certainty as to which specific aquatic features are jurisdictional
tributaries, and which are not. Commenters should explain how any
suggestions are consistent with the Clean Water Act, applicable
caselaw, and the scientific literature regarding connectivity of
aquatic features.
3. Why do the agencies conclude all tributaries are ``waters of the
United States''?
    Assertion of jurisdiction over tributaries as defined in this
proposed rule is appropriate under Rapanos both as a legal matter and
as a scientific matter based on available science and the agencies'
professional judgment and field expertise. The agencies conclude based
on their scientific and technical expertise that tributaries, as
defined in the proposed rule, in a watershed are similarly situated and
have a significant nexus alone or in combination with other tributaries
because they significantly affect the chemical, physical, or biological
integrity of traditional navigable waters, interstate waters, or the
territorial seas.
a. Legal Basis for Defining All Tributaries as ``Waters of the United
States''
    In Rapanos, both the plurality opinion and Justice Kennedy's
opinion discussed the Court's prior opinion in Riverside Bayview to
begin their analysis of the scope of the CWA. Justice Scalia stated,
``In Riverside Bayview, we stated that the phrase [`waters of the
United States'] in the Act referred primarily to `rivers, streams, and
other hydrographic features more conventionally identifiable as
``waters''' than the wetlands adjacent to such features. 474 U.S., at
131 (emphasis added).'' Rapanos, 547 U.S. at 734. Justice Kennedy
began, ``As the plurality points out, and as Riverside Bayview holds,
in enacting the Clean Water Act Congress intended to regulate at least
some waters that are not navigable in the traditional sense. Ante at
12; Riverside Bayview, 474 U.S. at 133; see also SWANCC, supra, at
167.'' Id at 780. This conclusion is supported by ``the evident breadth
of congressional concern for protection of water quality and aquatic
ecosystems.'' Riverside Bayview, supra, at 133; see also Milwaukee v.
Illinois, 451 U.S. 304, 318 (1981) (describing the Act as ``an all-
encompassing program of water pollution regulation''). In Rapanos,
Justice Kennedy established a standard for determining whether wetlands
should be considered to possess the requisite nexus in the context of
assessing whether wetlands are jurisdictional: ``if the wetlands,
either alone or in combination with similarly situated [wet]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. While Justice Kennedy focused on
adjacent wetlands in light of the facts of the cases before him, it is
reasonable to utilize the same standard for tributaries. As discussed
in this preamble, based on a detailed examination of the scientific
literature, the agencies conclude that tributaries as they propose to
define them perform the requisite functions identified by Justice
Kennedy for them to be considered, as a category, to be ``waters of the
United States.'' Assertion of jurisdiction over tributaries with a bed
and banks and OHWM is also consistent with Rapanos because five
Justices did not reject the current regulations that assert
jurisdiction over non-navigable tributaries of traditional navigable
waters and interstate waters.
    The agencies analyzed the Report and other scientific literature to
determine whether tributaries to traditional navigable waters,
interstate waters, or the territorial seas have a significant nexus to
constitute ``waters of the United States'' under the Act such that it
is reasonable to assert CWA jurisdiction over all such tributaries as a
category by rule. The agencies' analysis of the available scientific
literature, including the Report, demonstrates through an ecological
rationale that tributaries draining to a traditional navigable water,
interstate water, or the territorial seas have a significant nexus to
such waters, especially because of their ability to transport
pollutants to such waters that would impair their chemical, physical,
or biological integrity.
    One of the primary purposes and functions of the CWA is to prevent
the discharge of petroleum wastes and other chemical wastes, biological
and medical wastes, sediments, nutrients and all other forms of
pollutants into the ``waters of the United States,'' because such
pollutants endanger the nation's

public health, drinking water supplies, shellfish, fin fish, recreation
areas, etc. Because the entire tributary system of the traditional
navigable, interstate waters or the territorial seas is interconnected,
pollutants that are dumped into any part of the tributary system
eventually are washed downstream to traditional navigable waters,
interstate waters, or the territorial seas where those pollutants
endanger public health and the environment.
    The CWA regulates and controls pollution at its source, in part
because most pollutants do not remain at the site of the discharge, but
instead flow and are washed downstream through the tributary system to
endanger drinking water supplies, fisheries, and recreation areas.
These fundamental facts about the movement of pollutants and the
interconnected nature of the tributary system demonstrate why all
tributaries of traditional navigable waters, interstate waters, and the
territorial seas, alone or in combination with other tributaries in a
watershed have a significant nexus with those downstream waters. The
significant nexus relating to pollution transport (or prevention of
such transport) from all tributaries of traditional navigable waters,
interstate waters, and the territorial seas to their downstream waters
in and of itself justifies the assertion of CWA jurisdiction over all
tributaries by rule.
b. The Agencies Conclude That Tributaries, as Defined in the Proposed
Rule, Have a Significant Nexus
    The finding of significant nexus is based on the chemical,
physical, and biological interrelationship between a water, the
tributary network, and traditional navigable waters, interstate waters,
and the territorial seas. Based on their scientific and technical
expertise, the agencies conclude that tributaries, as defined in
today's proposed rule, have a significant nexus and are appropriately
identified as jurisdictional by rule. Rapanos, 547 U.S. at 781-82 (J.
Kennedy). (For more discussion, see Appendix A).
(1) Tributaries Significantly Affect the Physical Integrity of (a)(1)
Through (a)(3) Waters
    Physical connections between tributaries and traditional navigable
waters, interstate waters, and the territorial seas result from the
hydrologic transport of numerous materials, including water, sediment
and organic matter (e.g., leaves, wood) from tributaries to downstream
waters. This transport affects the physical characteristics of
downstream waters. Tributaries, even when seasonally dry, are the
dominant source of water in most rivers, rather than direct
precipitation or groundwater input to main stem river segments.
    One of the primary functions of tributaries is transporting
sediment to downstream waters. Tributaries, particularly headwaters,
shape and maintain river channels by accumulating and gradually or
episodically releasing sediment and large woody debris into river
channels. Sediment transport is also provided by ephemeral streams.
Effects of the releases of sediment and large woody debris are
especially evident at tributary-river confluences, where
discontinuities in flow regime and temperature demonstrate physical
alteration of river structure and function by headwater streams.
    Tributaries have vitally important effects on the physical
integrity of (a)(1) through (a)(3) waters, contributing not only the
majority of the flow in these waters but affecting the structure of the
waters. These effects occur even when the tributaries flow infrequently
(such as ephemeral tributaries) and even when the tributaries are
significant distances from the (a)(1) through (a)(3) water (such as
some headwater tributaries). Tributaries provide flow to downstream
rivers necessary to support navigation. The agencies conclude that the
tributaries alone or together with other tributaries in a watershed
have a significant effect on the physical integrity of downstream
waters.
(2) Tributaries Significantly Affect the Chemical Integrity of (a)(1)
Through (a)(3) Waters
    Tributaries also influence the chemical composition of downstream
waters, through the transport and removal of chemical elements and
compounds, such as nutrients, ions, dissolved and particulate organic
matter, pollutants, and contaminants. Ecosystem processes in
tributaries transform, remove, and transport these substances to
downstream waters. In turn, these chemical compounds can influence
water quality, sediment deposition, nutrient availability, and biotic
functions in rivers. Because water flow is the primary mechanism by
which chemical substances are transported downstream, chemical effects
are closely related to hydrological connectivity. Long-distance
movement of contaminants provides another line of evidence for chemical
connectivity between tributaries and traditional navigable waters,
interstate waters, and the territorial seas and significantly affects
these waters.
    Within tributaries, there are processes that occur that transform
and export nutrients and carbon to downstream waters, serving important
source functions that influence the chemical integrity of downstream
waters. Organic carbon, in both dissolved and particulate forms,
exported from tributaries is consumed by downstream organisms. The
organic carbon that is exported downstream thus supports biological
activity (including metabolism) throughout the river network.
    Tributaries have important effects on the chemical integrity of
(a)(1) through (a)(3) waters, acting as both sinks and sources of
chemical substances. They provide sink functions by trapping chemicals
through absorption to sediments in the stream substrate (e.g.,
phosphorous adsorption to clay particles). They provide source
functions by transporting chemicals to downstream (a)(1) through (a)(3)
waters as chemicals dissolved in the waters or as chemicals attached to
suspended sediments. Thus the tributaries of a watershed, alone or in
combination, significantly affect the chemical integrity of downstream
waters.
(3) Tributaries Significantly Affect the Biological Integrity of (a)(1)
Through (a)(3) Waters
    Tributaries, including intermittent and ephemeral streams, are
critical in the life cycles of many organisms capable of moving
throughout river networks. In fact, many organisms, such as anadromous
salmon, have complex life cycles which involve migration through the
river network, from headwaters to downstream rivers and oceans and
back, over the course of their lives. Anadromous fish spend the
majority of their life cycles in saltwater, but migrate upstream to
inland freshwater systems in order to spawn and reproduce. More
generally, in addition to providing critical habitat for complex life
cycle completion, tributaries provide refuge from predators and adverse
physical conditions in rivers, and they are reservoirs of genetic- and
species-level diversity. These connections between tributaries and
(a)(1) through (a)(3) waters significantly influence the biologic
integrity of these waters.
    Tributaries have important effects on the biological integrity of
(a)(1) through (a)(3) waters, contributing materials to downstream food
networks and supporting populations for aquatic species, including
economically important species such as salmon, etc.,

and other essential habitat needs for species that utilize both
tributaries and downstream (a)(1) through (a)(3) waters. These effects
occur even when the tributaries flow infrequently (such as ephemeral
tributaries) and even when the tributaries are large distances from the
(a)(1) through (a)(3) water (such as some headwater tributaries). When
all the tributaries in a watershed are considered together, these
effects are significant.
(4) Small, Intermittent, and Ephemeral Tributaries Significantly Affect
the Chemical, Physical, and Biological Integrity of (a)(1) Through
(a)(3) Waters
    As discussed above, the agencies conclude that tributaries,
including headwaters, intermittent, and ephemeral streams, and
especially when all tributaries in a watershed are considered in
combination, have a significant nexus to traditional navigable waters,
interstate waters, or the territorial seas based on their contribution
to the chemical, physical, and biological integrity of (a)(1) through
(a)(3) waters. Tributaries, including headwater streams, within a
watershed draining to a traditional navigable water, interstate water,
or the territorial seas collectively shape the chemical, physical, and
biological integrity of (a)(1) through (a)(3) waters.
    Tributaries that are small, flow infrequently, or are a substantial
distance from the nearest (a)(1) through (a)(3) water (e.g., headwater
perennial, intermittent, and ephemeral tributaries) are essential
components of the tributary network and have important effects on the
chemical, physical, and biological integrity of (a)(1) through (a)(3)
waters, contributing many of the same functions downstream as larger
streams. When their functional contributions to the chemical, physical,
and biological conditions of downstream waters are considered at a
watershed scale, the scientific evidence supports a legal determination
that they meet the ``significant nexus'' standard articulated by
Justice Kennedy in Rapanos.
(5) Tributary Lakes, Ponds, and Wetlands Significantly Affect the
Chemical, Physical, and Biological Integrity of (a)(1) Through (a)(3)
Waters
    Although the above discussion refers primarily to stream
tributaries, lake, pond and wetland tributaries also have the same or
similar connections and functions that significantly affect (a)(1)
through (a)(3) waters. Lakes and ponds that contribute surface water to
downstream (a)(1) through (a)(3) waters satisfy the agencies'
definition of tributary. They may be at the headwaters of the tributary
network (e.g., a lake with no stream inlets that has an outlet to the
tributary network) or located outside of the headwaters, or farther
downstream from the headwaters (e.g., a lake with both a stream inlet
and a stream outlet to the tributary network). Similarly, wetland
tributaries are wetlands that are located within the stream channel
itself or that form the start of the stream channel, such as channel-
origin wetlands that are part of the headwaters of the tributary
network.
    As noted above, while these wetlands may function as part of the
``tributary network,'' the agencies are seeking comment on whether it
would provide greater regulatory clarity to exclude such wetlands from
the definition of ``tributary'' because they generally lack a defined
bed, bank and OHWM. These features are well understood by the public
and agency field staff and have traditionally been the defining
characteristics of tributaries. Rather, wetlands in headwaters or
connecting tributaries would remain jurisdictional as adjacent waters
under the definition of ``adjacent'' and its supporting terms (e.g.,
neighboring, floodplain, and riparian area) in this proposal.
    Tributary lakes and ponds serve many important functions that
affect the chemical, physical, and biological conditions downstream.
Lakes can store floodwaters, sediment, and nutrients, as these
materials have the opportunity to settle out, at least temporarily, as
water moves through the lake downstream. Lakes, as with other
tributaries, can also contribute flow, nutrients, sediment, and other
materials downstream.
(6) Man-Made or Man-Altered Tributaries Significantly Affect the
Chemical, Physical, and Biological Integrity of (a)(1) Through (a)(3)
Waters
    This proposal expressly states that a tributary, including
wetlands, can be a natural, man-altered, or man-made water body and
includes waters such as rivers, streams, lakes, impoundments, canals,
and ditches that meet the definition of tributary and are not excluded
from the definition of ``waters of the United States'' by paragraphs
(b)(3) and (b)(4) of the proposed rule. The agencies' proposed rule
clarifies that man-made and man-altered tributaries are ``waters of the
United States'' because man-made and man-altered tributaries perform
many of the same functions as natural tributaries, especially the
conveyance of water that carries nutrients, pollutants, and other
substances to traditional navigable waters, interstate waters, or the
territorial seas. Man-made and man-altered tributaries also provide
corridors for movement of organisms between headwaters and traditional
navigable waters, interstate waters, or the territorial seas. The
significant nexus between a tributary and a traditional navigable
water, interstate water, or the territorial seas is not broken where
the tributary flows through a culvert or other structure. The
scientific literature recognizes that features that convey water,
whether they are natural, man-made, or man-altered, provide the
connectivity between streams and downstream rivers.
    Tributary ditches and other man-made or man-altered waters, if they
meet the definition of ``tributary,'' have a significant nexus to
(a)(1) through (a)(3) waters due to their effects on the chemical,
physical, or biological integrity of those downstream waters. As
described above, tributaries of all flow regimes have a significant
nexus to downstream (a)(1) through (a)(3) waters. Due to the often
straightened and channelized nature of ditches, these tributaries
quickly move water downstream to (a)(1) through (a)(3) waters. Ditches
and canals, like other tributaries, export sediment, nutrients, and
other materials downstream. Due to their often channelized nature,
ditches are very effective at transporting water and these materials,
including nitrogen, downstream. It is the agencies' position that
ditches that meet the definition of tributary (which does not include
ditches excluded under paragraphs (b)(3) and (b)(4)) provide the same
chemical, physical, and biological functions as other water bodies
defined as tributaries under the proposed rule.

