[Federal Register Volume 79, Number 76 (Monday, April 21, 2014)]
[Proposed Rules]
[Pages 22188-22274]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2014-07142]



[[Page 22187]]

Vol. 79

Monday,

No. 76

April 21, 2014

Part II





Department of Defense





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Department of the Army, Corps of Engineers





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33 CFR Part 328





Environmental Protection Agency





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40 CFR Parts 110, 112, 116, et al.





 Definition of ``Waters of the United States'' Under the Clean Water 
Act; Proposed Rule

  Federal Register / Vol. 79 , No. 76 / Monday, April 21, 2014 / 
Proposed Rules  

[[Page 22188]]


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DEPARTMENT OF DEFENSE

Department of the Army, Corps of Engineers

33 CFR Part 328

ENVIRONMENTAL PROTECTION AGENCY

40 CFR Parts 110, 112, 116, 117, 122, 230, 232, 300, 302, and 401

[EPA-HQ-OW- 2011-0880; FRL-9901-47-OW]
RIN 2040-AF30


Definition of ``Waters of the United States'' Under the Clean 
Water Act

AGENCY: U.S. Army Corps of Engineers, Department of the Army, 
Department of Defense; and Environmental Protection Agency (EPA).

ACTION: Proposed rule.

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SUMMARY: The Environmental Protection Agency (EPA) and the U.S. Army 
Corps of Engineers (Corps) are publishing for public comment a proposed 
rule defining the scope of waters protected under the Clean Water Act 
(CWA), in light of the U.S. Supreme Court cases in U.S. v. Riverside 
Bayview, Rapanos v. United States, and Solid Waste Agency of Northern 
Cook County v. U.S. Army Corps of Engineers (SWANCC), and Rapanos v. 
United States (Rapanos). This proposal would enhance protection for the 
nation's public health and aquatic resources, and increase CWA program 
predictability and consistency by increasing clarity as to the scope of 
``waters of the United States'' protected under the Act.

DATES: Submit comments on or before July 21, 2014.

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-HQ-OW-
2011-0880 by one of the following methods:
     Federal eRulemaking Portal: http://www.regulations.gov. 
Follow the instructions for submitting comments.
     Email: [email protected]. Include EPA-HQ-OW-2011-0880 in 
the subject line of the message.
     Mail: Send the original and three copies of your comments 
to: Water Docket, Environmental Protection Agency, Mail Code 2822T, 
1200 Pennsylvania Avenue NW., Washington, DC 20460, Attention: Docket 
ID No. EPA-HQ-OW-2011-0880.
     Hand Delivery/Courier: Deliver your comments to EPA Docket 
Center, EPA West, Room 3334, 1301 Constitution Avenue NW., Washington, 
DC 20460, Attention Docket ID No. EPA-HQ-OW-2011-0880. Such deliveries 
are accepted only during the Docket's normal hours of operation, which 
are 8:30 a.m. to 4:30 p.m., Monday through Friday, excluding legal 
holidays. Special arrangements should be made for deliveries of boxed 
information. The telephone number for the Water Docket is 202-566-2426.
    Instructions: Direct your comments to Docket ID No. EPA-HQ-OW-2011-
0880. EPA's policy is that all comments received will be included in 
the public docket without change and may be made available on-line at 
http://www.regulations.gov, including any personal information 
provided, unless the comment includes information claimed to be 
Confidential Business Information (CBI) or other information whose 
disclosure is restricted by statute. Do not submit information that you 
consider to be CBI, or otherwise protected, through http://www.regulations.gov or email. The http://www.regulations.gov Web site 
is an ``anonymous access'' system, which means EPA will not know your 
identity or contact information unless you provide it in the body of 
your comment. If you send an email directly to EPA without going 
through http://www.regulations.gov, your email address will be 
automatically captured and included as part of the comment that is 
placed in the public docket and made available on the Internet. If you 
submit an electronic comment, EPA recommends that you include your name 
and other contact information in the body of your comment and with any 
disk or CD-ROM you submit. If EPA cannot read your comment due to 
technical difficulties and cannot contact you for clarification, EPA 
might not be able to consider your comment. Avoid the use of special 
characters and any form of encryption, and ensure that electronic files 
are free of any defects or viruses. For additional information about 
EPA's public docket, visit the EPA Docket Center homepage at http://www.epa.gov/epahome/dockets.htm.
    Docket: All documents in the docket are listed in the http://www.regulations.gov index. Some information, however, is not publicly 
available, e.g., CBI or other information whose disclosure is 
restricted by statute. Certain other material, such as copyrighted 
material, is publicly available only in hard copy. Publicly available 
docket materials are available electronically at http://www.regulations.gov or in hard copy at the Water Docket, EPA Docket 
Center, EPA West, Room 3334, 1301 Constitution Avenue NW., Washington, 
DC. The Public Reading Room is open from 8:30 a.m. to 4:30 p.m., Monday 
through Friday, excluding legal holidays. The telephone number for the 
Public Reading Room is 202-566-1744, and the telephone number for the 
Water Docket is 202-566-2426.

FOR FURTHER INFORMATION CONTACT: Ms. Donna Downing, Office of Water 
(4502-T), Environmental Protection Agency, 1200 Pennsylvania Avenue 
NW., Washington, DC 20460; telephone number 202-566-2428; email 
address: [email protected]. Ms. Stacey Jensen, Regulatory Community of 
Practice (CECW-CO-R), U.S. Army Corps of Engineers, 441 G Street NW., 
Washington, DC 20314; telephone number 202-761-5856; email address: 
[email protected].

SUPPLEMENTARY INFORMATION: The SWANCC and Rapanos decisions resulted in 
the agencies evaluating the jurisdiction of waters on a case-specific 
basis far more frequently than is best for clear and efficient 
implementation of the CWA. This approach results in confusion and 
uncertainty to the regulated public and results in significant 
resources being allocated to these determinations by Federal and State 
regulators. The agencies are proposing this rule to fully carry out 
their responsibilities under the Clean Water Act. The agencies are 
providing clarity to regulated entities as to whether individual water 
bodies are jurisdictional and discharges are subject to permitting, and 
whether individual water bodies are not jurisdictional and discharges 
are not subject to permitting.
    Developing a final rule to provide the intended level of certainty 
and predictability, and minimizing the number of case-specific 
determinations, will require significant public involvement and 
engagement. Such involvement and engagement will allow the agencies to 
make categorical determinations of jurisdiction, in a manner that is 
consistent with the scientific body of information before the 
agencies--particularly on the category of waters known as ``other 
waters.''
    The agencies propose to define ``waters of the United States'' in 
section (a) of the proposed rule for all sections of the CWA to mean: 
Traditional navigable waters; interstate waters, including interstate 
wetlands; the territorial seas; impoundments of traditional navigable 
waters, interstate waters, including interstate wetlands, the 
territorial seas, and tributaries, as defined, of such waters; 
tributaries, as defined, of traditional navigable waters, interstate 
waters,\1\ or the territorial seas;

[[Page 22189]]

and adjacent waters, including adjacent wetlands. Waters in these 
categories would be jurisdictional ``waters of the United States'' by 
rule--no additional analysis would be required. The agencies emphasize 
that the categorical finding of jurisdiction for tributaries and 
adjacent waters was not based on the mere connection of a water body to 
downstream waters, but rather a determination that the nexus, alone or 
in combination with similarly situated waters in the region, is 
significant based on data, science, the CWA, and caselaw.
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    \1\ ``Interstate waters'' in this preamble refers to all 
interstate waters including interstate wetlands.
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    In addition, the agencies propose that ``other waters'' (those not 
fitting in any of the above categories) could be determined to be 
``waters of the United States'' through a case-specific showing that, 
either alone or in combination with similarly situated ``other waters'' 
in the region, they have a ``significant nexus'' to a traditional 
navigable water, interstate water, or the territorial seas. The rule 
would also offer a definition of significant nexus and explain how 
similarly situated ``other waters'' in the region should be identified.
    The agencies acknowledge that there may be more than one way to 
determine which waters are jurisdictional as ``other waters.'' To best 
meet their goals and responsibilities, the agencies request comment on 
alternate approaches to determining whether ``other waters'' are 
similarly situated and have a ``significant nexus'' to a traditional 
navigable water, interstate water, or the territorial seas. In the 
discussion of ``other waters'' later in the preamble, the agencies seek 
comment on these other approaches and whether they could better meet 
the goals of greater predictability and consistency through increased 
clarity, while simultaneously fulfilling the agencies' responsibility 
to the CWA's objectives and policies to protect water quality, public 
health, and the environment. Commenters will specifically be asked to 
comment on whether and how these alternate approaches may be more 
consistent with the goal of clarity, and the CWA, the best available 
science, and the caselaw.
    In particular, the agencies are interested in comments, scientific 
and technical data, caselaw, and other information that would further 
clarify which ``other waters'' should be considered similarly situated 
for purposes of a case-specific significant nexus determination. The 
agencies seek comment on a number of alternative approaches. These 
alternatives include potentially determining waters in identified 
ecological regions (ecoregions) or hydrologic-landscape regions are 
similarly situated for purposes of evaluating a significant nexus, as 
well as the basis for determining which ecoregions or hydrologic-
landscape regions should be so identified. The agencies also solicit 
comment on whether the legal, technical and scientific record would 
support determining limited specific subcategories of waters are 
similarly situated, or as having a significant nexus sufficient to 
establish jurisdiction.
    Just as the agencies are seeking comment on a variety of 
approaches, or combination of approaches, as to which waters are 
jurisdictional, the agencies also request comment on determining which 
waters should be determined non-jurisdictional. The agencies 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.
    The agencies pose the questions because of the strong intent to 
provide as much certainty to the regulated public and the regulators as 
to which waters are and are not subject to CWA jurisdiction. These 
comments on alternate approaches will inform the agencies in addition 
to the comments on the case-specific determination proposed in the 
rule.
    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 EPA's Office of Research and Development synthesis of 
published peer-reviewed scientific literature discussing the nature of 
connectivity and effects of streams and wetlands on downstream waters 
(U.S. Environmental Protection Agency, Connectivity of Streams and 
Wetlands to Downstream Waters: A Review and Synthesis of the Scientific 
Evidence, (Washington, DC: U.S. Environmental Protection Agency, 2013)) 
(``Report'') and other available scientific information.
    The agencies also propose to exclude specified waters from the 
definition of ``waters of the United States'' in section (b) of the 
proposed rule. The agencies propose no change to the exclusion for 
waste treatment systems designed consistent with the requirements of 
the CWA, no change to the exclusion for prior converted cropland,\2\ 
and no change to the regulatory status of water transfers. The agencies 
propose, for the first time, to exclude by regulation certain waters 
and features over which the agencies have as a policy matter generally 
not asserted CWA jurisdiction. Codifying these longstanding practices 
supports the agencies' goals of providing greater clarity, certainty, 
and predictability for the regulated public and the regulators. Waters 
and features that are determined to be excluded under section (b) of 
the proposed rule will not be jurisdictional under any of the 
categories in the proposed rule under section (a). There is no 
recapture provision for these excluded waters in the proposal.
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    \2\ The term ``waters of the United States'' does not include 
prior converted cropland, which is currently defined by the U.S. 
Department of Agriculture (USDA) for purposes of the Agriculture Act 
of 2014 at 7 CFR 122.2. EPA and the Corps use the USDA definition of 
prior converted cropland for purposes of determining jurisdiction 
under the CWA.
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    In light of the Supreme Court decisions in SWANCC and Rapanos, 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'').
    The rule does not affect longstanding permitting exemptions in the 
CWA for farming, silviculture, ranching and other specified activities. 
Where waters would be determined jurisdictional under the proposed 
rule, applicable exemptions in the CWA would continue to preclude 
application of CWA permitting requirements.
    Finally, the agencies retain the existing regulatory definitions 
for the terms ``adjacent'' and ``wetlands.'' The agencies propose for 
the first time to define the terms ``neighboring,'' ``riparian area,'' 
``floodplain,'' ``tributary,'' and ``significant nexus.''
    This proposal does not affect Congressional policy to preserve the 
primary responsibilities and rights of states to prevent, reduce, and 
eliminate pollution, to plan the development and use of land and water 
resources, and to consult with the Administrator with respect to the 
exercise of the Administrator's authority under the CWA. CWA section 
101(b).
    This proposal also does not affect Congressional policy not to 
supersede, abrogate or otherwise impair the authority of each State to 
allocate quantities of water within its jurisdiction and neither does 
it affect the policy of Congress that nothing in the CWA shall be 
construed to supersede or abrogate rights to quantities of water which 
have been established by any state. CWA section 101(g).
    This proposal requests public comment on issues associated with the

[[Page 22190]]

agencies' proposed regulatory definition of ``waters of the United 
States.'' Because the agencies do not address the exclusions from the 
definition of ``waters of the United States'' for waste treatment 
systems and prior converted cropland or the existing definition of 
``wetlands'' in this proposed rule the agencies do not seek comment on 
these existing regulatory provisions. This notice also solicits 
information and data from the general public, the scientific community, 
and tribal, state and local resource agencies on the aquatic resource, 
implementation, and economic implications of a definition of ``waters 
of the United States'' as described in the proposal. The goal of the 
agencies is to ensure the regulatory definition is consistent with the 
CWA, as interpreted by the Supreme Court, and as supported by science, 
and to provide maximum clarity to the public, as the agencies work to 
fulfill the CWA's objectives and policy to protect water quality, 
public health, and the environment.

Table of Contents

I. General Information
A. How can I get copies of this document and related information?
B. Under what legal authority is this proposed rule issued?
II. Background
A. Executive Summary
B. The Clean Water Act and Regulatory Definition of Waters of the 
United States
C. Background on Scientific Review and Significant Nexus Analysis
    1. Scientific Synthesis
    2. Summary of Significant Nexus Conclusions
III. Proposed Definition of Waters of the United States
A. Summary of Proposed Rule
B. Traditional Navigable Waters
C. Interstate Waters
D. Territorial Seas
E. Impoundments
F. Tributaries
G. Adjacent Waters
H. Other Waters
I. Waters That Are Not Waters of the United States
IV. Related Acts of Congress, Executive Orders, and Agency 
Initiatives
A. Executive Order 12866: Regulatory Planning and Review
B. Paperwork Reduction Act
C. Regulatory Flexibility Act
D. Unfunded Mandates Reform Act
E. Executive Order 13132: Federalism
F. Executive Order 13175: Consultation and Coordination With Indian 
Tribal Governments
G. Executive Order 13045: Protection of Children From Environmental 
Health and Safety Risks
H. Executive Order 13211: Actions Concerning Regulations That 
Significantly Affect Energy Supply, Distribution, or Use
I. National Technology Transfer and Advancement Act
J. Executive Order 12898: Federal Actions To Address Environmental 
Justice in Minority Populations and Low-Income Populations
K. Environmental Documentation
Appendix A. Scientific Evidence
Appendix B. Legal Analysis

I. General Information

 A. How can I get copies of this document and related information?

    1. Docket. EPA and the Corps of Engineers have established an 
official public docket for this action under Docket Id. No. EPA-HQ-OW-
2011-0880. The official public docket consists of the document 
specifically referenced in this action, any public comments received, 
and other information related to this action. Although a part of the 
official docket, the public docket does not include Confidential 
Business Information (CBI) or other information whose disclosure is 
restricted by statute. The official public docket is the collection of 
materials that is available for public viewing at the OW Docket, EPA 
West, Room 3334, 1301 Constitution Ave. NW., Washington, DC 20004. This 
Docket Facility is open from 8:30 a.m. to 4:30 p.m., Monday through 
Friday, excluding legal holidays. The OW Docket telephone number is 
202-566-2426. A reasonable fee will be charged for copies.
    2. Electronic Access. You may access this Federal Register document 
electronically through the EPA Internet under the ``Federal Register'' 
listings at http://www.regulations.gov. An electronic version of the 
public docket is available through EPA's electronic public docket and 
comment system, EPA Dockets. You may use EPA Dockets at http://www.regulations.gov to view public comments, access the index listing 
of the contents of the official public docket, and to access those 
documents in the public docket that are available electronically. For 
additional information about EPA's public docket, visit the EPA Docket 
Center homepage at http://www.epa.gov/epahome/dockets.htm. Although not 
all docket materials may be available electronically, you may still 
access any of the publicly available docket materials through the 
Docket Facility identified earlier.

B. Under what legal authority is this proposed rule issued?

    The authority for this proposed rule is the Federal Water Pollution 
Control Act, 33 U.S.C. 1251, et seq.

II. Background

 A. Executive Summary

    The U.S. Environmental Protection Agency (EPA) and the U.S. Army 
Corps of Engineers (Corps) publish for public comment a proposed rule 
defining the scope of waters protected under the Clean Water Act (CWA), 
in light of the U.S. Supreme Court cases in U.S. v. Riverside Bayview 
Homes, Solid Waste Agency of Northern Cook County v. U.S. Army Corps of 
Engineers (SWANCC), and Rapanos v. United States (Rapanos). The 
purposes of the proposed rule are to ensure protection of our nation's 
aquatic resources and make the process of identifying ``waters of the 
United States'' less complicated and more efficient. The rule achieves 
these goals by increasing CWA program transparency, predictability, and 
consistency. This rule will result in more effective and efficient CWA 
permit evaluations with increased certainty and less litigation. This 
rule provides increased clarity regarding the CWA regulatory definition 
of ``waters of the United States'' and associated definitions and 
concepts.
    EPA's Office of Research and Development prepared a draft peer-
reviewed synthesis of published peer-reviewed scientific literature 
discussing the nature of connectivity and effects of streams and 
wetlands on downstream waters (U.S. Environmental Protection Agency, 
Connectivity of Streams and Wetlands to Downstream Waters: A Review and 
Synthesis of the Scientific Evidence, (Washington, DC: U.S. 
Environmental Protection Agency, 2013)) (``Report''). The Report is 
under review by EPA's Science Advisory Board, and the rule will not be 
finalized until that review and the final Report are complete. This 
proposal is also supported by a body of peer-reviewed scientific 
literature on the connectivity of tributaries, wetlands, adjacent open 
waters, and other open waters to downstream waters and the important 
effects of these connections on the chemical, physical, and biological 
integrity of those downstream waters.
    Appendix A of this preamble summarizes currently available 
scientific literature and the Report that are part of the 
administrative record for this proposal and explains how this 
scientific information supports the proposed rule. Additional data and 
information likely will become available during the rulemaking process, 
including that provided during the public comment process, and by 
additional research, studies, and investigations that take place before 
the rulemaking process is concluded. The

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agencies are specifically requesting information that would inform the 
decision on how best to address ``other waters.'' At the conclusion of 
the rulemaking process, the agencies will review the entirety of the 
completed administrative record and determine at that time what, if 
any, adjustments are appropriate for the final rule.
    ``Waters of the United States,'' which include wetlands, rivers, 
streams, lakes, ponds and the territorial seas, provide many functions 
and services critical for our nation's economic and environmental 
health.\3\ In addition to providing habitat, rivers, lakes, ponds and 
wetlands cleanse our drinking water, ameliorate storm surges, provide 
invaluable storage capacity for some flood waters, and enhance our 
quality of life by providing myriad recreational opportunities, as well 
as important water supply and power generation benefits. A desire to 
protect these vital resources led Congress to pass the CWA in 1972 in 
order to restore and maintain the chemical, physical, and biological 
integrity of our nation's waters while recognizing, preserving, and 
protecting the primary responsibilities and rights of states to 
prevent, reduce, and eliminate pollution within their borders. Decades 
of experience implementing the CWA's programs and existing science 
provide strong support for the regulatory and policy underpinnings of 
the proposed rule. The proposed rule was developed with an enhanced 
understanding of the importance of all aspects of tributary, wetland, 
and lake and pond systems and the ecological functions and services 
they provide.
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    \3\ The agencies use the term ``water'' and ``waters'' in the 
proposed rule in categorical reference to rivers, streams, ditches, 
wetlands, ponds, lakes, playas, and other types of natural or man-
made aquatic systems. The agencies use the terms ``waters'' and 
``water bodies'' interchangeably in this preamble. The terms do not 
refer solely to the water contained in these aquatic systems, but to 
the system as a whole including associated chemical, physical, and 
biological features.
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    The proposed rule will reduce documentation requirements and the 
time currently required for making jurisdictional determinations. It 
will provide needed clarity for regulators, stakeholders and the 
regulated public for identifying waters as ``waters of the United 
States,'' and reduce time and resource demanding case-specific analyses 
prior to determining jurisdiction and any need for permit or 
enforcement actions.
    The modern Clean Water Act was established by the Federal Water 
Pollution Control Act Amendments of 1972, which was substantially 
amended in 1977 and 1987. (The 1972 amendments were to the Federal 
Water Pollution Control Act originally enacted in 1948.) As stated in 
section 101(a), the objective of the CWA is to restore and maintain the 
chemical, physical, and biological integrity of the Nation's waters. 
Prior to the CWA, the Rivers and Harbors Appropriations Act of 1899 
protected navigation and protected some waters from discharges of 
pollution.
    The 1899 Act continues in force and applies primarily to the 
``navigable waters of the United States.'' The 1948 Federal Water 
Pollution Control Act called for programs eliminating or reducing the 
pollution of interstate waters and tributaries thereof, and improving 
the sanitary condition of surface and underground waters. The 
jurisdictional scope of the CWA is ``navigable waters,'' defined in 
section 502(7) of the statute as ``waters of the United States, 
including the territorial seas.'' Both the legislative history and the 
caselaw confirm that ``waters of the United States'' in the CWA are not 
limited to the traditional navigable waters. It is the CWA definition 
that is the subject of this proposed rule.
    The term ``navigable waters'' is used in a number of provisions of 
the CWA, including the section 402 National Pollutant Discharge 
Elimination System (NPDES) permit program, the section 404 permit 
program, the section 311 oil spill prevention and response program,\4\ 
the water quality standards and total maximum daily load programs under 
section 303, and the section 401 state water quality certification 
process. However, while there is only one CWA definition of ``waters of 
the United States,'' there may be other statutory factors that define 
the reach of a particular CWA program or provision.\5\
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    \4\ While section 311 uses the phrase ``navigable waters of the 
United States,'' EPA has interpreted it to have the same breadth as 
the phrase ``navigable waters'' used elsewhere in section 311, and 
in other sections of the CWA. See United States v. Texas Pipe Line 
Co., 611 F.2d 345, 347 (10th Cir. 1979); United States v. Ashland 
Oil & Transp. Co., 504 F.2d 1317, 1324-25 (6th Cir. 1974). In 2002, 
EPA revised its regulatory definition of ``waters of the United 
States'' in 40 CFR part 112 to ensure that the actual language of 
the rule was consistent with the regulatory language of other CWA 
programs. Oil Pollution & Response; Non-Transportation-Related 
Onshore & Offshore Facilities, 67 FR 47042, July 17, 2002. A 
district court vacated the rule for failure to comply with the 
Administrative Procedure Act, and reinstated the prior regulatory 
language. American Petroleum Ins. v. Johnson, 541 F.Supp. 2d 165 (D. 
DC 2008). However, EPA interprets ``navigable waters of the United 
States'' in CWA section 311(b), in the pre-2002 regulations, and in 
the 2002 rule to have the same meaning as ``navigable waters'' in 
CWA section 502(7).
    \5\ For example, the CWA section 402 (33 U.S.C. Sec.  1342) 
program regulates discharges of pollutants from ``point sources'' to 
``waters of the United States,'' whether these pollutants reach 
jurisdictional waters directly or indirectly. The plurality opinion 
in Rapanos noted that ``there is no reason to suppose that our 
construction today significantly affects the enforcement of Sec.  
1342. . . . The Act does not forbid the `addition of any pollutant 
directly to navigable waters from any point source,' but rather the 
`addition of any pollutant to navigable waters.' '' 547 U.S. at 743. 
Clean Water Act section 311(b)(1) provides: ``[I]t is the policy of 
the United States that there should be no discharges of oil or 
hazardous substances into or upon the navigable waters of the United 
States [or] adjoining shorelines . . . or which may affect natural 
resources belonging to, appertaining to, or under the exclusive 
management authority of the United States.'' (Emphasis added.) 
``Discharge'' is broadly defined in CWA section 311(a)(2) to include 
``any spilling, leaking, pumping, pouring, emitting, emptying or 
dumping,'' with certain enumerated exceptions, and is not limited to 
point source discharges.
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    The CWA leaves it to EPA and the Corps to define the term ``waters 
of the United States.'' Existing regulations (last codified in 1986) 
define ``waters of the United States'' as traditional navigable waters, 
interstate waters, all other waters that could affect interstate or 
foreign commerce, impoundments of waters of the United States, 
tributaries, the territorial seas, and adjacent wetlands. 33 CFR 328.3; 
40 CFR 122.2.
    The U.S. Supreme Court addressed the scope of ``waters of the 
United States'' protected by the CWA in United States v. Riverside 
Bayview Homes, 474 U.S. 121 (1985), which involved wetlands adjacent to 
a traditional navigable water in Michigan. In a unanimous opinion, the 
Court deferred to the Corps' judgment that adjacent wetlands are 
``inseparably bound up'' with the waters to which they are adjacent, 
and upheld the inclusion of adjacent wetlands in the regulatory 
definition of ``waters of the United States.'' The Court observed that 
the broad objective of the CWA to restore the integrity of the nation's 
waters ``incorporated a broad, systemic view of the goal of maintaining 
and improving water quality. . . . Protection of aquatic ecosystems, 
Congress recognized, demanded broad federal authority to control 
pollution, for `[w]ater moves in hydrologic cycles and it is essential 
that discharge of pollutants be controlled at the source.' In keeping 
with these views, Congress chose to define the waters covered by the 
Act broadly.'' Id. at 133 (citing Senate Report 92-414).
    The issue of CWA regulatory jurisdiction over ``waters of the 
United States'' was addressed again by the Supreme Court in Solid Waste 
Agency of Northern Cook County v. U.S. Army Corps of Engineers, 531 
U.S. 159 (2001). In SWANCC, the Court (in a 5-4 opinion) held that the 
use of ``isolated'' nonnavigable intrastate ponds by migratory birds 
was not by itself a sufficient basis for the exercise of Federal 
regulatory authority under the

[[Page 22192]]

CWA. The Court noted that in the Riverside case it had ``found that 
Congress' concern for the protection of water quality and aquatic 
ecosystems indicated its intent to regulate wetlands `inseparably bound 
up with the ``waters'' of the United States' '' and that ``[i]t was the 
significant nexus between the wetlands and `navigable waters' that 
informed our reading of the CWA'' in that case. Id. at 167.
    Five years after SWANCC, the Court again addressed the CWA term 
``waters of the United States'' in Rapanos v. United States, 547 U.S. 
715 (2006). Rapanos involved two consolidated cases in which the CWA 
had been applied to wetlands adjacent to nonnavigable tributaries of 
traditional navigable waters. All Members of the Court agreed that the 
term ``waters of the United States'' encompasses some waters that are 
not navigable in the traditional sense. A four-Justice plurality in 
Rapanos interpreted the term ``waters of the United States'' as 
covering ``relatively permanent, standing or continuously flowing 
bodies of water. . .'' id. at 739, that are connected to traditional 
navigable waters, id. at 742, as well as wetlands with a continuous 
surface connection to such relatively permanent water bodies, id. The 
Rapanos plurality noted that its reference to ``relatively permanent'' 
waters did ``not necessarily exclude streams, rivers, or lakes that 
might dry up in extraordinary circumstances, such as drought,'' or 
``seasonal rivers, which contain continuous flow during some months of 
the year but no flow during dry months. . . .'' Id. at 732 n.5 
(emphasis in original).
    Justice Kennedy's concurring opinion took a different approach than 
the plurality's. Justice Kennedy concluded that the term ``waters of 
the United States'' encompasses wetlands that ``possess a `significant 
nexus' to waters that are or were navigable in fact or that could 
reasonably be so made.'' Id. at 759 (Kennedy, J., concurring in the 
judgment) (quoting SWANCC, 531 U.S. at 167). He stated that wetlands 
possess the requisite significant nexus 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. Kennedy's opinion notes that such a relationship with 
navigable waters must be more than ``speculative or insubstantial.'' 
Id. Because Justice Kennedy identified ``significant nexus'' as the 
touchstone for CWA jurisdiction, the agencies determined that it is 
reasonable and appropriate to apply the ``significant nexus'' standard 
for CWA jurisdiction that Justice Kennedy's opinion applied to adjacent 
wetlands to other categories of water bodies as well (such as to 
tributaries of traditional navigable waters or interstate waters, and 
to ``other waters'') to determine whether they are subject to CWA 
jurisdiction, either by rule or on a case-specific basis.
    The four dissenting Justices in Rapanos would have affirmed the 
court of appeals' application of the pertinent regulatory provisions, 
concluding that the term ``waters of the United States'' encompasses, 
inter alia, all tributaries and wetlands that satisfy either the 
plurality's standard or that of Justice Kennedy. Id. at 810 & n.14 
(Stevens, J., dissenting). Neither the plurality nor the Kennedy 
opinion invalidated any of the regulatory provisions defining ``waters 
of the United States.''
    The proposed rule would revise the existing definition of ``waters 
of the United States'' consistent with the science and the above 
Supreme Court cases. The proposed rule retains much of the structure of 
the agencies' longstanding definition of ``waters of the United 
States,'' and many of the existing provisions of that definition where 
revisions are not required in light of Supreme Court decisions or other 
bases for revision. As a result of the Supreme Court decisions in 
SWANCC and Rapanos, the scope of regulatory jurisdiction of the CWA in 
this proposed rule is narrower than that under the existing 
regulations.
    The most substantial change is the proposed deletion of the 
existing regulatory provision that defines ``waters of the ``United 
States'' as all other waters such as intrastate lakes, rivers, streams 
(including intermittent streams), mudflats, sandflats, wetlands, 
sloughs, prairie potholes, wet meadows, playa lakes, or natural ponds, 
the use, degradation or destruction of which could affect interstate or 
foreign commerce including any such waters: Which are or could be used 
by interstate or foreign travelers for recreational or other purposes; 
from which fish or shellfish are or could be taken and sold in 
interstate or foreign commerce; or which are used or could be used for 
industrial purposes by industries in interstate commerce. 33 CFR 
328.3(a)(3); 40 CFR 122.2. Under the proposed rule, these ``other 
waters'' (those which do not fit within the proposed categories of 
waters jurisdictional by rule) would only be jurisdictional upon a 
case-specific determination that they have a significant nexus as 
defined by the proposed rule. Waters in a watershed in which there is 
no connection to a traditional navigable water, interstate water or the 
territorial seas would not be ``waters of the United States.'' In 
addition, the proposed rule would for the first time explicitly exclude 
some features and waters over which the agencies have not generally 
asserted jurisdiction and in so doing would eliminate the authority of 
the agencies to determine in case specific circumstances that some such 
waters are jurisdictional ``waters of the United States.''
    The agencies propose a rule that is clear and understandable and 
that protects the nation's waters, consistent with the law and 
currently available scientific and technical expertise. Continuity with 
the existing regulations, where possible, will reduce confusion and 
will reduce transaction costs for the regulated community and the 
agencies. To that same end, the agencies also propose, where consistent 
with the law and their scientific and technical expertise, categories 
of waters that are and are not jurisdictional, as well as categories of 
waters and wetlands that require a case-specific significant nexus 
evaluation to determine whether they are ``waters of the United 
States'' and protected by the CWA. Finally, the agencies propose 
definitions for some of the terms used in the proposed regulation.
    This preamble also presents several alternative options for 
determining the jurisdictional status of certain ``other waters'' that 
would rely less, or not at all, on case-specific significant nexus 
evaluations. The agencies may adopt one or a combination of these 
options for the final rule, after considering public comment and the 
evolving scientific literature on connectivity of waters. This preamble 
also seeks comment on a number of other ways that the agencies might 
provide even greater clarity, certainty, and predictability in 
determining which ``other waters'' are and are not subject to CWA 
jurisdiction. The agencies evaluated extensive peer reviewed science in 
making their determination in the proposed rule. However, the agencies 
also seek additional information that would enhance the predictability 
and accuracy of its jurisdictional determinations. The agencies request 
the type of information on the evolving scientific literature on 
connectivity of waters that could allow the agencies to rely less on 
case-specific significant nexus evaluations.
    Under the proposed first section of the regulation, section (a), 
the agencies propose to define the ``waters of the United States'' for 
all sections

