we're giving
no scope at all to that clear statement of the congressional
policy.'').
---------------------------------------------------------------------------

    The agencies conclude that the 2015 Rule did not fully recognize
the ``partnership between the States and the Federal Government'' in
meeting the ``shared objective'' of the Act. Arkansas v. Oklahoma, 503
U.S. 91, 101 (1992); see also Motor Vehicle Mfrs. Ass'n v. State Farm
Mut. Auto. Ins. Co., 463 U.S. 29, 43 (1983) (``Normally, an agency rule
would be arbitrary and capricious if the agency has . . . entirely
failed to consider an important aspect of the problem[.]''). As
discussed in more detail below, by over-emphasizing the importance of
CWA section 101(a) while not adequately considering and according due
weight to section 101(b), the agencies extended federal jurisdiction
over waters that ``raise[d] significant constitutional questions,'' 531
U.S. at 173, and ``intru[ded] into traditional state authority''
without ``a `clear and manifest' statement from Congress.'' 547 U.S. at
738 (Scalia, J., plurality) (quoting BFP v. Resolution Trust
Corporation, 511 U.S. 531, 544 (1994)).
3. In Repealing the 2015 Rule, the Agencies Seek To Avoid
Constitutional Questions Relating to the Scope of CWA Authority
    The agencies now find that the 2015 Rule raised significant
questions of Commerce Clause authority and encroached on traditional
State land-use regulation without a clear statement from Congress. As
explained in Section III.B.2, the Supreme Court has stated that
``[w]here an administrative interpretation of a statute invokes the
outer limits of Congress' power, we expect a clear indication that
Congress intended that result.'' SWANCC, 531 U.S. at 172-73. The Court
has further stated that this is particularly true ``where the
administrative interpretation alters the federal-state framework by
permitting federal encroachment upon a traditional state power.'' Id.
at 173; see also Atascadero State Hospital v. Scanlon, 473 U.S. 234,
242-43 (1985) (``If Congress intends to alter the `usual constitutional
balance between the States and the Federal Government,' it must make
its intention to do so `unmistakably clear in the language of the
statute[.]' ''); Gregory v. Ashcroft, 501 U.S. 452, 460-61 (1991)
(``the plain statement rule . . . acknowledg[es] that the States retain
substantial sovereign powers under our constitutional scheme, powers
with which Congress does not readily interfere'').
    Congress relied on the broad authority of the Commerce Clause when
it enacted the CWA, but it limited the exercise of that authority to
its power over navigation. SWANCC, 531 U.S. at 168 n.3. In doing so,
the Supreme Court has explained that Congress specifically sought to
avoid ``federal encroachment upon a traditional state power.'' Id. at
172. The Court in SWANCC found that ``[r]ather than expressing a desire
to readjust the federal-state balance in this manner, Congress chose
[in the CWA] to `recognize, preserve, and protect the primary
responsibilities and rights of States . . . to plan the development and
use . . . of land and water resources . . .'' Id. at 174 (quoting 33
U.S.C. 1251(b)). The Court found no clear statement from Congress that
it had intended to permit federal encroachment on traditional State
power and construed the CWA to avoid the significant constitutional
questions related to the scope of federal authority authorized therein.
Id. Similarly, the plurality in Rapanos stated that ``[w]e ordinarily
expect a `clear and manifest' statement from Congress to authorize an
unprecedented intrusion into traditional State authority. The phrase
`the waters of the United States' hardly qualifies.'' Rapanos, 547 U.S.
at 737-38 (Scalia, J., plurality) (citations omitted).
    In SWANCC, the Court rejected the argument that the use of
nonnavigable, isolated, intrastate waters by migratory birds fell
within the power of Congress to regulate activities that in the
aggregate have a substantial effect on interstate commerce, or that the
targeted use of the ponds at issue as a municipal landfill was
commercial in nature. 531 U.S. at 173. Such arguments, the Court noted,
``raise[d] significant constitutional questions,'' id., and ``would
result in a significant impingement of the States' traditional and
primary power over land and water use.'' Id. at 174. Similarly, in
Rapanos, the plurality applied the clear statement rule when it
rejected the Corps' attempt to extend CWA jurisdiction to the waters at
issue in that case. 547 U.S. at 737-38 (Scalia, J., plurality). The
plurality concluded that any attempt by the Federal government to
regulate such water would not only be ``an unprecedented intrusion into
traditional state authority,'' but would also ``stretch[ ] the outer
limits of Congress' commerce power and raise[ ] difficult questions
about the ultimate scope of that power.'' Id. at 738.