G. Adjacent Waters

    The agencies propose to revise the existing jurisdictional category
of ``adjacent wetlands,'' which currently limits consideration to only
wetlands, to include ``adjacent waters.'' The proposed ``adjacent
waters'' category would replace ``adjacent wetlands'' and would include
wetlands and other waterbodies that meet the proposed definition of
adjacent, including ``neighboring.'' To be jurisdictional, it would be
necessary to determine that a wetland or other waterbody meets the
definition of ``adjacent'' water under proposed paragraph (a)(6).
Adjacent waters are integrally linked to the chemical, physical, or
biological functions of the (a)(1) through (a)(5) waterbodies to which
they are adjacent. Waters adjacent to (a)(1) through (a)(3) waters have
a significant nexus to those (a)(1) through (a)(3) waters. Waters
adjacent to impoundments, (a)(4) and tributaries, (a)(5), are
integrally linked to

the chemical, physical, or biological functions of the impoundments or
tributaries and, through those waters, are integrally linked to the
chemical, physical or biological functions of traditional navigable
waters, interstate waters or the territorial seas. As such, where
waterbodies are adjacent to (a)(4) or (a)(5) waters, they also have a
significant nexus to (a)(1) through (a)(3) waters. See Appendix A,
Scientific Evidence (Part I, Discussion of Major Conclusions 2.B-C;
Part II, ii) and Appendix B, Legal Analysis.
    The proposed rule proposes to change ``adjacent wetlands'' to
``adjacent waters'' so that water bodies such as ponds and oxbow lakes,
as well as wetlands, adjacent to jurisdictional waters are ``waters of
the United States'' by rule. Second, the proposed rule adds a
definition of the term ``neighboring,'' a term which appears in the
existing definition of ``adjacent.'' The agencies propose a definition
for ``neighboring'' to identify those adjacent waters that the agencies
concluded have a significant nexus to (a)(1) through (a)(3) waters. To
bring greater clarity to the meaning of ``neighboring,'' the proposed
rule adds scientifically-based definitions for the terms ``riparian
area'' and ``floodplain'' to define the lateral reach of the term
``neighboring.'' Under the proposed rule, all waters, including
wetlands, adjacent to a water identified in paragraphs (a)(1) through
(5); would be ``waters of the United States.'' The term adjacent means
bordering, contiguous or neighboring. Waters, including wetlands,
separated from other waters of the United States by man-made dikes or
barriers, natural river berms, beach dunes and the like are ``adjacent
waters.'' The term neighboring, for purposes of the term ``adjacent,''
includes waters located within the riparian area or floodplain of a
water identified in paragraphs (a)(1) through (5), or waters with a
shallow subsurface hydrologic connection or confined surface hydrologic
connection to such a jurisdictional water. The term riparian area means
an area bordering a water where surface or subsurface hydrology
directly influence the ecological processes and plant and animal
community structure in that area. Riparian areas are transitional areas
between aquatic and terrestrial ecosystems that influence the exchange
of energy and materials between those ecosystems. Finally, the term
floodplain means an area bordering inland or coastal waters that was
formed by sediment deposition from such water under present climatic
conditions and is inundated during periods of moderate to high water
flows.
1. What are ``adjacent waters'' under the proposed rule?
    ``Adjacent waters'' are wetlands, ponds, lakes and similar water
bodies that provide similar functions which have a significant nexus to
traditional navigable waters, interstate waters, and the territorial
seas. These include waters and wetlands that are adjacent to
traditional navigable waters, interstate waters, and the territorial
seas as well as waters and wetlands adjacent to other jurisdictional
waters such as tributaries and impoundments. The inclusion of adjacent
waters in this category is supported by the Report, the collective body
of scientific literature, the agencies' growing body of scientific and
technical knowledge and practical expertise addressing the connectivity
and ecological interactions of these waters on (a)(1) through (a)(3)
waters, and by the determination made in this rulemaking that all
adjacent waters in a watershed have a significant nexus with their
traditional navigable waters, interstate waters or the territorial
seas.
    Under the existing rule, only wetlands adjacent to ``waters of the
United States'' are defined as ``waters of the United States.'' As
noted in San Francisco Baykeeper v. Cargill Salt, 481 F.3d 700 (9th
Cir. 2007), this provision of the agencies' regulations only defines
adjacent wetlands, not adjacent ponds, as ``waters of the United
States.'' Prior to SWANCC, adjacent non-wetland waters were often
jurisdictional under the ``other waters,'' or ``(a)(3)'' provision of
the existing regulations which the agencies are proposing to eliminate.
Waters, including wetlands, that meet the proposed definition of
adjacency, including the new proposed definition of neighboring, have a
significant nexus to (a)(1) through (a)(3) waters, and this proposed
rule would include all adjacent waters, including wetlands, as ``waters
of the United States'' by rule.
    The existing definition of ``adjacent'' would be generally retained
under today's proposal, with a clarification with respect to an
existing provision addressing wetlands adjacent to other wetlands. The
proposed rule states that the term adjacent means bordering, contiguous
or neighboring. Waters, including wetlands, separated from other waters
of the United States by man-made dikes or barriers, natural river
berms, beach dunes and the like are ``adjacent waters.'' Within the
definition of ``adjacent,'' the terms bordering and contiguous are well
understood, and for continuity and clarity the agencies would continue
to interpret and implement those terms consistent with existing policy
and practice.
    The proposed rule also contains for the first time a definition of
the term ``neighboring.'' The term ``neighboring'' has generally been
interpreted broadly in practice. The agencies provide a regulatory
definition of ``neighboring'' that captures those waters that in
practice the agencies have identified as having a significant effect on
the chemical, physical, and biological integrity of traditional
navigable waters, interstate waters, or the territorial seas.
``Neighboring'' is defined as including waters located within the
riparian area or floodplain of a water identified in paragraphs (a)(1)
through (5), or waters with a confined surface or shallow subsurface
hydrologic connection to such a jurisdictional water.
    The terms ``riparian area'' and ``floodplain'' are also defined to
further clarify how the agencies interpret the term ``neighboring.''
Those new terms are found at paragraphs (c)(1) through (c)(4) of the
proposed rule. The agencies emphasize that these terms help to identify
waters, including wetlands, that may be ``adjacent'' and would,
therefore, be ``waters of the United States'' under this proposed rule.
Absolutely no uplands located in ``riparian areas'' and ``floodplains''
can ever be ``waters of the United States'' subject to jurisdiction of
the CWA.
    Most waters, including wetlands, that are neighboring to a water
body are found within its riparian zone or floodplain. However, there
are some neighboring waters that might be located outside of the
riparian zone or floodplain, such as wetlands immediately next to a
highly incised and manipulated stream that no longer has a riparian
area or a floodplain. Waters, including wetlands, determined to have a
shallow subsurface hydrologic connection or confined surface hydrologic
connection to an (a)(1) through (a)(5) water would also be ``waters of
the United States'' by rule as adjacent waters falling within the
definition of ``neighboring.''
    In circumstances where a particular water body is outside of the
floodplain and riparian area of a tributary, but is connected by a
shallow subsurface hydrologic connection or confined surface hydrologic
connection with such tributary, the agencies will also assess the
distance between the water body and tributary in determining whether or
not the water body is adjacent. ``Adjacent'' as defined in the
agencies' regulations has always included an element of reasonable
proximity. See Riverside Bayview, 474 at