[[Page 22193]]

(including sections 301, 311, 401, 402, 404) of the CWA to mean:
     All waters which are currently used, were used in the 
past, or may be susceptible to use in interstate or foreign commerce, 
including all waters which are subject to the ebb and flow of the tide;
     All interstate waters, including interstate wetlands;
     The territorial seas;
     All impoundments of a traditional navigable water, 
interstate water, the territorial seas or a tributary;
     All tributaries of a traditional navigable water, 
interstate water, the territorial seas or impoundment;
     All waters, including wetlands, adjacent to a traditional 
navigable water, interstate water, the territorial seas, impoundment or 
tributary; and
     On a case-specific basis, other waters, including 
wetlands, provided that those waters alone, or in combination with 
other similarly situated waters, including wetlands, located in the 
same region, have a significant nexus to a traditional navigable water, 
interstate water or the territorial seas.
    As discussed in further detail below, the rule would not change the 
following provisions of the existing rule (although some provisions 
have been renumbered): Traditional navigable waters; interstate waters; 
the territorial seas; and impoundments of ``waters of the United 
States.'' In paragraph (a)(5) of the proposed rule, the agencies 
propose that all tributaries as defined in the proposed rule are 
``waters of the United States.'' While tributaries are ``waters of the 
United States'' under the existing regulation, the rule would for the 
first time include a regulatory definition of ``tributary.''
    With this proposed rule, the agencies conclude, based on existing 
science and the law, that a significant nexus exists between 
tributaries (as defined in the proposed rule) and the traditional 
navigable waters, interstate waters, and the territorial seas into 
which they flow; and between adjacent water bodies (as defined in the 
proposed rule) and traditional navigable waters, interstate waters, and 
the territorial seas, respectively. Consequently, this rule establishes 
as ``waters of the United States,'' all tributaries (as defined in the 
proposal), of the traditional navigable waters, interstate waters, and 
the territorial seas, as well as all adjacent waters (including 
wetlands). This will eliminate the need to make a case-specific 
significant nexus determination for tributaries or for their adjacent 
waters because it has been determined that as a category, these waters 
have a significant nexus and thus are ``waters of the United States.''
    In paragraph (a)(6) of the proposed rule, the rule would clarify 
that adjacent waters, rather than simply adjacent wetlands, are 
``waters of the United States.'' The rule would further clarify the 
meaning of ``adjacent'' by defining one of its elements, 
``neighboring.'' The related terms of ``riparian area'' and 
``floodplain'' are also defined in the proposed rule.
    The rule states that on a case-specific basis ``other waters'' that 
have a significant nexus to a traditional navigable water, interstate 
water or the territorial seas are ``waters of the United States.'' 
Unlike the categories of waters in paragraphs (a)(1) through (6), which 
would be jurisdictional by definition, these ``other waters'' would not 
be ``waters of the United States'' by definition; rather, these ``other 
waters'' would only be jurisdictional provided that they have been 
determined on a case-specific basis to have a significant nexus to a 
paragraph (a)(1) through (a)(3) water. Therefore, the rule also 
includes a definition of ``significant nexus.''
    ``Significant nexus'' is not itself a scientific term. The 
relationship that waters can have to each other and connections 
downstream that affect the chemical, physical, or biological integrity 
of traditional navigable waters, interstate waters, or the territorial 
seas is not an all or nothing situation. The existence of a connection, 
a nexus, does not by itself establish that it is a ``significant 
nexus.'' There is a gradient in the relation of waters to each other, 
and this is documented in the Report. The agencies propose a case-
specific analysis in establishing jurisdiction over these ``other 
waters'' as consistent with the current science, the CWA, and the 
caselaw. A case-specific analysis allows for a determination of 
jurisdiction at the point on the gradient in the relationship that 
constitutes a ``significant nexus.'' In the proposed regulation the 
rule defines the following terms: adjacent, neighboring, riparian area, 
floodplain, tributary, wetlands, and significant nexus. However, the 
agencies also recognize that relying on a case-specific analysis 
provides less certainty to the regulated public on the jurisdictional 
status of other waters and is considering other approaches, as 
discussed later in this preamble.
    The proposed section (b) excludes specified waters and features 
from the definition of ``waters of the United States.'' Waters and 
features that are determined to be excluded under section (b) of the 
proposed rule will not be jurisdictional under any of the categories in 
the proposed rule under section (a), even if they would otherwise 
satisfy the regulatory definition. Those waters and features that would 
not be ``waters of the United States'' are:
     Waste treatment systems, including treatment ponds or 
lagoons, designed to meet the requirements of the Clean Water Act.
     Prior converted cropland. Notwithstanding the 
determination of an area's status as prior converted cropland by any 
other Federal agency, for the purposes of the Clean Water Act the final 
authority regarding Clean Water Act jurisdiction remains with EPA.
     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 an impoundment of a jurisdictional 
water.
     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.
    The rule does not affect longstanding exemptions in the CWA for 
farming, silviculture, ranching and other activities, does not change 
regulatory exclusions for waste treatment systems and prior converted 
cropland, and does not change the regulatory status of water transfers. 
Where waters would be determined jurisdictional under the proposed 
rule, applicable exemptions of the CWA would continue to preclude 
application of CWA permitting requirements. For example, if ``other 
waters'' are aggregated as similarly situated in the region and 
determined to be jurisdictional, any exempt activities that include a 
discharge to those waters would remain outside the regulatory 
requirements of the CWA. Exempted discharges are established under CWA 
sections 402, 502, and 404 and include:

[[Page 22194]]

Agricultural stormwater discharges; return flows from irrigated 
agriculture; normal farming, silvicultural, and ranching activities; 
upland soil and water conservation practices; construction or 
maintenance of farm or stock ponds or irrigation ditches; maintenance 
of drainage ditches; and construction or maintenance of farm, forest, 
and temporary mining roads.
    To provide additional clarity to farmers, the agencies are today 
also issuing an interpretive rule clarifying the applicability of the 
permitting exemption provided under section 404(f)(1)(A) of the CWA to 
discharges of dredged or fill material associated with certain 
agricultural conservation practices based on the Natural Resources 
Conservation Service conservation practice standards and that are 
designed and implemented to protect and enhance water quality. This 
interpretive rule was developed in coordination with the U.S. 
Department of Agriculture, was signed by EPA and the Army, and became 
effective immediately. The agencies recognize, however, the value of 
receiving public comment on the interpretive rule and are publishing it 
by separate notice in the Federal Register. The public is encouraged to 
provide their comments on the interpretive rule to the docket on the 
interpretive rule, Docket Id. No. EPA-HQ-OW-2013-0820, and not to this 
docket. The interpretive rule and the request for comments can be found 
at http://water.epa.gov/lawsregs/guidance/wetlands/agriculture.cfm and 
at http://www.regulations.gov via Docket Id. No. EPA-HQ-OW-2013-0820.
    The proposed rule is expected to reduce documentation requirements 
and the time it takes to make approved jurisdictional determinations by 
decreasing the number of jurisdictional determinations that require 
case-specific significant nexus analysis evaluations. It will improve 
clarity for regulators, stakeholders and the regulated public by 
defining certain categories of waters as ``waters of the United 
States'' that previously required case-specific analyses prior to 
establishing CWA jurisdiction through the approved jurisdictional 
determination procedures. A comprehensive review of a growing body of 
scientific literature, as well as the agencies' growing body of 
scientific and technical knowledge and field expertise, led the 
agencies to conclude that it is reasonable to establish certain 
categories of waters that are jurisdictional by rule as they have a 
significant nexus to an (a)(1) through (a)(3) water, specifically 
tributaries to traditional navigable waters, interstate waters, or the 
territorial seas, and their adjacent waters and wetlands. Case-specific 
jurisdictional determinations would still be required for the ``other 
waters'' category in paragraph (a)(7) of the proposed rule. Under the 
alternate approaches affecting ``other waters'' described later in the 
preamble, the agencies request comment on the case-specific analysis.
    A review of the scientific literature, including the Report of the 
peer-reviewed science, shows that tributaries and adjacent waters play 
an important role in maintaining the chemical, physical, and biological 
integrity of traditional navigable waters, interstate waters, and the 
territorial seas--and of other jurisdictional waters--because of their 
hydrological and ecological connections to and interactions with those 
waters. Therefore, it is appropriate to protect all tributaries and 
adjacent waters, because the tributaries, adjacent waters, and the 
downstream traditional navigable waters, interstate waters, and the 
territorial seas function as an integrated system. Water flows through 
tributaries to downstream traditional navigable waters, interstate 
waters, and the territorial seas, and that water carries pollutants 
that affect the chemical, physical, and biological integrity of the 
(a)(1) through (a)(3) waters, including water quality, fisheries, 
recreation, and other ecological services.
    In discussing the significant nexus standard, Justice Kennedy 
stated: ``The required nexus must be assessed in terms of the statute's 
goals and purposes. Congress enacted the [CWA] to `restore and maintain 
the chemical, physical, and biological integrity of the Nation's 
waters. . . .' '' 547 U.S. at 779. To protect the integrity of the 
waters subject to the CWA, the significant nexus standard must be 
implemented in a manner that restores and maintains any of these three 
attributes of traditional navigable waters, interstate waters, or the 
territorial seas. Waters adjacent to tributaries also provide 
ecological functions that, in conjunction with the functions provided 
by the tributaries they are adjacent to, have a significant influence 
on the chemical, physical, and biological integrity of downstream 
traditional navigable waters, interstate waters, and the territorial 
seas.
    Examples of the important functions provided by adjacent waters are 
the sequestering or transformation of pollutants to reduce inputs to 
tributaries and subsequently to downstream (a)(1) through (a)(3) 
waters, water storage, and sediment trapping. Thus, in some instances, 
the significance of adjacent waters is to prevent or delay a 
hydrological connection with downstream waters and store water and/or 
pollutants. Given the large scale systematic interactions that occur, 
and the substantial effects that result, among tributaries, adjacent 
waters, and the downstream traditional navigable waters, interstate 
waters, or the territorial seas, a significant nexus exists that 
warrants making those categories of waters jurisdictional by rule.
    States and tribes play a vital role in the implementation and 
enforcement of the CWA. Section 101(b) of the CWA states that it is 
Congressional policy to preserve the primary responsibilities and 
rights of states to prevent, reduce, and eliminate pollution, to plan 
the development and use of land and water resources, and to consult 
with the Administrator with respect to the exercise of the 
Administrator's authority under the CWA.
    Of particular importance, states and tribes may be authorized by 
the EPA to administer the permitting programs of sections 402 and 404. 
Forty-six states and the Virgin Islands are authorized to administer 
the NPDES program under section 402, while two states administer the 
section 404 program. Additional CWA programs that utilize the 
definition of ``waters of the United States'' and are of importance to 
the states and tribes include the section 311 oil spill prevention and 
response program, the water quality standards and total maximum daily 
load programs under section 303, and the section 401 state water 
quality certification process.
    States and tribes, consistent with the CWA, retain full authority 
to implement their own programs to more broadly or more fully protect 
the waters in their state. Under section 510 of the Act, unless 
expressly stated in the CWA, nothing in the Act precludes or denies the 
right of any state or tribe to establish more protective standards or 
limits than the Federal CWA. Many states and tribes, for example, 
protect groundwater, and some others protect wetlands that are vital to 
their environment and economy but which are outside the regulatory 
jurisdiction of the CWA. Nothing in this proposed rule would limit or 
impede any existing or future state or tribal efforts to further 
protect their waters. In fact, providing greater clarity regarding what 
waters are subject to CWA jurisdiction will reduce the need for 
permitting authorities, including the states and tribes that have 
authorized section 402 and 404 CWA permitting programs, to make 
jurisdictional determinations on a case-specific basis, leaving them 
with more resources to protect their waters.

[[Page 22195]]

    This proposal also recognizes the unique role of states related to 
water quantity and as stated in the CWA. The proposal does not affect 
Congressional policy not to supersede, abrogate or otherwise impair the 
authority of each state to allocate quantities of water within its 
jurisdiction and neither does it affect the policy of Congress that 
nothing in the CWA shall be construed to supersede or abrogate rights 
to quantities of water which have been established by any state. CWA 
section 101(g).
    While a principal goal of this rulemaking is to improve clarity for 
determining jurisdiction under the CWA in light of the two most recent 
Supreme Court cases with the dual benefits of improving certainty and 
greater efficiency for determining whether waters are covered, there 
are other tools and approaches underway to increase efficiency as well. 
For example, to improve efficiencies, the EPA and the Corps are working 
in partnership with states to develop new tools and resources that have 
the potential to improve precision of desk based jurisdictional 
determinations at lower cost and improved speed than the existing 
primarily field-based approaches. In the normal course of making 
jurisdictional determinations, information derived from field 
observation is not always required in cases where a ``desktop'' 
analysis furnishes 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.
    EPA and the Corps are very interested in identifying other emerging 
technologies or approaches that would save time and money and improve 
efficiency for regulators and the regulated community in determining 
which waters are subject to CWA jurisdiction. The agencies specifically 
invite comment on this topic.
    The proposed rule will benefit the nation by helping to protect the 
services and functions these important water bodies provide consistent 
with the overarching objective of the CWA.

B. The Clean Water Act and Regulatory Definition of ``Waters of the 
United States''

    The Federal Water Pollution Control Act Amendments, now known as 
the Clean Water Act, were enacted in 1972. The objective of the CWA is 
to restore and maintain the chemical, physical, and biological 
integrity of the Nation's waters. CWA section 101(a). Its specific 
provisions were designed to improve the protection of the nation's 
waters provided under earlier statutory schemes such as certain 
sections of the Rivers and Harbors Appropriations Act of 1899 (``RHA'') 
(33 U.S.C. 03, 407, 411) and the Federal Water Pollution Control Act of 
1948 (62 Stat. 1155) and its subsequent amendments through 1970. The 
jurisdictional scope of the CWA is ``navigable waters,'' defined in the 
statute as ``waters of the United States, including the territorial 
seas.'' CWA section 502(7). The CWA leaves it to the agencies to define 
the term ``waters of the United States.'' Existing agency regulations 
define ``waters of the United States'' as traditional navigable waters, 
interstate waters, all other waters that could affect interstate or 
foreign commerce, impoundments of waters of the United States, 
tributaries, the territorial seas, and adjacent wetlands. 33 CFR 328.3; 
40 CFR 230.3(s). Counterpart and substantively similar regulatory 
definitions appear at 40 CFR 110.1, 112.2, 116.3, 117.1, 122.2, 232.2, 
300.5, part 300 App. E, 302.3 and 401.11.
    The current regulatory definition of ``waters of the United 
States'' provides two specific exclusions from ``waters of the United 
States.'' Waste treatment systems designed to meet the requirements of 
the CWA and prior converted cropland are not ``waters of the United 
States'' under the agencies' current regulations. Under the regulations 
for prior converted cropland, notwithstanding the determination of an 
area's status as prior converted cropland by any other Federal agency, 
for the purposes of the Clean Water Act, the final authority regarding 
Clean Water Act jurisdiction remains with EPA. 33 CFR 328.3(a)(8).

C. Background on Scientific Review and Significant Nexus Analysis

1. Scientific Synthesis
    EPA's Office of Research and Development prepared a draft peer-
reviewed synthesis of published peer-reviewed scientific literature 
discussing the nature of connectivity and effects of streams and 
wetlands on downstream waters (U.S. Environmental Protection Agency, 
Connectivity of Streams and Wetlands to Downstream Waters: A Review and 
Synthesis of the Scientific Evidence, (Washington, DC: U.S. 
Environmental Protection Agency, 2013), (the ``Report'')). The draft 
Report provides a review and synthesis of the scientific information 
pertaining to chemical, physical, and biological connections from 
streams, wetlands, and open waters such as oxbow lakes, to downstream 
larger water bodies such as rivers, lakes, and estuaries in watersheds 
across the United States and the strength of those connections. While 
the scientific literature does not use the term ``significant nexus,'' 
there is a substantial body of scientific literature on the chemical, 
physical, and biological connections between tributaries and adjacent 
waters and ``other waters'' and the downstream larger waters, and on 
the strength and the effect of these connections.
    Connectivity is a foundational concept in hydrology and freshwater 
ecology. Connectivity is the degree to which components of a system are 
joined, or connected, by various transport mechanisms and is determined 
by the characteristics of both the physical landscape and the biota of 
the specific system. The structure and function of downstream waters 
are highly dependent on the constituent materials contributed by and 
transported through waters located elsewhere in the watershed. 
Connectivity for purposes of interpreting the scope of ``waters of the 
United States'' under the CWA serves to demonstrate the ``nexus'' 
between upstream water bodies and the downstream traditional navigable 
water, interstate water, or the territorial sea. Based on the 
literature, the Office of Research and Development was able to assess 
the types of connections between the tributaries and adjacent waters 
and the chemical, physical, and biological integrity of downstream 
traditional navigable waters, interstate waters, and the territorial 
seas.
    However, as Justice Kennedy found in Rapanos, a mere hydrologic 
connection may not suffice in all cases to establish CWA jurisdiction 
and there needs to be ``some measure of the significance of the 
connection for downstream water quality.'' 547 U.S. at 784-785 (``mere 
hydrologic connection should not suffice in all cases; the connection 
may be too insubstantial for the hydrologic linkage to establish the 
required nexus with navigable waters as traditionally understood''). 
The literature does not use the term ``significant'' but does provide 
information on the strength of the effects on the chemical, physical, 
and biological functioning of the downstream water bodies from the 
connections among tributaries and adjacent waters and ``other waters'' 
and those downstream waters.
    While ``strength'' of connections to and effects on the integrity 
of downstream waters and the ``significance'' of the nexus to the 
integrity of downstream waters are clearly related inquiries, 
``significant'' is not a scientific term but rather a

[[Page 22196]]

determination of the agencies in light of the law and science. The 
relative strength of downstream effects informs the agencies' 
conclusions about the significance of those effects for purposes of 
interpreting the CWA. The data and conclusions in the Report concerning 
the strength of the relevant connections and effects of certain types 
of waters on downstream waters provide a foundation for the agencies' 
determinations that certain waters have effects on the chemical, 
physical, and biological integrity of traditional navigable waters, 
interstate waters, or the territorial seas that are ``significant'' and 
thus constitute a significant nexus. As clarified in the proposed 
definition of ``significant nexus'' and consistent with Justice 
Kennedy's guidance, for an effect to be significant it must be more 
than speculative or insubstantial.
    The Office of Research and Development's review and synthesis of 
more than a thousand publications from peer-reviewed scientific 
literature focuses on evidence of those connections from various 
categories of waters, evaluated singly or in aggregate, which affect 
downstream waters and the strength of that effect. Much of the 
scientific literature relied on does not use the terms traditional 
navigable waters, interstate waters, or the territorial seas. However, 
evidence of strong chemical, physical, and biological connections to 
larger rivers, estuaries and lakes applies to that subset of rivers, 
estuaries and lakes that are traditional navigable waters, interstate 
waters, or the territorial seas. The objectives of the Report are (1) 
to provide a context for considering the evidence of connections 
between downstream waters and their tributary waters, and (2) to 
summarize current understanding about these connections, the factors 
that influence them, and the mechanisms by which the connections affect 
the function or condition of downstream waters. The connections and 
mechanisms discussed in the Report include transport of physical 
materials and chemicals such as water, wood, sediment, nutrients, 
pesticides, and mercury; functions that adjacent waters perform, such 
as storing and cleansing water; movement of organisms or their seeds 
and eggs; and hydrologic and biogeochemical interactions occurring in 
and among surface and groundwater flows, including hyporheic zones and 
alluvial aquifers.
    The Report concludes that the scientific literature clearly 
demonstrates that streams, regardless of their size or how frequently 
they flow, strongly influence how downstream waters function. Streams 
supply most of the water in rivers, transport sediment and organic 
matter, provide habitat for many species, and take up or change 
nutrients that could otherwise impair downstream waters. The Report 
also concludes that wetlands and open waters in floodplains of streams 
and rivers and in riparian areas (transition areas between terrestrial 
and aquatic ecosystems) have a strong influence on downstream waters. 
Such waters act as the most effective buffer to protect downstream 
waters from nonpoint source pollution (such as nitrogen and 
phosphorus), provide habitat for breeding fish and aquatic insects that 
also live in streams, and retain floodwaters, sediment, nutrients, and 
contaminants that could otherwise negatively impact the condition or 
function of downstream waters.
    Regarding wetlands and open waters located outside of floodplains 
and riparian areas, the Report finds that they provide many benefits to 
rivers, lakes, and other downstream waters. If the wetland or open 
water has a surface or shallow subsurface water connection to the river 
network, it affects the condition of downstream waters. Where the 
wetland or open water is not connected to the river network through 
surface or shallow subsurface water, the type and degree of 
connectivity varies geographically, topographically, and ecologically, 
such that the significance of the connection is difficult to generalize 
across the entire group of waters.
    Lastly, the Report concludes that to understand the health, 
behavior, and sustainability of downstream waters, the effects of small 
water bodies in a watershed need to be considered in aggregate. The 
contribution of material by, or an important water-retention function 
of, a particular stream, other open water, or wetland might be small, 
but the aggregate contribution by an entire class of streams, other 
open waters, and wetlands (e.g., all ephemeral streams in the river 
network) can be substantial.
    In the proposed rule, the agencies interpreted the scope of 
``waters of the United States'' in the CWA based on the information and 
conclusions in the Report, other relevant scientific literature, the 
agencies' technical expertise, and the objectives and requirements of 
the Clean Water Act. In light of this information, the agencies made 
judgments about the nexus between the relevant waters and the 
significance of that nexus and concluded that tributaries and adjacent 
waters, each as defined by the proposed rule, have a significant nexus 
such that they are appropriately jurisdictional by rule.
    The Report is currently undergoing peer review by EPA's Scientific 
Advisory Board (SAB) and is available at http://yosemite.epa.gov/sab/sabproduct.nsf/fedrgstr_activites/Watershed%20Connectivity%20Report?OpenDocument. A previous version of 
the Report dated October 11, 2011 underwent an independent peer review 
organized by the Eastern Research Group, Inc. (ERG). The purpose of the 
ERG-organized peer review was to determine whether the review and 
interpretation of the scientific literature was complete and correct, 
and if the conclusions in the Report were supported by the evidence. 
ERG was responsible for identifying and selecting the expert reviewers, 
managing the review, organizing and facilitating a one-day peer review 
meeting, and preparing the peer review summary report. ERG provided the 
reviewers with a letter of instruction and the technical charge, which 
asked for their comments on the various aspects of the draft report.
    ERG convened the one-day meeting on January 31, 2012, in 
Washington, DC. The meeting was closed to the public and considered an 
internal EPA deliberative process. Observers from EPA and the Corps 
attended to listen to the discussions. At the close of the meeting, the 
reviewers developed some brief highlights of their discussions, which 
were provided with written post-meeting comments from individual 
reviewers in a report from ERG titled ``Peer Review Meeting of EPA's 
Draft Report: Connectivity of Streams and Wetlands to Downstream 
Waters--A Review and Synthesis of the Scientific Evidence, Post-Meeting 
Comments,'' dated February 16, 2012. The Office of Research and 
Development revised its Report in response to the peer review comments 
and submitted the Report to the SAB for peer review and a public 
process. This peer review report is available in the docket for the 
proposed rule.
    The agencies have identified key aspects of the Report throughout 
this preamble and in Appendix A. The Report summarizes and assesses 
much of the currently available scientific literature that is part of 
the administrative record for this proposal, and informs the agencies 
during this rulemaking. Additional data and information will become 
available during the rulemaking process, including that provided during 
the public comment process, and by additional research, studies, and 
investigations that take place before the

[[Page 22197]]

rulemaking process is concluded. The agencies have relied on the best 
available scientific data and information--peer-reviewed literature--
and would find, to the extent possible, additional peer-reviewed 
literature to be the most useful submissions. At the conclusion of the 
rulemaking process, the agencies will review the entirety of the 
completed administrative record, including the final Report reflecting 
SAB review, and make any adjustments to the final rule that are 
appropriate based on this record. As noted below, the agencies 
particularly intend to review the rule provisions related to ``other 
waters'' in light of this record, and are soliciting comment on several 
alternative approaches to applying the science and the law for 
determining whether ``other waters'' are similarly situated and have a 
``significant nexus'' to a traditional navigable water, interstate 
water, or the territorial seas.
2. Summary of Significant Nexus Conclusions
    As the agencies developed this proposed definition of ``waters of 
the United States,'' the agencies carefully considered available 
scientific literature and propose a rule consistent with their 
conclusions that a particular category of waters either alone or in 
combination with similarly situated waters in the region, significantly 
affects the chemical, physical, or biological integrity of traditional 
navigable waters, interstate waters, or the territorial seas.
    As discussed in this preamble and Appendix A, tributaries as 
proposed to be defined perform the requisite functions for them to be 
considered ``waters of the United States'' by rule. Tributary streams 
exert a strong influence on the character and functioning of downstream 
traditional navigable waters, interstate waters, and the territorial 
seas, either individually or cumulatively. All tributary streams, 
including perennial, intermittent, and ephemeral streams, are 
physically and chemically connected to downstream traditional navigable 
waters, interstate waters, and the territorial seas via channels and 
associated alluvial deposits where water and other materials are 
concentrated, mixed, transformed, and transported. Headwater streams 
(which can be ephemeral, intermittent or perennial), in particular, 
supply most of the water to downstream traditional navigable waters, 
interstate waters, and the territorial seas and are the most abundant 
stream-type in most river networks. In addition to water, tributary 
streams supply sediment, wood, organic matter, nutrients, chemical 
contaminants, and many of the organisms found in downstream traditional 
navigable waters, interstate waters, and the territorial seas. 
Tributary streams are biologically connected to downstream traditional 
navigable waters, interstate waters, and the territorial seas by 
dispersal and migration of aquatic and semi-aquatic organisms, 
including fish, amphibians, plants, and invertebrates, that use both 
upstream and downstream habitats during one or more stages of their 
life cycles, or provide food resources to downstream communities. 
Chemical, physical, and biological connections between tributary 
streams and downstream traditional navigable waters, interstate waters, 
and the territorial seas interact via processes such as nutrient 
spiraling, in which tributary stream communities assimilate and 
chemically transform large quantities of nitrogen that would otherwise 
increase nutrient loading downstream.
    As discussed in this preamble and Appendix A, adjacent waters, as 
defined in this proposal, perform the requisite functions for them to 
be considered ``waters of the United States'' by rule. Adjacent waters 
are either directly chemically, physically, or biologically connected 
with traditional navigable waters, interstate waters, and the 
territorial seas they are adjacent to, or they are connected to such 
waters through tributaries. These chemical, physical, and biological 
connections affect the integrity of downstream traditional navigable 
waters, interstate waters, and the territorial seas through the export 
of channel-forming sediment and woody debris, storage of local 
groundwater sources of baseflow for downstream waters and their 
tributaries, and transport of organic matter. Wetlands and open waters 
located in riparian and floodplain areas remove and transform nutrients 
such as nitrogen and phosphorus. They provide nursery habitat for fish, 
and colonization opportunities for stream invertebrates. Adjacent 
waters, including those located in riparian and floodplain areas, serve 
an important role in the integrity of traditional navigable waters, 
interstate waters, and the territorial seas because they also act as 
sinks for water, sediment, nutrients, and contaminants that could 
otherwise negatively impact traditional navigable waters, interstate 
waters, and the territorial seas.
    Finally, some non-adjacent waters may have, in certain 
circumstances, a significant nexus to traditional navigable waters, 
interstate waters, and the territorial seas, but at this time the 
agencies are not proposing that a category of such ``other waters'' is 
jurisdictional by rule. These ``other waters'' may provide numerous 
functions of potential benefit to traditional navigable waters, 
interstate waters, and the territorial seas, including storage of 
floodwater; retention of nutrients, metals, and pesticides; and re-
charge of groundwater sources of river baseflow. The functions of these 
``other waters'' may affect downstream traditional navigable waters, 
interstate waters, and the territorial seas, depending on the 
characteristics of the connection to the river network. For ``other 
waters,'' connectivity varies within a watershed and over time, making 
it difficult to generalize about their connections to, or isolation 
from, traditional navigable waters, interstate waters, and the 
territorial seas. These ``other waters'' would be evaluated on a case-
specific basis under the proposed rule.
    Under the existing regulations, ``other waters'' (such as 
intrastate rivers, lakes and wetlands that are not otherwise 
jurisdictional under other sections of the rule) could be determined to 
be jurisdictional if the use, degradation or destruction of the water 
could affect interstate or foreign commerce. Jurisdictional decisions 
for these waters are being made on a case-specific basis. As a 
practical matter in the past, the agencies generally relied on the 
presence of migratory birds to indicate an effect on interstate 
commerce. In 2001, the Supreme Court in SWANCC rejected the use of 
migratory birds as a sole basis to establish jurisdiction over such 
``isolated'' intrastate nonnavigable waters.
    The proposed rule provides that ``other waters'' can be 
jurisdictional where there is a case-specific showing of a significant 
nexus to traditional navigable waters, interstate waters, or the 
territorial seas. ``Significant nexus'' is not itself a scientific 
term. The science of connections and effects on the chemical, physical, 
or biological integrity of traditional navigable waters, interstate 
waters, or the territorial seas informs an analysis of the facts and 
circumstances of the waters being considered under a ``significant 
nexus'' analysis.
    Scientific literature establishes that ``other waters'' can have a 
relationship to each other and connections downstream that affect the 
chemical, physical, or biological integrity of traditional navigable 
waters, interstate waters, or the territorial seas. This relationship 
is not an all or nothing situation. The existence of a connection, a 
nexus, does not by itself establish that it is a ``significant nexus.'' 
There is a

[[Page 22198]]

gradient in the relation of waters to each other, and this is 
documented in the Report. The agencies propose a case-specific analysis 
in establishing jurisdiction over these ``other waters'' as consistent 
with the current science, the CWA, and the caselaw. A case-specific 
analysis allows for a determination of jurisdiction at the point on the 
gradient in the relationship that constitutes a ``significant nexus.''
    The support for a determination that the nexus is significant will 
be based on a record that documents the scientific basis for concluding 
which functions are provided by the waters and why their effects on a 
traditional navigable water, interstate water, or the territorial seas 
are significant, including that they are more than speculative or 
insubstantial. The agencies considered multiple options for determining 
how best to balance the science and the policy options available to 
address ``other waters.'' Those options ranged from establishing 
jurisdiction over all ``other waters'' with a nexus to traditionally 
navigable waters, interstate waters, or the territorial seas, with the 
agencies determining categorically the nexus to be significant, to 
declining to assert jurisdiction over any ``other waters.''
    The agencies did not adopt the all in or the all out approach to 
``other waters.'' Based on the information currently available in the 
scientific literature, applicable caselaw, and the agencies' policy 
judgment about how best to provide clarity and certainty to the public 
regarding the jurisdictional status of ``other waters'' the agencies 
today propose the case-specific significant nexus analysis presented in 
this rule and explained in the preamble.
    In addition to the proposed ``other waters'' approach in this rule, 
the agencies are requesting comment on a range of alternate approaches 
to inform their decision on how best to address ``other waters.'' The 
agencies will consider the full administrative record, including 
comments requested and received, and the final Report, as revised in 
response to the SAB review, when developing the final rule, and may 
adopt one of the alternative approaches or combination of approaches 
and the proposal.
    The agencies solicit comment on identifying subcategories of 
``other waters'' that have a significant nexus to traditional navigable 
waters, interstate waters, and the territorial seas and could be 
jurisdictional by rule, and subcategories of ``other waters'' where a 
significant nexus or its absence could not be determined as a class and 
could be subject to a case-specific analysis under the rule. The Report 
indicates that there is evidence of very strong connections in some 
subcategories that are not included as jurisdictional by rule. The 
agencies solicit comment on making such subcategories of waters with 
very strong connections jurisdictional by rule as well as on making 
subcategories of waters that do not have such connections subject to a 
case-specific analysis or categorically non-jurisdictional under the 
rule. Such comment should explain with supporting documentation why a 
particular subcategory of ``other waters'' might or might not have a 
significant nexus to traditional navigable waters, interstate waters, 
or the territorial seas.
    The agencies do not propose absolute standards such as flow rates, 
surface acres, or a minimum number of functions for ``other waters'' to 
establish a significant nexus. A determination of the relationship of 
``other waters'' to traditional navigable waters, interstate waters, 
and the territorial seas, and consequently the significance to these 
waters, requires sufficient flexibility to account for the variability 
of conditions across the country and the varied functions that 
different waters provide. The case-specific analysis called for in the 
proposed rule recognizes geographic and hydrologic variability in 
determining whether an ``other water'' or group of ``other waters'' 
possesses a ``significant nexus'' with traditional navigable waters, 
interstate waters, or the territorial seas.