    As described in Section III.C.1, and as several commenters noted,
the 2015 Rule extended federal jurisdiction to waters similar to those
at issue in SWANCC. As a result, the agencies conclude that, like the
application of the federal rule giving rise to the SWANCC decision, the
2015 Rule pressed the outer bounds of Congress' Commerce Clause
authority and encroached on traditional State rights without a clear
statement from Congress. Under the 2015 Rule, certain nonnavigable,
isolated, intrastate waters like those at issue in SWANCC would be
deemed federally jurisdictional as ``adjacent'' waters or other waters
found on a case-specific basis to have a ``significant nexus'' with
primary waters. The agencies' expansive interpretation of Justice
Kennedy's significant nexus standard, and in particular the agencies'
broad interpretation of the phrase ``similarly situated lands in the
region,'' resulted in a definition of ``waters of the United States''
that included certain isolated ponds and wetlands nearly a mile from
the nearest ephemeral ``tributary'' or that connect only once in a
century to waters more traditionally understood as navigable, and
thereby pressed the boundaries of federal jurisdiction.

    The 2015 Rule reached so far into the landscape that, as commenters
noted, it is difficult for private property owners to know whether
their lands are subject to federal jurisdiction. This is particularly
evident in the agencies' discussion of the (a)(7) and (a)(8)
categories. For example, the agencies noted in 2015 that it is possible
to assert federal jurisdiction over a single wetland feature if the
agencies determine that a subset of similarly situated waters in the
watershed have, in combination, a significant nexus to the primary
waters. But the agencies expressly rejected the ability to determine
that a single wetland feature is not subject to jurisdiction unless and
until all similarly situated waters in the watershed of the nearest
primary watershed are evaluated. See 80 FR 37094-95 (``A conclusion
that significant nexus is lacking may not be based on consideration of
a subset of similarly situated waters because under the significant
nexus standard the inquiry is how the similarly situated waters in
combination affect the integrity of downstream waters.''). Effectively,
under the 2015 Rule, a single landowner with an isolated wetland
located within a large watershed could not receive a negative approved
jurisdictional determination unless the Federal government is satisfied
that all ``similarly situated'' wetlands within that watershed do not
significantly affect the integrity of the downstream primary water.
    This expansive and uncertain cloud of potential federal regulation
over all or potentially all water features within an entire watershed
raises the very concerns that the constitutional avoidance doctrine and
clear statement rule are designed to address. As Justice Kennedy
observed in 2016, ``the reach and systemic consequences of Clean Water
Act jurisdiction remain a cause for concern'' and ``continues to raise
troubling questions regarding the Government's power to cast doubt on
the full use and enjoyment of private property throughout the Nation.''
Hawkes, 136 S. Ct. at 1816-17 (Kennedy, J., concurring) (also
describing the Act's reach as ``ominous''). The agencies conclude that
the 2015 Rule amplified those concerns by misapplying the significant
nexus standard established in SWANCC and further described by Justice
Kennedy in Rapanos. Just as Justice Kennedy wrote in summary of SWANCC,
the 2015 Rule likewise ``would raise significant questions of Commerce
Clause authority and encroach on traditional state land-use
regulation,'' Rapanos, 547 U.S. at 776 (Kennedy, J., concurring), while
generating ``problematic applications of the statute.'' Id. at 783. The
agencies' conclusion is consistent with the court's holding in Georgia
v. Wheeler. There, the court found that ``like the majority in SWANCC
and the plurality in Rapanos concluded, the [2015] Rule's vast
expansion of jurisdiction over waters and land traditionally within the
states' regulatory authority cannot stand absent a clear statement from
Congress in the CWA. Since no such statement has been made, the [2015
Rule] is unlawful under the CWA.'' Georgia v. Wheeler, No. 2:15-cv-079,
2019 WL 3949922, at *23 (S.D. Ga. Aug. 21, 2019). To avoid questionable
applications of the Act and a ``theory of jurisdiction that presses the
envelope of constitutional validity,'' 547 U.S. at 738 (Scalia, J.,
plurality), the agencies repeal the 2015 Rule in its entirety.