133-34 (``Following the lead of the Environmental Protection Agency,
see 38 FR 10834 (1973), the Corps has determined that wetlands adjacent
to navigable waters do as a general matter play a key role in
protecting and enhancing water quality: . . . `For this reason, the
landward limit of Federal jurisdiction under Section 404 must include
wetlands that are in reasonable proximity to other waters of the United
States, as these wetlands are part of this aquatic system.' '' quoting
42 FR 37128, July 19, 1977). Therefore, the determination of whether a
particular water meets the definition of ``neighboring'' because the
water is connected by a shallow subsurface or confined surface
hydrologic connection is made in the context of the terms
``neighboring'' and ``adjacent'' as used in the regulation.
    The element of reasonable proximity is informed by the scientific
literature, supplemented by agency practice, which leads to a
recognition of the role of hydrologic connections in supporting a
significant chemical, physical, and biological relationship between
water bodies, but this relationship can be reduced as the distance
between water bodies increases. The agencies recognize that in specific
circumstances, the distance between water bodies may be sufficiently
far that even the presence of a hydrologic connection may not support
an adjacency determination.
    While the agencies' best professional judgment has always been a
factor in determining whether a particular wetland is ``adjacent''
under the existing definition, the agencies recognize that this may
result in some uncertainty as to whether a particular water connected
through confined surface or shallow subsurface hydrology is an
``adjacent'' water. The agencies therefore request comment on whether
there are other reasonable options for providing clarity for
jurisdiction over waters with these types of connections.
    Options could include asserting jurisdiction over all waters
connected through a shallow subsurface hydrologic connection or
confined surface hydrologic connection regardless of distance;
asserting jurisdiction over adjacent waters only if they are located in
the floodplain or riparian zone of a jurisdictional water; considering
only confined surface connections but not shallow subsurface
connections for purposes of determining adjacency; or establishing
specific geographic limits for using shallow subsurface or confined
surface hydrological connections as a basis for determining adjacency,
including, for example, distance limitations based on ratios compared
to the bank-to-bank width of the water to which the water is adjacent.
The agencies note that under the proposed rule any waters not fitting
within (a)(1) through (a)(6) categories would instead be treated as
``other waters.''
    Both confined surface and shallow subsurface connections are forms
of direct hydrologic connections between adjacent waters and (a)(1)
through (a)(5) waters. For purposes of this rule, confined surface
connections consist of permanent, intermittent or ephemeral surface
connections through directional flowpaths, such as (but not limited to)
swales, gullies, rills, and ditches. In some cases, these connections
will be a result of ``fill and spill'' hydrology. A directional
flowpath is a path where water flows repeatedly from the wetland or
open water to the nearby ``water of the United States'' that at times
contains water originating in the adjacent wetland or open water as
opposed to just directly from precipitation.
    For the purposes of this rule, ``fill and spill'' describes
situations where wetlands or open waters fill to capacity during
intense precipitation events or high cumulative precipitation over time
and then spill to the downstream jurisdictional water. Report at 5-62
(citing T.C. Winter and D.O. Rosenberry, ``Hydrology of Prairie Pothole
Wetlands during Drought and Deluge: A 17-year Study of the Cottonwood
Lake Wetland Complex in North Dakota in the Perspective of Longer Term
Measured and Proxy Hydrological Records,'' Climatic Change 40:189-209
(1998); S.G. Leibowitz, and K.C. Vining, ``Temporal connectivity in a
prairie pothole complex,'' Wetlands 23:13-25 (2003)). Water connected
through such flows originates from the adjacent wetland or open water,
travels to the downstream jurisdictional water, and is connected to
those downstream waters by swales or other directional flowpaths on the
surface. Surface hydrologic connections via physical features or
discrete features described above allow for confined, direct hydrologic
flows between an adjacent water and the (a)(1) through (a)(5) water
that it neighbors.
    A shallow subsurface hydrologic connection is lateral water flow
through a shallow subsurface layer, such as can be found, for example,
in steeply sloping forested areas with shallow soils, or in soils with
a restrictive layer that impedes the vertical flow of water, or in
karst systems, especially karst pans. K.J. Devito, et al.,
``Groundwater-Surface Water Interactions in Headwater Forested Wetlands
of the Canadian Shield,'' Journal of Hydrology 181:127-47 (1996); M.A.
O'Driscoll, and R.R. Parizek, ``The Hydrologic Catchment Area of a
Chain of Karst Wetlands in Central Pennsylvania, USA,'' Wetlands
23:171-79 (2003); B.J. Cook, and F.R. Hauer, ``Effects of Hydrologic
Connectivity on Water Chemistry, Soils, and Vegetation Structure and
Function in an Intermontane Depressional Wetland Landscape,'' Wetlands
27:719-38 (2007).
    A shallow subsurface connection also exists, for example, when the
adjacent water and neighboring (a)(1) through (a)(5) water are in
contact with the same shallow aquifer. Shallow subsurface connections
may be found both within the ordinary root zone and below the ordinary
root zone (below 12 inches), where other wetland delineation factors
may not be present. A combination of physical factors may reflect the
presence of a shallow subsurface connection, including (but not limited
to) stream hydrograph (for example, when the hydrograph indicates an
increase in flow in an area where no tributaries are entering the
stream), soil surveys (for example, exhibiting indicators of high
transmissivity over an impermeable layer), and information indicating
the water table in the stream is lower than in the shallow subsurface.
    Shallow subsurface connections are distinct from deeper groundwater
connections, which do not satisfy the requirement for adjacency, in
that the former exhibit a direct connection to the water found on the
surface in wetlands and open waters. Water does not have to be
continuously present in the confined surface or shallow subsurface
hydrologic connection and the flow between the adjacent water and the
jurisdictional water may move in one or both directions. While they may
provide the connection establishing jurisdiction, these shallow
subsurface flows are not ``waters of the United States.''
    For waters outside of the riparian area or floodplain, confined
surface hydrologic connections (as described above) are the only types
of surface hydrologic connections that satisfy the requirements for
adjacency. Waters outside of the riparian area or floodplain that lack
a shallow subsurface hydrologic connection or a confined surface
hydrologic connection would be analyzed as ``other waters'' under
paragraph (a)(7) of the proposed rule.
    Application of the terms ``riparian area,'' ``floodplain,'' and
``hydrologic connection'' would be based in part on best professional
judgment and experience applied to the definitions contained in this
rule. The new definitions of riparian area and floodplain are designed
to provide greater consistency, clarity, and certainty in determining
the

circumstances under which a particular water meets the definition of
the term adjacent. The addition of these two terms to the definition of
``neighboring'' is based on the scientific literature and agencies'
knowledge of and expertise on river systems, which shows that water
bodies such as wetlands, ponds, and oxbow lakes located within the
riparian areas and floodplains of (a)(1) through (a)(5) waters
generally have substantial hydrologic and ecologic connections with the
waters that they neighbor.
    These proposed definitions are adapted from scientific definitions
using the concepts that are most relevant and useful in the context of
the CWA. Use of the floodplain in characterizing the term
``neighboring'' is intended to provide greater clarity and
predictability in the determination of when waters are adjacent. The
scientific literature clearly demonstrates the enhanced hydrologic
connectivity that is present between a tributary and waters within the
floodplain of that tributary. There is, however, variability in the
size of the floodplain, which is dependent on factors such as the
flooding frequency being considered, size of the tributary, and
topography. As a general matter, large tributaries in low gradient
topography will generally have large floodplains (e.g., the lower
Mississippi Delta) whereas small headwater streams located in steep
gradients will have the smallest floodplains. It may thus be
appropriate for the agencies to consider a floodplain associated with a
lower frequency flood when determining adjacency for a smaller stream,
and to consider a floodplain associated with a higher frequency flood
when determining adjacency for a larger stream. When determining
whether a water is located in a floodplain, the agencies will use best
professional judgment to determine which flood interval to use (for
example, 10 to 20 year flood interval zone). The agencies request
comment on whether the rule text should provide greater specificity
with regard to how the agencies will determine if a water is located in
the floodplain of a jurisdictional water.
    As noted above, the agencies retain the general existing definition
of adjacency and have never interpreted the term to include wetlands
that are a great distance from a jurisdictional water. The agencies
intend to similarly interpret the new definition of ``neighboring.''
This new definition is designed to provide greater clarity by
identifying specific areas and characteristics for jurisdictional
adjacent waters, but the agencies request comment for additional
clarification. Commenters should support where possible from scientific
literature any suggestions for additional clarification of current
explicit limits on adjacency, such as a specific distance or a specific
floodplain interval.
    The agencies seek comment on specific options for establishing
additional precision in the definition of ``neighboring'' through:
explicit language in the definition that waters connected by shallow
subsurface hydrologic or confined surface hydrologic connections to an
(a)(1) through (a)(5) water must be geographically proximate to the
adjacent water; circumstances under which waters outside the floodplain
or riparian zone are jurisdictional if they are reasonably proximate;
support for or against placing geographic limits on what waters outside
the floodplain or riparian zone are jurisdictional; determining that
only waters within the floodplain, only waters within the riparian
area, or only waters within the floodplain and riparian area (but not
waters outside these areas with a shallow subsurface or confined
surface hydrologic connection) are adjacent; identification of
particular floodplain intervals within which waters would be considered
adjacent; and any other scientifically valid criteria, guidelines or
parameters that would increase clarity with respect to neighboring
waters.
    Finally, the agencies are also proposing to delete the
parenthetical from the existing ``adjacent wetlands'' regulatory
provision The phrase ``other than waters that are themselves wetlands''
was intended to preclude asserting CWA jurisdiction over wetlands that
were simply adjacent to another wetland (such as an ``isolated''
wetland, as opposed to a wetland adjacent to a tributary). However, in
practice some wetlands that were indeed adjacent to a tributary were
found to not meet the definition of ``adjacent'' simply because another
adjacent wetland was located between the adjacent wetland and the
tributary. With this proposed change, the agencies intend to ensure
that all waters that meet the proposed definition of ``adjacent'' are
``waters of the United States,'' regardless of whether or not another
adjacent water is located between those waters and the tributary.
    If, for example, one wetland is in the riparian area of a
``tributary'' as defined in today's proposed rule, and a different
wetland is in the floodplain of that tributary, both wetlands would
meet the definition of ``adjacent'' and be ``waters of the United
States,'' even if the riparian wetland is located between the
floodplain wetland and the tributary. Waters located near an adjacent
water but which are not themselves (independently) adjacent to an
(a)(1) through (a)(5) water would, under the proposed rule, not be
regulated under (a)(6). However, waters, including wetlands, that are
adjacent to a wetland that meets the definition of a tributary would be
considered adjacent waters.
2. Why do the agencies conclude that adjacent waters are ``waters of
the United States?''
a. Legal Basis for Defining All Adjacent Waters as ``Waters of the
United States''
    For those wetlands adjacent to traditional navigable waters,
Justice Kennedy stated in Rapanos that the agencies' existing
regulation ``rests upon a reasonable inference of ecologic
interconnection, and the assertion of jurisdiction for those wetlands
is sustainable under the Act by showing adjacency alone.'' 547 U.S. at
780. For all other adjacent waters, including adjacent wetlands,
Justice Kennedy has provided a framework for establishing categories of
waters which are per se ``waters of the United States.'' First, he
provided that wetlands are jurisdictional if they ``either alone or in
combination with similarly situated [wet]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. While the issue was not before the Supreme Court, it is
reasonable to also assess whether non-wetland waters have a significant
nexus, as Justice Kennedy's opinion makes clear that a significant
nexus is the touchstone for CWA jurisdiction. Justice Kennedy also
stated that the agencies could through regulation or adjudication
identify categories of waters that ``are likely, in the majority of
cases, to perform important functions for an aquatic system
incorporating navigable waters.'' 547 U.S. at 780-81.
    Adjacent waters as defined in today's proposed rule, alone or in
combination with other adjacent waters in a watershed that drain to a
traditional navigable water, interstate water or the territorial seas,
significantly affect the chemical, physical, or biological integrity of
those waters. Waters that are adjacent to (a)(1) through (a)(5) waters,
including wetlands, oxbow lakes and adjacent ponds, are integral parts
of stream networks because of their ecological functions and how they
interact with each other, and with downstream traditional navigable
waters, interstate waters, or the territorial seas. In other words,
tributaries and their adjacent waters, and the traditional navigable
waters,

interstate waters, and territorial seas to which those waters flow, are
an integrated ecological system, and discharges of pollutants,
including discharges of dredged or fill material, into these components
of that ecological system, must be regulated under the CWA to restore
and maintain the chemical, physical, and biological integrity of these
waters.
    The agencies' proposed rule is consistent with the statute, the
Supreme Court's decisions, the best available science, and scientific
and technical expertise. See both Appendices A and B.
b. Adjacent Waters Under This Proposed Rule Have a Significant Nexus to
(a)(1) Through (a)(3) Waters
    The agencies' proposal to determine ``adjacent waters'' to be
jurisdictional by rule is supported by the substantial chemical,
physical, and biological relationship between adjacent waters, alone or
in combination with similarly situated waters, and (a)(1) through
(a)(5) waters. Adjacent wetlands and other adjacent waters such as
ponds and oxbow lakes perform important functions for the nearby
streams and lakes, and these functions are significant for the
chemical, physical, and biological integrity of adjacent and downstream
waters. See Appendix A.
    One reason why the agencies propose in this rulemaking that all
adjacent waters have a significant nexus with their traditional
navigable waters, interstate waters, or the territorial seas is closely
related to a primary reason (explained above) why all tributaries of
navigable and interstate waters have a significant nexus with those
waters. That is, all adjacent waters should be jurisdictional by rule
because the discharge of many pollutants (such as nutrients, petroleum
wastes and other toxic pollutants) into adjacent waters often flow into
and thereby pollute the traditional navigable waters, interstate
waters, and the territorial seas.
    Based on science and agency expertise, the agencies conclude that
adjacent waters, as defined in the proposed rule, ``are likely, in the
majority of cases, to perform important functions for an aquatic system
incorporating navigable waters.'' Rapanos, 547 U.S. at 781-82. The
agencies identified the characteristics of adjacent waters that as a
class have a significant nexus to (a)(1) through (a)(3) waters: They
are waters that are bordering to or are contiguous with (a)(1) through
(a)(5) waters, including wetlands; they are waters that lie within the
riparian area or floodplain of (a)(1) through (a)(5) waters; or they
are waters that have a shallow subsurface or confined surface
hydrologic connection with (a)(1) through (a)(5) waters. These
characteristics ensure that the adjacent waters are part of ``an
aquatic system incorporating navigable waters,'' 547 U.S. at 781-82;
and that they perform important functions to maintain the chemical,
physical, or biological integrity of (a)(1) through (a)(3) waters.
    In showing chemical, physical, and biological connections between
adjacent waters and other jurisdictional waters, adjacent waters,
including wetlands, may be separated by land or other features not
regulated under the CWA, but those intervening uplands do not eliminate
or impede the functional interactions between (a)(1) through (a)(5)
waters and the waters, including wetlands, that are adjacent to them.
For instance, two waters may be separated by upland but be connected
through surface or shallow subsurface connections with water and
chemicals readily exchanging between them. Similarly, uplands
separating two waters may not act as a barrier to species that rely on
and that regularly move between the two waters. Therefore, the proposed
rule reflects an understanding that adjacent waters affect the
chemical, physical, and biological integrity of waters to which they
are adjacent and to (a)(1) through (a)(3) waters even where the two
waters may be separated by features that are not jurisdictional, such
as uplands, berms, roads, levees, and similar features. The presence of
these features does not extinguish jurisdiction, a conclusion contained
in the agencies' existing regulation at 33 CFR 328.3(c).
(1) Riparian and Floodplain Waters Significantly Affect the Chemical,
Physical, and Biological Integrity of (a)(1) Through (a)(3) Waters
    Riparian and floodplain waters, including wetlands, that are
adjacent to (a)(1) through (a)(3) waters play an integral role in
maintaining the chemical, physical, and biological integrity of those
waters. In addition, riparian and floodplain waters, including
wetlands, that are adjacent to (a)(4) and (a)(5) waters provide an
important role in maintaining the chemical, physical, and biological
integrity of traditional navigable waters, interstate waters, and the
territorial seas. Among the ways in which riparian and floodplain
waters, including wetlands, that are adjacent to (a)(4) and (a)(5)
waters significantly affect the chemical, physical, or biological
integrity of traditional navigable waters, interstate waters, and the
territorial seas is by significantly affecting the chemical, physical,
and biological integrity of the (a)(4) and (a)(5) waters to which they
are adjacent, and those waters in turn significantly affect the
chemical, physical, or biological integrity of traditional navigable
waters, interstate waters, and the territorial seas.
    (2) Waters, Including Wetlands, Determined To Have a Confined
Surface or a Shallow Subsurface Hydrologic Connection Significantly
Affect the Chemical, Physical, and Biological Integrity of (a)(1)
Through (a)(3) Waters.
    The proposed rule includes as adjacent those waters that are
``neighboring'' because they possess a shallow subsurface or confined
surface hydrologic connection to a jurisdictional water, and therefore
can exchange water, along with chemicals and organisms within that
water, with an (a)(1) through (a)(5) water, and subsequently have a
significant effect, particularly in combination with other adjacent
waters in the watershed, on the chemical, physical, or biological
integrity of a downstream traditional navigable water, interstate
water, and the territorial seas.
    Confined surface connections that provide a discrete pathway for
water to be exchanged between the potentially adjacent wetland or water
and an (a)(1) through (a)(5) water present the clearest evidence of a
hydrologic connection. Shallow subsurface connections are also
relevant, yet are more difficult to identify and document. Evidence
shows that waters, including wetlands, located outside of the riparian
area or floodplain, but which still have a shallow subsurface or
confined surface hydrologic connection to an (a)(1) through (a)(5)
water, will have a significant nexus to downstream (a)(1) through
(a)(3) waters. Note that nothing under the proposed rule would cause
the shallow subsurface connections themselves to become jurisdictional.
    Examples of confined surface water hydrologic connections that
demonstrate adjacency are swales, gullies, and rills. The frequency,
duration, and volume of flow associated with these confined surface
connections can vary greatly depending largely on factors such as
precipitation, snowmelt, landforms, soil types, and water table
elevation. It is the presence of this hydrologic connection which
provides the opportunity for neighboring waters to influence the
chemical, physical, or biological integrity of (a)(1) through (a)(5)
waters.
    In circumstances where a particular water is outside of the
floodplain and riparian area of a jurisdictional water, a connection
can be established by confined surface or shallow subsurface