III. Proposed Definition of ``Waters of the United States''

A. Summary of Proposed Rule

    This proposed rule retains much of the structure of the agencies' 
longstanding definition of ``waters of the United States,'' and many of 
the existing provisions of that definition where revisions are not 
warranted. The agencies' goal is to promulgate a rule that is clear and 
understandable and protects the nation's waters, supported by science 
and consistent with the law. Continuity with the existing regulations, 
where possible, will minimize confusion and will reduce transaction 
costs for the regulated community and the agencies. To that same end, 
the agencies also propose, where supported by scientific literature and 
consistent with the law, bright line categories of waters that are and 
are not jurisdictional. Waters in the ``other waters'' category are not 
a per se jurisdictional category. While the agencies considered 
multiple options for addressing jurisdiction over ``other waters,'' the 
agencies concluded that they could not determine that all ``other 
waters'' were jurisdictional, or that all ``other waters'' were not 
jurisdictional. Therefore, the proposed rule requires a case-specific 
significant nexus evaluation to determine if such ``other waters'' are 
subject to CWA jurisdiction and the agencies are requesting comment on 
several alternate approaches, including approaches that would not 
include case-specific analysis, to inform the final rule. Finally, the 
agencies are for the first time proposing definitions for some of the 
terms used in the proposed regulation.
    Under section (a) the agencies propose to define the ``waters of 
the United States'' for all sections of the CWA to mean:
     All waters which are currently used, were used in the 
past, or may be susceptible to use in interstate or foreign commerce, 
including all waters which are subject to the ebb and flow of the tide;
     All interstate waters, including interstate wetlands;
     The territorial seas;
     All impoundments of a traditional navigable water, 
interstate water, the territorial seas or a tributary;
     All tributaries of a traditional navigable water, 
interstate water, the territorial seas or impoundment;
     All waters, including wetlands, adjacent to a traditional 
navigable water, interstate water, the territorial seas, impoundment or 
tributary; and
     On a case-specific basis, other waters, including 
wetlands, provided that those waters alone, or in combination with 
other similarly situated waters, including wetlands, located in the 
same region, have a significant nexus to a traditional navigable water, 
interstate water or the territorial seas.
    As discussed in further detail below, the agencies do not propose 
to change the following provisions (although some provisions have been 
renumbered): Traditional navigable waters ((a)(1), see Section III.B of 
this preamble); interstate waters ((a)(2), see Section III.C of this 
preamble); the territorial seas ((a)(3), see Section III.D of this 
preamble); and impoundments of ``waters of the United States'' ((a)(4), 
see Section III.E of this preamble). In paragraph (a)(5), the agencies 
are proposing that tributaries to waters identified in paragraphs 
(a)(1) through (a)(4) are ``waters of the United States.'' While 
tributaries are ``waters of the United States'' under the existing 
regulation, the agencies propose for the first time a regulatory 
definition of ``tributary'' and propose that only those waters that 
meet the definition and flow

[[Page 22199]]

directly or indirectly to an (a)(1) through (a)(3) water are ``waters 
of the United States'' (see Section III.F of this preamble). In 
paragraph (a)(6), the agencies propose that adjacent waters, rather 
than simply adjacent wetlands, are ``waters of the United States.'' The 
agencies also propose for the first time to define an aspect of 
adjacency--``neighboring''--and related terms (see Section III.G of 
this preamble). Finally, the agencies propose to define ``waters of the 
United States'' to include on a case-specific basis, other waters, 
including wetlands, provided that those waters alone, or in combination 
with other similarly situated waters, including wetlands, located in 
the same region, have a significant nexus to a water identified in 
paragraphs (a)(1) through (3). Unlike the per se jurisdictional 
categories in paragraphs (a)(1) through (6) of this section, such 
``other waters'' are not per se jurisdictional under (a)(7); rather, 
these ``other waters'' are only jurisdictional provided that they have 
a significant nexus to (a)(1) through (a)(3) waters. Therefore, the 
agencies are providing a definition of ``significant nexus'' (see 
Section III.H of this preamble).
    The second section of the proposed regulation, section (b), 
excludes specified waters from the definition of ``waters of the United 
States.'' Those waters and features would not be ``waters of the United 
States'' even if they would otherwise be included within the categories 
in (a)(1) through (a)(7) above. They are:
     Waste treatment systems, including treatment ponds or 
lagoons, designed to meet the requirements of the Clean Water Act.
     Prior converted cropland. Notwithstanding the 
determination of an area's status as prior converted cropland by any 
other Federal agency, for the purposes of the Clean Water Act the final 
authority regarding Clean Water Act jurisdiction remains with EPA.
     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 a jurisdictional 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.
    The agencies do not propose any changes to the existing exclusions 
for waste treatment systems designed consistent with the requirements 
of the CWA and for prior converted cropland. The CWA and current 
regulations also provide a number of exemptions from permitting for 
discharges associated with specific activities. The rule does not 
affect any of the exemptions from CWA section 404 permitting 
requirements 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 rule also does not affect either the 
existing statutory and regulatory exemptions from NPDES permitting 
requirements, such as for agricultural stormwater discharges and return 
flows from irrigated agriculture, or the status of water transfers. CWA 
section 402(l)(1); CWA section 402(l)(2); CWA section 502(14); 40 CFR 
122.3(f); 40 CFR 122.2. The agencies propose for the first time to 
exclude by rule in section (b) certain waters and features over which 
the agencies have as a policy matter generally not asserted 
jurisdiction (see Section III.I of this preamble).
    Finally, in section (c) of the proposed rule the agencies define a 
number of terms, of which ``adjacent'' and ``wetlands'' are unchanged 
from existing definitions 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'' in this section, 
includes waters located within the riparian area or floodplain of a 
water identified in paragraphs (a)(1) through (5) of this section, 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. 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.
    The term tributary means a water physically characterized by the 
presence of a bed and banks and ordinary high water mark, as defined at 
33 CFR 328.3(e), which contributes flow, either directly or through 
another water, to a water identified in paragraphs (a)(1) through (4). 
In addition, wetlands, lakes, and ponds are tributaries (even if they 
lack a bed and banks or ordinary high water mark) if they contribute 
flow, either directly or through another water to a water identified in 
paragraphs (a)(1) through (3). A water that otherwise qualifies as a 
tributary under this definition does not lose its status as a tributary 
if, for any length, there are one or more man-made breaks (such as 
bridges, culverts, pipes, or dams), or one or more natural breaks (such 
as wetlands at the head of or along the run of a stream, debris piles, 
boulder fields, or a stream that flows underground) so long as a bed 
and banks and an ordinary high water mark can be identified upstream of 
the break. A tributary, including wetlands, can be a natural, man-
altered, or man-made water and includes waters such as rivers, streams, 
lakes, ponds, impoundments, canals, and ditches not excluded in 
paragraphs (b)(3) or (4).
    The term wetlands means those areas that are inundated or saturated 
by surface or groundwater at a frequency and duration sufficient to 
support, and that under normal circumstances do support, a prevalence 
of vegetation typically adapted for life in saturated soil conditions. 
Wetlands generally include swamps, marshes, bogs and similar areas.
    The term significant nexus means 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 (3)),\6\ significantly affects

[[Page 22200]]

the chemical, physical, or biological integrity of a water identified 
in paragraphs (a)(1) through (3). 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 (3).
---------------------------------------------------------------------------

    \6\ The terms ``in the region'' and ``watershed'' are used 
interchangeably in this document. The agencies have interpreted ``in 
the region'' to mean the watershed that drains to the nearest water 
identified in paragraphs (a)(1) through (a)(3), which we refer to as 
the single point of entry watershed.
---------------------------------------------------------------------------

B. Traditional Navigable Waters

    EPA and the Corps' existing regulations include within the 
definition of ``waters of the United States'' all waters that are 
currently used, or were used in the past, or may be susceptible to use 
in interstate or foreign commerce, including all waters which are 
subject to the ebb and flow of the tide. See, e.g., 33 CFR 328.3(a)(1); 
40 CFR 230.3(s)(1); 40 CFR 122.2 (``waters of the U.S.''). This section 
of the regulation encompasses those waters that are often referred to 
as ``traditional navigable waters.'' The agencies do not propose to 
make any changes to this section of the regulation. See, Appendix B, 
Legal Analysis.
    For purposes of CWA jurisdiction, waters will be considered 
traditional navigable waters, and thus (a)(1) waters under the proposed 
rule, if:
     They are subject to section 9 or 10 of the Rivers and 
Harbors Appropriations Act of 1899;
     A Federal court has determined that the water body is 
navigable-in-fact under Federal law;
     They are waters currently being used for commercial 
navigation, including commercial waterborne recreation (for example, 
boat rentals, guided fishing trips, or water ski tournaments);
     They have historically been used for commercial 
navigation, including commercial waterborne recreation; or
     They are susceptible to being used in the future for 
commercial navigation, including commercial waterborne recreation. 
Susceptibility for future use may be determined by examining a number 
of factors, including the physical characteristics and the capacity of 
the water to be used in commercial navigation, including commercial 
recreational navigation (for example, size, depth, and flow velocity), 
and the likelihood of future commercial navigation, including 
commercial waterborne recreation. While a traditional navigable water 
need not be capable of supporting navigation at all times, the 
frequency, volume, and duration of flow are relevant considerations for 
determining if a water body has the physical characteristics suitable 
for navigation. A likelihood of future commercial navigation, including 
commercial waterborne recreation, can be demonstrated by current 
boating or canoe trips for recreation or other purposes. A 
determination that a water is susceptible to future commercial 
navigation, including commercial waterborne recreation, must be 
supported by evidence.
    This proposal does not affect the scope of waters subject to state 
assumption of the section 404 regulatory program under section 404(g) 
of the CWA. See CWA section 404(g). The scope of waters that are 
subject to state and tribal permitting is a separate inquiry and must 
be based on the statutory language in CWA section 404. States 
administer approved CWA section 404 programs for ``waters of the United 
States'' within the state, except those waters remaining under Corps 
jurisdiction pursuant to CWA section 404(g)(1) as identified in a 
Memorandum of Agreement \7\ between the state and the Corps. 40 CFR 
233.14; 40 CFR 233.70(c)(2); 40 CFR 233.71(d)(2). Clarification of 
waters that are subject to assumption by states or tribes or retention 
by the Corps could be made through a separate process under section 
404(g).
---------------------------------------------------------------------------

    \7\ Link to Michigan's and New Jersey's Memorandum of Agreement 
with the Army Corps of Engineers identifying which waters of the US 
remain under the Corps' jurisdiction. http://water.epa.gov/type/wetlands/initiative_index.cfm.
---------------------------------------------------------------------------

 C. Interstate Waters

    The existing EPA and Corps regulations define ``waters of the 
United States'' to include interstate waters, including interstate 
wetlands and the agencies' proposal today does not change that 
provision of the regulations. Interstate waters would continue to be 
``waters of the United States'' even if they are not navigable for 
purposes of Federal regulation under (a)(1) and do not connect to such 
waters. Moreover, because interstate waters are ``waters of the United 
States'' under the CWA, the agencies are proposing to continue to 
include as jurisdictional tributaries to interstate waters, waters 
adjacent to interstate waters, waters adjacent to tributaries of 
interstate waters, and ``other waters'' that have a significant nexus 
to interstate waters.
    As discussed in more detail in Appendix B to this preamble, the 
language of the CWA indicates that Congress intended the term 
``navigable waters'' to include interstate waters without imposing a 
requirement that they be traditional navigable waters themselves or be 
connected to traditional navigable waters. The precursor statutes to 
the CWA always subjected interstate waters and their tributaries to 
Federal jurisdiction. The text of the CWA, specifically CWA section 303 
that establishes ongoing requirements for interstate waters, in 
conjunction with the definition of navigable waters, provides clear 
indication of Congress' intent to protect interstate waters that were 
previously subject to Federal regulation. Other provisions of the 
statute provide additional textual evidence of the scope of the primary 
jurisdictional term of the CWA.
    While congressional intent is clear, the agencies also have a 
longstanding regulatory interpretation that interstate waters fall 
within the scope of CWA jurisdiction. The agencies' interpretation was 
promulgated contemporaneously with the passage of the CWA and is 
consistent with the statutory and legislative history of the CWA. 
Furthermore, the Supreme Court has never addressed the CWA's coverage 
of interstate waters, and it is not reasonable to read its decisions in 
SWANCC and Rapanos to question the jurisdictional status of interstate 
waters or to impose additional jurisdictional requirements on 
interstate waters.
    It is reasonable to assert jurisdiction over tributaries, adjacent 
wetlands and ``other waters'' that have a significant nexus to 
interstate waters consistent with the framework established by Justice 
Kennedy in Rapanos for establishing jurisdiction over waters with a 
significant nexus to traditional navigable waters. Justice Kennedy's 
standard seeks to ensure that waters Congress intended to subject to 
Federal jurisdiction are indeed protected, both by recognizing that 
waters and wetlands with a significant nexus to traditional navigable 
waters and interstate waters have important beneficial effects on those 
waters, and by recognizing that polluting or destroying waters with a 
significant nexus can harm downstream jurisdictional waters. As 
Congress intended to protect interstate waters, the agencies propose to 
also protect interstate waters by defining ``waters of the United 
States'' to include tributaries to interstate waters, waters adjacent 
to interstate waters, waters adjacent to tributaries of interstate 
waters, and ``other waters'' that have a significant nexus to 
interstate waters. For additional discussion of the agencies' 
interpretation of the CWA with respect

[[Page 22201]]

to interstate waters, see Appendix B to this preamble.

D. Territorial Seas

    The CWA and its existing regulations include ``the territorial 
seas'' as a ``water of the United States.'' The agencies propose to 
make no changes to that provision of the regulation other than to move 
the provision to earlier in the regulation. The CWA defines ``navigable 
waters'' to include the territorial seas at section 502(7). The CWA 
goes on to define the ``territorial seas'' as ``the belt of the seas 
measured from the line of ordinary low water along that portion of the 
coast which is in direct contact with the open sea and the line marking 
the seaward limit of inland waters, and extending seaward a distance of 
three miles.'' The territorial seas establish the seaward limit of 
``waters of the United States.'' As the territorial seas are also 
clearly protected by the CWA (they are also traditional navigable 
waters), it is reasonable to use for protecting the territorial seas 
Justice Kennedy's significant nexus framework that protects traditional 
navigable waters. The proposed rule reflects that.

 E. Impoundments

    The agencies do not propose to make any substantive changes to the 
existing regulatory language with respect to impoundments of waters 
otherwise defined as `waters of the United States' under this 
definition. The changes proposed are clarifying.
    Impoundments are jurisdictional because as a legal matter an 
impoundment of a ``water of the United States'' remains a ``water of 
the United States'' and because scientific literature demonstrates that 
impoundments continue to significantly affect the chemical, physical, 
or biological integrity of downstream waters traditional navigable 
waters, interstate waters, or the territorial seas. The Supreme Court 
has confirmed that damming or impounding a ``water of the United 
States'' does not make the water non-jurisdictional. See S. D. Warren 
Co. v. Maine Bd. of Envtl. Prot., 547 U.S. 370, 379 n.5 (2006) (``[N]or 
can we agree that one can denationalize national waters by exerting 
private control over them.''). Similarly, when presented with a 
tributary to the Snake River which flows only about two months per year 
because of an irrigation diversion structure installed upstream, the 
Ninth Circuit has opined ``it is doubtful that a mere man-made 
diversion would have turned what was part of the waters of the United 
States into something else and, thus, eliminated it from national 
concern.'' U.S. v. Moses, 496 F.3d 984 (9th Cir. 2007), cert. denied, 
554 U.S. 918 (2008). As a matter of policy and law, impoundments do not 
de-federalize a water, even where there is no longer flow below the 
impoundment. Where flow continues below the impoundment, it is 
straightforward to analyze the stream network, above and below the 
impoundment, for connection to downstream traditional navigable waters, 
interstate waters, or the territorial seas.
    The agencies also note that an impoundment of a water that is not a 
``water of the United States'' can become jurisdictional if, for 
example, the impounded waters become navigable-in-fact and covered 
under paragraph (a)(1) of the rule.
    The existing agency regulations provide that impoundments of 
``waters of the United States'' remain ``waters of the United States'' 
and the agencies do not propose any substantive revisions to that 
component of the regulation. In addition, tributaries to an impoundment 
of a ``water of the United States'' are ``waters of the United States'' 
under this proposed rule. As a matter of law and science, an 
impoundment does not cut off a connection between upstream tributaries 
and a downstream (a)(1) through (a)(3) water, so tributaries above the 
impoundment are still considered tributary to a downstream (a)(1) 
through (a)(3) water even where the flow of water is impeded due to the 
impoundment. Scientific literature, as well as the agencies' scientific 
and technical expertise, and practical knowledge confirm that 
impoundments have chemical, physical, and biological effects on 
downstream waters (see Appendix A, Scientific Evidence).
    Appendix A discusses the conclusion that it is reasonable to 
maintain jurisdiction over impoundments of ``waters of the United 
States'' not only as a legal matter, but because impoundments do not 
sever the effects the impounded ``waters of the United States'' have on 
the chemical, physical, or biological integrity of (a)(1) through 
(a)(3) waters.

F. Tributaries

    Under this proposal, the agencies provide a definition of 
``tributary'' supported by the scientific literature. The agencies also 
propose that all waters that meet the proposed definition of tributary 
are ``waters of the United States'' by rule, unless excluded under 
section (b), because tributaries and the ecological functions they 
provide, alone or in combination with other tributaries in the 
watershed, significantly affect the chemical, physical, and biological 
integrity of traditional navigable waters, interstate waters, and the 
territorial seas.
    With today's proposed regulation, the agencies confirm that these 
tributary waters have a significant nexus to a traditional navigable 
water, interstate water, or territorial sea such that they are ``waters 
of the United States'' without the need for a separate, case-specific 
significant nexus analysis. In practice, under this proposal any water 
that meets the definition of tributary (and is not excluded under 
section (b) of the proposed rule) is a ``water of the United States,'' 
and the agencies would only need to determine that a water meets the 
definition of ``tributary.'' See Appendix A, Scientific Evidence (Part 
I, Discussion of Major Conclusions 2.A; Part II, i); and Appendix B, 
Legal Analysis.
    Tributaries have a significant impact on the chemical, physical, 
and biological integrity of waters into which they eventually flow--
including traditional navigable waters, interstate waters, and the 
territorial seas--and they have a significant nexus and thus are 
jurisdictional as a category. The great majority of tributaries are 
headwater streams, and whether they are perennial, intermittent, or 
ephemeral, they play an important role in the transport of water, 
sediments, organic matter, nutrients, and organisms to downstream 
environments. Tributaries serve to store water, thereby reducing 
flooding, provide biogeochemical functions that help maintain water 
quality, trap and transport sediments, transport, store and modify 
pollutants, provide habitat for plants and animals, and sustain the 
biological productivity of downstream rivers, lakes and estuaries.
1. What is a ``tributary'' for purposes of the proposed regulation?
    The proposed rule defines ``tributary'' as a water physically 
characterized by the presence of a bed and banks and ordinary high 
water mark, as defined at 33 CFR 328.3(e), which contributes flow, 
either directly or through another water, to a water identified in 
paragraphs (a)(1) through (4). In addition, wetlands, lakes, and ponds 
are tributaries (even if they lack a bed and banks or ordinary high 
water mark) if they contribute flow, either directly or through another 
water to a water identified in paragraphs (a)(1) through (3). A water 
that otherwise qualifies as a tributary under this definition does not 
lose its status as a tributary if, for any length, there are one or 
more man-made breaks (such as bridges, culverts, pipes, or dams), or 
one or more natural breaks (such as wetlands at the head of

[[Page 22202]]

or along the run of a stream, debris piles, boulder fields, or a stream 
that flows underground) so long as a bed and banks and an ordinary high 
water mark can be identified upstream of the break. A tributary, 
including wetlands, can be a natural, man-altered, or man-made water 
and includes waters such as rivers, streams, lakes, ponds, 
impoundments, canals, and ditches not excluded in paragraph (b)(3) or 
(4).
    While the agencies have not defined tributary in any previous 
regulation, this proposed definition is consistent with long-standing 
practice and historical implementation of CWA programs. It is important 
to note that today's proposed definition also is based on best 
available science and the intent of the CWA.
    To meet this definition, a water need not contribute flow directly 
to an (a)(1) through (a)(4) water. As the definition makes clear, the 
water may contribute flow directly or may contribute flow to another 
water or waters which eventually flow into an (a)(1) through (a)(4) 
water. Essentially, the water must be part of a tributary system that 
drains to an (a)(1) through (a)(4) water. Under the proposed 
definition, to be a ``tributary,'' in addition to requiring that a 
water contribute flow to a traditional navigable water, interstate 
water or the territorial sea, the water must also have a bed and banks 
and ordinary high water mark (except where a wetland is a tributary), 
because these features generally are physical indicators of flow. The 
agencies identified these tributary characteristics as indicative that 
the water is the type of hydrologic feature protected under the CWA 
because, for example, of a tributary's ability to transport pollutants 
to downstream traditional navigable waters, interstate waters, and the 
territorial seas, and thereby have a significant effect on the 
chemical, physical, or biological integrity of a water identified in 
paragraphs (a)(1) through (a)(4).
    The flow in the tributary may be ephemeral, intermittent or 
perennial, but the tributary must drain, or be part of a network of 
tributaries that drain, into an (a)(1) through (a)(4) water under 
today's proposed rule. When considering whether the tributary being 
evaluated eventually flows to an (a)(1) through (a)(4) water, the 
tributary connection may be traced using direct observation or U.S. 
Geological Survey maps, aerial photography or other reliable remote 
sensing information, or other appropriate information. A bed and banks 
and ordinary high water mark (OHWM) generally are physical indicators 
of water flow. These physical indicators can be created by ephemeral, 
intermittent, and perennial flows.
    The agencies' proposed definition of ``tributary'' includes waters 
such as rivers, streams, lakes, impoundments, wetlands, canals, and 
ditches not excluded in section (b) that, either directly or through 
other tributaries, convey water to traditional navigable waters, 
interstate waters, or the territorial seas. A tributary is a 
longitudinal surface feature that results from directional surface 
water movement and sediment dynamics demonstrated by the presence of 
bed and banks, bottom and lateral boundaries, or other indicators of 
OHWM. The movement of water through a tributary can transport 
pollutants to downstream (a)(1) through (a)(4) waters, as either 
chemicals dissolved or suspended in the water column or adsorbed to 
sediment particles.
    The existing Corps regulations define OHWM as the line on the shore 
established by the fluctuations of water and indicated by physical 
characteristics such as a clear, natural line impressed on the banks, 
shelving, changes in the character of soil, destruction of terrestrial 
vegetation, the presence of litter and debris, or other appropriate 
means that consider the characteristics of the surrounding areas. 33 
CFR 328.3(e). That definition is not changed by today's proposed rule. 
In many tributaries, the bed is that part of the channel below the 
OHWM, and the banks often extend above the OHWM. Indicators of an OHWM 
may vary from region to region across the country.
    Under the proposed definition of tributary, the upper limit of a 
tributary is established where the channel begins. Note that wetlands 
can be providing flow into a tributary at the upper limit of the 
channel and these would also be jurisdictional. The OHWM generally 
defines the lateral limits of a water, and its absence generally 
determines whether a tributary's channel or bed and banks has ended 
such that the upper limit of the jurisdictional tributary is 
identified. However, a natural or man-made break in bed and banks or 
OHWM does not constitute the upper limit of a tributary where bed and 
banks or OHWM can be found farther upstream, as discussed below.
    In many tributaries, there are often natural or man-made breaks in 
the presence of a bed and banks or ordinary high water mark while 
hydrologic connectivity remains. For example, in some regions of the 
country where there is a very low gradient, the banks of a tributary 
may be very low or may even disappear at times. Also, in many 
intermittent and ephemeral tributaries, including dry-land systems in 
the arid and semi-arid west, OHWM indicators can be discontinuous 
within an individual tributary due to the variability in hydrologic and 
climatic influences. The agencies proposed definition of ``tributary'' 
addresses these circumstances and states that waters that meet the 
definition of tributary remain tributaries even if such breaks occur. A 
water that otherwise qualifies as a tributary under the proposed 
definition does not lose its status as a tributary if, for any length, 
there are one or more man-made breaks (such as bridges, culverts, 
pipes, or dams), or one or more natural breaks (such as debris piles, 
boulder fields, or a stream segment that flows underground) so long as 
a bed and banks and an ordinary high water mark can be identified 
upstream of the break. The presence of a bed and banks and an ordinary 
high water mark upstream of the break generally demonstrates that the 
tributary continues upstream of the break.
    Waters that meet the definition of tributary under the proposed 
rule are jurisdictional even if there is an impoundment at some point 
along the connection from the tributary to the (a)(1) through (a)(3) 
water.
    Longstanding agency practice has identified tributaries as 
including ``natural, man-altered or manmade'' water bodies. Natural, 
man-altered, and manmade tributaries provide many of the same 
functions, especially as conduits for the movement of water and 
pollutants to other tributaries or directly to traditional navigable 
waters, interstate waters, or the territorial seas. The discharge of a 
pollutant into a tributary generally has the same effect downstream 
whether the tributary waterway is natural or manmade (see further 
discussion below and Appendix A). Given the extensive human 
modification of watercourses and hydrologic systems throughout the 
country, it is often difficult to distinguish between natural 
watercourses and watercourses that are wholly or partly manmade or man-
altered. For example, tributaries that have been channelized in 
concrete or otherwise have been human-altered, may still meet the 
definition of tributaries under the agencies' proposed regulation so 
long as they still contribute flow to an (a)(1) through (a)(4) water. 
The agencies' proposed definition of tributary provides a non-exclusive 
list of the types of waters, natural, man-altered and man-made, that 
may be tributaries: Wetlands, rivers, streams, lakes, ponds, 
impoundments, canals, and ditches not excluded in