4. The Distance-Based Limitations Were Not a Logical Outgrowth of the
Proposed Rule and Were Not Supported by an Adequate Record
    The agencies inserted the distance limitations into the final 2015
Rule for the stated purpose of increasing CWA program predictability
and consistency and reducing the instances in which permitting
authorities would need to make jurisdictional determinations on a case-
specific basis. 80 FR 37054. These distance limitations therefore were
important in achieving the stated purposes of the rulemaking and were
employed in two specific ways. First, the 2015 Rule defined
``neighboring'' to encompass all waters located within 100 feet of the
ordinary high water mark of a category (a)(1) through (a)(5)
``jurisdictional by rule'' water; all waters located within the 100-
year floodplain of a category (a)(1) through (a)(5) ``jurisdictional by
rule'' water and not more than 1,500 feet from the ordinary high water
mark of such water; all waters located within 1,500 feet of the high
tide line of a category (a)(1) through (a)(3) ``jurisdictional by
rule'' water; and all waters within 1,500 feet of the ordinary high
water mark of the Great Lakes. 80 FR 37105. The agencies' proposed rule
did not include these distance limitations in the definition of
``adjacent'' or ``neighboring.'' See 79 FR 22263. By defining
``neighboring'' within (a)(6) ``adjacent'' waters in the final rule to
include these distance limitations, however, the 2015 Rule
categorically defined waters within large swaths of land within the
distance limits as jurisdictional. Second, the 2015 Rule applied
distance limitations when identifying certain waters that would be
subject to a case-specific analysis to determine if they had a
``significant nexus'' to a water that is jurisdictional. 80 FR 37104-
05. Waters in section (a)(8) of the 2015 Rule were subject to a case-
by-case jurisdictional determination if they are located within the
100-year floodplain of any category (a)(1) through (a)(3)
``jurisdictional by rule'' water or within 4,000 feet of the high tide
line or ordinary high water mark of any category (a)(1) through (a)(5)
``jurisdictional by rule'' water. Id. These quantitative measures did
not appear in the proposed rule nor did they have adequate record
support.
    In the SNPRM, the agencies requested public comment regarding the
distance-based limitations in the 2015 Rule. 83 FR 32241. The agencies
``solicit[ed] comment on whether these distance-based limitations
mitigated or affected the agencies' change in interpretation of the
similarly situated waters in the 2015 Rule.'' Id. The SNPRM also noted
``the concerns raised by some commenters and the federal courts,'' and
that ``the agencies have reviewed data previously relied upon to
conclude that the 2015 Rule would have no or `marginal at most' impacts
on jurisdictional determinations.'' Id. at 32243. The agencies thus
specifically ``solicit[ed] comment on whether the agencies
appropriately characterized or estimated the potential scope of CWA
jurisdiction that could change under the 2015 Rule, including whether
the documents supporting the 2015 Rule appropriately considered the
data relevant to and were clear in that assessment.'' Id. Furthermore,
the agencies sought comment on ``any other issues that may be relevant
to the agencies' consideration of whether to repeal the 2015 Rule, such
as whether any potential procedural deficiencies limited effective
public participation in the development of the 2015 Rule.'' Id. at
32249.
    The agencies received a number of comments in response to the NPRM
and SNPRM regarding the distance-based limitations in the 2015 Rule.
While some commenters suggested that the 2015 Rule's distance-based
limitations were adequately supported and represented a permissible
exercise of agency experience and expertise, other commenters asserted
that the distance-based limitations were arbitrary and lacked support
in the administrative record for the 2015 Rule. Multiple commenters
also expressed concern that the public did not have an opportunity to
comment on the distance limitations used in the 2015 Rule and argued
that those specific measures were not a logical outgrowth of the
proposal. Other commenters disagreed that the 2015

Rule was not a logical outgrowth of the proposal and suggested that the
agencies had provided adequate notice of the use of distance
limitations in the final rule.
    After the public comment period on the SNPRM closed, the U.S.
District Court for the Southern District of Texas remanded the 2015
Rule to the agencies for failing to comply with the APA, and the U.S.
District Court for the Southern District of Georgia remanded the 2015
Rule to the agencies after identifying substantive and procedural
errors with respect to numerous provisions, including the rule's
distance limitations. In response to these remands, this final rule
addresses many of the errors identified by those courts as well as the
concerns raised by some commenters regarding the distance-based
limitations used in the 2015 Rule.
a. The Distance-Based Limitations Were Not a Logical Outgrowth of the
Proposed Rule
    The agencies are aware that litigants challenging the 2015 Rule
alleged various APA deficiencies, including allegations that the
distance-based limitations were inserted into the final rule without