hydrology that makes the water neighboring, and thus adjacent. The
scientific literature recognizes the role of hydrologic connections in
supporting a substantial chemical, physical, or biological relationship
between water bodies, but this relationship can be reduced as the
distance between water bodies increases because of various factors,
such as soil characteristics, geology, climate, precipitation patterns,
etc. The distance between water bodies may be sufficiently great that
even the presence of an apparent hydrologic connection may not support
an adjacency determination. The greater the distance, the less
likelihood that there is an actual shallow subsurface or confined
surface hydrologic connection, because of the greater potential for the
water to infiltrate the soil to deeper groundwater, or for transmission
losses in any gully or swale (for example) that may appear to be
hydrologic connections. Within a watershed, wetlands and open waters
that are closer to tributaries will have a higher probability of being
hydrologically connected and of being determined adjacent than more
distant waters, assuming that conditions governing type and quantity of
flows (e.g., slope, soil, and aquifer permeability) are similar. Report
at 5-2. A determination of adjacency based on shallow subsurface or
confined surface hydrologic connection outside the riparian area or
floodplain requires clear documentation.

H. ``Other Waters''

    The ``other waters'' paragraph of the proposed rule is at (a)(7).
To be clear, these ``other waters'' are not jurisdictional as a single
category; rather, as the proposed rule language states, ``other
waters'' are jurisdictional provided that they are found, on a case-
specific basis, to have a significant nexus to an (a)(1) through (a)(3)
water. Thus, the introductory phrase ``on a case-specific basis'' is
designed to signal clearly that this provision of the definition of
``waters of the United States'' does not mean ``other waters'' are
``waters of the United States'' by definition in the same way as those
defined as jurisdictional in proposed paragraphs (a)(1) through (a)(6).
    ``Other waters'' will be evaluated either individually, or as a
group of waters where they are determined to be similarly situated in
the region. Waters are similarly situated where they perform similar
functions and are located sufficiently close together or when they are
sufficiently close to a jurisdictional water. How these ``other
waters'' are aggregated for a case-specific significant nexus analysis
depends on the functions they perform and their spatial arrangement
within the ``region'' or watershed. For other waters that perform
similar functions, their landscape position within the watershed (i.e.,
the ``region'') relative to each other or to a jurisdictional water is
generally the determinative factor for aggregating waters in a
significant nexus analysis, which will focus on the degree to which the
functions provided by those ``other waters'' affect the chemical,
physical, or biological integrity of (a)(1) through (a)(3) waters and
whether such effects are significant. See Appendix A, Scientific
Evidence (Part I, Discussion of Major Conclusions 2.C; Part II, iii)
and Appendix B, Legal Analysis.
    Significant nexus is proposed to be defined to mean that a water,
including wetlands, either alone or in combination with other similarly
situated waters in the region (i.e., the watershed that drains to the
nearest water identified in paragraphs (a)(1) through (a)(3) of this
section), significantly affects the chemical, physical, or biological
integrity of a water identified in paragraphs (a)(1) through (a)(3) of
this section. For an effect to be significant, it must be more than
speculative or insubstantial. Other waters, including wetlands, are
similarly situated when they perform similar functions and are 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 with regard to their effect on the chemical, physical, or
biological integrity of a water identified in paragraphs (a)(1) through
(a)(3).
    Other waters with a significant nexus can be found to be
jurisdictional on a case-specific basis where these waters do not fit
within the definition of another of the proposed categories of ``waters
of the United States'' under paragraphs (a)(1) through (a)(6) and are
not excluded from the definition of ``waters of the United States''
under proposed section (b).
    A significant nexus analysis may be based on a particular water
alone or based on the effect that the water has in combination with
other similarly situated waters in the region. Where effects will be
analyzed in combination, the agencies will aggregate those effects. The
agencies propose to interpret the ``region'' within which similarly
situated waters would be aggregated as the watershed that drains to the
nearest traditional navigable water, interstate water, or the
territorial seas.
    For purposes of analyzing whether an ``other water'' has a
significant nexus, the agencies are proposing that ``other waters'' are
similarly situated if they perform similar functions and they are
either (1) located sufficiently close together so that they can be
evaluated as a single landscape unit with regard to their effect on the
chemical, physical, or biological integrity of a water identified in
paragraphs (a)(1) through (a)(3), or (2) located sufficiently close to
a ``water of the United States'' for such an evaluation of their
effect. These criteria are explained in a subsequent section.
    Consistent with Justice Kennedy's opinion in Rapanos, the agencies
propose today and are soliciting comment on establishing a case-
specific analysis of whether ``other waters,'' including wetlands, that
do not meet the criteria for any of the proposed jurisdictional
categories in (a)(1) through (a)(6) and are not proposed to be excluded
by rule under section (b), are susceptible to a case-specific analysis
of whether they alone, or in combination with other similarly situated
waters, have a significant nexus to a traditional navigable water, an
interstate water, or the territorial seas, and therefore are ``waters
of the United States.''
1. Significant Nexus Analysis for ``Other Waters''
a. ``Other Waters''
    ``Other waters'' are those waters, including wetlands, that are
subject to a case-specific significant nexus determination, and do not
meet the criteria of any of the categories of waters in (a)(1) through
(a)(6), and also are not one of the waters and features excluded from
the definition of ``waters of the United States'' in section (b). In
the existing regulation, there is a non-exclusive list of the types of
``other waters'' which may be found to be ``waters of the United
States.'' The agencies do not propose to re-promulgate this list of
``other waters'' because it is unnecessary and has led to confusion
where it has been incorrectly read as an exclusive list.
    Of additional concern was that the existing descriptive list of
types of ``other waters'' includes some waters that would be
jurisdictional under one of the proposed categories of ``waters of the
United States'' that would be jurisdictional by rule, such as tributary
streams. The agencies want to avoid questions of whether an
intermittent stream that meets the definition of tributary also needs a
separate significant nexus analysis. Under the proposed rule, that
tributary stream does not require the significant nexus analysis.
Removing the list of water

types does not imply that any of the waters listed in the existing
regulation are never jurisdictional under the proposed rule. When one
of the waters on the current enumerated list does not fall under a
proposed category for jurisdiction (for example, adjacent waters under
(a)(6) or tributaries under (a)(5)), those waters would be
jurisdictional if found to have a significant nexus under proposed
paragraph (a)(7) on a case-specific basis.8
b. Significant Nexus
    The agencies recognize that Supreme Court decisions in SWANCC and
Rapanos placed limits on the scope of ``other waters'' that may be
determined to be jurisdictional. Therefore, the agencies' proposal
today provides that waters not determined to be jurisdictional as a
category are jurisdictional only if they are determined on a case-
specific basis to have a significant nexus to a traditional navigable
water, an interstate water, or the territorial seas. The agencies also
request comment and information below on how the science could support
other approaches that could provide greater regulatory certainty
regarding the jurisdictional status of ``other waters'', including
expanding the list of waters jurisdictional by rule, expanding the list
of waters not jurisdictional by rule, and narrowing the ``other
waters'' subject to a case-specific analysis, including eliminating the
case-specific analysis where the science does not support it. The
agencies will review the administrative record, including comments
received, the scientific literature, and the final Report, in
determining how to address ``other waters'' in the final rule.
    Justice Kennedy explained the SWANCC decision in his concurring
opinion in Rapanos: ``In Solid Waste Agency of Northern Cook Cty. v.
Army Corps of Engineers, 531 U.S. 159 (2001) (SWANCC), the Court held,
under the circumstances presented there, that to constitute `navigable
waters' under the Act, a water or wetland must possess a `significant
nexus' to waters that are or were navigable in fact or that could
reasonably be so made.'' 547 U.S. at 759. The agencies interpret the
significant nexus standard to apply to the ``other waters'' portion of
the existing regulation since the Court in SWANCC was considering the
validity of the Corps' assertion of jurisdiction over ponds and
mudflats under (a)(3) of the Corps' regulations (33 CFR 328.3).
    To comport with the SWANCC and Rapanos decisions, the agencies
propose to delete the requirement that an ``other water'' be one the
use, degradation or destruction of which could affect interstate or
foreign commerce and to replace it with the requirement that the
``other water'' meet Justice Kennedy's significant nexus standard. The
current regulations assert jurisdiction more broadly than what is
proposed today. With this proposed regulation, the agencies would limit
jurisdiction over ``other waters'' to only those that are determined on
a case-specific basis to have a significant nexus to an (a)(1) through
(a)(3) water.
    For purposes of assessing whether a particular water is a ``water
of the United States'' because it, alone or in combination with other
similarly situated waters, has a significant nexus to an (a)(1) through
(a)(3) water, the agencies are proposing to define ``significant
nexus'' plus each of the key elements used in the definition of
``significant nexus.''
i. In the Region
    The agencies propose to interpret the phrase ``in the region'' to
mean the watershed that drains to the nearest traditional navigable
water, interstate water, or the territorial seas through a single point
of entry. That concept is reflected in the definition of ``significant
nexus'' at (c)(7). Since Justice Kennedy did not define the ``region,''
the agencies determined that because the movement of water from
watershed drainage basins to river networks and lakes shapes the
development and function of these systems in a way that is critical to
their long term health, the watershed is a reasonable and technically
appropriate extent on which to identify waters that together may have
an effect on the chemical, physical, or biological integrity of a
particular (a)(1), through (a)(3) water. See Appendix A, Scientific
Evidence (Part I, Background; Part II, 4, iii, A).
    The agencies choose to use the single point of entry watershed as
the appropriate scale for the region. 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. There will likely be other
traditional navigable waters, interstate waters, and ultimately the
territorial seas further downstream from the ``nearest'' such water,
and these further downstream waters would likely have larger
watersheds, but the agencies determined that a reasonable
interpretation of ``in the region'' is the watershed that drains to the
nearest (i.e. first downstream) such water. Any nexus between other
waters and an (a)(1) through (a)(3) water will be strongest with this
nearest such water, and its drainage area is likely to be of a size
commonly understood as a ``region.''
    The agencies generally use available mapping tools that are based
on the National Hydrography Dataset (NHD) to demarcate boundaries of
the single point of entry watershed. This point of entry approach
identifies a group of waters that flow to a single location and
represents the scientifically appropriate sized area for conducting a
significant nexus evaluation in most cases. In the arid West, the
agencies recognize there may be situations where the single point of
entry watershed is very large, and it may be resource intensive to
demarcate watershed boundaries and all relevant waters in the
watershed. Under those circumstances, for practical administrative
purposes the agencies could use the NHD mapping tool to demarcate
catchments surrounding the water to be evaluated that, in combination,
are roughly the size of the typical nearby 10-digit hydrologic unit
code (HUC-10) watershed. This combination of catchments would be used
for conducting a significant nexus evaluation. Such an approach can
help resolve some practical concerns about using available mapping
tools on very large single point of entry watersheds in the arid West.
    The watershed includes all lands, streams, wetlands, lakes, and
other waters within its boundaries. Only waters within the watershed
that meet standards set out in (a)(1) through (a)(7) of the proposed
rule would be considered ``waters of the United States.'' In light of
the scientific literature, the longstanding approach of the agencies to
implementation of the CWA, and the statutory goals underpinning Justice
Kennedy's significant nexus framework, the watershed draining to the
nearest (a)(1) through (a)(3) water is the appropriate ``region'' for a
significant nexus analysis.
ii. Similarly Situated
    Justice Kennedy provided guidance to the agencies that establishing
a significant nexus requires examining whether a water ``alone or in
combination with similarly situated [wet]lands in the region,
significantly affect[s] the chemical, physical, and biological
integrity of other covered waters more readily understood as
`navigable.' '' 547 U.S. at 780. The proposed rule adopts the concept
of the ``alone or in combination with similarly situated waters'' test.