[[Page 22203]]

paragraph (b)(3) or (4) of the proposed rule.
    Under the agencies' proposal, when a tributary flows through a 
wetland into another tributary (e.g., a run-of-stream wetland), losing 
its OHWM through the wetland, it remains a tributary, and the wetland 
itself is considered a tributary. Wetlands may contribute flow to a 
stream or river through channelized flow or diffuse flow, and sometimes 
both. Wetlands may also serve as water sources at the upper limit of 
headwater streams where the channel begins. In light of their potential 
to be important contributors of flow to tributaries to traditional 
navigable waters, interstate waters, or the territorial seas, the 
agencies propose a definition of tributary which includes such 
wetlands. In other instances, wetlands may serve as the connection 
between a tributary and another tributary or even a traditional 
navigable water, interstate water, or the territorial seas. For wetland 
tributaries, water may flow through braided channels that also include 
wetlands or through a run-of-stream wetland that does not have a bed 
and banks and OHWM.
    It is the agencies' intent that the definitions in this proposed 
rule provide as much clarity and regulatory certainty as possible. 
While it is important to include wetlands that connect upstream and 
downstream portions of a tributary as jurisdictional waters because 
they have a significant nexus to downstream (a)(1) through (a)(4) 
waters, the agencies recognize that it may add an element of 
uncertainty to the definition of tributary to include features as 
tributaries which do not have a bed and bank and OHWM. An alternate 
approach would be to clarify that wetlands that connect tributary 
segments are adjacent wetlands, and as such are jurisdictional waters 
of the United States under (a)(6). In this approach, a tributary would 
be defined as having a bed and bank and OHWM, and the upper limit of 
the tributary would be defined by the point where these features cease 
to be identifiable. (Note that natural or manmade breaks would still 
not sever jurisdiction if a tributary segment with a bed and bank and 
OHWM could be identified upstream of the break.) Wetlands would not be 
considered tributaries, but would remain jurisdictional as adjacent 
waters. Wetlands that contribute flow, for example at the upper reaches 
of the tributary system, would be considered adjacent waters. The 
agencies request comment on this alternate approach, as well as any 
other suggestions commenters may have on how to clarify the definition 
of tributaries and provide a clear explanation of their lateral and 
upstream extent.
    Tidal ditches subject to the ebb and flow of the tide are not 
evaluated as tributaries, but are jurisdictional under paragraph (a)(1) 
of the proposed regulation as they are under the current regulation.
    The agencies are proposing to clearly exclude from the definition 
of ``waters of the United States'' two types of ditches that might 
otherwise be evaluated as tributaries: Ditches that are excavated 
wholly in uplands, drain only uplands, and have less than perennial 
flow; and ditches that do not contribute flow, either directly or 
through another water, to a water identified in paragraphs (a)(1) 
through (4). The proposed rule for the first time excludes certain 
ditches by rule rather than simply through preamble and guidance. Even 
before the decisions in SWANCC and Rapanos, the agencies excluded 
certain ditches from jurisdiction because they either are not part of 
the tributary system or because they are excavated wholly in uplands, 
drain only uplands, and are dry for much of the year, i.e. upland 
ditches. The agencies are proposing to continue this exclusion and, to 
provide improved consistency and clarity, further define flow 
characteristics of upland ditches that are and are not jurisdictional. 
The proposed rule would exclude from jurisdiction upland ditches with 
less than perennial flow. The scientific concept of perennial flow is a 
widely accepted and well understood hydrologic characteristic of 
tributaries. Perennial flow means that water is present in a tributary 
year round when rainfall is normal or above normal. Identifying upland 
ditches with perennial flow is straightforward and will provide for 
consistent, predictable, and technically accurate determinations at any 
time of year. The agencies specifically seek comment on the appropriate 
flow regime for a ditch excavated wholly in uplands and draining only 
uplands to be included in the exclusion of 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.
    Only those ditches not excluded by the proposed regulation and that 
meet the proposed definition of tributary are ``waters of the United 
States.'' Ditches that are excluded from the definition of ``waters of 
the United States'' under (b)(3) and (b)(4) cannot be recaptured and 
considered jurisdictional under any of the jurisdictional categories in 
section (a) of the proposed rule, such as a ditch that crosses a state 
line. This is true for all other features excluded under section (b) as 
well. Ditches not excluded under paragraphs (b)(3) and (4) of the 
proposed regulation meet the definition of tributary where they have a 
bed and banks and ordinary high water mark and they contribute flow 
directly or indirectly through another water to (a)(1) through (a)(4) 
waters. Such jurisdictional ditches may include, but are not limited 
to, the following:
     Natural streams that have been altered (e.g., channelized, 
straightened or relocated);
     ditches that have been excavated in ``waters of the United 
States,'' including jurisdictional wetlands;
     ditches that have perennial flow; and
     ditches that connect two or more ``waters of the United 
States.''
    In an effort to distinguish ditches that are not ``waters of the 
United States'' from those that are ``waters of the United States,'' 
the proposal states that ditches with less than perennial flow that are 
excavated in uplands, rather than in wetlands or other types of waters, 
for their entire length are not tributaries and are not ``waters of the 
United States'' under the proposed rule. Ditches that are perennial 
generally have water present year round when rainfall is normal or 
above normal. Under this exclusion, water that only stands or pools in 
a ditch is not considered perennial flow and, therefore, any such 
upland ditch would not be subject to regulation. In addition, ditches 
that do not contribute flow to the tributary system of a traditional 
navigable water, interstate water or the territorial seas are not 
``waters of the United States,'' even if the ditch has perennial flow.
    Historical evidence, such as photographs, prior delineations, or 
topographic maps, may be used to determine whether a water body was 
excavated wholly in uplands and drains only uplands, and has less than 
perennial flow. Site characteristics may also be present to inform the 
determination of whether the water body is a ditch, such as shape, 
sinuosity, flow indications, etc., as ditches are often created in a 
linear fashion with little sinuosity and may not connect to another 
``water of the United States.'' Ditches created by altering natural 
waters would be considered ``waters of the United States,'' so long as 
they contribute flow to another jurisdictional water. Ditches may have 
been created for a number of purposes, such as irrigation, water 
management or treatment, and roadside drains. In order to be excluded,

[[Page 22204]]

however, the ditch must be 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 water 
identified in paragraphs (a)(1) through (4) are not ``waters of the 
United States.''
2. What is not a tributary for purposes of this proposal?
    Waters that do not contribute flow, either directly or through 
another water, to a water identified in paragraphs (a)(1) through (4) 
of the proposed regulation are not considered jurisdictional as 
tributaries under the CWA. However, even if such waters are not 
``tributaries,'' they may be jurisdictional under other paragraphs of 
the proposed rule. Note that waters specifically listed under the 
proposed section (b), including ditches as defined in paragraphs (b)(3) 
and (b)(4), would not be considered ``waters of the United States'' in 
any case. In addition, ephemeral features located on agricultural lands 
that do not possess a bed and bank are not tributaries. The defined bed 
and bank no longer exists due to past normal farming practices such as 
plowing or discing (see section 404(f)(1)(A)),\8\ and these farming 
practices often pre-date the CWA. Such farm field features are not 
tributaries even though they may contribute flow during some rain 
events or snowmelt.
---------------------------------------------------------------------------

    \8\ A discharge of dredged or fill material into an existing 
tributary which converts a ``water of the U.S.'' into a non-
jurisdictional water requires authorization under section 404 of the 
CWA.
---------------------------------------------------------------------------

    Section J below discusses in more detail the agencies' proposed 
rule excluding specific waters and features from the definition of 
``waters of the United States.'' Of importance with respect to 
tributaries is the exclusion of gullies, rills, non-wetland swales, and 
certain ditches. These features are not considered tributaries under 
this proposed rule, even though rills and gullies and non-wetland 
swales (as described in Section J), may contribute flow to a tributary 
in systems with steep side slopes.
    Non-jurisdictional geographic features (e.g., non-wetland swales, 
ephemeral upland ditches) may still serve as a confined surface 
hydrologic connection between an adjacent wetland or water and a 
traditional navigable water, interstate water or the territorial sea, 
provided there is an actual exchange of water between those waters, and 
the water is not lost to deep groundwater through infiltration (i.e., 
transmission losses). In addition, these geographic features may 
function as ``point sources,'' such that discharges of pollutants to 
waters through these features could be subject to other CWA authorities 
(e.g., CWA section 402 and its implementing regulations).
    The agencies request comment on all aspects of the proposed 
definition of tributaries and in particular on whether and how this 
definition can be revised to provide increased clarity as to the 
distinction between jurisdictional tributaries, as defined, and non-
jurisdictional features such as gullies, rills and non-wetland swales. 
The agencies seek comments on how to provide greater regulatory 
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

[[Page 22205]]

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.,

[[Page 22206]]

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

[[Page 22207]]

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

[[Page 22208]]

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

[[Page 22209]]

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,

[[Page 22210]]

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

[[Page 22211]]

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

[[Page 22212]]

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.

[[Page 22213]]

    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

[[Page 22214]]

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

[[Page 22215]]

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

[[Page 22216]]

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

[[Page 22217]]

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

[[Page 22218]]

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

[[Page 22219]]

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

[[Page 22220]]

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,

[[Page 22221]]

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 
Townships, the International City/County Management Association, and 
the Environmental Council of States. In addition, the National 
Association of Clean Water Agencies (NACWA) and the Association of 
Clean Water Administrators (ACWA) were invited to participate. As part 
of the consultation 12 counties, 8 associations and various state 
agencies and offices from five states (Alaska, Wyoming, Kansas, 
Tennessee, and Texas) submitted written comments. In addition, EPA held 
numerous outreach calls with state and local government agencies 
seeking their technical input. More than 400 people from a variety of 
state and local agencies and associations, including the Western 
Governors' Association, the Western States Water Council and the 
Association of State Wetland Managers participated in various calls and 
meetings.
    The agencies engaged in voluntary federalism consultation on this 
rule and we will continue to work closely with the states with respect 
to development of a final rule. Additionally, EPA and the Corps are 
specifically soliciting comments on this proposed action from state and 
local officials. The agencies will include a detailed narrative of 
intergovernmental concerns raised during the course of the rule's 
development and a description of the agencies' efforts to address them 
with the final rule.

F. Executive Order 13175: Consultation and Coordination With Indian 
Tribal Governments

    Subject to the Executive Order (E.O.) 13175 (65 FR 67249, November 
9, 2000) Agencies may not issue a regulation that has tribal 
implications, that imposes substantial direct compliance costs, and 
that is not required by statute, unless the Federal government provides 
the funds necessary to pay the direct compliance costs incurred by 
tribal governments, or the Agencies consult with tribal officials early 
in the process of developing the proposed regulation and develops a 
tribal summary impact statement. This action does not have tribal 
implications as specified in E.O. 13175.
    In compliance with the EPA Policy on Consultation and Coordination 
with Indian Tribes (May 4, 2011), EPA consulted with tribal officials 
to gain an understanding of and, where appropriate, to address the 
tribal implications of the proposed rule. In the course of this 
consultation EPA coordinated with the Corps, and the Corps jointly 
participated in aspects of the consultation process. In the fall of 
2011 EPA sent a Tribal Consultation Notification letter to all 
federally-recognized tribal leaders, via mail and email, inviting 
tribal officials to participate in outreach and consultation events and 
provide comments to EPA in coordination with the Corps. Close to 200 
tribal representatives and more than 40 tribes participated in the 
consultation process, which included multiple webinars and national 
teleconferences and face-to-face meetings. In addition, EPA received 
written comments from 3 tribes during the consultation period. In the 
spirit of E.O. 13175, and consistent with EPA and Corps policy to 
promote communications between the agencies and tribal governments, the 
agencies specifically solicit additional comment on this proposed 
action from tribal officials.

G. Executive Order 13045: Protection of Children From Environmental 
Health and Safety Risks

    This action is not subject to E.O. 13045 because the environmental 
health or safety risks addressed by this action do not present a 
disproportionate risk to children.

H. Executive Order 13211: Actions Concerning Regulations That 
Significantly Affect Energy Supply, Distribution, or Use

    This action is not a ``significant energy action'' as defined in 
Executive Order 13211 (66 FR 28355, May 22, 2001), because it is not 
likely to have a significant adverse effect on the supply, 
distribution, or use of energy.

I. National Technology Transfer and Advancement Act

    Section 12(d) of the National Technology Transfer and Advancement 
Act of 1995 (``NTTAA''), Public Law 104-113, 12(d) (15 U.S.C. 272 note) 
directs Federal agencies to use voluntary consensus standards in its 
regulatory activities unless to do so would be inconsistent with 
applicable law or otherwise impractical. Voluntary consensus standards 
are technical standards (e.g., materials specifications, test methods, 
sampling procedures, and business practices) that are developed or 
adopted by voluntary consensus standards bodies. NTTAA directs Federal 
agencies to provide Congress, through OMB, explanations when the Agency 
decides not to use available and applicable voluntary consensus 
standards.
    This proposed rulemaking does not involve technical standards. 
Therefore, the agencies are not considering the use of any voluntary 
consensus standards.

J. Executive Order 12898: Federal Actions To Address Environmental 
Justice in Minority Populations and Low-Income Populations

    Executive Order (E.O.) 12898 (59 FR 7629, Feb. 16, 1994) 
establishes Federal executive policy on environmental justice. Its main 
provision directs Federal agencies, to the greatest extent practicable 
and permitted by law, to make environmental justice part of their 
mission by identifying and addressing, as appropriate, 
disproportionately high and adverse human health or environmental 
effects of their programs, policies, and activities on minority 
populations and low-income populations in the United States.
    The agencies have determined that this proposed rule will not have 
disproportionately high and adverse human health or environmental 
effects on minority or low-income populations. The proposed rule 
defines the scope of waters protected under the CWA. The increased 
clarity regarding the definition of ``waters of the United States'' 
will be of benefit to all regulators, stakeholders, and interested 
parties. However, in the spirit of Executive Order 12898, we 
specifically request comment regarding potential environmental justice 
issues raised by the proposed rule, and will fully consider those 
comments when preparing the final rule.

[[Page 22222]]

K. Environmental Documentation

    The U.S. Army Corps of Engineers has prepared a draft environmental 
assessment in accordance with the National Environmental Policy Act 
(NEPA). The Corps has made a preliminary determination that the section 
404 aspects of today's proposed rule do not constitute a major Federal 
action significantly affecting the quality of the human environment, 
and thus preparation of an Environmental Impact Statement (EIS) will 
not be required. The proposed rule will increase and make more 
efficient the protection of the aquatic environment. Additionally, the 
Corps complies with NEPA programmatically for general permits, and 
specifically for each and every standard individual permit application 
before making final permit decisions.
    The implementation of the procedures prescribed in this proposed 
regulation would not authorize anyone (e.g., any landowner or permit 
applicant) to perform any work involving regulated activities in 
``waters of the United States'' without first seeking and obtaining an 
appropriate CWA authorization, which concurrently documents compliance 
with all applicable environmental laws.

Appendix A

Scientific Evidence

Overview of Scientific Literature on Aquatic Resource Connectivity and 
Downstream Effects

    In preparation for this proposal, more than a thousand peer-
reviewed scientific papers and other data that address connectivity 
of aquatic resources and effects on downstream waters were reviewed 
and considered. EPA's Office of Research and Development (ORD) has 
prepared a draft peer-reviewed synthesis of published peer-reviewed 
scientific literature discussing the nature of connectivity and 
effects of tributaries and wetlands on downstream waters (U.S. 
Environmental Protection Agency, Connectivity of Streams and 
Wetlands to Downstream Waters: A Review and Synthesis of the 
Scientific Evidence, (Washington, DC: U.S. Environmental Protection 
Agency, 2013), hereinafter, ``Report''). This draft Report similarly 
has been considered in the development of this proposal. The Report 
is currently undergoing peer review led by EPA's Scientific Advisory 
Board (SAB) and is available at http://yosemite.epa.gov/sab/sabproduct.nsf/fedrgstr_activites/Watershed%20Connectivity%20Report?OpenDocument. The Report also 
underwent an earlier peer review, and the results of this peer 
review are available in the docket for this proposed rule. The 
Report summarizes and assesses much of the currently available 
scientific literature that is part of the administrative record for 
this proposal. The agencies anticipate that additional data and 
information will become available during the rulemaking process, 
including that provided during the public comment process, and by 
additional research, studies, and investigations that take place 
before the rulemaking process is concluded. At the conclusion of the 
rulemaking process, the agencies will review the entirety of the 
completed administrative record, including the final Report 
reflecting SAB review, and will make any adjustments to the final 
rule deemed to be appropriate at that time. The Report is under 
review by the Science Advisory Board, and the rule will not be 
finalized until that review and the final report are complete. Part 
I of this Appendix provides the conclusions of the review and 
synthesis. Part II provides additional detail of the scientific 
literature and the agencies' reasoning in support of this proposal.

Part I: Synthesis of Peer-Reviewed Scientific Literature

Background

    The draft Report prepared by ORD reviews and synthesizes the 
peer-reviewed scientific literature on the connectivity or isolation 
of streams and wetlands relative to large water bodies such as 
rivers, lakes, estuaries, and oceans. The purpose of the review and 
synthesis is to summarize current understanding about these 
connections, the factors that influence them, and the mechanisms by 
which connected waters, singly or in aggregate, affect the function 
or condition of downstream waters. The focus of the Report is on 
surface and shallow subsurface connections from small or temporary 
streams, non-tidal wetlands, and certain open waters. Specific types 
of connections considered in the Report include transport of 
physical materials and chemicals such as water, wood, and sediment, 
nutrients, pesticides, and mercury; movement of organisms or their 
seeds or eggs; and hydrologic and biogeochemical interactions 
occurring in surface and groundwater flows, including hyporheic 
zones and alluvial aquifers.
    The draft Report prepared by ORD consists of six chapters. 
Following an executive summary and an introduction to the Report, 
chapter 3 presents a conceptual framework describing the hydrologic 
elements of a watershed, the types of chemical, physical, and 
biological connections that link them, and watershed and climatic 
factors that influence connectivity at various temporal and spatial 
scales. It also provides background on the structure and function of 
streams and wetlands viewed from an integrated watershed 
perspective. In a discussion of connectivity, the watershed scale is 
the appropriate context for interpreting technical evidence about 
individual watershed components, reviewed in subsequent chapters. 
Chapter 4 surveys the literature on stream networks (lotic systems) 
in terms of chemical, physical, and biological connections between 
upstream and downstream habitats. Two case studies from the 
literature examine in greater detail longitudinal connectivity and 
downstream effects in prairie streams and arid streams of the 
Southwest. Chapter 5 reviews the literature on connectivity and 
effects of non-tidal wetlands and certain open waters (lentic 
systems) on downstream waters. This chapter is further subdivided 
into two broad categories of landscape settings based on 
directionality of hydrologic flows: Bidirectional settings, in which 
wetlands and open waters can have two-way hydrologic exchanges with 
other water bodies (e.g., riparian and floodplain wetlands and open 
waters), and unidirectional settings, in which water flows only from 
the wetland or open water towards the downstream water (e.g., most 
wetlands and open waters outside of riparian areas and floodplains). 
Directionality of hydrologic flow was selected as an organizational 
principle for this section because it has a dominant role in 
determining the types of connectivity and downstream effects (if 
any) of wetlands. However, the use of these landscape settings for 
hydrologic directionality should not be construed as suggesting 
directionality of geochemical or biological flows. Also, the terms 
``unidirectional'' and ``bidirectional'' describe the landscape 
setting in which wetlands and open waters occur, and do not refer to 
wetland type or class. Four case studies from the literature examine 
evidence pertaining to connectivity and downstream effects of oxbow 
lakes, Carolina and Delmarva bays, prairie potholes, and vernal 
pools in greater detail.
    Chapter 6 presents and discusses key findings and major 
conclusions of the review, which also are included at the end of 
each review section and in this executive summary.

Summary of Major Conclusions

    Based on the review and synthesis of more than a thousand 
publications from the peer-reviewed scientific literature, the 
available evidence supports three major conclusions:
    1. The scientific literature demonstrates that streams, 
individually and cumulatively, exert a strong influence on the 
character and functioning of downstream waters. All tributary 
streams, including perennial, intermittent, and ephemeral streams, 
are chemically, physically, and biologically connected to downstream 
rivers via channels and associated alluvial deposits where water and 
other materials are concentrated, mixed, transformed, and 
transported. Headwater streams (headwaters) are the most abundant 
stream-type in most river networks, and supply most of the water in 
rivers. In addition to water, streams supply sediment, wood, organic 
matter, nutrients, chemical contaminants, and many of the organisms 
found in rivers. Streams are biologically connected to downstream 
waters by the dispersal and migration of aquatic and semi-aquatic 
organisms, including fish, amphibians, plants, microorganisms, and 
invertebrates, that use both up- and downstream habitats during one 
or more stages of their life cycles, or provide food resources to 
downstream communities. Chemical, physical, and biological 
connections between streams and downstream waters interact via 
processes such as nutrient spiraling, in which stream communities 
assimilate and chemically transform large quantities of nitrogen and 
other nutrients that would otherwise increase nutrient loading 
downstream.

[[Page 22223]]

    2. Wetlands and open waters in landscape settings that have 
bidirectional hydrologic exchanges with streams or rivers (e.g., 
wetlands and open waters in riparian areas and floodplains) are 
chemically, physically, and biologically connected with rivers via 
the export of channel-forming sediment and woody debris, temporary 
storage of local groundwater that supports baseflow in rivers, and 
transport of stored organic matter. They remove and transform excess 
nutrients such as nitrogen and phosphorus. They provide nursery 
habitat for breeding fish, colonization opportunities for stream 
invertebrates, and maturation habitat for stream insects. Moreover, 
wetlands in this landscape setting serve an important role in the 
integrity of downstream waters because they also act as sinks by 
retaining floodwaters, sediment, nutrients, and contaminants that 
could otherwise negatively impact the condition or function of 
downstream waters.
    3. Wetlands and open waters in landscape settings that lack 
bidirectional hydrologic exchanges with downstream waters (e.g., 
many prairie potholes, vernal pools, and playa lakes) provide 
numerous functions that can benefit downstream water quality and 
integrity. These functions include storage of floodwater; retention 
and transformation of nutrients, metals, and pesticides; and re-
charge of groundwater sources of river baseflow. The functions and 
effects of this diverse group of wetlands, which the Report refers 
to as ``unidirectional wetlands,'' affect the condition of 
downstream waters if there is a surface or shallow subsurface water 
connection to the river network. In unidirectional wetlands that are 
not connected to the river network through surface or shallow 
subsurface water, the type and degree of connectivity varies 
geographically within a watershed and over time. Because such 
wetlands occur on a gradient of connectivity, it is difficult to 
generalize about their effects on downstream waters. Generalization 
for this class is further complicated because, for certain functions 
(e.g., sediment removal and water storage), downstream effects are 
due to wetland isolation, rather than connectivity. The literature 
reviewed does not provide sufficient information to evaluate or 
generalize about the degree of connectivity (absolute or relative) 
or the downstream effects of wetlands in unidirectional landscape 
settings. However, evaluations of individual geographically isolated 
wetlands or groups of geographically isolated wetlands could be 
possible through case-by-case analysis. Further, while the review 
did not specifically address other unidirectional water bodies, the 
conclusions apply to these water bodies (e.g., ponds and lakes that 
lack surface water inlets) as well, since the same principles govern 
hydrologic connectivity between these water bodies and downstream 
waters.
    Section 3 below provides an overview of the conceptual 
framework, with further discussion of the key findings for streams, 
riparian and floodplain areas, and unidirectional wetlands.

1. Conceptual Framework Overview

    Connectivity is a foundational concept in hydrology and 
freshwater ecology. The structure and function of downstream waters 
are highly dependent on the constituent materials contributed by and 
transported through water bodies located elsewhere in the watershed. 
Most of the materials in a river, including water, sediment, wood, 
organic matter, nutrients, chemical contaminants, and certain 
organisms, originate outside of the river, from upstream 
tributaries, wetlands, or other components of the river system, and 
are transported to the river by water movement, wind, or other 
means. Therefore, streams and wetlands fundamentally affect river 
structure and function by altering transport of various types of 
materials to the river. This alteration of material transport 
depends on two key factors: (1) Connectivity (or isolation) between 
streams, wetlands and rivers that enables (or prevents) the movement 
of materials between the system components; and (2) functions within 
streams and wetlands that supply, remove, transform, provide refuge 
for, or delay transport of materials.
    The ORD Report defines connectivity as the degree to which 
components of a system are joined, or connected, by various 
transport mechanisms. Connectivity is determined by the 
characteristics of both the physical landscape and the biota of the 
specific system. Isolation is the opposite of connectivity; or the 
degree to which system components are not joined. Both connectivity 
and isolation have important effects on downstream waters. For 
example, stream channels convey water and channel-forming sediment 
to rivers, whereas wetlands that lack output channels can reduce 
flooding and store excess sediment. Materials transport connects 
different ecosystem types, at multiple spatial and temporal scales. 
For example, streams flowing into and out of wetlands or between 
lakes form continuous or seasonal connections across ecosystem 
boundaries. Similarly, aquatic food webs connect terrestrial 
ecosystems, streams, wetlands, and downstream waters.
    Water movement through the river system is the primary, but 
certainly not the only, mechanism providing physical connectivity 
within river networks. It provides a ``hydraulic highway'' that 
transports chemical, physical, and biological materials associated 
with the water (e.g., sediment, woody debris, contaminants, and 
organisms). Because the movement of water is fundamental to 
understanding watershed connectivity, Chapter 3 begins with a review 
and an explanation of the hydrologic foundation of river systems, 
and terms and concepts used throughout the Report are defined.
    Numerous factors influence watershed connectivity. Climate, 
watershed topography, soil and aquifer permeability, the number and 
types of contributing waters, their spatial distribution in the 
watershed, interactions among aquatic organisms, and human 
alteration of watershed features, among other things, can act 
individually or in concert to influence stream and wetland 
connectivity to, and effects on, downstream waters. For example, all 
else being equal, materials traveling shorter distances could enter 
the river with less transformation or dilution, thus increasing a 
beneficial or harmful effect. In other cases, sequential 
transformations such as nutrient spiraling (defined and discussed 
below) connect distant water bodies and produce beneficial effects 
on downstream waters. Infrequent events that temporarily connect 
nearby or distant streams or wetlands to rivers also can have large, 
long-lasting effects. Most of the major changes in sediment load and 
river channel structure that are critical to maintaining river 
health--including meanders of rivers in floodplains and creation of 
oxbow lakes--are a result of large floods that provide infrequent, 
intense connections with more distant streams and riparian or 
floodplain waters.
    Based on a review of the peer-reviewed scientific literature, 
the Report identifies five functions by which streams, wetlands, and 
open waters influence material transport into downstream waters:

 Source: The net export of materials, such as water and food 
resources
 Sink: The net removal or storage of materials, such as 
sediment and contaminants
 Refuge: The protection of materials, especially organisms
 Transformation: The transformation of materials, especially 
nutrients and chemical contaminants, into different physical or 
chemical forms
 Lags: The delayed or regulated release of materials, such 
as storm water

    These functions are not static or mutually exclusive (e.g., a 
wetland can be both a source of organic matter and a sink for 
nitrogen) and can change over time (e.g., one wetland can be a water 
sink when evapotranspiration is high and a water source when 
evapotranspiration is low). Further, some functions work in 
conjunction with others. For example, a lag function can include 
transformation of materials prior to their delayed release. In a 
particular stream, wetland, or open water, the presence or absence 
of these functions depends upon the biota, hydrology, and 
environmental conditions in the watershed.
    When considering effects on downstream waters, it is helpful to 
distinguish between actual function and potential function of a 
stream, wetland, or open water. For example, a wetland with 
appropriate conditions for denitrification is a potential sink for 
nitrogen, a nutrient that can be a contaminant when present in high 
concentrations. This function is conditional; if nitrogen were to 
enter a wetland (from agricultural runoff, for example), the wetland 
has the capacity to remove this nitrogen from the water. The wetland 
will not serve this function, however, if no nitrogen enters the 
wetland. Even if a stream or wetland is not currently serving an 
actual function, it has the potential to provide that function when 
a new material enters it, or when environmental conditions change. 
Thus, potential functions play a critical role in protecting those 
waters from future impacts.

[[Page 22224]]

2. Discussion of Major Conclusions

A. Streams

    The scientific literature demonstrates that streams, 
individually or cumulatively, exert a strong influence on the 
character and functioning of downstream waters. All tributary 
streams, including perennial, intermittent, and ephemeral streams, 
are chemically, physically, or biologically connected to downstream 
rivers via channels and associated alluvial deposits where water and 
other materials are concentrated, mixed, transformed, and 
transported. Headwater streams (headwaters) are the most abundant 
stream type in most river networks, and supply most of the water in 
rivers. In addition to water, streams supply sediment, wood, organic 
matter, nutrients, chemical contaminants, and many of the organisms 
found in rivers. Streams are biologically connected to downstream 
waters by dispersal and migration of aquatic and semi-aquatic 
organisms, including fish, amphibians, plants, microorganisms, and 
invertebrates, that use both up- and downstream habitats during one 
or more stages of their life cycles, or provide food resources to 
downstream communities. Chemical, physical, and biological 
connections between streams and downstream waters interact via 
processes such as nutrient spiraling, in which stream communities 
assimilate and chemically transform large quantities of nitrogen and 
other nutrients that would otherwise increase nutrient loading 
downstream.
    Key findings:
    a. Streams are hydrologically connected to downstream waters via 
channels that convey surface and subsurface water year-round 
(perennial flow), weekly to seasonally (intermittent flow), or only 
in direct response to precipitation (ephemeral flow). Streams are 
the dominant source of water in most rivers, and the great majority 
of tributaries are perennial, intermittent, and ephemeral headwater 
streams. For example, headwater streams, which are the smallest 
channels where stream flows begin, are the source of approximately 
60% of the total mean annual flow to all northeastern U.S. streams 
and rivers.
    b. Headwaters convey water into local storage compartments such 
as ponds, shallow aquifers, or river banks and into regional and 
alluvial aquifers. These local storage compartments are important 
sources of water for baseflow in rivers. The ability of streams to 
keep flowing even during dry periods typically depends on the 
delayed (lagged) release of local groundwater, also referred to as 
shallow groundwater, originating from these water sources, 
especially in areas with shallow groundwater tables and pervious 
subsurfaces. For example, in the southwestern United States, short-
term shallow groundwater storage in alluvial floodplain aquifers, 
with gradual release into stream channels by intermittent and 
ephemeral streams, is a major source of annual flow in rivers.
    c. Even infrequent flows through ephemeral or intermittent 
channels influence fundamental biogeochemical processes by 
connecting the channel and shallow groundwater with other landscape 
elements. Infrequent, high-magnitude events are especially important 
for transmitting materials from headwater streams in most river 
networks. For example, headwater streams, including ephemeral and 
intermittent streams, shape river channels by accumulating and 
gradually or episodically releasing stored materials such as 
sediment and large woody debris. These materials provide substrate, 
habitat for aquatic organisms, and slow the flow of water through 
channels.
    d. Connectivity between streams and rivers provides 
opportunities for materials, including nutrients and chemical 
contaminants, to be sequentially altered as they are transported 
downstream. Although highly efficient at transport of water and 
other physical materials, streams are not pipes. They are dynamic 
ecosystems with permeable beds and banks that interact with 
terrestrial and aquatic ecosystems above and below the surface. The 
connections formed by surface and subsurface streamflows act as a 
series of complex chemical, physical, and biological alterations 
that occur as materials move through different parts of the river 
system. The amount and quality of such materials that eventually 
reach a river are determined by the aggregate effect of these 
sequential alterations that begin at the source waters, which can be 
at some distance from the river. The greater the distance a material 
travels between a particular stream reach and the river, the greater 
the opportunity for that material to be altered in intervening 
stream reaches, which can allow for uptake, assimilation, or 
beneficial transformation. One example of sequential alteration with 
significant beneficial effects on downstream waters is the process 
of nutrient spiraling, in which nutrients entering headwater streams 
are transformed by various aquatic organisms and chemical reactions 
as they are transported downstream by streamflow. Nutrients which 
enter the headwater stream (e.g., via overland flow) are first 
removed from the water column by streambed algal and microbial 
populations. Fish or insects feeding on algae and microbes take up 
some of those nutrients, which are subsequently released back to the 
stream via excretion and decomposition, and the cycle is repeated. 
In each phase of the cycling process--from dissolved inorganic 
nutrients in the water column, through microbial uptake, subsequent 
transformations through the food web, and back to dissolved 
nutrients in the water column--nutrients are subject to downstream 
transport. Stream and wetland capacities for nutrient cycling have 
important implications for the form and concentration of nutrients 
exported to downstream waters.
    e. The literature review found strong evidence that headwater 
streams function as nitrogen sources (export) and sinks (uptake and 
transformation) for river networks. One study estimated that rapid 
nutrient cycling in small streams that were free from agricultural 
or urban impacts removed 20-40% of the nitrogen that otherwise would 
be delivered to downstream waters. Nutrients are necessary to 
support aquatic life, but excess nutrients create conditions leading 
to eutrophication and hypoxia, in which oxygen concentrations fall 
below the level necessary to sustain most within and near-bed animal 
life. Thus, the role of streams in influencing nutrient loads can 
have significant repercussions for hypoxic areas in downstream 
waters.
    f. Headwaters provide critical habitat during one or more life 
cycle stages of many organisms capable of moving throughout river 
networks. This review found strong evidence that headwaters provide 
habitat for complex life-cycle completion, refuge from predators or 
adverse physical conditions in rivers, and reservoirs of genetic- 
and species-level diversity. Use of headwater streams as habitat is 
especially obvious for the many species that migrate between small 
streams and marine environments during their life cycles (e.g., 
Pacific and Atlantic salmon, American eels, certain lamprey 
species), and the presence of these species within river networks 
provides robust evidence of biological connections between 
headwaters and larger rivers. In prairie streams, many fishes swim 
upstream into tributaries to release eggs, which develop as they are 
transported downstream. Small streams also provide refuge habitat 
for riverine organisms seeking protection from temperature extremes, 
flow extremes, low dissolved oxygen, high sediment levels, or the 
presence of predators, parasites, and competitors.