    The proposed regulation in the definition of ``significant nexus''
at (c)(7) clarifies that other waters, including wetlands, are
similarly situated when they perform similar functions and are 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
with regard to their effect on the chemical, physical, or biological
integrity of a water identified in paragraphs (a)(1) through (a)(3)
This combination of functionality and proximity to each other or to a
``water of the United States'' meets the standard provided by Justice
Kennedy. Examining both functionality and proximity also limits the
``other waters'' that can be aggregated for purposes of determining
jurisdiction.
    It is appropriate to analyze the chemical, physical, or biological
effects ``other waters'' perform individually or together with all
similarly situated ``other waters'' in the region under Justice
Kennedy' s standard. Today, the agencies are proposing to identify
factors to apply in the determination of when ``other waters'' should
be considered either individually or as a single landscape unit for
purposes of a significant nexus analysis. The agencies propose that
``similarly situated'' requires an evaluation of either a single water
or group of waters (i.e., a single landscape unit) in the region that
can reasonably be expected to function together in their effect on the
chemical, physical, or biological integrity of downstream traditional
navigable waters, interstate waters, or the territorial seas.
    In addition, the agencies propose that ``other waters'' located
close to a jurisdictional water are more likely to influence such
waters and therefore, to affect the integrity of downstream (a)(1)
through (a)(3) waters. These ``other waters,'' which do not meet the
proposed definition of adjacent waters, may be assessed together when
determining on a case-specific basis whether a significant nexus
exists, because of their similar functions and similar location in the
landscape.
    Similarly situated waters may be identified as sufficiently close
together for purposes of this paragraph of the proposed regulation when
they are within a contiguous area of land with relatively homogeneous
soils, vegetation and landform (e.g., plain, mountain, valley, etc.).
As a general matter, it would be inappropriate, for example, to
consider ``other waters'' as ``similarly situated'' if these ``other
waters'' are located in different landforms, have different elevation
profiles, or have different soil and vegetation characteristics, unless
the ``other 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 an (a)(1)
through (a)(3) water. In determining whether other waters are
sufficiently close to each other or to a water of the United States,
the agencies would also consider hydrologic connectivity to each other
or a jurisdictional water.
    In determining whether groups of other waters perform ``similar
functions'' the agencies would also consider functions such as habitat,
water storage, sediment retention, and pollution sequestration. These
and other relevant considerations would be used by the agencies to
document the hydrologic, geomorphic and ecological characteristics and
circumstances of the waters. Examples include: documentation of
chemical, physical, and biological interactions of the similarly
situated ``other waters;'' aerial photography; topographical or terrain
maps and information; other available geographic information systems
(GIS) data; National Wetlands Inventory Maps; and state and local
information. The evaluation would use any available site information
and pertinent field observations where available, relevant scientific
studies or data, or other relevant jurisdictional determinations that
have been completed in the region.
    Under the proposed rule, the agencies would assess the combined
effects of similarly situated ``other waters'' in the region on the
chemical, physical, or biological integrity of (a)(1) through (a)(3)
waters in conducting a significant nexus analysis. The factors
identified above would be used by the agencies in determining ``other
waters'' in the region that are similarly situated and should,
therefore, be considered together in conducting a significant nexus
analysis. The agencies recognize that consideration of these factors
will often limit aggregation of ``other waters'' for purposes of
assessing significant nexus or will require that ``other waters'' be
considered individually with no aggregation.
iii. Significant Nexus
    The agencies propose to define the term ``significant nexus''
consistent with language in SWANCC and Rapanos. The proposed definition
recognizes that not all waters have this requisite connection to
traditional navigable waters, interstate waters, or the territorial
seas sufficient to be determined jurisdictional. Justice Kennedy was
clear that waters with a significant nexus must significantly affect
the chemical, physical, or biological integrity of a downstream
navigable water and that the requisite nexus must be more than
``speculative or insubstantial,'' Rapanos, at 780, and the agencies
propose to define significant nexus in precisely those terms.
    It is important to note that in Rapanos, Justice Kennedy did not
conclude that the wetlands adjacent to tributaries in the cases before
the Court were not ``waters of the United States.'' Rather, Justice
Kennedy concluded that the proper inquiry to determine their
jurisdictional status--whether or not the wetlands had a ``significant
nexus''--had not been made by the Corps or the courts below. Justice
Kennedy stated that in both the consolidated cases before the Court the
record contained the types of evidence relevant to the determination of
a significant nexus according to the principles he identified. Justice
Kennedy stated ``[m]uch the same evidence should permit the
establishment of a significant nexus with navigable-in-fact waters,
particularly if supplemented by further evidence about the significance
of the tributaries to which the wetlands are connected.'' Id. Thus,
Justice Kennedy concluded that ``the end result in these cases and many
others to be considered by the Corps may be the same as that suggested
by the dissent, namely, that the Corps' assertion of jurisdiction is
valid.'' See Appendix B, Legal Analysis.
    The agencies will determine whether the water they are evaluating,
in combination with other similarly situated waters in the region, has
a significant nexus to the nearest traditional navigable water,
interstate water or the territorial seas. Functions of waters that
might demonstrate a significant nexus include sediment trapping,
nutrient recycling, pollutant trapping and filtering, retention or
attenuation of flood waters, runoff storage, export of organic matter,
export of food resources, and provision of aquatic habitat. A
hydrologic connection is not necessary to establish a significant
nexus, because, as Justice Kennedy stated, in some cases the lack of a
hydrologic connection would be a sign of the water's function in
relationship to the traditional navigable water, interstate water or
the territorial seas. These functional relationships include retention
of flood waters or pollutants that would otherwise flow downstream to
the traditional navigable water, interstate water or the territorial
seas. See 547 U.S. at 775 (citations omitted) (J. Kennedy) (``it may be
the absence of an interchange of waters prior to the dredge and fill
activity that

makes protection of the wetlands critical to the statutory scheme'').
For example, a report that reviewed the results of multiple scientific
studies concluded that depressional wetlands lacking a surface outlet
functioned together to significantly reduce or attenuate flooding.
Report at 5-26 (citing A. Bullock and M. Acreman, ``The Role of
Wetlands in the Hydrological Cycle,'' Hydrology and Earth System
Sciences 7:358-389 (2003)).
    When evaluating an ``other water'' individually or cumulatively for
the presence of a significant nexus to an (a)(1) through (a)(3) water,
there are a variety of factors that can be considered that will
influence the chemical, physical, or biological connections the ``other
water'' has with the downstream (a)(1) through (a)(3) water. The
likelihood of a significant connection is greater with increasing size
and decreasing distance from the identified (a)(1) through (a)(3)
water, as well as with increased density of the ``other waters'' for
``other waters'' that can be considered in combination with similarly
situated waters.
    Evidence of chemical connectivity and the effect on waters can be
found by identifying: Whether the properties of the water in question
are similar or dissimilar to an identified (a)(1) through (a)(3) water;
signs of retention, release, or transformation of nutrients or
pollutants; and the effect of landscape position on the strength of the
connection to the nearest ``water of the United States,'' and through
it to an (a)(1) through (a)(3) water. In addition, relevant factors
influencing chemical connectivity include hydrologic connectivity (see
physical factors, below), surrounding land use and land cover, the
landscape setting, and deposition of chemical constituents (e.g. acidic
deposition).
    Evidence of physical connectivity and the effect on (a)(1) through
(a)(3) waters can be found by identifying evidence of physical
connections, such as flood water or sediment retention (flood
prevention). Presence of indicators of hydrologic connections between
the other water and jurisdictional water are also indictors of a
physical connection. Factors influencing physical connectivity include
rain intensity, duration of rain events or wet season, soil
permeability, and distance of hydrologic connection between the ``other
water'' and the (a)(1) through (a)(3) water, depth from surface to
water table, and any preferential flowpaths.
    Evidence of biological connectivity and the effect on waters can be
found by identifying: resident aquatic or semi-aquatic species present
in the ``other water'' and the tributary system (e.g., amphibians,
aquatic and semi-aquatic reptiles, aquatic birds); whether those
species show life-cycle dependency on the identified aquatic resources
(foraging, feeding, nesting, breeding, spawning, use as a nursery area,
etc.); and whether there is reason to expect presence or dispersal
around the ``other water,'' and if so whether such dispersal extends to
the tributary system or beyond or from the tributary system to the
``other water.'' Factors influencing biological connectivity include
species' life history traits, species' behavioral traits, dispersal
range, population size, timing of dispersal, distance between ``other
water'' and an (a)(1) through (a)(3) water, the presence of habitat
corridors or barriers, and the number, area, and spatial distribution
of habitats. Non-aquatic species or species such as non-resident
migratory birds that are not demonstrating a life cycle dependency on
the identified aquatic resources are not evidence of biological
connectivity for purposes of this rule.
    When making a jurisdictional determination for an ``other water,''
the administrative record will include available information supporting
the determination. In addition to location and other descriptive
information regarding the water at issue, the record will include a
clear explanation of the rationale for the jurisdictional conclusion
and a description of the information used to determine whether the
``other water'' has a significant nexus. Information relevant to a
finding that an ``other water'' alone or in combination with similarly
situated ``other waters'' in the region can come from many sources.
Such information need not always be specific to the water whose
jurisdictional status is being evaluated. Regional and national studies
of the same type of water or similarly situated waters can help to
inform a significant nexus analysis as long as they are applicable to
the water being evaluated. Information derived from field observation
is not required in cases where a ``desktop'' analysis can provide
sufficient information to make the requisite findings. However, for
more complex or difficult jurisdictional determinations, it may be
helpful to supplement such information with field observation.
    The agencies solicit comment regarding this approach to ``other
waters,'' recognizing that a case-specific analysis of significant
nexus is resource-intensive for the regulating agencies and the
regulated community alike. In addition, the agencies solicit comment on
additional scientific research and data that might further inform
decisions about ``other waters.'' In particular the agencies solicit
information about whether current scientific research and data
regarding particular types of waters are sufficient to support the
inclusion of subcategories of types of ``other waters,'' either alone
or in combination with similarly situated waters, that can
appropriately be identified as always lacking or always having a
significant nexus.
iv. Additional Request for Public Comment on ``Other Waters''
    As stated above, significant goals of the agencies in developing
this proposed rule are to provide greater clarity, certainty, and
predictability to the public as to what waters are and are not subject
to the jurisdiction of the CWA. The agencies will achieve these goals
consistent with the CWA, as interpreted by the Supreme Court, and as
supported by the best available science. The agencies also will fulfill
their responsibility to the CWA's objectives and policies to protect
water quality, public health, and the environment.
    The agencies acknowledge that there may be more than one way to
determine which waters are jurisdictional as ``other waters.'' This
proposal is for a case-specific analysis of whether ``other waters,''
including wetlands, alone, or in combination with other similarly
situated waters located in the same region, have a significant nexus to
a traditional navigable water, interstate water, or the territorial
seas. The agencies make this proposal based on an analysis of the
current state of the science available to them. In this proposal, the
agencies continue to solicit additional science (peer-reviewed whenever
possible) that could lead to greater clarity, certainty, and
predictability of which waters are and are not within the jurisdiction
of the CWA.
    To best meet their goals and responsibilities, the agencies solicit
comment and information on the state of the science, and its relation
to the CWA and the caselaw, to determine if there are opportunities to
provide greater clarity, certainty, and predictability for establishing
jurisdiction over ``other waters.'' This includes the possibility of
determining that additional waters should be jurisdictional by rule
such as in paragraphs (a)(1) through (a)(6), and the possibility that
additional waters should be excluded from jurisdiction by rule such as
in section (b). The agencies' decision on how best to address
jurisdiction over ``other waters'' in the

final rule will be informed by the final version of the Report and
other available scientific information.
    The agencies request public comment on whether these alternative
approaches present options for determining the jurisdictional status of
``other waters'' that could rely less, or not at all, on case-specific
analysis of whether waters are similarly situated for conducting a
significant nexus analysis. Possible alternative options to the case-
specific determination in the ``other waters'' proposal are described
below. The agencies might adopt any combination of today's ``other
waters'' proposal and the alternative options for the final rule, after
considering public comment and the evolving scientific literature on
connectivity of waters.
    The agencies solicit comment on how the agencies propose to find
``other waters'' to be similarly situated in this proposed rule,
whether other methods of identifying similarly situated ``other
waters'' would be reasonable, and whether no ``other waters'' should be
determined to be similarly situated. In each instance, the comments
should address how the actions of the agencies would be consistent with
the science, including any science not currently before the agencies,
the CWA, and the caselaw.
    The agencies considered multiple approaches and options for how
best to address whether ``other waters'' were jurisdictional under the
CWA. In addition to the case-specific analysis in the proposal, the
agencies seek comment on the following alternatives:
    1. Determine by rule that ``other waters'' are similarly situated
in certain areas of the country.
    The case-specific analysis in the proposed rule approaches the
question of what ``other waters'' are similarly situated for purposes
of aggregation in the same manner throughout the U.S. The agencies
could determine by rule that ``other waters'' are similarly situated in
only certain areas of the country, and not in other areas. Under this
option, the agencies would identify ecological regions (ecoregions)
which contain ``other waters'' that are ``similarly situated'' as
provided in the proposed rule. Where waters are determined to be
similarly situated, those waters are aggregated for evaluation of
whether they have a significant nexus to a traditional navigable water,
interstate water, or the territorial seas. The agencies expect that
determining all ``other waters'' within an ecoregion to be similarly
situated would result in these ``other waters'' being determined to
have a significant nexus and being found jurisdictional.
    Waters not located in these identified ecoregions or other
specified areas would be determined to not be similarly situated and
their effects would not be aggregated for purposes of a significant
nexus determination. The result of not finding waters to be similarly
situated would most likely be a finding of no significant nexus and no
jurisdiction. The agencies particularly seek comment on whether the
science supports differing approaches with respect to which ``other
waters'' are similarly situated in certain areas of the U.S based on
distinguishing factors in those areas.
    The agencies also request comment on factors that could lead
``other waters'' to be aggregated in some areas but analyzed
individually in other areas for purposes of informing a case-specific
significant nexus analysis. The agencies request comment on whether
some resource types are more or less likely to be similarly situated
than others, and if there are ways to identify regions within which
aggregation of ``other waters'' would be routinely applied rather than
a case-specific determination. The agencies also request comment about
whether ``other waters'' that are not found in identifiable mapped
regions should be analyzed individually on a case-specific basis for a
significant nexus, aggregated in some other way for a significant nexus
analysis, or categorically excluded from jurisdiction.
    An ecoregion is an area within the United States that includes
generally similar ecosystems and that has similar types, qualities, and
quantities of environmental resources. (J.M. Omernik, ``Perspectives on
the Nature and Definition of Ecological Regions,'' Environmental
Management 34(Supplement 1):S27-S38 (2004)). Ecoregions cover
relatively large areas of land or water, and contain characteristic,
geographically distinct assemblages of natural communities and species.
The biodiversity of flora, fauna and ecosystems that characterize an
ecoregion tends to be distinct from that of other ecoregions. (Id.)
    Level III ecoregions are the second most detailed level of
ecoregions nationally, with 105 Level III ecoregions in the
conterminous United States, and have been refined over the years in
several state-level projects conducted in collaboration with the EPA
and other Federal and State agencies. U.S. Environmental Protection
Agency, ``Level III Ecoregions of the Continental United States,'' map
scale 1:7,500,000 (Corvallis, OR: U.S. EPA--National Health and
Environmental Effects Research Laboratory, 2013), available at http://www.epa.gov/wed/pages/ecoregions/level_iii_iv.htm. For this reason,
the agencies consider Level III ecoregions to be the most appropriate
level for analysis. The ``other waters'' in these ecoregions are within
a contiguous area of land with relatively homogeneous soils, vegetation
and landform (e.g., plain, mountain, valley, etc.), and generally
provide similar functions to the downstream traditional navigable
waters, interstate waters, or the territorial seas. A possible list of
Level III ecoregions where waters are similarly situated and
aggregation could be used include:

1. Coast Range
4. Cascades
6. Central California Foothills and Coastal Mountains
7. Central California Valley
8. Southern California Mountains
9. Eastern Cascades Slopes and Foothills
10. Columbia Plateau
27. Central Great Plains
34. Western Gulf Coastal Plain
42. Northwestern Glaciated Plains
44. Nebraska Sand Hills
46. Northern Glaciated Plains
47. Western Corn Belt Plains
48. Lake Agassiz Plain
50. Northern Lakes and Forests
51. North Central Hardwood Forests
59. Northeastern Coastal Zone
63. Middle Atlantic Coastal Plain
65. Southeastern Plains
75. Southern Coastal Plain
78. Klamath Mountains/California High North Coast Range
81. Sonoran Basin and Range
83. Eastern Great Lakes Lowlands
84. Atlantic Coastal Pine Barrens
85. Southern California/Northern Baja Coast
See Map A in docket.
    The agencies would consider the ``other waters'' in a single point
of entry watershed in these identified ecoregions as similarly situated
for purposes of aggregation for a significant nexus analysis. The
agencies expect that this approach would lead to all similarly situated
other waters within single point of entry watersheds within an
ecoregion being found jurisdictional through case-specific analysis of
significant nexus. Alternately, the agencies could determine that the
similarly situated waters within each ecoregion have a significant
nexus and are jurisdictional by rule and therefore do not require a
case-specific significant nexus analysis.
    The agencies request comment on the list of ecoregions above and
whether this list is appropriate, and whether there are other
ecoregions or distinct areas that should be included or excluded from
this list. This list does not include regions in Alaska or Hawaii and
the agencies request comment on

appropriate regions to use to analyze ``other waters'' in those states.
The agencies also request comment on whether using Level III ecoregions
is appropriate or whether a finer gradation of ecoregions would be more
appropriate.
    The factors the agencies used in developing the list above are:
    a. Density of ``other waters'' such that there can be periodic
surface hydrologic connections among the waters, for example in West
Coast vernal pools.
    b. Soil permeability and surface or shallow subsurface flow such
that the ``other waters'' can be considered hydrologically connected,
such as many Texas coastal prairie wetlands.
    c. Water chemistry which indicates that the ``other waters'' are
part of the same system and influenced by the same processes.
    d. Physical capacity of ``other waters'' to provide flood and
sediment retention; this is a case where several small wetlands
together may have a different effect than a single large wetland
providing the same function, for example prairie potholes in the
Missouri Coteau.
    e. Co-location of waters to each other or similarly to the
tributary system such that their cumulative and additive effects on
pollutant removal through parallel, serial, or sequential processing
are apparent, such as the role of pocosins in maintaining water quality
in estuaries.
    f. ``Other waters'' that are sufficiently near each other or the
tributary system and thus function as an integrated habitat that can
support the life cycle of a species or more broadly provide habitat to
a large number of a single species.
    The agencies request comment on the factors above and whether this
list of factors is appropriate, and whether there are other factors
that should be included or excluded from this list. Comments should
address the science that supports each comment.
    In addition to ecoregions, another method of mapping boundaries
where waters could be considered to be similarly situated for a
significant nexus analysis would be to rely on hydrologic-landscape
regions. Hydrologic-landscape regions are groups of watersheds that are
clustered together on the basis of similarities in land-surface form,
geologic texture, and climate characteristics. (D.M. Wolock, et al.
``Delineation and Evaluation of Hydrologic-Landscape Regions in the
United States Using Geographic Information System Tools and
Multivariate Statistical Analyses,'' Environmental Management
34(Supplement 1):S71-S88 (2004)). Hydrologic-landscape regions are
based on a concept that reflects fundamental hydrologic processes that
are expected to affect water quality and other environmental
characteristics.
    The agencies seek comment on the technical bases for using
ecoregions and hydrologic-landscape regions under this option.
Commenters may also address whether some other method or combination of
methods (certain ecoregions and hydrologic-landscape regions, for
example) of mapping geographic boundaries is better supported by the
science. Comments should also address whether and how this option is
consistent with the science and the caselaw.
    If the agencies choose to determine by rule that ``other waters''
in certain ecoregions or other geographic boundaries are similarly
situated, the agencies could also determine that waters not located in
identified ecoregions or otherwise specifically identified areas are
not similarly situated for purposes of establishing a significant nexus
and jurisdiction. The agencies also request comment on whether ``other
waters'' that are not found in identifiable mapped ecoregions or other
areas should be analyzed individually on a case-specific basis for
determining a significant nexus, and on whether or not case-specific
analysis of whether there are similarly situated ``other waters'' in
the area is advisable.
    2. Determine by rule that certain additional subcategories of
waters would be jurisdictional rather than addressed with a case-
specific analysis, and that other subcategories of waters would be non-
jurisdictional.
    The agencies could choose to determine that there is science
available to determine by rule that certain additional subcategories of
``other waters'' are similarly situated and have a significant nexus
and are jurisdictional by rule rather than addressed with a case-
specific significant nexus analysis under paragraph (a)(7). Such an
approach would lead to certain subcategories of ``other waters'' being
determined jurisdictional in the same way that waters under paragraphs
(a)(1) through (a)(6) are jurisdictional without a case-specific
significant nexus analysis. Under this option the agencies could
determine that waters such as prairie potholes, Carolina and Delmarva
bays, pocosins, Texas coastal prairie wetlands, western vernal pools,
and perhaps other categories of waters, either alone or in combination
with other waters of the same type in a single point of entry
watershed, have a significant nexus and are jurisdictional by rule. See
Appendix A, Part II, iii.C(1). These waters would not require a case-
specific significant nexus analysis to determine jurisdiction.
    In addition, the agencies could determine that other subcategories
of waters are not jurisdictional and lack a significant nexus to an
(a)(1) through (a)(3) water. Under this option the agencies could
conclude that ``other waters'' such as playa lakes in the Great Plains,
even in combination with other playa lakes in a single point of entry
watershed, lack a significant nexus and therefore are not
jurisdictional. See Appendix A, Part II, iii.C(1).
    Under this approach, where a playa lake, or other excluded category
of water, would be within a category established by paragraphs (a)(1)
through (a)(6) of the proposed rule (e.g., the playa is an interstate
water or the playa is adjacent to an (a)(1) through (a)(5) water), the
playas would be jurisdictional. (See R.W. Tiner, ``Geographically
Isolated Wetlands of the United States,'' Wetlands 23(3):494-516
(2003); M.G. Forbes, et al., ``Nutrient Transformation and Retention by
Coastal Prairie Wetlands, Upper Gulf Coast, Texas,'' Wetlands 32(4):
705-715 (2012)).
    The agencies seek comment on how they should categorize the
remaining ``other waters.'' The agencies seek comment on whether these
remaining ``other waters'' should be non-jurisdictional because they
would lack a significant nexus to a traditional navigable water,
interstate water, or the territorial seas.
    There is substantial value to the regulated public and all other
stakeholders in providing increased certainty regarding which ``other
waters'' are jurisdictional and which are not. By expanding the
categories of waters determined jurisdictional and expanding the
categories of waters not categorized as jurisdictional, the agencies
can better address the clarity, certainty, and predictability goals of
this rule. However, the agencies acknowledge that the science may not
be sufficient today to conclusively determine whether all categories of
other waters significantly affect the chemical, physical and biological
integrity of (a)(1) through (a)(3) waters. The agencies seek comment on
the science used in support of the proposed rule, plus any additional
science they should consider when determining jurisdiction. The
agencies also seek comment on how inconclusiveness of the science
relates to the use of case-specific determinations. As the science
develops, the agencies could determine