B. Riparian/Floodplain Waters

    Wetlands and open waters in landscape settings that have 
bidirectional hydrologic exchanges with streams or rivers (e.g., 
wetlands and open waters in riparian areas and floodplains) are 
chemically, physically, or biologically connected with rivers via 
the export of channel-forming sediment and woody debris, temporary 
storage of local groundwater that supports baseflow in rivers, and 
transport of stored organic matter. They remove and transform excess 
nutrients such as nitrogen and phosphorus. They provide nursery 
habitat for breeding fish, colonization opportunities for stream 
invertebrates, and maturation habitat for stream insects. Moreover, 
wetlands in this landscape setting serve an important role in the 
integrity of downstream waters because they also act as sinks by 
retaining floodwaters, sediment, nutrients, and contaminants that 
could otherwise negatively impact the condition or function of 
downstream waters.
    Key Findings:
    a. Riparian areas act as buffers that are among the most 
effective tools for mitigating nonpoint source pollution. The 
wetland literature shows that collectively, riparian wetlands 
improve water quality through assimilation, transformation, or 
sequestration of nutrients, sediment and other pollutants--such as 
pesticides and metals--that can affect downstream water quality. 
These pollutants enter wetlands via various pathways that include 
various sources such as dry and wet atmospheric deposition, some 
runoff from upland agricultural and urban areas, spray drift, and 
subsurface water flows, as well as point sources such as outfalls, 
pipes, and ditches.
    b. Riparian and floodplain areas connect upland and aquatic 
environments through both surface and subsurface hydrologic flow 
paths. These areas are therefore uniquely situated in watersheds to 
receive and process

[[Page 22225]]

waters that pass over densely vegetated areas and through subsurface 
zones before reaching streams and rivers. When contaminants reach a 
riparian or floodplain area, such materials can be sequestered in 
sediments, assimilated into the wetland plants and animals, 
transformed into less harmful forms or compounds, or lost to the 
atmosphere. Wetland potential for biogeochemical transformations 
(e.g., denitrification) that can improve the quality of water 
entering streams and rivers is influenced by factors present in 
riparian areas and floodplains, including anoxic conditions, shallow 
water tables, slow organic matter decomposition, wetland plant 
communities, permeable soils, and complex topography.
    c. Riparian and floodplain areas can reduce flood peaks by 
storing and desynchronizing floodwaters. They also can contribute to 
maintenance of flow by recharging alluvial aquifers. Many studies 
have documented the ability of riparian and floodplain areas to 
reduce flood pulses by storing excess water from streams and rivers. 
One review of wetland studies reported that riparian wetlands 
reduced or delayed floods in 23 of 28 studies. For example, peak 
discharges between upstream and downstream gauging stations on the 
Cache River in Arkansas were reduced 10-20% primarily due to 
floodplain water storage.
    d. Riparian and floodplain areas store large amounts of sediment 
and organic matter from upland areas before those sediments enter 
the stream. For example, riparian areas have been shown to filter 
80-90% of sediments leaving agricultural fields in North Carolina. 
(A. Cooper, et al., ``Riparian Areas as Filters for Agricultural 
Sediment,'' Soil Science Society of America Proceedings 51:416-420 
(1987); R.B. Daniels, and J.G. Gilliam, ``Sediment and Chemical Load 
Reduction by Grass and Riparian Filters,'' Soil Science Society of 
America Journal 60:246-251 (1996); R.J. Naiman, and H. Decamps, 
``The Ecology of Interfaces: Riparian Zones,'' Annual Review of 
Ecology and Systematics 28:621-658 (1997)).
    e. Ecosystem function within a river system is driven by 
interactions between the physical environment and the diverse 
biological communities living within the river system. Movements of 
organisms connect aquatic habitats and populations in different 
locations through several processes important for the survival of 
individuals, populations, and species, and for the functioning of 
the river ecosystem. For example, lateral expansion and contraction 
of the river in its floodplain results in an exchange of matter and 
organisms, including fish populations that are adapted to use 
floodplain habitat for feeding and spawning during high water. 
Refuge populations of aquatic plants in floodplains can become 
important seed sources for the river network, especially if 
catastrophic flooding scours vegetation and seed banks in other 
parts of the channel. Many invertebrates exploit temporary 
hydrologic connections between rivers and floodplain wetland 
habitats, moving into these wetlands to feed, reproduce, or avoid 
harsh environmental conditions and then returning to the river 
network. Amphibians and aquatic reptiles in many parts of the 
country commonly use both streams and wetlands, including wetlands 
in riparian and floodplain areas, to hunt, forage, overwinter, rest, 
or hide from predators.

C. Unidirectional Wetlands

    Wetlands and open waters in landscape settings that lack 
bidirectional hydrologic exchanges with downstream waters (e.g., 
many prairie potholes, vernal pools, and playa lakes) provide 
numerous functions that can benefit downstream water quality and 
integrity. These functions include storage of floodwater; retention 
and transformation of nutrients, metals, and pesticides; and re-
charge of groundwater sources of river baseflow. The functions and 
effects of this diverse group of wetlands, hereafter referred to as 
``unidirectional wetlands,'' clearly affect the condition of 
downstream waters if there is a surface or shallow subsurface water 
connection to the river network. In unidirectional wetlands that are 
not connected to the river network through surface or shallow 
subsurface water, the type and degree of connectivity varies 
geographically within a watershed and over time. Because such 
wetlands occur on a gradient of connectivity, it is difficult to 
generalize about their effects on downstream waters. This evaluation 
is further complicated because, for certain functions (e.g., 
sediment removal and water storage), downstream effects arise from 
wetland isolation, rather than connectivity. The literature reviewed 
does not provide sufficient information to evaluate or generalize 
about the degree of connectivity (absolute or relative) or the 
downstream effects of wetlands in unidirectional landscape settings. 
However, evaluations of connectivity of individual wetlands or 
groups of wetlands could be possible through case-by-case analysis. 
Further, while the review did not specifically address other 
unidirectional water bodies, the conclusions apply to these water 
bodies (e.g., ponds and lakes that lack surface water inlets) as 
well, since the same principals govern hydrologic connectivity 
between these water bodies and downstream waters.
    Key Findings:
    a. Water storage by wetlands well outside of riparian or 
floodplain areas can affect streamflow. Hydrologic models of prairie 
potholes in the Starkweather Coulee subbasin (North Dakota) that 
drain to Devils Lake indicate that increasing the volume of pothole 
storage across the sub-basin by approximately 60% caused simulated 
total annual streamflow to decrease 50% during a series of dry years 
and 20% during wet years. Similar simulation studies of watersheds 
that feed the Red River of the North in North Dakota and Minnesota 
demonstrated qualitatively comparable results, suggesting that the 
ability of potholes to modulate streamflow may be widespread across 
portions of the prairie pothole region. This work also indicates 
that reducing wetland water storage capacity by connecting formerly 
isolated potholes through ditching or drainage to the Devils Lake 
and Red River basins could increase stormflow and contribute to 
downstream flooding. In many agricultural areas already crisscrossed 
by extensive drainage systems, total streamflow and baseflow are 
enhanced by directly connecting potholes to stream networks. The 
impacts of changing streamflow are numerous, including altered flow 
regime, stream geomorphology, habitat, and ecology. The presence or 
absence of an effect of prairie pothole water storage on streamflow 
depends on many factors, including patterns of precipitation, 
topography and degree of human alteration. For example, in parts of 
the prairie pothole region with low precipitation, low stream 
density, and little human alteration, hydrologic connectivity 
between prairie potholes and streams or rivers is likely to be low.
    b. Unidirectional wetlands act as sinks and transformers for 
various pollutants, especially nutrients, which pose a serious 
pollution problem in the United States. In one study, sewage 
wastewaters were applied to forested unidirectional wetlands in 
Florida for a period of 4.5 years. More than 95% of the phosphorus, 
nitrate, ammonium, and total nitrogen were removed by the wetland 
during the study period, and 66-86% of the nitrate removed was 
attributed to the process of denitrification. In another study, 
sizeable phosphorus retention occurred in unidirectional marshes 
that comprised only 7% of the lower Lake Okeechobee basin area in 
Florida. A unidirectional bog in Massachusetts was reported to 
sequester nearly 80% of nitrogen inputs from various sources, 
including atmospheric deposition, and prairie pothole wetlands in 
the upper Midwest were found to remove >80% of the nitrate load via 
denitrification. A large unidirectional prairie marsh was found to 
remove 86% of nitrate, 78% of ammonium, and 20% of phosphate through 
assimilation and sedimentation, sorption, and other mechanisms. 
Together, these and other studies indicate that on-site removal of 
nutrients by unidirectional wetlands is significant and 
geographically widespread. The effects of this removal on rivers are 
generally not reported in the literature.
    c. Biological connectivity can occur between unidirectional 
wetlands and downstream waters through movement of amphibians, 
aquatic seeds, macroinvertebrates, reptiles, and mammals. Many 
species in those groups that use both stream and wetland habitats 
are capable of dispersal distances equal to or greater than 
distances between many unidirectional wetlands and river networks. 
Unidirectional wetlands can be hydrologically connected directly to 
river networks through channels, non-channelized surface flow, or 
subsurface flows. A wetland surrounded by uplands is defined as 
``geographically isolated.'' Our review found that in some cases, 
wetland types such as vernal pools and coastal depressional wetlands 
are collectively, and incorrectly, referred to as geographically 
isolated. Technically, the term ``geographically isolated'' should 
be applied only to the particular wetlands within a type or class 
that are completely surrounded by uplands. Furthermore, ``geographic 
isolation'' should not be confused with functional isolation, 
because geographically isolated wetlands can still have hydrological 
and biological connections to downstream waters.

[[Page 22226]]

    d. Unidirectional wetlands occur along a gradient of hydrologic 
connectivity-isolation with respect to river networks, lakes, or 
marine/estuarine water bodies. This gradient includes, for example, 
wetlands that serve as origins for stream channels that have 
permanent surface water connections to the river network; wetlands 
with outlets to stream channels that discharge to deep groundwater 
aquifers; geographically isolated wetlands that have local 
groundwater or occasional surface water connections to downstream 
waters; and geographically isolated wetlands that have minimal 
hydrologic connection to other water bodies (but which could include 
surface and subsurface connections to other wetlands). The existence 
of this gradient among wetlands of the same type or in the same 
geographic region can make it difficult to determine or generalize, 
from the literature alone, the degree to which particular wetlands 
(individually or as classes), including geographically isolated 
wetlands, are hydrologically connected.
    e. A related issue is that spatial scale must be considered when 
determining geographic isolation. Individual wetlands that are 
geographically isolated could be connected to downstream waters when 
considered as a complex (a group of interacting wetlands). This 
principle was demonstrated in a recent study that examined a 
depressional wetland complex on the Texas coastal plain. These 
wetlands have been considered as a type of geographically isolated 
wetlands. Collectively, however, they are geographically and 
hydrologically connected to downstream waters in the area. During an 
almost 4-year study period, nearly 20% of the precipitation that 
fell on the wetland complex flowed as surface runoff through an 
intermittent stream to a nearby waterway, the Armand Bayou. Thus, 
wetland complexes could have connections to downstream waters 
through stream channels even when the individual wetland components 
are geographically isolated.

3. Closing Comments

    The strong hydrologic connectivity of river networks is apparent 
in the existence of stream channels that form the physical structure 
of the network itself. Given the discussion above, it is clear that 
streams and rivers are much more than a system of physical channels 
for conveying water and other materials downstream, but the presence 
of physical channels is one strong line of evidence for surface 
water connections from tributaries, or water bodies of other types, 
to downstream waters. Physical channels are defined by continuous 
bed and bank structures, which may include apparent disruptions 
(such as by bedrock outcrops, braided channels, flow-through 
wetlands) associated with changes in the material and gradient over 
and through which water flows. The continuation of bed and banks 
down gradient from such disruptions is evidence of the surface 
connection with the channel that is up gradient of the perceived 
disruption.
    The structure and function of rivers are highly dependent on the 
constituent materials that are stored in and transported through 
them. Most of these materials, broadly defined here as any chemical, 
physical, or biological entity, including, but not limited to, 
water, heat energy, sediment, wood, organic matter, nutrients, 
chemical contaminants, and organisms, originate outside of the 
river: They originate from either the upstream river network or 
other components of the river system, and then are transported to 
the river by water movement or other mechanisms. Thus, the 
fundamental way in which streams and wetlands affect river structure 
and function is by altering fluxes of materials to the river. The 
control of material fluxes depends on two key factors: (1) Functions 
within streams and wetlands that affect material fluxes, and (2) 
connectivity (or isolation) between streams and wetlands and rivers 
that allows (or prevents) transport of materials between the 
systems.
    Absence of channels does not, however, mean that a wetland or 
open water is isolated or only infrequently connected to downstream 
waters. Areas that are infrequently flooded by surface water can be 
connected more regularly through shallow groundwater or through 
dispersal among biological populations and communities. Such 
wetlands and open waters also can reduce flood peaks by storing 
flood waters, filter large amounts of sediment and nutrients from 
upland areas, influence stream geomorphology by providing woody 
debris and sediment, and regulate stream temperature. They also 
serve as sources of food for river biota and sources of genetic 
diversity for populations of stream invertebrates.
    Unidirectional wetlands can reduce and attenuate floods through 
water storage, and can recharge groundwater, thereby contributing to 
stream and river baseflow. These wetlands also affect nutrient 
delivery and improve water quality by functioning as sources of food 
and as sinks for metals, pesticides, excess nutrients. Biological 
connectivity can also occur between unidirectional wetlands and 
downstream waters, through movement of amphibians, aquatic insects, 
aquatic reptiles, migratory birds, and riverine mammals that require 
or opportunistically use both river and wetland or open water 
habitats. However, given a geographically isolated wetland for which 
a surface water connection cannot be observed, it is difficult to 
assess its degree of connectivity with the river network without 
site-specific data.
    Additionally, caution should be used in interpreting 
connectivity for wetlands based on their being designated as 
``geographically isolated'' since (a) the term can be mistakenly 
applied to a heterogeneous group of wetlands that can include 
wetlands that are not geographically isolated, (b) wetlands with 
permanent channels could be miscategorized as geographically 
isolated if the designation is based on maps or imagery with 
inadequate spatial resolution, obscured views, etc., and (c) wetland 
complexes could have connections to downstream waters through stream 
channels even if individual wetlands within the complex are 
geographically isolated. Thus, the term ``geographically isolated'' 
should only be applied to groups of wetlands if they fit the 
technical definition (i.e., they are surrounded by uplands). 
Further, even geographically isolated wetlands can be connected to 
other wetlands and downstream waters through groundwater 
connections, occasional spillage, or biological connections. Thus, 
the term ``geographically isolated'' should not be used to infer 
lack of hydrologic, chemical, or biological connectivity.
    Lastly, to understand the health, behavior, and sustainability 
of downstream waters, effects of small water bodies in a watershed 
need to be considered in aggregate. The contribution of material by 
a particular stream and wetland might be small, but the aggregate 
contribution by an entire class of streams and wetlands (e.g., all 
ephemeral streams in the river network) might be substantial. For 
example, western vernal pools typically occur within ``vernal pool 
landscapes'' or complexes of pools in which swales connect pools to 
each other and to seasonal streams, and in which the hydrology and 
ecology are tightly coupled with the local and regional geological 
processes that formed them. The vernal pool basins, swales, and 
seasonal streams are part of a single surface water and shallow 
groundwater system connected to the river network when seasonal 
precipitation exceeds storage capacity of the wetlands. Since rivers 
develop and respond over time and are functions of the whole 
watershed, understanding the integration of contributions and 
effects over time is also necessary to have an accurate 
understanding of the system, taking into account the duration and 
frequency of material export and delivery to downstream waters. In 
addition, when considering the effect of an individual stream or 
wetland, it is important to include the cumulative effect of all 
materials that originate from it, rather than each material 
individually, to understand that water body's influence on 
downstream waters.

Part II: Additional Scientific Support

i. Tributaries

    The agencies propose that all waters that meet the proposed 
definition of tributary are ``waters of the United States'' because 
they meet Justice Kennedy's test for jurisdiction under Rapanos. In 
other words, the agencies are asserting that all tributaries have a 
significant nexus with traditional navigable waters, interstate 
waters, and/or the territorial seas. EPA and the Corps' longstanding 
definition of ``waters of the United States'' has included 
tributaries. That regulation was based on the agencies' historic 
view of the scope of the CWA and the general scientific 
understanding about the ecological and hydrological relationship 
between waters.
    Tributaries have a substantial impact on the chemical, physical, 
or biological integrity of waters into which they eventually flow--
including traditional navigable waters, interstate waters, and the 
territorial seas. The great majority of tributaries are headwater 
streams, and whether they are perennial, intermittent, or ephemeral, 
they play an important role in the transport of water, sediments, 
organic matter, pollutants, nutrients, and organisms to downstream 
environments. Tributaries serve to store

[[Page 22227]]

water (thereby reducing flooding), provide biogeochemical functions 
that help maintain water quality, trap and transport sediments, 
transport, store and modify pollutants, provide habitat for plants 
and animals, and sustain the biological productivity of downstream 
rivers, lakes and estuaries. These conclusions are strongly 
supported in the scientific literature, as discussed below.
    Headwater streams are the smallest channels where stream flows 
begin, and often occur at the outer rims of a watershed. Typically 
these are first-order streams (i.e., they do not have any other 
streams flowing into them). However, headwater streams can include 
streams with multiple tributaries flowing into them and can be 
perennial, intermittent or ephemeral, but are still located near the 
channel origins of the tributary system in a watershed.
    Protection of tributaries under the CWA is critically important 
because they serve many important functions which directly influence 
the integrity of downstream waters. It is necessary to regulate the 
entire tributary system to fulfill the objective of the CWA, because 
discharges of pollutants into the tributary system adversely affect 
the chemical, physical, or biological integrity of these waters. For 
example, destruction or modification of headwater streams has been 
shown to affect the integrity of downstream waters, in part through 
changes in hydrology, chemistry and stream biota. M.C. Freeman, et 
al., ``Hydrologic Connectivity and the Contribution of Stream 
Headwaters to Ecological Integrity at Regional Scales,'' Journal of 
the American Water Resources Association 43:5-14. (2007); M.S. 
Wipfli., et al., ``Ecological Linkages between Headwaters and 
Downstream Ecosystems: Transport of Organic Matter, Invertebrates, 
and Wood Down Headwater Channels,'' Journal of the American Water 
Resources Association 43:72-85 (2007). Additionally, activities such 
as discharging a pollutant into one part of the tributary system are 
well-documented to affect, at times, other parts of the system, even 
when the point of discharge is far upstream from the navigable water 
that experiences the effect of the discharge. In order to protect 
traditional navigable waters, interstate waters, and the territorial 
seas it is also critically important to protect tributaries as 
defined in today's proposal that are upstream from those waters.

A. The Agencies Have Concluded That Tributaries, as Defined in the 
Proposed Rule, Have a Significant Nexus

    The scientific literature documents that tributary streams, 
including perennial, intermittent, and ephemeral streams, and 
certain categories of ditches are integral parts of river networks 
because they are directly connected to rivers via permanent surface 
features (channels and associated alluvial deposits) that 
concentrate, mix, transform, and transport water and other 
materials, including food resources, downstream. Tributaries 
transport, and often transform, chemical elements and compounds, 
such as nutrients, ions, dissolved and particulate organic matter 
and contaminants, influencing water quality, sediment deposition, 
nutrient availability, and biotic functions in rivers. Streams also 
are biologically connected to downstream waters by dispersal and 
migration, processes which have critical implications for aquatic 
populations of organisms that use both headwater and river or open 
water habitats to complete their life cycles or maintain viable 
populations. The scientific literature clearly demonstrates that 
cumulatively, streams exert strong influence on the character and 
functioning of rivers. In light of these well documented connections 
and functions, the agencies concluded that tributaries, as defined, 
alone or in combination with other tributaries in a watershed, 
significantly affect the chemical, physical, or biological integrity 
of a traditional navigable water, interstate water, or the 
territorial seas. The scientific literature supports this conclusion 
for ephemeral tributaries, as well as for intermittent and perennial 
tributaries; for tributaries both near to and far from the 
downstream traditional navigable water, interstate water, or the 
territorial seas; and for natural tributaries or man-altered 
tributaries, which may include certain ditches and canals.
    The discussion below summarizes the key points in the literature 
regarding the chemical, physical, and biological connections and 
functions of tributaries that significantly affect downstream 
waters. In addition, the evidence regarding headwater streams and 
non-perennial streams, types of tributaries whose important 
functional relationships to downstream traditional navigable waters 
and interstate waters might not be obvious, is summarized. The 
scientific literature does not use legal terms like ``traditional 
navigable water,'' ``interstate water,'' or ``the territorial 
seas.'' Rather, the literature assesses tributaries in terms of 
their connections to and effects on downstream waters in a 
watershed. While the agencies define as ``waters of the United 
States'' tributaries only in watersheds which drain to a traditional 
navigable water, interstate water, or the territorial seas, that 
distinction does not affect the conclusions of the scientific 
literature with respect to the effects of tributaries on downstream 
waters.

B. Tributaries Significantly Affect the Physical Integrity of (a)(1) 
Through (a)(3) 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. See, e.g., Report at 
4-3 (citing T.C. Winter, 2007, ``The role of groundwater in 
generating streamflow in headwater areas and in maintaining base 
flow,'' Journal of the American Water Resources Association 43:15-
25; P.A. Bukaveckas, ``Rivers,'' in G.E. Likens, ed., Encyclopedia 
of Inland Waters, Vol. 1 (Elsevier: Oxford, 2009)). Distant 
headwaters with stronger connections to groundwater or consistently 
higher precipitation levels than downstream reaches contribute more 
water to downstream rivers. In the northeastern United States 
headwater streams contribute greater than 60% of the water volume in 
larger tributaries, including navigable rivers. See, e.g., id. 
(citing R.B. Alexander, et. al., ``The role of headwater streams in 
downstream water quality,'' Journal of the American Water Resources 
Association 43:41-59 (2007)). The contributions of tributaries to 
river flows are often readily measured or observed, especially 
immediately below confluences, where tributary flows increase the 
flow volume and alter physical conditions, such as water 
temperature, in the main stream. The physical effects of tributaries 
are particularly clear after intense rainfall occurs over only the 
upper tributary reaches of a river network. For example, a study of 
ephemeral tributaries to the Rio Grande in New Mexico found that 
after a storm event contributions of the stormflow from ephemeral 
tributaries accounted for 76% of the flow of the Rio Grande. See, 
e.g., id. at 4-5 (citing E.R. Vivoni, et. al., ``Analysis of a 
Monsoon Flood Event in an Ephemeral Tributary and Its Downstream 
Hydrologic Effects,'' Water Resources Research 42:W03404 (2006)). A 
key effect of tributaries on the hydrologic response of river 
networks to storm events is dispersion, or the spreading of water 
output from a drainage basin over time. Hydrologic dispersion of 
connected tributaries influence the timing and volume of water 
reaching a river network outlet. See, e.g., id. at 4-5 to 4-6 
(citing P. M. Saco and P. Kumar, ``Kinematic dispersion in stream 
networks coupling hydraulics and network geometry,'' Water Resources 
Research 38:1244 (2002)). Tributaries also can reduce the amount of 
water that reaches downstream rivers and minimize downstream 
flooding, often through infiltration or seepage through channel beds 
and banks or through evapotranspiration. See, e.g., id. at 4-8 
(citing S.K. Hamilton, et al., ``Persistence of Aquatic Refugia 
between Flow Pulses in a Dryland River System (Cooper Creek, 
Australia),'' Limnology and Oceanography 50:743-754 (2005); J.F. 
Costelloe, et.al., ``Determining Loss Characteristics of Arid Zone 
River Waterbodies,'' River Research and Applications 23:715-731 
(2007)).
    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 clearly 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 clearly demonstrate 
physical alteration of river structure and function by headwater 
streams. Report at 4-10, 4-14. Sediment movement is critical for 
maintaining the river network, including rivers that are considered 
to be traditional navigable waters, as fluvial (produced by the 
action of a river or stream) sediments are eroded from some channel 
segments, and deposited in others downstream to form channel 
features, stream and riparian habitat which supports the biological 
communities resident downstream, and influence the river 
hydrodynamics. See, e.g., J.L. Florsheim, et al., ``Bank Erosion as 
a Desirable Attribute of Rivers,'' Bioscience 58:519-29 (2008); 
Report at 4-9 (citing M. Church, ``Bed material transport and the 
morphology of alluvial river channels,'' Annual Review of Earth and

[[Page 22228]]

Planetary Sciences: 325-354 (2006)). While essential to river 
systems, too much sediment can impair ecological integrity by 
filling interstitial spaces, blocking sunlight transmission through 
the water column, and increasing contaminant and nutrient 
concentrations. Report at 4-9 (citing P.J. Wood and P.D. Armitage, 
``Biological Effects of Fine Sediment in the Lotic Environment,'' 
Environmental Management 21:203-217 (1997)). Over sedimentation thus 
can reduce photosynthesis and primary productivity within the stream 
network and otherwise have harmful effects on downstream biota, 
including on the health and abundance of fish, aquatic macrophytes 
(plants), and aquatic macroinvertebrates that inhabit downstream 
waters. See, e.g., Wood and Armitage 1997. Headwater streams tend to 
trap and store sediments behind large structures, such as boulders 
and trees, that are transported downstream only during infrequent 
large storm events. See Report at 4-10, 4-12 (citing L.E. Benda, and 
T.W. Cundy, ``Predicting deposition of debris flows in mountain 
channels,'' Canadian Geotechnical Journal 27:409-417 (1990); T. Gomi 
and R.C. Sidle, ``Bed load transport in managed steep-gradient 
headwater streams of southeastern Alaska,'' Water Resources Research 
39:1336 (2003); L.E. Benda, et al., ``Geomorphology of steepland 
headwaters: The transition from hillslopes to channels,'' Journal of 
the American Water Resources Association 41:835-851 (2005); P.E. 
Bigelow, et al., ``On Debris Flows, River networks, and the Spatial 
Structure of Channel Morphology,'' Forest Science 53:220-238 (2007); 
J.P.R. Gooderham, et al., ``Upstream Heterogeneous Zones: Small 
Stream Systems Structured by a Lack of Competence?'' Journal of the 
North American Benthological Society 26:365-374 (2007)).
    Tributaries can greatly influence water temperatures in 
tributary networks. This is important because water temperature is a 
critical factor governing the distribution and growth of aquatic 
life, both directly (through its effects on organisms) and 
indirectly (through its effects on other physiochemical properties, 
such as dissolved oxygen and suspended solids). Id. at 4-13 (citing 
J.D. Allan, Stream Ecology--Structure and Function of Running Waters 
(New York, NY: Chapman & Hall, 1995)). For instance, water 
temperature controls metabolism and level of activity in cold-
blooded species like fish, amphibians, and aquatic invertebrates. 
See, e.g., G.G. Ice, ``Chapter 3: Stream Temperature and Dissolved 
Oxygen,'' in J.D. Stednick, ed., Hydrologic and Biological Responses 
to Forest Practices (Springer, 2008). Temperature can also control 
the amount of dissolved oxygen in streams, as colder water holds 
more dissolved oxygen, which fish and other fauna need to breathe. 
Connections between tributaries and downstream rivers can affect 
water temperature in river networks. See, e.g., Report at 4-13 
(citing S. Knispel, and E. Castella, ``Disruption of a Longitudinal 
Pattern in Environmental Factors and Benthic Fauna by a Glacial 
Tributary,'' Freshwater Biology 48:604-618 (2003); S.P. Rice, et 
al., ``The Ecological Importance of Tributaries and Confluences,'' 
in S.P. Rice, et al., ed., River Confluences, Tributaries and the 
Fluvial Network, (Chichester, UK: John Wiley & Sons, 2008), pp. 209-
242)). In particular, tributaries provide both cold and warm water 
refuge habitats that are critical for protecting aquatic life. Id. 
at 4-32. Because headwater tributaries often depend on groundwater 
inputs, temperatures in these systems tend to be warmer in the 
winter (when groundwater is warmer than ambient temperatures) and 
colder in the summer (when groundwater is colder than ambient 
temperatures) relative to downstream waters. Id. (citing G. Power, 
et al., ``Groundwater and Fish: Insights from Northern North 
America,'' Hydrological Processes 13:401-422 (1999)). Thus 
tributaries provide organisms with both warm water and coldwater 
refuges at different times of the year. Id. (citing R.A. Curry, et 
al., ``Use of Small Streams by Young Brook Trout Spawned in a 
Lake,'' Transactions of the American Fisheries Society 126:77-83 
(1997); C.V. Baxter, and F.R. Hauer, ``Geomorphology, Hyporheic 
Exchange and Selection of Spawning Habitat by Bull Trout (Salvelinus 
confluentus),'' Canadian Journal of Fisheries and Aquatic Sciences 
57: 1470-1481 (2000); T.R. Labbe, and K.D. Fausch, ``Dynamics of 
Intermittent Stream Habitat Regulate Persistence of a Threatened 
Fish at Multiple Scales,'' Ecological Applications 10:1774-1791 
(2000); M.J. Bradford, et al., ``Ecology of Juvenile Chinook Salmon 
in a Small Non-natal Stream of the Yukon River Drainage and the Role 
of Ice Conditions on Their Distribution and Survival,'' Canadian 
Journal of Zoology-Revue Canadienne De Zoologie 79:2043-2054 
(2001)). For example, when temperature conditions in downstream 
waters are adverse, fish can travel upstream and use tributaries as 
refuge habitat. Id. (citing Curry et al. 1997; M.A. Cairns, et al., 
``Influence of Summer Stream Temperatures on Black Spot Infestation 
of Juvenile Coho Salmon in the Oregon Coast Range,'' Transactions of 
the American Fisheries Society 134:1471-1479 (2005)). Tributaries 
also help buffer temperatures in downstream waters. Id. at 4-13 to 
4-14 (citing D. Caissie, ``The thermal regime of rivers: A review,'' 
Freshwater Biology 51:1389-1406 (2006). Temperatures in tributaries 
affect downstream water temperature many kilometers away. Id. at 4-
14 (citing B. Gardner, and P.J. Sullivan, ``Spatial and Temporal 
Stream Temperature Prediction: Modeling Nonstationary Temporal 
Covariance Structures,'' Water Resources Research 40:W01102 doi 
(2004); B.R. Johnson, et al., ``Use of Spatially Explicit 
Physicochemical Data to Measure Downstream Impacts of Headwater 
Stream Disturbance,'' Water Resources Research 46:W09526 (2010)).