that additional categories of ``other waters'' are similarly situated
and have a significant nexus and are jurisdictional by rule, or that as
a class they do not have such a significant nexus and might not be
jurisdictional.
    If waters are categorized as non-jurisdictional because of a lack
of science available today, the agencies request comment on how to best
accommodate evolving science in the future that could indicate a
significant nexus for these ``other waters.'' Specifically, the
agencies request comment as to whether this should be done through
subsequent rulemaking, or through some other approach, such as through
a process established in this rulemaking.
    The agencies also seek comment on how the science supports
retaining the case-specific determination for the remaining ``other
waters'' that are neither specifically included nor excluded from
jurisdiction. Retaining the case-specific analysis for these other
waters would not enhance clarity of jurisdiction for these other
waters, but it would retain the ability for a jurisdictional
determination consistent with the objective of the CWA to restore and
maintain the chemical, physical, and biological integrity of the
nation's waters. In the alternative, the agencies seek comment on
whether it would be appropriate to categorize remaining ``other
waters'' as not jurisdictional. The agencies specifically seek comment
on how these ``other waters'' should be considered.
    3. Additional ``other waters'' approaches.
    The agencies request comment on additional ``other waters''
approaches considered, but not proposed by the agencies.
    The agencies could determine that no ``other waters'' are similarly
situated, and all significant nexus analyses would be made on a case-
specific basis for each individual ``other water.'' The agencies expect
that this likely would result in few if any other waters being found
jurisdictional. The agencies recognize that if they determine there are
no similarly situated ``other waters,'' there are issues about
consistency with existing scientific information and studies regarding
the functional relationship of ``other waters'' of the same type, and
their contribution to the chemical, physical, or biological integrity
of streams, rivers, lakes, and similar waters. There are also questions
of how finding no ``other waters'' to be similarly situated reconciles
with the portion of Justice Kennedy's opinion discussing ``similarly
situated'' waters in the region that ``significantly affect'' the
chemical, physical, or biological integrity of waters more
traditionally understood as navigable. While the agencies do not
propose to determine that no ``other waters'' are similarly situated
and aggregated, the agencies specifically seek comment on whether and
how choosing to find no ``other waters'' similarly situated would be
consistent with the science, the CWA, and the caselaw.
    The agencies also considered and seek comment on all ``other
waters'' in a single point of entry watershed being evaluated as a
single landscape unit with regard to their effect on traditional
navigable waters, interstate waters, and the territorial seas.
    The agencies seek comment that would inform a decision that these
``other waters'' in a single point of entry watershed perform similar
functions and are located sufficiently close together or to a paragraph
(a)(1) through (a)(5) water so that they can be aggregated and
evaluated as a single landscape unit with regard to their effects on
the nearest (a)(1) through (a)(3) water. Generally, the agencies
anticipate that if the other waters in a single point of entry
watershed are aggregated as a single unit, these waters would be
determined to have a significant nexus and be jurisdictional.
    The agencies recognize that if they choose to aggregate all other
waters in a single point of entry watershed, there likely is
insufficient existing scientific information to support the
determination that all ``other waters'' in watersheds across the nation
are similarly situated as provided in this rule and described in the
caselaw. There are also questions of how determining ``other waters''
in a single point of entry watershed to be similarly situated
reconciles with the portion of Justice Kennedy's opinion discussing
``similarly situated'' waters in the region that ``significantly
affect'' the chemical, physical, or biological integrity of waters more
traditionally understood as navigable. While the agencies do not
propose to determine that ``other waters'' in a single point of entry
watershed are similarly situated and aggregated, the agencies seek
comment on whether and how choosing to find such ``other waters''
similarly situated would be consistent with the science, the CWA, and
the caselaw.
    The agencies' determination will be informed by the final version
of the Report and other available scientific information.

I. Waters That Are Not ``Waters of the United States''

    The agencies' longstanding regulations exclude waste treatment
systems designed to meet the requirements of the CWA and prior
converted cropland from the definition of ``waters of the United
States.'' The agencies propose no changes to these exclusions and
therefore they would continue as a part of this rulemaking. The
agencies also propose to codify for the first time longstanding
practices that have generally considered certain features and types of
waters not to be ``waters of the United States.'' Codifying these
longstanding practices supports the agencies' goals of providing
greater clarity, certainty, and predictability for the regulated public
and the regulators. Under today's proposal, the waters identified in
section (b) as excluded would not be ``waters of the United States,'',
even if they would otherwise fall within one of the categories in
(a)(1) through (a)(7).
    The agencies propose ministerial actions with respect to the
placement of the two existing exemptions for waste treatment systems
and prior converted cropland. They will be in proposed new section (b).
For the waste treatment systems exclusion, the agencies propose to
delete a cross-reference in the current language to an EPA regulation
that is no longer in the Code of Federal Regulations. The parenthetical
to be deleted states: ``(other than cooling ponds as defined in 40 CFR
423.11(m) which also meet the criteria of this definition).'' The
agencies do not consider this deletion to be a substantive change to
the waste treatment systems exclusion or how it is applied. In fact,
the agencies do not propose to make conforming changes to ensure that
each of the existing definitions of the ``waters of the United States''
for the various CWA programs have the exact same language with respect
to the waste treatment system exclusion. The regulations implementing
the various CWA programs were promulgated and amended at different
times and therefore there are some differences in language. For
example, compare EPA's regulations for the section 402 program, 40 CFR
122.2 with the Corps' regulations for the 404 program, 33 CFR 328.3.
The agencies do not propose to address the substance of the waste
treatment system exclusion and thus will leave each regulation as is
with the exception of deleting the cross-reference.
    In addition, this regulation does not address or change in any way
the many

statutory exemptions from CWA permitting requirements. The proposed
rule does not affect any of the exemptions provided by CWA section
404(f), including those for normal farming, silviculture, and ranching
activities. CWA section 404(f); 40 CFR 232.3; 33 CFR 323.4. The
proposed rule also does not address or change the statutory and
regulatory exemptions from NPDES permitting requirements such as those
for agricultural stormwater discharges, return flows from irrigated
agriculture, or the status of water transfers. CWA section 402(l)(1)
(exempting discharges composed entirely of return flows from irrigated
agriculture from section 402 permit requirements); CWA section
502(14)(excluding agricultural stormwater discharges and return flows
from irrigated agriculture from the term point source.); 40 CFR
122.3(f) (excluding return flows from irrigated agriculture from the
NPDES program); 40 CFR 122.2 (excluding return flows from irrigated
agriculture or agricultural storm water runoff from the term point
source.).
    Finally, in new paragraphs (b)(3) through (5), the agencies
propose, for the first time by rule, to exclude some waters and
features that the agencies have by longstanding practice generally
considered not to be ``waters of the United States.'' Specifically, the
agencies propose that the following are not ``waters of the United
States'' notwithstanding whether they would otherwise be jurisdictional
under section (a):
     Ditches that are excavated wholly in uplands, drain only
uplands, and have less than perennial flow.
     Ditches that do not contribute flow, either directly or
through another water, to a traditional navigable water, interstate
water, the territorial seas or impoundment.
     The following features:
    [cir] Artificially irrigated areas that would revert to upland
should application of irrigation water to that area cease;
    [cir] Artificial lakes or ponds created by excavating and/or diking
dry land and used exclusively for such purposes as stock watering,
irrigation, settling basins, or rice growing;
    [cir] Artificial reflecting pools or swimming pools created by
excavating and/or diking dry land;
    [cir] Small ornamental waters created by excavating and/or diking
dry land for primarily aesthetic reasons;
    [cir] Water-filled depressions created incidental to construction
activity;
    [cir] Groundwater, including groundwater drained through subsurface
drainage systems; and
    [cir] Gullies and rills and non-wetland swales.
    Most of these features and waters have been identified by the
agencies as generally not ``waters of the United States'' in previous
preambles or guidance documents. The agencies' have always preserved
the authority to determine in a particular case that any of these
waters are a ``water of the United States.'' One of the agencies' goals
in this proposed rule is to increase clarity and certainty about the
scope of ``waters of the United States.'' To that end, the agencies
propose not simply that these features and waters are ``generally'' not
``waters of the United States,'' but that they are expressly not
``waters of the United States'' by rule. The agencies would not retain
the authority to determine that any of these waters was a ``water of
the United States'' because it would otherwise be jurisdictional under
section (a). For example, the agencies could not find that a water had
a significant nexus and was an ``other waters'' under paragraph (a)(7),
or that it was an interstate water under paragraph (a)(2). These waters
would not be jurisdictional by rule.
    In determining that these features and waters are not ``waters of
the United States,'' the agencies are by the decisions of the Supreme
Court. In Riverside Bayview, the Supreme Court deferred to the
agencies' regulations and noted the difficulty of drawing lines
identifying where waters end. The plurality opinion in Rapanos also
noted that there were certain features that were not primarily the
focus of the CWA. See 547 U.S. at 734. In this section of the proposed
rule, the agencies are drawing lines and concluding that certain waters
and features are not subject to the jurisdiction of the Clean Water
Act.
    A similar list of waters and features not generally ``waters of the
United States'' was provided by the Corps in a 1986 preamble to the
existing rule defining ``waters of the United States'' (51 FR 41206,
41217, November 13, 1986) and by the EPA in a 1988 preamble (53 FR
20764, June 6, 1988). In today's proposed rule, the agencies have
clarified and added to the list in order to provide a full description
of the waters that will not be ``waters of the United States'' by rule.
The agencies have never interpreted ``waters of the United States'' to
include groundwater and the proposed rule explicitly excludes
groundwater, including groundwater drained through subsurface drainage
systems.
    In clarifying the list of waters not subject to CWA jurisdiction,
the agencies did not include ``puddles'' from the lists of waters
generally not considered jurisdictional in previous preambles or
guidance documents. This is not because puddles are considered
jurisdictional, it is because ``puddles'' is not a sufficiently precise
hydrologic term or a hydrologic feature capable of being easily
understood. Because of the lack of common understanding and precision
inherent in the term ``puddles,'' the agencies determined that adding
puddles would be contrary to the agencies' stated goals of increased
clarity, predictability, and certainty. In addition, one commonly
understood meaning for the term ``puddle'' is a relatively small,
temporary pool of water that forms on pavement or uplands immediately
after a rainstorm, snow melt, or similar event. Such a puddle cannot
reasonably be considered a water body or aquatic feature at all,
because usually it exists for only a brief period of time before the
water in the puddle evaporates or sinks into the ground. Puddles of
this sort obviously are not, and have never been thought to be, waters
of the United States subject to CWA jurisdiction. Listing puddles also
could have created the misapprehension that anything larger than a
puddle was jurisdictional. That is not the agencies' intent.
    Gullies are relatively deep channels that are ordinarily formed on
valley sides and floors where no channel previously existed. They are
commonly found in areas with low-density vegetative cover or with soils
that are highly erodible. See, e.g., N.C. Brady and R.R. Weil, The
Nature and Properties of Soils, 13th Edition (Upper Saddle River, NJ:
Prentice Hall, 2002). Rills are formed by overland water flows eroding
the soil surface during rain storms. See, e.g., L.B. Leopold, A View of
the River (Cambridge: Harvard University Press, 1994). Rills are less
permanent on the landscape than streams and typically lack an OHWM,
whereas gullies are younger than streams in geologic age and also
typically lack an OHWM; time has shaped streams into geographic
features distinct from gullies and rills. See, e.g., American Society
of Civil Engineers, Task Committee on Hydrology Handbook, Hydrology
Handbook (ASCE Publications, 1996).
    The two main processes that result in the formation of gullies are
downcutting and headcutting, which are forms of longitudinal (incising)
erosion. These actions ordinarily result in erosional cuts that are
often deeper than they are wide, with very steep banks, often small