C. Tributaries Significantly Affect the Chemical Integrity of (a)(1) 
Through (a)(3) Waters

    Tributaries transform and export significant amounts of 
nutrients and carbon to downstream waters, serving important source 
functions that greatly 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. See, e.g., Report at 4-22 (citing S.G. Fisher and 
G.E. Likens, ``Energy Flow in Bear Brook, New Hampshire: An 
Integrative Approach to Stream Ecosystem Metabolism,'' Ecological 
Monographs 43: 421-439 (1973); J.L. Meyer, ``The Microbial Loop in 
Flowing Waters,'' Microbial Ecology 28:195-199 (1994); J.B. Wallace, 
et al. ``Multiple Trophic Levels of a Forest Stream Linked to 
Terrestrial Litter Inputs,'' Science 277:102-104 (1997); R.O. Hall 
and J.L. Meyer, ``The Trophic Significance of Bacteria in a 
Detritus-Based Stream Food Web,'' Ecology 79:1995-2012 (1998); R.O. 
Hall, et al., ``Organic Matter Flow in Stream Food Webs with Reduced 
Detrital Resource Base,'' Ecology 81:3445-3463 (2000); C. 
Augspurger, et al., ``Tracking Carbon Flow in a 2-Week-Old and 6-
Week-Old Stream Biofilm Food Web,'' Limnology and Oceanography 
53:642-650 (2008)). Much or most of the organic carbon that is 
exported from tributaries has been altered either physically or 
chemically by ecosystem processes within the tributary streams, 
particularly by headwater streams.
    Nutrient export from tributaries has a large effect on 
downstream water quality, as excess nutrients from surface runoff 
from lawns and agricultural fields can cause algal blooms that 
reduce dissolved oxygen levels and increase turbidity in rivers, 
lakes, estuaries, and territorial seas. Water low in dissolved 
oxygen cannot support aquatic life; it is widely-recognized that 
this phenomenon has resulted in the devastation of commercial and 
recreational fisheries in the northern Gulf of Mexico. Committee on 
Environment and Natural Resources, Integrated Assessment of Hypoxia 
in the Northern Gulf of Mexico (Washington, DC: National Science and 
Technology Council, 2000). The amount of nitrogen that is exported 
downstream varies depending on stream size, and how much nitrogen is 
present in the system. Nitrogen loss is greater in smaller, shallow 
streams, most likely because denitrification and settling of 
nitrogen particles occur at slower rates in deeper channels. Report 
at 4-16 (citing R.G. Alexander, et al., ``Effect of Stream Channel 
Size on the Delivery of Nitrogen to the Gulf of Mexico,'' Nature 
403:758-761 (2000)). At low loading rates, the biotic removal of 
dissolved nitrogen from water is high and occurs primarily in small 
tributaries, reducing the loading to larger tributaries and rivers 
downstream. At high nitrogen loading rates, tributaries become 
nitrogen saturated and are not effectively able to remove nitrogen, 
resulting in high nitrogen export to rivers. Id. at 4-18 (citing 
P.J. Mulholland, et al., ``Stream Denitrification across Biomes and 
Its Response to Anthropogenic Nitrate Loading,'' Nature 452:202-205 
(2008)). The transport of nitrogen and phosphorus downstream has 
also been well-documented, particularly in the cases of the Gulf of 
Mexico and the Chesapeake Bay. Tributary streams in the uppermost 
portions of the Gulf and Bay watersheds transport the majority of 
nutrients to the downstream waters; an estimated 85% of nitrogen 
arriving at the hypoxic zone in the Gulf originates in the

[[Page 22229]]

upper Mississippi (north of Cairo, Illinois) and the Ohio River 
Basins. D. Goolsby, et al., Topic Report 3, Flux and Sources of 
Nutrients in the Mississippi-Atchafalaya River Basin (Washington, 
DC: National Science and Technology Council Committee on Environment 
and Natural Resources, 1999). The export of nutrients from streams 
in the Mississippi River Basin has an effect on anoxia, or low 
oxygen levels, in the Gulf. Report at 4-17 (citing N.N. Rabalais, et 
al., ``Gulf of Mexico Hypoxia, a.k.a. `the Dead Zone,' '' Annual 
Review of Ecology and Systematics 33:235-263 (2002)). Similarly, 
nutrient loads from virtually the entire 64,000 square mile 
watershed affect water quality in the Chesapeake Bay. Simulation 
tools have been used to determine the nutrient and sediment load 
reductions that must be made at many different points throughout the 
entire watershed in order to achieve acceptable water quality in the 
mainstem of the Bay. These reductions included specific annual 
nitrogen caps on the upper reaches of the Susquehanna River in New 
York State, more than 400 miles from the mouth of the Chesapeake 
Bay. See e.g., U.S. Environmental Protection Agency (EPA), Region 
III, Chesapeake Bay Program Office, Setting and Allocating the 
Chesapeake Bay Basin Nutrient and Sediment Loads: The Collaborative 
Process, Technical Tools and Innovative Approaches, EPA 903-R-03-007 
(Washington, DC: EPA, 2003); Rabalais et al. 2002.
    Although tributaries export nutrients, carbon, and contaminants 
downstream, they also transform these substances. Phosphorous and 
nitrogen arrive at downstream waters having already been cycled, or 
taken up and transformed by living organisms, many times in 
headwater and smaller tributaries. Report at 4-19 to 4-20, 6-3 to 6-
4 (citing J.R. Webster, and B.C. Patten, ``Effects of watershed 
perturbation on stream potassium and calcium dynamics,'' Ecological 
Monographs 49:51-72 (1979); J.D. Newbold, et al., ``Measuring 
nutrient spiraling in streams,'' Canadian Journal of Fisheries and 
Aquatic Sciences 38:860-863 (1981); J. Elwood, et al., ``Resource 
spiraling: An operational paradigm for analyzing lotic ecosystems,'' 
in T.D. Fontaine and S.M. Bartell, ed., Dynamics of Lotic Ecosystems 
(Ann Arbor, MI: Ann Arbor Science, 1983), pp. 3-23; S.H. Ensign, and 
M.W. Doyle, ``Nutrient Spiraling in Streams and River Networks,'' 
Journal of Geophysical Research-Biogeosciences 111:G04009 (2006)). 
In addition, some of the nutrient that is taken up as readily 
available inorganic forms is released back to the water as organic 
forms that are less available for biotic uptake. Id. at 4-20 (citing 
P.J. Mulholland, et al., ``Production of Soluble, High Molecular 
Weight Phosphorus and Its Subsequent Uptake by Stream Detritus,'' 
Verhandlungen des Internationalen Verein Limnologie 23:1190-1197 
(1988); S.P. Seitzinger, et al., ``Bioavailability of DON from 
Natural and Anthropogenic Sources to Estuarine Plankton,'' Limnology 
and Oceanography 47:353-366 (2002)). Similarly, nutrient 
incorporated into particulates is not entirely regenerated, but 
accumulates in longitudinally increasing particulate loads (i.e. 
increases moving downstream). Id. at 4-20 (citing J.L Merriam, et 
al., ``Characterizing Nitrogen Dynamics, Retention and Transport in 
a Tropical Rainforest Stream Using an in situ N-15 Addition,'' 
Freshwater Biology 47:143-160 (2002); M.R. Whiles, and W.K. Dodds, 
``Relationships between Stream Size, Suspended Particles, and 
Filter-Feeding Macroinvertebrates in a Great Plains Drainage 
Network,'' Journal of Environmental Quality 31:1589-1600 (2002); 
R.O. Hall, et al., ``Hydrologic Control of Nitrogen Removal, 
Storage, and Export in a Mountain Stream,'' Limnology and 
Oceanography 54:2128-2142 (2009)). Headwater streams have seasonal 
cycles in the concentrations of phosphorous and nitrogen that are 
delivered downstream by accumulating nutrient derived from 
temporarily growing streambed biomass. Id. (citing P.J. Mulholland, 
and W.R. Hill, ``Seasonal Patterns in Streamwater Nutrient and 
Dissolved Organic Carbon Concentrations: Separating Catchment Flow 
Path and In-Stream Effects,'' Water Resources Research 33:1297-1306 
(1997); P.J. Mulholland, ``The Importance of In-stream Uptake for 
Regulating Stream Concentrations and Outputs of N and P from a 
Forested Watershed: Evidence from Long-Term Chemistry Records for 
Walker Branch Watershed,'' Biogeochemistry 70:403-426 (2004)). Such 
variations have been demonstrated to affect downstream productivity. 
Id. (citing P.J. Mulholland, et al., ``Longitudinal Patterns of 
Nutrient Cycling and Periphyton Characteristics in Streams: a Test 
of Upstream-Downstream Linkage,'' Journal of the North American 
Benthological Society 14:357-370 (1995)). Nitrification, the 
microbial transformation of ammonium to nitrate, affects the form of 
downstream nutrient delivery. Nitrification occurs naturally in 
undisturbed headwater streams, but increases sharply in response to 
ammonium inputs, thereby reducing potential ammonium toxicity from 
pollutant inputs. Id. (citing Newbold, et al., ``Phosphorus Dynamics 
in a Woodland Stream Ecosystem: a Study of Nutrient Spiraling,'' 
Ecology 64:1249-1265 (1983); S.C. Chapra, Surface Water Quality 
Modeling (McGraw-Hill, 1996); E.S. Bernhardt, et al., ``Whole-system 
Estimates of Nitrification and Nitrate Uptake in Streams of the 
Hubbard Brook Experimental Forest,'' Ecosystems 5:419-430 (2002)). 
Denitrification, the removal of nitrate from streamwater through 
transformation to atmospheric nitrogen, is widespread among 
headwater streams; research indicates that small, unimpacted 
tributaries can reduce up to 40% of downstream nitrogen delivery 
through denitrification. Id. at 4-20 to 4-21 (citing P.J. 
Mulholland, et al., ``Stream Denitrification across Biomes and Its 
Response to Anthropogenic Nitrate Loading,'' Nature 452:202-205 
(2008)). Small tributaries also affect the downstream delivery of 
nutrients through abiotic processes. Streams can reduce phosphorus 
concentrations through sorption (i.e., ``sticking'') to stream 
sediments. Id. at 4-21 (citing J.L. Meyer, ``The Role of Sediments 
and Bryophytes in Phosphorus Dynamics in a Headwater Stream 
Ecosystem,'' Limnology and Oceanography 24:365-375 (1979)). This is 
particularly beneficial to downstream chemical integrity where 
phosphorus sorbs to contaminants such as metal hydroxide 
precipitates. Id. (citing J.A. Simmons, ``Phosphorus Removal by 
Sediment in Streams Contaminated with Acid Mine Drainage,'' Water 
Air and Soil Pollution 209:123-132 (2010)).
    Tributaries also store significant amounts of nutrients and 
carbon, functioning as important sinks (lags) for river networks so 
that they do not reach downstream traditional navigable waters, 
interstate waters, or the territorial seas. Small tributary streams 
in particular often have the greatest effect on downstream water 
quality, in terms of storage and reducing inputs to downstream 
waters. For instance, uptake and transformation of inorganic 
nitrogen often occurs most rapidly in the smallest tributaries. See, 
e.g., id. at 4-18 (citing B.J. Peterson, et al., ``Control of 
Nitrogen Export from Watersheds by Headwater Streams,'' Science 
292:86-90 (2001)). Small tributaries affect the downstream delivery 
of nutrients such as phosphorus through abiotic processes; such 
streams can reduce phosphorus concentrations by sorption to stream 
sediments.
    Tributaries can also serve as a temporary or permanent source or 
sink for contaminants, for instance substances like metals, sodium, 
and even dead fish carcasses that adversely affect organisms when 
occurring at excessive or elevated concentrations to reduce the 
amounts that reach downstream traditional navigable waters, 
interstate waters, or the territorial seas. The transport of 
contaminants to downstream waters can impact water quality 
downstream, if they are not stored in tributaries. See, e.g., id. at 
4-26 (citing X. Wang, et al., ``Water Quality Changes as a Result of 
Coalbed Methane Development in a Rocky Mountain Watershed,'' Journal 
of the American Water Resources Association 43:1383-1399 (2007)). 
Tributaries can also serve as at least a temporary sink for 
contaminants that would otherwise impair downstream water quality. 
See, e.g., id. at 133-134 (citing W.L. Graf, Plutonium and the Rio 
Grande: Environmental Change and Contamination in the Nuclear Age 
(New York: Oxford University Press, 1994)).
    The distances and extent of metal contaminant transport was 
shown in separate studies in the upper Arkansas River in Colorado, 
and Clark Fork River in Montana, where past mining activities 
impacted the headwater tributaries. River bed sediments showed that 
metals originating from the mining and smelting areas in the 
headwaters were reaching water bodies up to 550 km downstream. Id. 
at 4-26 to 4-27 (citing E.V. Axtmann, and S.N. Luoma, ``Large-scale 
Distribution of Metal Contamination in the Fine-grained Sediments of 
the Clark Fork River, Montana, USA,'' Applied Geochemistry 6:75-88 
(1991); B.A. Kimball, et al., ``Effects of Colloids on Metal 
Transport in a River Receiving Acid Mine Drainage, Upper Arkansas 
River, Colorado, USA,'' Applied Geochemistry 10:285-306 (1995)).
    Military studies of the distribution, transport, and storage of 
radionuclides (e.g., plutonium, thorium, uranium) have provided 
convincing evidence for distant chemical

[[Page 22230]]

connectivity in river networks because the natural occurrence of 
radionuclides is extremely rare. From 1942 to 1952, prior to the 
full understanding of the risks of radionuclides to human health and 
the environment, plutonium dissolved in acid was discharged 
untreated into several intermittent headwater streams that flow into 
the Rio Grande at the Los Alamos National Laboratory, New Mexico. 
Id. at 4-28 (citing W.L. Graf, Plutonium and the Rio Grande: 
Environmental Change and Contamination in the Nuclear Age (New York: 
Oxford University Press, 1994); S.L. Reneau, et al., ``Geomorphic 
Controls on Contaminant Distribution along an Ephemeral Stream,'' 
Earth Surface Processes and Landforms 29:1209-1223 (2004)). Also 
during this time, nuclear weapons testing occurred west of the upper 
Rio Grande near Socorro, New Mexico (Trinity blast site) and in 
Nevada, where fallout occurred on mountainous areas with thin soils 
that are readily transported to headwater streams in the upper Rio 
Grande basin. The distribution of plutonium within the Rio Grande 
illustrates how headwater streams transport and store contaminated 
sediment that has entered the basin through fallout and from direct 
discharge. Los Alamos Canyon, while only representing 0.4% of the 
drainage area at its confluence with the Rio Grande, had a mean 
annual bedload contribution of plutonium almost seven times that of 
the mainstem. Id. (citing Graf 1994). Much of the bedload 
contribution occurred sporadically during intense storms that were 
out of phase with flooding on the upper Rio Grande. Total estimated 
contributions of plutonium between the two sources to the Rio Grande 
were approximately 90% from fallout to the landscape and 10% from 
direct effluent discharge at Los Alamos National Laboratory. Id. 
(citing Graf 1994).

C. Tributaries Significantly Affect the Biological Integrity of (a)(1) 
Through (a)(3) Waters

    Tributaries are biologically linked to downstream waters through 
the movement of living organisms or their reproductive propagules, 
such as eggs or seeds. For organisms that drift with water flow, 
biological connections depend on hydrological connections. However, 
many aquatic organisms are capable of active movement with or 
against water flow, and others disperse actively or passively over 
land by walking, flying, drifting, or ``hitchhiking.'' All of these 
different types of movement form the basis of biological 
connectivity between headwater tributaries and downstream waters.
    Headwater tributaries increase the amount and quality of habitat 
available to aquatic organisms. Under adverse conditions, small 
tributaries provide safe refuge, allowing organisms to persist and 
recolonize downstream areas once adverse conditions have abated. 
See, e.g., Report at 4-29 (citing J.L. Meyer and J.B. Wallace, 
``Lost Linkages and Lotic Ecology: Rediscovering Small Streams,'' 
Pages 295-317 in M.C. Press, N. J. Huntly, and S. Levin, editors. 
Ecology: Achievement and Challenge (Oxford, UK: Blackwell Science, 
2001); A. Meyer et al., ``The Effect of Low Flow and Stream Drying 
on the Distribution and Relative Abundance of the Alien Amphipod, 
Echinogammarus berilloni (Catta, 1878) in a Karstic Stream System 
(Westphalia, Germany),'' Crustaceana 77:909-922 (2004); A.D. Huryn 
et al., ``Landscape Heterogeneity and the Biodiversity of Arctic 
Stream Communities: A Habitat Template Analysis,'' Canadian Journal 
of Fisheries and Aquatic Sciences 62:1905-1919 (2005)). Use of 
tributaries by salmon and other anadromous fish for spawning is 
well-documented, but even non-migratory species can travel great 
distances within the river and tributary networks. See, e.g., id. at 
4-31 (citing O.T. Gorman, ``Assemblage Organization of Stream 
Fishes: The Effects of Rivers on Adventitious Streams,'' American 
Naturalist 128(4): 611-616 (1986); A. L. Sheldon, ``Conservation of 
Stream Fishes: Patterns of Diversity, Rarity, and Risk,'' 
Conservation Biology 2:149-156 (1988); N.P. Hitt and P.L. 
Angermeier, ``Evidence for Fish Dispersal from Spatial Analysis of 
Stream Network Topology,'' Journal of the North American 
Benthological Society 27:304-320 (2008)). Tributaries also serve as 
an important source of food for biota in downstream rivers. 
Tributaries export plankton, vegetation, fish eggs, insects, 
invertebrates like worms or crayfish, smaller fish that originate in 
upstream tributaries and other food sources that drift downstream to 
be consumed by other animals. See, e.g., id. at 4-29 (citing D.J. 
Progar and A.R. Modenke, ``Insect Production from Temporary and 
Perennially Flowing Headwater Streams in Western Oregon,'' Journal 
of Freshwater Ecology 17:391-407 (2002)). For example, many fish 
feed on drifting insects, and numerous studies document the 
downstream drift of stream invertebrates that then are eaten by fish 
in larger rivers. See, e.g., id. at 4-29 to 4-30 (citing S. Nakano 
and M. Murakami, ``Reciprocal Subsidies: Dynamic Interdependence 
between Terrestrial and Aquatic Food Webs,'' Proceedings of the 
National Academy of Sciences USA 98:166-170 (2001); M.S. Wipfli and 
D.P. Gregovich, ``Export of Invertebrates and Detritus from Fishless 
Headwater Streams in Southeastern Alaska: Implications for 
Downstream Salmonid Production,'' Freshwater Biology 47:957-969 
(2002)).
    Biological connectivity also allows gene flow, or genetic 
connectivity, among tributary and river populations. Gene flow is 
needed to maintain genetic diversity in a species, a basic 
requirement for that species to be able to adapt to environmental 
change. Populations connected by gene flow have a larger breeding 
population size, making them less prone to the deleterious effects 
of inbreeding and local extinction. Id. at 4-33 (citing R. Lande and 
S. Shannon, ``The role of genetic variation in adaptation and 
population persistence in a changing environment,'' Evolution 
50:434-437 (1996)). Genetic connectivity exists at multiple scales 
and can extend beyond one a single river catchment, and for species 
capable of long distance movement (such as salmon), reveals complex 
interactions among spatially distant populations of aquatic 
organisms Id. (citing J.M. Hughes, et al., ``Genes in Streams: Using 
DNA to Understand the Movement of Freshwater Fauna and Their 
Riverine Habitat,'' Bioscience 59:573-583 (2009); C.D. Anderson, 
``Considering spatial and temporal scale in landscape-genetic 
studies of gene flow,'' Molecular Ecology 19:3565-3575 (2010)).

D. Headwater Tributaries Significantly Affect the Chemical, Physical, 
or Biological Integrity of (a)(1) Through (a)(3) Waters

    As discussed above, the scientific literature supports the 
conclusion that tributaries, including headwater streams, have a 
significant nexus to downstream waters based on their contribution 
to the chemical, physical, or biological integrity of (a)(1) through 
(a)(3) waters. Headwater tributaries, the small streams at the 
uppermost reaches of the tributary network, are the most abundant 
streams in the United States. See, e.g., id. at 4-2 (citing T.L. 
Nadeau and M.C. Rains, ``Hydrological connectivity between headwater 
streams and downstream waters: How science can inform policy,'' 
Journal of the American Water Resources Association 43:118-133 
(2007)). Collectively, they help shape the chemical, physical, and 
biological integrity of downstream waters, and provide many of the 
same functions as non-headwater streams. See, e.g., id. at 1-7 to 1-
8, 4-1. For example, headwater streams reduce the amount of sediment 
delivered to downstream waters by trapping sediment from water and 
runoff. See, e.g., M. Dieterich and N.H. Anderson, ``Dynamics of 
Abiotic Parameters, Solute Removal and Sediment Retention in Summer-
Dry Headwater Stream of Western Oregon,'' Hydrobiologia 379: 1-15 
(1998). Headwater streams shape river channels by accumulating and 
gradually or episodically releasing sediment and large woody debris 
into river channels. They are also responsible for most nutrient 
cycling and removal, and thus transforming and changing the amount 
of nutrients delivered to downstream waters. See, e.g., Report at 4-
18 (citing B.J. Peterson, et al., ``Control of Nitrogen Export from 
Watersheds by Headwater Streams,'' Science 292: 86-90 (2001)). A 
close connection exists between the water quality of these streams 
and the water quality of traditional navigable waters, interstate 
waters, and the territorial seas. See, e.g., State of Ohio 
Environmental Protection Agency, Nonpoint Source Impacts on Primary 
Headwater Streams (Columbus, OH: Ohio Environmental Protection 
Agency, 2003). Activities such as discharging a pollutant into one 
part of the tributary system are well-documented to affect other 
parts of the system, even when the point of discharge is far 
upstream from the navigable water that experiences the effect of the 
discharge. See, e.g., F.M. Dunnivant and E. Anders, A Basic 
Introduction To Pollutant Fate and Transport: An Integrated Approach 
With Chemistry, Modeling, Risk Assessment, and Environmental 
Legislation (Hoboken, NJ: John Wiley & Sons, Inc., 2006).
    Headwater streams provide unique habitat and protection for 
amphibians, fish, and other aquatic or semi-aquatic species living 
in and near the stream that may use the downstream waters for other 
portions of their life stages. See, e.g., Report at 1-8; J.L. Meyer, 
et al., ``The Contribution of Headwater Streams to Biodiversity in 
River Networks,'' Journal of the American Water Resources

[[Page 22231]]

Association 43(1): 86-103 (2007). They also serve as migratory 
corridors for fish. Tributaries can improve or maintain biological 
integrity and can control water temperatures in the downstream 
waters. See, e.g., Report at 4-14 (citing J.L. Ebersole, et. al., 
``Cold water patches in warm streams: Physicochemical 
characteristics and the influence of shading,'' Journal of the 
American Water Resources Association 39:355-368 (2003); B. Gardner, 
and P.J. Sullivan, ``Spatial and temporal stream temperature 
prediction: Modeling nonstationary temporal covariance structures,'' 
Water Resources Research 40:1-9 (2004); B.R. Johnson, et al., ``Use 
of spatially explicit physicochemical data to measure downstream 
impacts of headwater stream disturbance,'' Water Resources Research 
46:W09526 (2010)). Headwater streams also provide refuge habitat for 
riverine organisms seeking protection from temperature extremes, 
flow extremes, low dissolved oxygen, high sediment levels, or the 
presence of predators, parasites, and competitors. See, e.g., id. at 
4-32 (citing J.C. Scrivener, et al., ``Juvenile Chinook salmon 
(Oncorhynchus tshawytscha) utilization of Hawks Creek, a small and 
nonnatal tributary of the Upper Fraser River,'' Canadian Journal of 
Fisheries and Aquatic Sciences 51:1139-1146 (1994); R.A. Curry, et 
al., ``Use of small streams by young brook trout spawned in a 
lake,'' Transactions of the American Fisheries Society 126:77-83 
(1997); A.M. Pires, et al., ``Seasonal changes in fish community 
structure of intermittent streams in the middle reaches of the 
Guadiana basin, Portugal,'' Journal of Fish Biology 54:235-249 
(1999); M.J Bradford, et al., ``Ecology of juvenile Chinook salmon 
in a small nonnatal stream of the Yukon River drainage and the role 
of ice conditions on their distribution and survival,'' Canadian 
Journal of Zoology-Revue Canadienne De Zoologie 79:2043-2054 (2001); 
M.A. Cairns, et al., ``Influence of summer stream temperatures on 
black spot infestation of juvenile coho salmon in the Oregon Coast 
Range,'' Transactions of the American Fisheries Society 134:1471-
1479 (2005); Wigington, P. J., et al., ``Coho salmon dependence on 
intermittent streams,'' Frontiers in Ecology and the Environment 
4:513-518 (2006)). Headwater streams serve as a source of food 
materials such as insects, larvae, and organic matter to nourish the 
fish, mammals, amphibians, and other organisms in downstream 
streams, rivers, and lakes. See, e.g., id. at 4-22, 4-24 (citing 
S.G., Fisher, and G.E. Likens, ``Energy flow in Bear Brook, New 
Hampshire: An integrative approach to stream ecosystem metabolism,'' 
Ecological Monographs 43:421-439 (1973); J.L. Meyer, ``The microbial 
loop in flowing waters,'' Microbial Ecology 28:195-199 (1994); J.B. 
Wallace, et al., ``Multiple trophic levels of a forest stream linked 
to terrestrial litter inputs,'' Science 277:102-104 (1997); R.O. 
Hall, and J.L. Meyer, ``The trophic significance of bacteria in a 
detritus-based stream food web,'' Ecology 79:1995-2012 (1998); R.O. 
Hall, et al., ``Organic matter flow in stream food webs with reduced 
detrital resource base,'' Ecology 81:3445-3463 (2000); T. Gomi, et 
al., ``Understanding processes and downstream linkages of headwater 
systems,'' Bioscience 52:905-916 (2002); C. Augspurger, et al., 
``Tracking carbon flow in a 2-week-old and 6-week-old stream biofilm 
food web,'' Limnology and Oceanography 53:642-650 (2008)). 
Disruptions in these biological processes affect the ecological 
functions of the entire downstream system. See, e.g., L.A. Kaplan, 
et al., ``Patterns of Dissolved Organic Carbon in Transport,'' 
Limnology and Oceanography 25: 1034-1043 (1980); R.L. Vannote, et. 
al., ``The River Continuum Concept,'' Canadian Journal of Fisheries 
and Aquatic Sciences 37: 130-37 (1980). Headwater streams can help 
to maintain base flow in the larger rivers downstream, which is 
particularly important in times of drought. See, e.g., Report at 4-
4, 4-66 (citing P.D. Brooks, and M.M. Lemon, ``Spatial variability 
in dissolved organic matter and inorganic nitrogen concentrations in 
a semiarid stream, San Pedro River, Arizona,'' Journal of 
Geophysical Research-Biogeosciences 112:G03S05.D (2007); Tetzlaff, 
and C. Soulsby, ``Sources of baseflow in larger catchments--using 
tracers to develop a holistic understanding of runoff generation,'' 
Journal of Hydrology 359:287-302 (2008)). At the same time, the 
network of headwater streams can regulate the flow of water into 
downstream waters, mitigating low flow and high flow extremes, 
reducing local and downstream flooding, and preventing excess 
erosion caused by flooding. See, e.g., United States, U.S. EPA and 
USDA/ARS Southwest Watershed Research Center, EPA/600/R-08/134, ARS/
2330462008: The Ecological and Hydrological Significance of 
Ephemeral and Intermittent Streams in the Arid and Semi-arid 
American Southwest (Washington, DC: U.S. EPA and USDA/ARS Southwest 
Watershed Research Center, Levick et al., 2008) (Levick et al. 
2008).