beds, and typically only carry water during precipitation events. The
principal erosional processes that modify streams are also downcutting
and headcutting. In streams, however, lateral erosion is also very
important. The result is that streams, except on steep slopes or where
soils are highly erodible, are characterized by the presence of bed and
banks and an OHWM as compared to typical erosional features that are
more deeply incised. It should be noted that some ephemeral streams are
called ``gullies'' or the like when they are not ``gullies'' in the
technical sense; such streams where they are tributaries under the
proposed definition would be considered ``waters of the United
States,'' regardless of the name they are given locally. The agencies
request comment on how they could provide greater clarity on how to
distinguish between erosional features such as gullies, which are
excluded from jurisdiction, and ephemeral tributaries, which are
categorically jurisdictional.
    Non-wetland natural and man-made swales would not be ``waters of
the United States'' under this proposal. In certain circumstances,
however, swales include areas that meet the regulatory definition of
``wetlands.'' Swales generally are considered wetlands when they meet
the applicable criteria in the Corps of Engineers Wetland Delineation
Manual and the appropriate regional supplement to that Wetland
Delineation Manual. Wetland swales would be evaluated as adjacent
waters under proposed (a)(6) or as ``other waters'' under proposed
(a)(7) depending upon whether they meet the proposed definition of
adjacent. Swales are distinct from streams in that they are non-
channelized, shallow trough-like depressions that carry water mainly
during rainstorms or snowmelt. Report at A-19. Swales typically lack
the OHWM that is characteristic of jurisdictional streams. The agencies
request comment on how they could provide greater clarity on how to
distinguish swales, which are excluded from jurisdiction, and ephemeral
tributaries, which are categorically jurisdictional.
    Finally, under paragraphs (b)(3) and (b)(4), the agencies propose
to clearly exempt from the definition of ``waters of the United
States'' two types of ditches: (1) Ditches that are excavated wholly in
uplands, drain only uplands, and have less than perennial flow, and (2)
ditches that do not contribute flow, either directly or through another
water, to a water identified in paragraphs (a)(1) through (4).
    The agencies have long distinguished between ditches that are
``waters of the United States'' and ditches that are not ``waters of
the United States.'' In a 1986 Corps preamble and a 1988 EPA preamble,
the agencies each stated that they generally do not consider non-tidal
drainage and irrigation ditches excavated on dry land to be ``waters of
the United States.'' 51 FR 41217, November 13, 1986, 53 FR 20764, June
6, 1988. More recently, the agencies have stated that they generally
would not assert jurisdiction over ``Ditches (including roadside
ditches) excavated wholly in and draining only uplands and that do not
carry a relatively permanent flow of water.'' ``Clean Water Act
Jurisdiction Following the Supreme Court's Decision in Rapanos v.
United States and Carabell v. United States'' (Dec. 2, 2008) at 1, 12
(2008 Rapanos guidance).
    The agencies recognize that there have been inconsistencies in
practice implementing agency policy with respect to ditches and this
proposed rule is designed to improve clarity, predictability, and
consistency. With this proposal, the agencies would no longer rely on
``generally not'' jurisdictional but would clearly establish that
specific types of ditches are not ``waters of the United States'' by
rule. Other ditches not excluded under paragraphs (b)(3) or (b)(4), if
they meet the new proposed definition of ``tributary'' would continue
to be ``waters of the United States,'' as they have been under the
longstanding implementation of the statute and regulations by the
agencies.
    The first type of ditch that is excluded needs to meet all three
criteria: (1) It is excavated wholly in uplands; (2) it drains only
uplands, and (3) it has less than perennial flow. Ditches that are
excavated wholly in uplands means ditches that at no point along their
length are excavated in a jurisdictional wetland (or other water).
Members of the public should consider whether a wetland is
jurisdictional before constructing a ditch that would drain the wetland
and connect either directly or through other waters to an (a)(1)
through (a)(3) water. The ditch must also contain less than perennial
flow to be excluded under this proposed provision. Perennial flow means
that the flow in the ditch occurs year-round under normal
circumstances; therefore, excluded ditches must be dug only in uplands,
drain only uplands, and have ephemeral or intermittent flow. As noted
above, the 2008 Rapanos guidance stated that the agencies generally
would not assert jurisdiction over ``ditches (including roadside
ditches) excavated wholly in and draining only uplands and that do not
carry a relatively permanent flow of water.'' The agencies recognize
that the term ``relatively permanent'' does not align with more
commonly understood technical descriptions of flow regime. The agencies
therefore believe it is appropriate to clarify the extent of this
exclusion using the flow regime terms that are familiar to the public
and agency field personnel. The agencies request comment on this
formulation of the ditch exclusion. The agencies specifically seek
comment on the appropriate flow regime for a ditch excavated wholly in
uplands and draining only uplands to be covered by the exclusion in
paragraph (b)(3). In particular, the agencies seek comment on whether
the flow regime in such ditches should be less than intermittent flow
or whether the flow regime in such ditches should be less than
perennial flow as proposed.
    The other type of ditch that would not be a ``water of the United
States'' is a ditch that does not contribute flow, either directly or
through another water, to a water identified in paragraphs (a)(1)
through (4). Essentially, ditches that do not contribute flow to the
tributary system of a traditional navigable water, interstate water or
territorial sea would not be ``waters of the United States.''
    It is important to note, however, that even when not jurisdictional
waters, these non-wetland swales, gullies, rills and specific types of
ditches may still be a surface hydrologic connection for purposes of
the proposed definition of adjacent under paragraph (a)(6) or for
purposes of a significant nexus analysis under paragraph (a)(7). For
example, a wetland may be a ``water of the United States,'' meeting the
proposed definition of ``neighboring'' because it is connected to such
a tributary by a non-jurisdictional ditch that does not meet the
definition of a ``tributary.'' In addition, these geographic features
may function as ``point sources'' under CWA section 502(14)), such that
discharges of pollutants to waters through these features would be
subject to other CWA regulations (e.g., CWA section 402).

IV. Related Acts of Congress, Executive Orders, and Agency Initiatives

A. Executive Order 12866: Regulatory Planning and Review and Executive
Order 13563: Improving Regulation and Regulatory Review

    Under Executive Order 12866 (58 FR 51735, October 4, 1993), this
action is a ``significant regulatory action.'' Accordingly, the EPA and
the Corps submitted this action to the Office of

Management and Budget (OMB) for review under Executive Orders 12866 and
13563 (76 FR 3821, January 21, 2011) and any changes made in response
to OMB recommendations have been documented in the docket for this
action.
    In addition, the EPA and the Corps of Engineers prepared an
analysis of the potential costs and benefits associated with this
action. This analysis is contained in ``Economic Analysis of Proposed
Revised Definition of Waters of the United States.'' A copy of the
analysis is available in the docket for this action.

B. Paperwork Reduction Act

    This action does not impose any information collection burden under
the provisions of the Paperwork Reduction Act, 44 U.S.C. 3501 et seq.
Burden is defined at 5 CFR 1320.3(b). An Agency may not conduct or
sponsor, and a person is not required to respond to, a collection of
information unless it displays a currently valid OMB control number.
The OMB control numbers for EPA's CWA section 402 program may be found
at 40 CFR 9.1. (OMB Control No. 2040-0004, EPA ICR No. 0229.19). For
the CWA section 404 regulatory program, the current OMB approval number
for information requirements is maintained by the Corps of Engineers
(OMB approval number 0710-0003). However, there are no new approval or
application processes required as a result of this rulemaking that
necessitate a new Information Collection Request (ICR).

C. Regulatory Flexibility Act

    The Regulatory Flexibility Act (RFA) generally requires an agency
to prepare a regulatory flexibility analysis of any rule subject to
notice-and-comment rulemaking requirements under the Administrative
Procedure Act or any other statute unless the agency certifies that the
rule will not have a significant economic impact on a substantial
number of small entities. Small entities include small businesses,
small organizations, and small governmental jurisdictions.
    For purposes of assessing the impacts of this final action on small
entities, ``small entity'' is defined as: (1) A small business that is
a small industrial entity as defined in the U.S. Small Business
Administration's size standards (see 13 CFR 121.201); (2) a small
governmental jurisdiction that is a government of a city, county, town,
school district, or special district with a population of less than
50,000; or (3) a small organization that is any not-for-profit
enterprise that is independently owned and operated and is not dominant
in its field.
    After considering the economic impacts of this proposed rule on
small entities, I certify that this proposed rule will not have a
significant economic impact on a substantial number of small entities.
See, e.g., Cement Kiln Recycling Coalition v. EPA, 255 F.3d 855 (D.C.
Cir. 2001); Michigan v. EPA, 213 F.3d 663 (D.C. Cir. 2000); Am.
Trucking Ass'n v. EPA, 175 F.3d 1027 (D.C. Cir. 1999); Mid-Tex Elec.
Co-op, Inc. v. FERC, 773 F.2d 327 (D.C. Cir. 1985).
    Under the RFA, the impact of concern is any significant adverse
economic impact on small entities, because the primary purpose of the
initial regulatory flexibility analysis is to identify and address
regulatory alternatives ``which minimize any significant economic
impact of the rule on small entities.'' 5 U.S.C. 603. The scope of
regulatory jurisdiction in this proposed rule is narrower than that
under the existing regulations. See 40 CFR 122.2 (defining ``waters of
the United States''). Because fewer waters will be subject to the CWA
under the proposed rule than are subject to regulation under the
existing regulations, this action will not affect small entities to a
greater degree than the existing regulations. As a consequence, this
action if promulgated will not have a significant adverse economic
impact on a substantial number of small entities, and therefore no
regulatory flexibility analysis is required.
    The proposed rule contemplated here is not designed to ``subject''
any entities of any size to any specific regulatory burden. Rather, it
is designed to clarify the statutory scope of ``the waters of the
United States, including the territorial seas'' (33 U.S.C. 1362(7)),
consistent with Supreme Court precedent. This question of CWA
jurisdiction will be informed by the tools of statutory construction
and the geographical and hydrological factors identified in Rapanos v.
United States, 547 U.S. 715 (2006), which are not factors readily
informed by the RFA.
    Nevertheless, the scope of the term ``waters of the United States''
is a question that has continued to generate substantial interest,
particularly within the small business community, because permits must
be obtained for many discharges of pollutants into those waters. In
light of this interest, the EPA and the Corps determined to seek early
and wide input from representatives of small entities while formulating
a proposed definition of this term that reflects the intent of Congress
consistent with the mandate of the Supreme Court's decisions. Such
outreach, although voluntary, is also consistent with the President's
January 18, 2011 Memorandum on Regulatory Flexibility, Small Business,
and Job Creation, which emphasizes the important role small businesses
play in the American economy. This process has enabled the agencies to
hear directly from these representatives, at a very preliminary stage,
about how they should approach this complex question of statutory
interpretation, together with related issues that such representatives
of small entities may identify for possible consideration in separate
proceedings. The agencies have also prepared a report summarizing their
small entity outreach to date, the results of this outreach, and how
these results have informed the development of this proposed rule. This
report is available in the docket for this proposed rule (cite).

D. Unfunded Mandates Reform Act

    This proposed rule contains no Federal mandates (under the
regulatory provisions of Title II of the Unfunded Mandates Reform Act
of 1995 (UMRA), 2 U.S.C. 1531-1538 for state, local, or tribal
governments or the private sector. This proposed rule does not directly
regulate or affect any entity and, therefore, is not subject to the
requirements of sections 202 and 205 of UMRA.
    The agencies determined that this proposed rule contains no
regulatory requirements that might significantly or uniquely affect
small governments. Moreover, the proposed definition of ``waters of the
United States'' applies broadly to CWA programs and the subsequently
affected entities, which are not uniquely applicable to small
governments. Thus, this proposed rule is not subject to the
requirements of section 203 of UMRA.

E. Executive Order 13132: Federalism

    This proposed rule seeks to clarify the definition of the extent of
CWA jurisdiction established by statute. State and local governments
have well-defined and long-standing relationships in implementing
affected CWA programs and these relationships will not be altered.
Forty-six states and the Virgin Islands have been authorized to
administer the NPDES program under section 402, while two states
administer the section 404 program. This action will not have
substantial direct effects on the states, on the relationship between
the national government and the states, or on the distribution of power
and responsibilities among the various levels of government. Thus,
Executive Order 13132 (64 FR 43255,

August 10, 1999) does not apply to this action. Consistent with EPA and
Corps policy to promote communications between the agencies and state
and local governments, and in recognition of the vital role states play
in implementation of the CWA, EPA voluntarily undertook federalism
consultation for this effort and met the terms of E.O. 13132 and EPA
guidance for implementing the Order. EPA held a series of meetings and
outreach calls with state and local governments and their
representatives soliciting input on a potential rule to define ``waters
of the United States.''
    As part of this consultation, early in the rulemaking process, EPA
held three in-person meetings and two phone calls in the fall and
winter of 2011. Organizations involved include the National Governors
Association, the National Conference of State Legislatures, the Council
of State Governments, the National Association of Counties, the
National League of Cities, the U.S. Conference of Mayors, the County
Executives of America, the National Associations of Towns and