F. Ephemeral and Intermittent Tributaries Significantly Affect the 
Chemical, Physical, or Biological Integrity of (a)(1) Through (a)(3) 
Waters

    Tributaries do not need to flow perennially to have a 
significant nexus to downstream waters. Approximately 59% of streams 
across the United States (excluding Alaska) flow intermittently or 
ephemerally; ephemeral and intermittent streams are particularly 
prevalent in the arid and semi-arid Southwest, where they account 
for over 81% of streams. Levick et al. 2008. Despite their 
intermittent or ephemeral flow, these streams nonetheless perform 
the same important ecological and hydrological functions documented 
in the scientific literature as perennial streams, through their 
movement of water, nutrients, and sediment to downstream waters. Id. 
The importance of intermittent and ephemeral streams is documented 
in a 2008 peer-reviewed report by EPA's Office of Research and 
Development and the U.S. Department of Agriculture's Agricultural 
Research Service, which addresses the hydrological and ecological 
significance of ephemeral and intermittent streams in the arid and 
semi-arid Southwestern United States and their connections to 
downstream waters; the report is a state-of-the-art synthesis of 
current knowledge of the ecology and hydrology in these systems. Id.
    Intermittent and ephemeral streams are chemically, physically, 
and biologically connected to downstream waters, and these 
connections have effects downstream. See, e.g., id. In some areas, 
stormflows channeled into alluvial floodplain aquifers by 
intermittent and ephemeral streams are the major source of annual 
streamflow in rivers. Perennial flows are not necessary for chemical 
connections. Periodic flows in ephemeral or intermittent tributaries 
can have a strong influence on biogeochemistry by connecting the 
channel and other landscape elements. See, e.g., Report at 4-16 
(citing H.M. Valett, et. al., ``Biogeochemical and Metabolic 
Responses to the Flood Pulse in a Semiarid Floodplain,'' Ecology 
86(1): 220-234 (2005)). This episodic connection can be very 
important for transmitting a substantial amount of material into 
downstream rivers. See, e.g., id. (citing Nadeau and Rains (2007)). 
Ephemeral desert streams have been shown to export particularly high 
sediment loadings. See, e.g., id. at 4-10 (citing M.A. Hassan, 
``Observations of Desert Food Bores,'' Earth Surface Processes and 
Landforms 15:481-485 (1990)). Ephemeral streams can also temporarily 
and effectively store large amounts of sediment that would otherwise 
wash downstream, contributing to the maintenance of downstream water 
quality and productive fish habitat. See, e.g., S.H. Duncan, et al., 
``Transport of Road-Surface Sediment through Ephemeral Stream 
Channels,'' Water Resources Bulletin 23(1): 113-119 (1987). This 
temporary storage of sediment thus helps maintain the chemical and 
biologic integrity of downstream waters.
    The Report provides case studies of prairie streams and 
Southwest intermittent and ephemeral streams, two stream types whose 
jurisdictional status has been called into question in the past. 
These case studies highlight the importance of these streams to 
downstream waters, despite their small size and ephemeral or 
intermittent flow regime. Prairie streams are frequently subjected 
to the extremes of drying and flooding, and intermittent or flashy 
hydrology is prevalent in river networks throughout most of the 
Great Plains. Report at 4-40 (citing W.J. Matthews, ``North American 
Prairie Streams as Systems for Ecological Study,'' Journal of the 
North American Benthological Society 7:387-409 (1988); A.V. Zale et 
al., ``The Physicochemistry, Flora, and Fauna of Intermittent 
Prairie Streams: A Review of the Literature,'' United States Fish 
and Wildlife Service Biological Report 89:1-44 (1989); N.L. Poff, 
``A Hydrogeography of Unregulated Streams in the United States and 
an Examination of Scale Dependence in Some Hydrological 
Descriptors,'' Freshwater Biology 36:71-91 (1996); W.K. Dodds, et 
al., ``Life on the Edge: The Ecology of Great Plains Prairie 
Streams,'' Bioscience 54:205-216 (2004)). Prairie streams typically 
represent a collection of spring-fed, perennial pools and reaches, 
embedded within larger, intermittently flowing segments. Id. at 4-55 
(citing T.R. Labbe, and K.D. Fausch, ``Dynamics of Intermittent 
Stream Habitat Regulate Persistence of a Threatened Fish at Multiple 
Scales,'' Ecological Applications 10:1774-1791 (2000)). These 
streams have

[[Page 22232]]

significant chemical, physical, and biological connections to 
downstream waters, despite extensive alteration of historical 
prairie regions by agriculture, water impoundment, water 
withdrawals, and other human activities, and the challenges these 
alterations create for assessing connectivity. Id. (citing W.J. 
Matthews, and H.W. Robinson, ``Influence of Drainage Connectivity, 
Drainage Area and Regional Species Richness on Fishes of the 
Interior Highlands in Arkansas,'' American Midland Naturalist 139:1-
19 (1998); W.K. Dodds, et al., ``Life on the Edge: The Ecology of 
Great Plains Prairie Streams,'' Bioscience 54:205-216 (2004)). The 
most notable connections are via flood propagation, contaminated 
sediment transport, nutrient retention, and the extensive transport 
and movement of fish species (including eggs and larvae) throughout 
these networks. Id. at 4-55 (citing H.F. Matthai, Floods of June 
1965 in South Platte River Basin, Colorado, Water Supply Paper 1850-
B (Washington, DC: U.S. Geological Survey, 1969); A.J. Horowitz, et 
al., ``The Effect of Mining on the Sediment-trace Element 
Geochemistry of Cores from the Cheyenne River Arm of Lake Oahe, 
South Dakota, USA,'' Chemical Geology 67:17-33 (1988); DC Marron, 
``The Transport of Mine Tailings as Suspended Sediment in the Belle 
Fourche River, West-central South Dakota, USA,'' International 
Association of Hydrologic Sciences 184:19-26 (1989); W.K. Dodds, et 
al., ``Nitrogen Transport from Tallgrass Prairie Watersheds,'' 
Journal of Environmental Quality 25:973-981 (1996); K.D. Fausch, and 
K.R. Bestgen, ``Ecology of Fishes Indigenous to the Central and 
Southwestern Great Plains,'' in F.L. Knopf and F.B. Samson, ed., 
Ecology and Conservation of Great Plains Vertebrates, (New York, NY: 
Springer-Verlag, 1997), pp. 131-166; S.P. Platania, and C.S. 
Altenbach, ``Reproductive Strategies and Egg Types of Seven Rio 
Grande Basin Cyprinids,'' Copeia 1998:559-569 (1998); K.M. Fritz, 
and W.K. Dodds, ``Resistance and Resilience of Macroinvertebrate 
Assemblages to Drying and Flood in a Tallgrass Prairie Stream 
System,'' Hydrobiologia 527:99-112 (2004); K.M. Fritz, and W.K. 
Dodds, ``Harshness: Characterization of Intermittent Stream Habitat 
over Space and Time,'' Marine and Freshwater Research 56:13-23 
(2005); N.R. Franssen, et al., ``Effects of Floods on Fish 
Assemblages in an Intermittent Prairie Stream,'' Freshwater Biology 
51:2072-2086 (2006); R.B. Alexander, et al., ``Differences in 
Phosphorus and Nitrogen Delivery to the Gulf of Mexico from the 
Mississippi River Basin,'' Environmental Science & Technology 
42:822-830 (2008); J.S. Perkins, and K.B. Gido, ``Stream 
Fragmentation Thresholds for a Reproductive Guild of Great Plains 
Fishes,'' Fisheries 36:371-383 (2011)).
    Southwestern intermittent and ephemeral streams exert strong 
influences on the structure and function of downstream waters, and 
the case study (included in the Report) echoes many of the findings 
of the functions of intermittent and ephemeral tributaries 
generally, which are described above. The case study focuses on the 
heavily studied San Pedro River, located in southeast Arizona, in 
particular, as a representative example of the hydrological behavior 
and the connectivity of rivers in the Southwest, but also examines 
evidence relevant to other Southwestern streams. The chemical, 
physical, and biological connections of Southwestern intermittent 
and ephemeral streams highlighted in the case study are summarized 
below. Flows from ephemeral streams are one of the major drivers of 
the dynamic hydrology of Southwest rivers (particularly of floods 
during monsoon seasons. Id. at 4-60, 4-67 (citing DC Goodrich, et 
al., ``Linearity of Basin Response as a Function of Scale in a 
Semiarid Watershed,'' Water Resources Research 33:2951-2965 (1997); 
F. Yuan, and S. Miyamoto, ``Characteristics of Oxygen-18 and 
Deuterium Composition in Waters from the Pecos River in American 
Southwest,'' Chemical Geology 255:220-230 (2008)). Downstream river 
fishes and invertebrates are adapted to the variable flow regimes 
that are influenced strongly by ephemeral tributary systems, which 
provide isolated pools as refuges for fish during dry periods. Id. 
at 4-68 to 4-69 (citing K.R. John, ``Survival of Fish in 
Intermittent Streams of the Chirichua Mountains, Arizona'' Ecology 
45:112-119 (1964); T.R. Labbe, and K.D. Fausch, ``Dynamics of 
Intermittent Stream Habitat Regulate Persistence of a Threatened 
Fish at Multiple Scales,'' Ecological Applications 10:1774-1791 
(2000); J.N. Rinne, and D. Miller, ``Hydrology, Geomorphology and 
Management: Implications for Sustainability of Native Southwestern 
Fishes,'' Reviews in Fisheries Science 14:91-110 (2006); D.A. Lytle, 
et al., ``Evolution of Aquatic Insect Behaviors across a Gradient of 
Disturbance Predictability,'' Proceedings of the Royal Society--
Series B 275:453-462 (2008)). Ephemeral tributaries in the Southwest 
also supply water to mainstem river alluvial aquifers, which aids in 
the sustaining river baseflows downstream. Id. at 4-64 (citing DC 
Goodrich, et al., ``Linearity of Basin Response as a Function of 
Scale in a Semiarid Watershed,'' Water Resources Research 33:2951-
2965 (1997); J.B. Callegary, et al., ``Rapid Estimation of Recharge 
Potential in Ephemeral-Stream Channels using Electromagnetic 
Methods, and Measurements of Channel and Vegetation 
Characteristics,'' Journal of Hydrology 344:17-31 (2007)). Ephemeral 
tributaries export sediment downstream during major hydrologic 
events; the sediment, in turn, contributes to materials that 
comprise alluvial aquifers and shape the fluvial geomorphology (the 
science of how rivers and streams form given the landscape setting) 
of downstream waters. Id. at 4-65 (citing G.C. Nanson, and J.C. 
Croke, ``A Genetic Classification of Floodplains,'' Geomorphology 
4:459-486 (1992)). The nutrient and biogeochemical integrity of 
downstream Southwestern rivers, such as the San Pedro River, is 
heavily influenced by nutrient export from ephemeral tributaries 
after storm flow events. Id. at 4-18, 4-66 (citing P.D. Brooks, and 
M.M. Lemon, ``Spatial Variability in Dissolved Organic Matter and 
Inorganic Nitrogen Concentrations in a Semiarid Stream, San Pedro 
River, Arizona,'' Journal of Geophysical Research-Biogeosciences 
112:G03S05 (2007)). Extensive downstream river riparian communities 
are supported by water, sediment and nutrients exported to the river 
from ephemeral tributaries; these riparian communities have a 
profound influence on the river attributes through shading, 
allochthonous (originating from outside of the channel) inputs of 
organic matter, detritus, wood, and invertebrates to the river. Id. 
at 4-65 to 4-66 (citing S.V. Gregory, et al., ``An Ecosystem 
Perspective of Riparian Zones: Focus on Links between Land and 
Water,'' Bioscience 41:540-551 (1991); R.J. Naiman, et al., Riparia: 
Ecology, Conservation, and Management of Streamside Communities 
(Burlington, MA: Elsevier, Inc., 2005); J.C. Stromberg, et al., 
``Effects of Stream Flow Intermittency on Riparian Vegetation of a 
Semiarid Region River (San Pedro River, Arizona),'' River Research 
and Applications 21:925-938 (2005), M. Baillie, et al., 
``Quantifying Water Sources to a Semiarid Riparian Ecosystem, San 
Pedro River, Arizona,'' Journal of Geophysical Research 112:G03S02 
(2007); National Research Council, Riparian Areas: Functions and 
Strategies for Management (Washington, DC: National Academy Press, 
2002)).

E. Tributary Lakes, Ponds, and Wetlands Significantly Affect the 
Chemical, Physical, or Biological Integrity of (a)(1) Through (a)(3) 
Waters

    As discussed elsewhere in this preamble, riparian and floodplain 
wetlands have a significant nexus to downstream waters, and wetlands 
that are tributaries are a subset of such wetlands. The fact that a 
wetland tributary is in-stream often enhances its ability to filter 
pollutants and contaminants that would otherwise make it downstream; 
in-stream wetlands also attenuate floodwaters. Lakes and ponds serve 
many important functions that affect the chemical, physical, and 
biological conditions downstream. Lake tributaries can act as sinks, 
storing floodwaters, sediment, and nutrients, as these materials 
have the opportunity to settle out, at least temporarily, as water 
moves through the lake to downstream waters. See, e.g., R.W. 
Phillips, et al., ``Connectivity and Runoff Dynamics in 
Heterogeneous Basins,'' Hydrological Processes 25(19): 3061-3075 
(2011). The attenuation of floodwaters can also maintain stream 
flows downstream. Id. Lakes, as with other tributaries, can also act 
as sources, contributing flow, nutrient, sediment, and other 
materials downstream. Total Maximum Daily Loads (TMDLs) for 
nutrients have been established for many in-stream lakes across the 
country in recognition of the ability of lakes to transport 
nutrients downstream, contributing to downstream impairments. See, 
e.g. Maine Department of Environmental Protection, Phosphorus 
Control Action Plan and Total Maximum Daily (Annual Phosphorous) 
Load Report, Daigle Pond, New Canada, Aroostook County, Maine, 
Daigle Pond PCAP--TMDL Report, Maine DEPLW--0789 (Maine DEP, 2006); 
U.S. Environmental Protection Agency, ``Section 6 Echo Park Lake 
TMDLs,'' Los Angeles Area Lakes TMDLs, January 2011 Revised Draft 
(2011). Lakes can also serve as habitat for species that then move 
downstream. For instance, brook trout that are stocked in headwater

[[Page 22233]]

lakes in Idaho and Montana are capable of invading most downstream 
habitat, including through very steep channel slopes and waterfalls. 
S.B. Adams, et al., ``Geography of Invasion in Mountain Streams: 
Consequences of Headwater Lake Fish Introductions,'' Ecosystems 
4(4): 296-307. These non-native species can then affect the 
biological integrity of downstream waters by impacting populations 
of native fish species, such as cutthroat trout, downstream. See, 
e.g., J.B. Dunham, et al., ``Alien Invasions in Aquatic Ecosystems: 
Toward an Understanding of Brook Trout Invasions and Potential 
Impacts on Inland Cutthroat Trout in Western North America,'' 
Reviews in Fish Biology and Fisheries 12(4): 373-391 (2002). For 
example, non-native trout were introduced in headwater tributary 
lakes to the Little Kern River in the southern Sierra Nevada and 
dispersed downstream, causing the near-extinction of the native 
Little Kern golden trout. R.A. Knapp, and K.R. Matthews, ``Effects 
on Nonnative Fishes on Wilderness Lake Ecosystems in the Sierra 
Nevada and Recommendations for Reducing Impacts,'' in D. N. Cole, et 
al., ed., Wilderness Science in a Time of Change Conference, Volume 
5: Wilderness Ecosystems, Threats, and Management, Missoula, 
Montana, May 23-27, 1999, Proceedings RMRS-P-15-VOL-5 (Ogden, UT: 
U.S. Department of Agriculture, Forest Service, Rocky Mountain 
Research Station, 2000), 312-317. These studies demonstrate the 
ability of organisms to travel from tributary lakes to downstream 
waters, which is not limited to just non-native species; many other 
species can also move downstream and back again.
    One type of wetlands located in-stream are unidirectional 
wetlands that are connected to the river network through a channel 
(e.g., wetlands that serve as stream origins; a definition of 
``unidirectional wetlands'' can be found in part I section 4.B 
above). These tributary wetlands are generally exemplary of 
tributary wetlands as a whole, and because the Report focuses in 
part on these wetlands, they are discussed here in further detail. 
These are wetlands from which a stream channel originates. Report at 
5-1 to 5-2. They are part of the stream network itself, and along 
with first- and second-order streams, form the headwaters of the 
river network. Such wetlands have a direct hydrologic connection to 
the tributary network via unidirectional flow from wetland to the 
headwater stream. Channel origin wetlands generally have important 
chemical, physical, and biological effects on (a)(1) through (a)(3) 
waters, including hydrologic, water quality, and habitat functions, 
regardless if the outflow from the wetland to the stream is 
perennial, intermittent, or ephemeral. Id. Like other wetlands, 
wetlands that serve as stream origins can transport channel-forming 
sediment and woody debris, transport stored organic matter, remove 
and transform pollutants and excess nutrients such as nitrogen and 
phosphorus, attenuate and store floodwaters, contribute to stream 
baseflow through groundwater recharge, and provide habitat for 
breeding fish, amphibians, reptiles, birds, and other aquatic and 
semi-aquatic species that move from the wetlands to the river 
network. Id. at 5-41.
    Wetlands that serve as stream origins connect via perennial, 
intermittent, or ephemeral drainages to river networks. Id. at 5-22 
to 5-23 (citing M.C. Rains, et al., ``The Role of Perched Aquifers 
in Hydrological Connectivity and Biogeochemical Processes in Vernal 
Pool Landscapes, Central Valley, California,'' Hydrological 
Processes 20:1157-1175 (2006); M.C. Rains, et al., ``Geological 
Control of Physical and Chemical Hydrology in California Vernal 
Pools,'' Wetlands 28:347-362 (2008); T.R. Morley, et al., ``The Role 
of Headwater Wetlands in Altering Streamflow and Chemistry in a 
Maine, USA Catchment,'' Journal of the American Water Resources 
Association 47:337-349 (2011)). Regardless of the permanence of 
flow, such wetlands have an impact on downstream water. Id. at 5-1 
to 5-2. Wetland seeps, for example, can form where groundwater 
discharges from breaks in slope. Id. at 5-21 (citing B.R. Hall, et 
al., ``Environmental Influences on Plant Species Composition in 
Ground-water Seeps in the Catskill Mountains of New York,'' Wetlands 
21:125-134 (2001); M.A. O'Driscoll, and D.R. DeWalle, ``Seeps 
Regulate Stream Nitrate Concentration in a Forested Appalachian 
Catchment,'' Journal of Environmental Quality 39:420-431 (2010)). 
They often have perennial connections to the stream, providing 
important sources of water downstream, particularly during summer 
baseflow. Id. at 5-22 (citing T.R. Morley, et al., ``The Role of 
Headwater Wetlands in Altering Streamflow and Chemistry in a Maine, 
USA Catchment,'' Journal of the American Water Resources Association 
47:337-349 (2011)). In Maine, for example, seeps were found to 
provide 40 to 80% of stream water during baseflow periods. Id. In 
other cases, surface connections between channel origin wetlands and 
streams are intermittent or ephemeral. For example, California 
vernal pools spill water a great number of days during the years via 
channels, providing water downstream. Id. (citing M.C. Rains, et 
al., ``The Role of Perched Aquifers in Hydrological Connectivity and 
Biogeochemical Processes in Vernal Pool Landscapes, Central Valley, 
California,'' Hydrological Processes 20:1157-1175 (2006); M.C. 
Rains, et al., ``Geological Control of Physical and Chemical 
Hydrology in California Vernal Pools,'' Wetlands 28:347-362 (2008)). 
In addition to surface water connections, groundwater flow can 
hydrologically connect wetlands that serve as stream origins with 
the stream network. Id. at 5-23.
    The hydrologic connection of the wetland to the stream can 
affect streamflow by altering baseflow or storm flow through several 
mechanisms, including surface storage and groundwater recharge. Id. 
at 5-25. Studies at the larger scale have shown that wetlands, by 
storing water, reduce peak streamflows and, thus, downstream 
flooding. Id. (citing J. Jacques, and D. L. Lorenz, Techniques for 
Estimating the Magnitude and Frequency of Floods of Ungauged Streams 
in Minnesota, Report 87-4170 (Washington, DC: U.S. Geological 
Survey, 1988); Vining, K.C., Simulation of Streamflow and Wetland 
Storage, Starkweather Coulee Subbasin, North Dakota, Water Years 
1981-98, Water-Resources Investigations Report 02-4113 (Bismarck, 
ND: U.S. Geological Survey, 2002), 33 p.; P. McEachern, et al., 
``Landscape Control of Water Chemistry in Northern Boreal Streams of 
Alberta,'' Journal of Hydrology 323:303-324 (2006); R.A. Gleason, et 
al. Estimating Water Storage Capacity of Existing and Potentially 
Restorable Wetland Depressions in a Subbasin of the Red River of the 
North, U.S. Geological Survey Open-File Report 2007-1159 (Reston, 
VA: U.S. Geological Survey, 2007), 36 p.). In some cases, however, 
where wetlands that serve as stream origins are already saturated 
prior to rainfall, they can convey stormwater quickly downstream and 
thus actually increase flood peaks. Id. at 227 (citing Bay, R., 
``Runoff from Small Peatland Watersheds,'' Journal of Hydrology 
9:90-102 (1969); A. Bullock, and M. Acreman, ``The Role of Wetlands 
in the Hydrological Cycle,'' Hydrology and Earth System Sciences 
7:358-389 (2003)). This is because the wetland soil, if completely 
saturated, cannot store any additional water, making the wetland 
enable to store floodwater.
    Wetlands that serve as stream origins have important chemical 
connections to downstream waters that affect the integrity of those 
waters. These wetlands contain diverse microbial populations that 
perform various chemical transformations, acting as source of 
compounds and influencing the water quality downstream. Id. at 5-28 
(citing K.R. Reddy, and R.D. DeLaune, Biogeochemistry of Wetlands: 
Science and Applications, 774 p. (2008)). Sulfate-reducing bacteria 
found in some headwater wetlands produce methylated mercury, which 
is then transported downstream by surface flows. Id. (citing O.K. 
Linqvist, et al., ``Mercury in the Swedish Environment--Recent 
Research on Causes, Consequences, and Remedial Measures,'' Water Air 
and Soil Pollution 55:xi-xiii (1991); G. Mierle, and R. Ingram, 
``The Role of Humic Substances in the Mobilization of Mercury from 
Watersheds,'' Water Air and Soil Pollution 56:349-357 (1991); C.T. 
Driscoll, et al., ``The Role of Dissolved Organic Carbon in the 
Chemistry and Bioavailability of Mercury in Remote Adirondack 
Lakes,'' Water Air and Soil Pollution 80:499-508 (1995); B.A. 
Branfireun, et al., ``In situ Sulphate Stimulation of Mercury 
Methylation in a Boreal Peatland: Toward a Link Between Acid Rain 
and Methylmercury Contamination in Remote Environments,'' Global 
Biogeochemical Cycles 13:743-750 (1999)). Wetlands, including those 
that serve as stream origins, are the principle sources of dissolved 
organic carbon (DOC) in forests to downstream waters. Id. (citing 
P.J. Mulholland, and E.J. Kuenzler, ``Organic Carbon Export from 
Upland and Forested Wetland Watersheds,'' Limnology and Oceanography 
24:960-966 (1979); N.R. Urban, et al., ``Export of Dissolved Organic 
Carbon and Acidity from Peatlands,'' Water Resources Research 
25:1619-1628 (1989); B.W. Eckhardt and T.R. Moore, ``Controls on 
Dissolved Organic Carbon Concentrations in Streams of Southern 
Quebec,'' Canadian Journal of Fisheries and Aquatic Sciences 
47:1537-1544 (1990); J.-F. Koprivnjak and T.R. Moore,

[[Page 22234]]

``Sources, Sinks, and Fluxes of Dissolved Organic Carbon in 
Subarctic Fen Catchments,'' Arctic and Alpine Research 24:204-210 
(1992); P. Kortelainen, ``Content of Total Organic Carbon in Finnish 
Lakes and Its Relationship to Catchment Characteristics,'' Canadian 
Journal of Fisheries and Aquatic Sciences 50:1477-1483 (1993); T.A. 
Clair, et al., ``Exports of Carbon and Nitrogen from River Basins in 
Canada's Atlantic Provinces,'' Global Biogeochemical Cycles 8:441-
450 (1994); D. Hope, et al., ``A Review of the Export of Carbon in 
River Water: Fluxes and Processes,'' Environmental Pollution 84:301-
324 (1994); P.J. Dillon and L.A. Molot, ``Effects of Landscape Form 
on Export of Dissolved Organic Carbon, Iron, and Phosphorus from 
Forested Stream Catchments,'' Water Resources Research 33:2591-2600 
(1997); S.E. Gergel, et al., ``Dissolved Organic Carbon as an 
Indicator of the Scale of Watershed Influence on Lakes and Rivers,'' 
Ecological Applications 9:1377-1390 (1999)). Export of DOC to 
downstream waters supports primary productivity, effects pH and 
buffering capacity, and regulates exposure to UV-B radiation. Id. at 
5-29 (citing K.N. Eshelman and H.F. Hemond, ``The Role of Organic 
Acids in the Acid-base Status of Surface Waters at Bickford 
Watershed, Massachusetts,'' Water Resources Research 21:1503-1510 
(1985); L.O. Hedin, et al., ``Patterns of Nutrient Loss from 
Unpolluted Old-growth Temperate Forests: Evaluation of 
Biogeochemical Theory,'' Ecology 76:493-509 (1995); D.W. Schindler 
and P.J. Curtis, ``The Role of DOC in Protecting Freshwaters 
Subjected to Climate Warming and Acidification from UV Exposure,'' 
Biogeochemistry 36:1-8 (1997); J.C. Nuff and G.P. Asner, ``Dissolved 
Organic Carbon in Terrestrial Ecosystems: Synthesis and a Model,'' 
Ecosystems 4:29-48 (2001)).
    Wetlands also act as sinks and transformers for pollutants, 
including excess nutrients, through such processes as 
denitrification, ammonia volatilization, microbial and plant biomass 
assimilation, sedimentation, sorption and precipitation, biological 
uptake, and long-term storage of plant detritus. Id. (citing K.C. 
Ewel and H.T. Odum, Cypress Swamps (Gainesville, FL: University 
Presses of Florida, 1984); S.J. Nixon and V.J. Lee, Wetlands and 
Water Quality: A Regional Review of Recent Research in the United 
States on the Role of Freshwater and Saltwater Wetlands as Sources, 
Sinks, and Transformers of Nitrogen, Phosphorus, and Various Heavy 
Metals, Technical Report Y-86-2 (Vicksburg, MS: U.S. Army Corps of 
Engineers, Waterways Experiment Station, 1986); C. Johnston, 
``Sediment and Nutrient Retention by Freshwater Wetlands: Effects on 
Surface Water Quality,'' Critical Reviews in Environmental Control 
21:491-565 (1991); K.R. Reddy, et al., ``Phosphorus Retention in 
Streams and Wetlands: A Review,'' Critical Reviews in Environmental 
Science and Technology 29:83-146 (1999); W.J. Mitsch and J.G. 
Gosselink, Wetlands, 4th edition (Hoboken, NJ: John Wiley & Sons 
Inc., 2007); K.R. Reddy, and R.D. DeLaune, Biogeochemistry of 
Wetlands: Science and Applications (Boca Raton, FL: CRC Press, 
2008); R.H. Kadlec and S.D. Wallace, Treatment Wetlands, 2nd edition 
(Boca Raton, FL: CRC Press, 2009)). Specifically, wetlands reduce 
phosphorus, nitrate, and ammonium by large percentages. Id. at 5-30 
(citing F.E. Dierberg and P.L. Brezonik, ``Nitrogen and Phosphorus 
Mass Balances in a Cypress Dome Receiving Wastewater,'' in K.C. Ewel 
and H.T. Odum, ed., Cypress Swamps (Gainesville, FL: University 
Presses of Florida, 1984), pp. 112-118; E.J. Dunne, et al., 
``Phosphorus Release and Retention by Soils of Natural Isolated 
Wetlands,'' International Journal of Environment and Pollution 
28:496-516 (2006); T.E. Jordan, et al., ``Comparing Functional 
Assessments of Wetlands to Measurements of Soil Characteristics and 
Nitrogen Processing,'' Wetlands 27:479-497 (2007)). These processes 
are important for protecting downstream waters from pollutants from 
agricultural runoff. Wetland microbial processes reduce other 
pollutants, such as pesticides, hydrocarbons, heavy metals, and 
chlorinated solvents. Id. (citing R.R. Brooks, et al., ``Cobalt and 
Nickel Uptake by the Nyssaceae,'' Taxon 26:197-201 (1977); C.M. Kao, 
et al., ``Non-point Source Pesticide Removal by a Mountainous 
Wetland,'' Water Science and Technology 46:199-206 (2002); P.I. 
Boon, ``Biogeochemistry and Bacterial Ecology of Hydrologically 
Dynamic Wetlands,'' in D. P. Batzer and R. R. Sharitz, ed., Ecology 
of Freshwater and Estuarine Wetlands (Berkeley, CA: University of 
California Press, 2006), pp. 115-176).
    Tributary wetlands have important biological connections 
downstream that impact the integrity of (a)(1) through (a)(3) 
waters. Emergent and aquatic vegetation found in wetlands disperse 
by water, wind, and hitchhiking on migratory animals from tributary 
wetlands downstream. Id. at 5-31 (citing M.B. Soons and G.W. Heil, 
``Reduced Colonization Capacity in Fragmented Populations of Wind-
Dispersed Grassland Forbs,'' Journal of Ecology 90:1033-1043 (2002); 
M.B. Soons, ``Wind Dispersal in Freshwater Wetlands: Knowledge for 
Conservation and Restoration,'' Applied Vegetation Science 9:271-278 
(2006); C. Nilsson, et al., ``The Role of Hydrochory in Structuring 
Riparian and Wetland Vegetation,'' Biological Reviews 85:837-858 
(2010)). Similarly, fish move between the river network and wetlands 
during times of surface water connections, and tributary wetlands by 
definition are connected on the surface to downstream waters. Id. at 
5-32 (citing J.W. Snodgrass, et al., ``Factors affecting the 
occurrence and structure of fish assemblages in isolated wetlands of 
the upper coastal plain, USA,'' Canadian Journal of Fisheries and 
Aquatic Sciences 53:443-454 (1996); K.D. Zimmer, et al., ``Effects 
of fathead minnow colonization and removal on a prairie wetland 
ecosystem,'' Ecosystems 4:346-357 (2001); M.J. Baber, et al., 
``Controls on fish distribution and abundance in temporary 
wetlands,'' Canadian Journal of Fisheries and Aquatic Sciences 
59:1441-1450 (2002); M.A. Hanson, et al., ``Biotic interactions as 
determinants of ecosystem structure in prairie wetlands: An example 
using fish,'' Wetlands 25:764-775 (2005); B.R. Herwig, et al., 
``Factors influencing fish distributions in shallow lakes in prairie 
and prairie-parkland regions of Minnesota, USA,'' Wetlands 30:609-
619 (2010)). Mammals that can disperse overland can also contribute 
to connectivity. Id. (citing C.E. Shanks, and G.C. Arthur, ``Muskrat 
movements and population dynamics in Missouri farm ponds and 
streams,'' Journal of Wildlife Management 16:138-148 (1952); W.R. 
Clark, ``Ecology of muskrats in prairie wetlands,'' in H.R. Murkin, 
et al., ed., Prairie Wetland Ecology: The Contribution of the Marsh 
Ecology Research Program, (Ames, IA: Iowa State University Press, 
2000), pp. 287-313). Insects also hitchhike on birds and mammals 
from tributary wetlands to the stream network, which can then serve 
as a food source for downstream waters. Id. (citing J. Figuerola, 
and A.J. Green, ``Dispersal of Aquatic Organisms by Waterbirds: A 
Review of Past Research and Priorities for Future Studies,'' 
Freshwater Biology 47:483-494 (2002); J. Figuerola, et al., 
``Invertebrate Eggs Can Fly: Evidence of Waterfowl-Mediated Gene 
Flow in Aquatic Invertebrates,'' American Naturalist 165:274-280 
(2005)). Insects that are flight-capable also use both stream and 
tributary wetlands, moving from the stream to the wetland to find 
suitable habitat for overwintering, refuge from adverse conditions, 
hunting, foraging, or breeding. Id. at 5-33 (citing D.D. Williams, 
``Environmental Constraints in Temporary Fresh Waters and Their 
Consequences for the Insect Fauna,'' Journal of the North American 
Benthological Society 15:634-650 (1996); A.J. Bohonak and D.G. 
Jenkins, ``Ecological and Evolutionary Significance of Dispersal by 
Freshwater Invertebrates,'' Ecology Letters 6:783-796 (2003)). 
Amphibians and reptiles, including frogs, toads, and newts, also 
move between streams or rivers and tributary wetlands to satisfy 
part of their life history requirements, feed on aquatic insects, 
and avoid predators. Id. (citing V.S. Lamoureux and D.M. Madison, 
``Overwintering Habitats of Radio-Implanted Green Frogs, Rana 
clamitans,'' Journal of Herpetology 33:430-435 (1999); K.J. Babbitt, 
et al., ``Patterns of Larval Amphibian Distribution Along a Wetland 
Hydroperiod Gradient,'' Canadian Journal of Zoology-Revue Canadienne 
De Zoologie 81:1539-1552 (2003); S.B. Adams, et al., ``Instream 
Movements by Boreal Toads (Bufo boreas boreas),'' Herpetological 
Review 36:27-33 (2005); D.M. Green, ``Bufo americanus, American 
Toad,'' in M. Lannoo, ed., Amphibian Declines: The Conservation 
Status of United States Species (Berkeley, CA: University of 
California Press, 2005), pp. 692-704; T.W. Hunsinger and M.J. 
Lannoo, ``Notophthalmus viridescens, Eastern Newt,'' in M. Lannoo, 
ed., Amphibian Declines: The Conservation Status of United States 
Species (Berkeley, CA: University of California Press, 2005), pp. 
912-914; J.W. Petranka, and C.T. Holbrook, ``Wetland Restoration for 
Amphibians: Should Local Sites Be Designed to Support 
Metapopulations or Patchy Populations?,'' Restoration Ecology 
14:404-411 (2006); A.L. Subalusky, et al., ``Ontogenetic Niche 
Shifts in the American Alligator Establish Functional Connectivity 
between Aquatic Systems,'' Biological Conservation 142:1507-1514 
(2009)).
    Lake, pond, and wetland tributaries, including wetlands that 
serve as stream origins, have important chemical, physical,

[[Page 22235]]

and biological connections downstream that affect (a)(1) through 
(a)(3) waters. Their direct hydrologic connection to the stream 
network facilitates the significant impact they have downstream. 
This impact on downstream waters occurs regardless of whether their 
flow is perennial, intermittent, or ephemeral. Thus, lake, pond, and 
wetland tributaries serve the same important functions as stream 
tributaries, which in turn greatly impact downstream (a)(1) through 
(a)(3) waters, particularly when their functional contributions to 
the chemical, physical, and biological conditions of downstream 
waters are combined at a watershed scale.

F. Man-Made or Man-Altered Tributaries Significantly Affect the 
Physical, Chemical and Biological Integrity of (a)(1) Through (a)(3) 
Waters

    The agencies' proposed rule clarifies that man-made and man-
altered tributaries as defined in the proposed rule are ``waters of 
the United States'' because the significant nexus between a 
tributary and a traditional navigable water or interstate water is 
not broken where the tributary flows through a culvert or other 
structure. Note that the proposal excludes certain ditches from CWA 
jurisdiction by rule in paragraphs (b)(3) and (b)(4). The scientific 
literature indicates that structures that convey water do not affect 
the connectivity between streams and downstream rivers. Indeed, 
because such structures can reduce water losses from 
evapotranspiration and seepage, such structures likely enhance the 
extent of connectivity by more completely conveying the water 
downstream.
    Man-made and man-altered tributaries include impoundments, 
ditches, canals, channelized streams, piped, and the like. Ditches 
and canals are wide-spread across the United States. Ditches may 
have been streams that were channelized. They are purposely 
constructed to allow the hydrologic flow of the tributary to 
continue downstream. Man-made and man-altered tributaries, despite 
human manipulation, usually continue to have chemical, physical, or 
biological connections downstream and to serve important functions 
downstream. Because these tributaries are hydrologically connected 
to downstream waters, the chemical and some biological connections 
to downstream waters that are supported by this hydrologic 
connection are still intact. Often-times man-made tributaries create 
connections where they did not previously exist, such as canals that 
connect two rivers in different watersheds.
    Tributary ditches and other man-made or man-altered waters that 
meet the definition of ``tributary'' have a significant nexus to 
(a)(1) through (a)(3) waters due to their impact, either 
individually or with other tributaries, on the chemical, physical, 
or biological integrity of those downstream waters. Tributary 
ditches and the like, as with other tributaries, have chemical, 
physical, and biological connections with downstream waters that 
substantially impact those waters. Tributary ditches and canals can 
have perennial, intermittent, or ephemeral flow. 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. See, e.g., J.P. 
Schmidt, et al., ``Nitrogen Export from Coastal Plain Field 
Ditches,'' Journal of Soil and Water Conservation 62(4):235-243; 
J.S. Strock, et al., ``Managing Natural Processes in Drainage 
Ditches for Nonpoint Source Nitrogen Control.'' Journal of Soil and 
Water Conservation 62(4): 188-196 (2007). Ditches provide habitat 
for fish and other aquatic organisms. See, e.g., P.C. Smiley, Jr., 
et al., ``Contribution of Habitat and Water Quality to the Integrity 
of Fish Communities in Agricultural Drainage Ditches,'' Journal of 
Soil and Water Conservation 63(6):218A-219A (2008). Fish and other 
aquatic organisms utilize canals and ditches to move to different 
habitats, sometimes over long distances. F.J. Rahel, ``Biogeographic 
Barriers, Connectivity and Homogenization of Freshwater Faunas: It's 
a Small World after All,'' Freshwater Biology 52(4): 696-710 (2007).
    These significant connections and functions continue even where 
the tributary has a natural or man-made break in its channel, bed 
and banks, or OHWM. The presence of a channel, bed and banks, and 
OHWM upstream or downstream of the break is an indication that 
connections still exist. The significant nexus between a tributary 
and a downstream water is not broken where the tributary flows 
underground for a portion of its length, such as in karst 
topography. The hydrologic connection still exists, meaning that the 
chemical and biological connections that are mediated by the 
hydrologic connection also still exist. Similarly, flow through 
boulder fields does not sever the hydrologic connection. When a 
tributary flows through a wetland enroute to another or the same 
tributary, the significant nexus still exists even though the bed 
and banks or ordinary high watermark is broken for the length of the 
wetland. As discussed in Part II, section 1.G. of this appendix, in-
stream wetlands provide numerous benefits downstream, and the 
presence of the wetland in stream can provide additional water 
quality benefits to the receiving waters. Flow in flat areas with 
very low gradients may temporarily break the tributary's bed and 
banks or OHWM, but these systems continue to have a significant 
nexus downstream. These are just illustrative examples of break in 
ordinary high watermark; there are several other types, all of which 
do not break the significant nexus between a tributary and the 
downstream (a)(1) through (a)(3) water.
    There are more than 80,000 dams in the United States, with over 
6,000 exceeding 15 meters in height. Report at 3-48 (citing U.S. 
Army Corps of Engineers, National Inventory of Dams (2009)). The 
purpose of a dam is to impound (store) water for any of several 
reasons (e.g. flood control, human water supply, irrigation, 
livestock water supply, energy generation, containment of mine 
tailings, recreation or pollution control). See http://www.damsafety.org/layout/subsection.aspx?groupid=14&contentid=47. 
Many dams fulfill a combination of the above functions. Because the 
purpose of a dam is to retain water effectively and safely, the 
water retention ability of a dam is of prime importance. Water may 
pass from the reservoir to the downstream side of a dam by: passing 
through the main spillway or outlet works; passing over an auxiliary 
spillway; overtopping the dam; seepage through the abutments; and 
seepage under the dam. Id. All water retention structures are 
subject to seepage through their foundations and abutments. 
Department of the Army, U.S. Army Corps of Engineers, Engineering 
and Design--Design, Construction and Maintenance of Relief Wells, EM 
1110-2-1914 (Washington, DC: Department of the Army, 1992), p. 1-1. 
Thus waters behind a dam still maintain a hydrologic connection to 
downstream waters.
    Numerous studies have shown that dams impede biotic movements, 
reducing biological connectivity between upstream and downstream 
locations. Report at 3-48 (citing E.A. Greathouse, et al., 
``Indirect Upstream Effects Of Dams: Consequences Of Migratory 
Consumer Extirpation In Puerto Rico,'' Ecological Applications 16: 
339-352 (2006); C.J. Hall, et al., ``The Historic Influence of Dams 
on Diadromous Fish Habitat with a Focus on River Herring and 
Hydrologic Longitudinal Connectivity,'' Landscape Ecology 26: 95-
107(2011)). Dams alter but typically do not sever the hydrologic 
connection between upstream and downstream waters. (See Part II, 
section 2.C. of this appendix). Upstream of large dams riparian 
areas are permanently inundated, increasing hydrological 
connectivity. Downstream, peak flows and the potential for overbank 
lateral flow are reduced; however, dams may also reduce flow 
variability downstream, resulting in higher minimum flows and 
reduced flow intermittency and thereby increasing hydrological (and 
potentially biological) connectivity. Id. (citing N.L. Poff, et al., 
``Homogenization of Regional River Dynamics by Dams and Global 
Biodiversity Implications,'' Proceedings of the National Academy of 
Sciences of the United States of America 104: 5732-5737 (2007)). 
Where an impoundment does stop flow, it also has significant effects 
on downstream waters. For example, the downstream segments have a 
reduced quantity of waters, less sediment, and reduced species 
biological connectivity with upstream refugia.
    Because dams reduce the amount of sediment delivered downstream, 
the reservoirs behind dams are actually very effective at retaining 
sediment, which can have significant effects in downstream waters. 
For instance, the Mississippi River's natural sediment load has been 
reduced by an estimated 50% through dam construction in the 
Mississippi Basin. M.D. Blum, and H. H. Roberts, ``Drowning of the 
Mississippi Delta Due to Insufficient Sediment Supply and Global 
Sea-Level Rise,'' Nature Geoscience 2(7): 488-491 (2009).
    Man-made or man-altered tributaries continue to have chemical, 
physical, and

[[Page 22236]]

biological connections that significantly affect the integrity of 
(a)(1) through (a)(3) waters. Though the man-made or man-altered 
nature of such tributaries can change the nature of the connections, 
it does not eliminate them. Thus, man-made and man-altered 
tributaries continue to serve the same important functions as 
``natural'' tributaries, which in turn greatly impact downstream 
(a)(1) through (a)(3) waters, particularly when their functional 
contributions to the chemical, physical, and biological conditions 
of downstream waters are combined at a watershed scale.

ii. Adjacent Waters

    Adjacent waters, including adjacent wetlands, alone or in 
combination with other adjacent waters in the watershed, have a 
substantial impact on the chemical, physical, or biological 
integrity of traditional navigable waters, interstate waters, and 
the territorial seas. In addition, waters adjacent to tributaries 
serve many important functions that directly influence the integrity 
of downstream waters including traditional navigable waters, 
interstate waters, and the territorial seas. Adjacent waters store 
water, which can reduce flooding of downstream waters, and the loss 
of adjacent waters has been shown, in some circumstances, to 
increase downstream flooding. Adjacent waters maintain water quality 
and quantity, trap sediments, store and modify potential pollutants, 
and provide habitat for plants and animals, thereby sustaining the 
biological productivity of downstream rivers, lakes and estuaries, 
which may be traditional navigable waters, interstate waters, or the 
territorial seas. The scientific literature and Report supports 
these conclusions, as discussed in greater detail below.

1. Adjacent Waters Under This Proposed Rule Have a Significant Nexus to 
(a)(1) Through (a)(3) Waters

    The discussion below summarizes the key points made in the 
Report and explains the technical basis for supporting a conclusion 
that adjacent waters, as defined in this proposed rule, have a 
significant nexus to waters identified in paragraphs (a)(1) through 
(a)(3) of the proposed rule. The geographic position of an 
``adjacent'' water relative to the stream is indicative of the 
relationship they share, with many of its defining characteristics 
resulting from the movement of materials and energy between the two. 
A review and analysis of the scientific literature supports the 
conclusion that individually or in combination with similarly 
situated waters in a watershed, adjacent waters have a significant 
effect on the chemical, physical, and biological integrity of 
downstream traditionally navigable waters, interstate waters, and 
the territorial seas.

a. Riparian and Floodplain Waters Significantly Affect the Chemical, 
Physical, or Biological Integrity of (a)(1) Through (a)(3) Waters

    Waters, including wetlands, often lie within landscape settings 
that have bidirectional hydrological exchange with (a)(1) through 
(a)(5) waters (e.g., wetlands and open waters in riparian areas and 
flood plains). Such waters play an integral role in the chemical, 
physical, and biological integrity of the waters to which they are 
adjacent. Riparian areas and floodplains often describe the same 
geographic region. Report at 3-4. Therefore, the discussion of the 
functions of waters, including wetlands, in riparian areas will 
typically apply to floodplains unless otherwise noted. Where 
connections arise specifically from the act of inundation of 
adjacent land during times of higher-than-normal water, the term 
``floodplain'' is solely used to describe the area.
    Riparian areas are transition zones between terrestrial and 
aquatic ecosystems that are distinguished by gradients in 
biophysical conditions, ecological processes, and biota. Id., Report 
at 31. Waters including wetlands in riparian areas significantly 
influence exchanges of energy and matter with aquatic ecosystems. 
See, e.g., id. (citing National Research Council, Riparian Areas: 
Functions and Strategies for Management (Washington, DC: The 
National Academies Press, 2002).
    Floodplains are low gradient areas bordering stream or river 
channels, lakes, and impoundments that were formed by sediment 
deposition from those waters under present climatic conditions. 
These natural geomorphic features are inundated during moderate to 
high water events. Id. (citing L.B. Leopold, A View of the River 
(Cambridge, MA: Harvard University Press, 1994); W.R. Osterkamp, 
Annotated Definitions of Selected Geomorphic Terms and Related Terms 
of Hydrology, Sedimentology, Soil Science and Ecology, USGS Open 
File Report 2008-1217 (Reston, VA: U.S. Department of the Interior, 
U.S. Geological Survey, 2008)). By ``present climactic conditions,'' 
the agencies mean that currently or recently active floodplains will 
be used to help determine whether wetlands or waters are adjacent to 
``waters of the United States.'' The proposed definition is limited 
to the present climactic conditions in order to best represent the 
floodplain that has an active and significant relationship with the 
stream or river channel. Historic floodplains that played a role in 
the river or lake dynamics in the past only will not be used to 
determine whether a water is adjacent. Floodplains formed under 
different climactic conditions that no longer connect to the stream 
channel that formed them are terraces. Id. It should be noted that 
``floodplain'' as defined in today's proposed rule does not 
necessarily equate to the 100-year floodplain as defined by the 
Federal Emergency Management Agency (FEMA). However, the FEMA 
defined floodplain may often coincide with the current definition 
proposed in this rule. Flood insurance rate maps are based on the 
probability of a flood event occurring (e.g., 100-year floods have a 
1% probability of occurring in a given year or 500 year-floods have 
a 0.2% probability of occurring in a particular year). Flood 
insurance rate maps are not based on an ecological definition of the 
term ``floodplain,'' and therefore may not be appropriate for 
identifying adjacent wetlands and waters for the purposes of CWA 
jurisdiction. Flood insurance rate maps are developed by applying 
models and other information to identify areas that would be 
inundated by a flood event of a particular probability of recurring.
    Riparian waters take many different forms. Some may be wetlands, 
which are defined in paragraph (c)(6) of the proposed rule. Others 
may be ponds, oxbow lakes, or other types of open waters. Oxbow 
lakes, commonly found in floodplains, are formed when river meanders 
are cutoff from the rest of the river. Id. at 5-42.

b. Riparian and Floodplain Waters Significantly Affect the Physical 
Integrity of (a)(1) Through (a)(3) Waters

    Scientific research shows waters and wetlands in riparian areas 
and floodplains to be important in protecting the physical integrity 
of aquatic resources. Because riparian and floodplain waters exhibit 
bidirectional exchange of water with the waters to which they are 
adjacent, they play an important role in determining the volume and 
duration of stream flow. Riparian and floodplain waters also have an 
essential role in regulating and stabilizing sediment transport to 
downstream waters. These characteristics are fundamental to the 
physical integrity of streams as well as downstream traditional 
navigable waters, interstate waters, and the territorial seas.
    Riparian and floodplain wetlands are important for the reduction 
or delay of floods. Id.at 3-22 (citing A. Bullock and M. Acreman, 
``The Role of Wetlands in the Hydrological Cycle,'' Hydrology and 
Earth System Sciences 7:358-389 (2003)). Waters in riparian areas 
control flooding during times of high precipitation or snowmelt by 
capturing water from overbank flow and storing excess stream water. 
Id. at 5-6. One study found that peak flows in the Cache River in 
Arkansas decreased by 10-20% mainly because of floodplain water 
storage. Id. (citing R. Walton, et al., ``Hydrology of the Black 
Swamp Wetlands on the Cache River, Arkansas,'' Wetlands 16:279-287 
(1996). Research has shown that floodplain wetlands in Ohio store 
about 40% of the flow of small streams. Id. at 5-6 to 5-7 (citing 
D.E. Gamble, et al., An Ecological and Functional Assessment of 
Urban Wetlands in Central Ohio. Columbus, Ohio, EPA Technical Report 
WET/2007-3B, (Columbus, OH: Ohio Environmental Protection Agency, 
Wetland Ecology Group, Division of Surface Water, 2007)). These and 
similar findings point to the close hydrological influence that 
waters in riparian and floodplain areas have on streams.
    Some adjacent waters are bordering or contiguous with (a)(1) 
through (a)(5) waters. Because of their close physical proximity to 
nearby water bodies, they readily exchange their waters through the 
saturated soils surrounding the stream or through surface exchange. 
This commingling of waters allows bordering or contiguous waters to 
both provide chemically transformed waters to streams and to absorb 
excess stream flow.
    Flow between neighboring waters and streams is more longitudinal 
(downslope) at headwaters and more lateral further downstream. Id. 
at 5-38, Table 5-3. These connections in part determine stream flow 
volume and duration. Waters, including wetlands, in riparian areas 
connect to neighboring water bodies through various surface and 
subsurface connections. See, e.g., id. at 3-4 (citing National 
Research Council,

[[Page 22237]]

Riparian Areas: Functions and Strategies for Management (Washington, 
DC: National Academy Press, 2002)). Floodplains, similarly, are 
closely associated with the groundwater found beneath and beside 
river channels (which are considered shallow aquifers) and waters in 
floodplains readily exchange water with such aquifers. Id. at 3-14 
(citing J.A. Stanford and J. V. Ward, ``An Ecosystem Perspective of 
Alluvial Rivers: Connectivity and the Hyporheic Corridor,'' Journal 
of the North American Benthological Society 12:48-60 (1993); C. 
Amoros and G. Bornette, ``Connectivity and Biocompexity in 
Waterbodies of Riverine Floodplains,'' Freshwater Biology 47:761-776 
(2002); G.C. Poole, et al., ``Multiscale Geomorphic Drivers of 
Groundwater Flow Paths: Subsurface Hydrologic Dynamics and Hyporheic 
Diversity,'' Journal of the North American Benthological Society 
25:288-303 (2006)). Riparian and floodplain wetlands are frequently 
contiguous with streams and other water bodies and significantly 
influence the hydrology of such water bodies. Id. at 5-6 (citing 
R.J. Naiman, et al., Riparia: Ecology, Conservation, and Management 
of Streamside Communities (Burlington, MA: Elsevier Academic Press, 
2005); P. Vidon, et al., ``Hot Spots and Hot Moments in Riparian 
Zones: Potential for Improved Water Quality Management,'' Journal of 
the American Water Resources Association 46:278-298 (2010)). 
Floodplain wetlands are important for the reduction or delay of 
floods. Id. (citing A. Bullock and M. Acreman, ``The Role of 
Wetlands in the Hydrological Cycle,'' Hydrology and Earth System 
Sciences 7:358-389 (2003)). Oxbow lakes also retain flood waters. 
Id. at 5-44. Adjacent ponds generally function similarly to oxbow 
lakes.
    Waters in riparian areas filter sediment washed down from 
uplands and collect sediment from overbank flow as the river or 
stream floods. Id. at 5-7. For example, riparian areas were observed 
to collect 80-90% of the sediment from farmlands in a study in North 
Carolina. Id. (citing A. Cooper, et al., ``Riparian Areas as Filters 
for Agricultural Sediment,'' Soil Science Society of America 
Proceedings 51:416-420 (1987); R.B. Daniels and J.G. Gilliam, 
``Sediment and Chemical Load Reduction by Grass and Riparian 
Filters,'' Soil Science Society of America Journal 60:246-251 
(1996); R.J. Naiman and H. Decamps, ``The Ecology of Interfaces: 
Riparian Zones,'' Annual Review of Ecology and Systematics 28:621-
658 (1997)). Maintaining the equilibrium between sediment deposition 
and sediment transport is important to maintain the physical shape 
and structure of stream channels. Significant changes to upstream 
channels can affect the chemical, physical, and biological condition 
of downstream (a)(1) through (a)(3) waters.
    The physical effects of excess sediment can impair chemical and 
ecological integrity in a variety of ways. Id. at 5-9 (citing P.J. 
Wood and P.D. Armitage, ``Biological Effects of Fine Sediment in the 
Lotic Environment,'' Environmental Management 21:203-217 (1997)). 
Excess sediment is linked to increasing contaminant and nutrient 
concentrations, all of which tributaries can transmit downstream, 
affecting water quality. Excess sediment may block and absorb 
sunlight transmission through the water column, inhibiting plant 
photosynthesis and warming the water in the stream. Sediment may 
fill the interstitial spaces between rocks in a streambed, which 
many fish and aquatic species use for mating, reproduction, and 
shelter from predators. This kind of physical degradation of 
tributary streambeds results in less suitable habitat available for 
animals and fish that move between upstream and downstream waters. 
Riparian waters that retain sediments thus protect downstream waters 
from the effects of excess sediment.
    Oxbow lakes play similar roles in the floodplain as they are an 
integral part of alluvial floodplains of meandering rivers. Id. at 
5-42 (citing K.O. Winemiller, et al., ``Fish Assemblage Structure in 
Relation to Environmental Variation among Brazos River Oxbow 
Lakes,'' Transactions of the American Fisheries Society 129:451-468 
(2000), K. Glinska-Lewczuk, ``Water Quality Dynamics of Oxbow Lakes 
in Young Glacial Landscape of NE Poland in Relation to Their 
Hydrological Connectivity,'' Ecological Engineering 35:25-37 
(2009)). They connect to rivers by periodic overland flow, typically 
from the river during flooding events, and bidirectional shallow 
subsurface flow through fine river soils (bidirectional means flow 
from river to lake and lake to river). Id. at 5-43 to 5-44. Oxbow 
lakes generally have an important influence on the condition and 
function of rivers. Id. at 5-48 to 5-49. That influence can vary 
with the distance from the river and the age of the oxbow, 
reflecting the frequency and nature of the exchange of materials 
that takes place between the two water bodies.
    Because adjacent waters support riparian vegetation, they affect 
the capacity of riparian vegetation to influence stream flow, 
morphology, and habitat provided in the nearby water body. 
Vegetation in riparian waters influences the amount of water in the 
stream by capturing and transpiring stream flow and intercepting 
groundwater and overland flow. Id. at 3-22, 5-7 (citing P. Meyboom, 
``Three Observations on Streamflow Depletion by Phreatophytes,'' 
Journal of Hydrology 2:248-261 (1964)). Riparian vegetation in 
adjacent waters also reduces stream bank erosion, serving to 
maintain the physical integrity of the channel. See, e.g., id. at 5-
8 (citing C.E. Beeson and P. F. Doyle, ``Comparison of Bank Erosion 
at Vegetated and Non-Vegetated Channel Bends,'' Journal of the 
American Water Resources Association 31:983-990 (1995)). In 
addition, inputs of woody debris from aquatic vegetation into waters 
make important contributions to the channel's geomorphology and the 
stream's aquatic habitat value. Id. (citing N.H. Anderson and J. R. 
Sedell, ``Detritus Processing by Macroinvertebrates in Stream 
Ecosystems,'' Annual Review of Entomology 24:351-377 (1979); M.E. 
Harmon, et al., ``Ecology of Coarse Woody Debris in Temperature 
Ecosystems,'' Advances in Ecological Research 15:133-302 (1986); F. 
Nakamura and F. J. Swanson, ``Effects of Coarse Woody Debris on 
Morphology and Sediment Storage of a Mountain Stream System in 
Western Oregon,'' Earth Surface Processes and Landforms 18:43-61 
(1993); T.E. Abbe and D. R. Montgomery, ``Large Woody Debris Jams, 
Channel Hydraulics and Habitat Formation in Large Rivers,'' 
Regulated Rivers: Research & Management 12:201-221 (1996); R.J. 
Naiman and H. Decamps, ``The Ecology of Interfaces: Riparian 
Zones,'' Annual Review of Ecology and Systematics 28:621-658 91997); 
A.M. Gurnell, et al., ``Large Wood and Fluvial Processes,'' 
Freshwater Biology 47:601-619 (2002)). Also, the riparian vegetation 
that overhangs streams provides shade, providing a critically 
important function of reducing fluctuations in water temperature 
helping to reduce excessive algal production and to maintain life-
supporting oxygen levels in streams and other waters. Id. at 5-9 
(citing S.V. Gregory, et al., ``An Ecosystem Perspective of Riparian 
Zones: Focus on Links between Land and Water,'' Bioscience 41:540-
551 (1991); E.C. Volkmar and R.A. Dahlgren, ``Biological Oxygen 
Demand Dynamics in the Lower San Joaquin River, California,'' 
Environmental Science & Technology 40:5653-5660 (2006)). Even small 
changes in water temperature can have significant impacts on the 
type and number of species present in waters, with higher 
temperatures generally associated with degraded habitat which 
supports only those species that can tolerate higher temperatures 
and reduced levels of dissolved oxygen. Higher water temperatures 
are associated with streams and rivers with less valuable 
recreational and commercial fisheries. As discussed below, these 
physical characteristics of headwater streams influence what types 
of organisms live in the region.
    Headwaters and nearby wetlands supply downstream waters with 
dissolved organic carbon as a result of decomposition processes from 
dead organic matter such as plants. The biological consequences of 
this dissolved organic carbon are discussed in more detail below. 
The presence of dissolved organic carbon can affect how light 
penetrates the water, an important factor in the growth of plants, 
algae, and other primary producers, and can protect aquatic 
organisms from the harmful effects of UV-B radiation. Id. at 5-28 to 
5-29 (citing K.N. Eshelman and H.F. Hemond, ``The role of organic 
acids in the acid-base status of surface waters at Bickford 
Watershed, Massachusetts,'' Water Resources Research 21:1503-1510 
(1985); J.E. Hobbie and R.G. Wetzel, ``Microbial control of 
dissolved organic carbon in lakes: Research for the future,'' 
Hydrobiologia 229:169-180 (1992); D.W. Schindler and P.J. Curtis, 
``The role of DOC in protecting freshwaters subjected to climate 
warming and acidification from UV exposure,'' Biogeochemistry 36:1-8 
(1997); K.R. Reddy and R.D. DeLaune, Biogeochemistry of Wetlands: 
Science and Applications, (Boca Raton, FL: CRC Press, 2008)).

c. Riparian and Floodplain Waters Significantly Affect the Chemical 
Integrity of (a)(1) Through (a)(3) Waters

    As stated above in the section on tributaries, pollutants such 
as petroleum waste products and other harmful pollutants dumped into 
any part of the tributary system are likely to flow downstream, or 
to be washed downstream, and thereby pollute traditional navigable 
waters, interstate

[[Page 22238]]

waters, and the territorial seas from which American citizens take 
their drinking water, shellfish, fin fish, water-based recreation, 
and many other uses. Some wetlands perform the valuable function of 
trapping or filtering out some pollutants (such as fertilizers, 
silt, and some pesticides), thereby reducing the likelihood that 
those pollutants will reach and pollute the tributaries of the 
downstream navigable or interstate waters (and eventually pollute 
those downstream waters themselves). However, many other pollutants 
(such as petroleum wastes and toxic chemical wastes), if dumped into 
wetlands or other waters that are adjacent to tributary streams, may 
reach those tributaries themselves, and thereafter flow downstream 
to pollute the nation's drinking water supply, fisheries, and 
recreation areas.
    Riparian and floodplain waters play a critical role in 
controlling the chemicals that enter streams and other ``waters of 
the United States'' and as a result are vital in protecting the 
chemical, physical, and biological integrity of downstream (a)(1) 
through (a)(3) waters. Runoff (the water that has not evaporated or 
infiltrated into the groundwater) from uplands is a large source of 
pollution, but research has shown that wetlands and other riparian 
waters trap and chemically transform a substantial amount of the 
nutrients, pesticides, and other pollutants before they enter 
streams, river, lakes and other waters.
    Chemicals and other pollutants enter waters from point sources, 
non-point sources, atmospheric deposition, upstream reaches, and 
through the hyporheic zone, a region beneath and alongside a stream 
bed where surface water and shallow groundwater mix. Id. at 5-10 
(citing SW. Nixon and V.J. Lee, Wetlands and Water Quality: A 
Regional Review of Recent Research in the United States on the Role 
of Freshwater and Saltwater Wetlands as Sources, Sinks, and 
Transformers of Nitrogen, Phosphorus, and Various Heavy Metals, 
Technical Report Y-86-2, (Vicksburg, MS: U.S. Army Corp of 
Engineers, Waterways Experiment Station, 1986); D.F. Whigham and 
T.E. Jordan, ``Isolated Wetlands and Water Quality,'' Wetlands 
23:541-549 (2003); S.L.Whitmire and S.K. Hamilton, ``Rates of 
Anaerobic Microbial Metabolism in Wetlands of Divergent Hydrology on 
a Glacial Landscape,'' Wetlands 28:703-714 (2008)). Throughout the 
stream network, but especially in headwater streams and their 
adjacent wetlands, chemicals are sequestered, assimilated, 
transformed, or lost to the atmosphere by microbes, fungi, algae, 
and macrophytes present in riparian waters and soils. Id. (citing 
SW. Nixon and V.J. Lee, Wetlands and Water Quality: A Regional 
Review of Recent Research in the United States on the Role of 
Freshwater and Saltwater Wetlands as Sources, Sinks, and 
Transformers of Nitrogen, Phosphorus, and Various Heavy Metals, 
Technical Report Y-86-2, (Vicksburg, MS: U.S. Army Corp of 
Engineers, Waterways Experiment Station, 1986); C. Johnston, 
``Sediment and Nutrient Retention by Freshwater Wetlands: Effects on 
Surface Water Quality,'' Critical Reviews in Environmental Control 
21:491-565 (1991); P.I. Boon, ``Biogeochemistry and Bacterial 
Ecology of Hydrologically Dynamic Wetlands,'' in D.P. Batzer and 
R.R. Sharitz, ed., Ecology of Freshwater and Estuarine Wetlands 
(Berkeley, CA: University of California Press, 2006), pp. 115-176; 
W.J. Mitsch and J.G. Gosselink, Wetlands, 4th edition, (Hoboken, NJ: 
John Wiley & Sons Inc., 2007); K.R., Reddy and R.D. DeLaune, 
Biogeochemistry of Wetlands: Science and Applications (Boca Raton, 
FL: CRC Press, 2008). These chemical processes reduce or eliminate 
pollution that would otherwise enter streams, rivers, lakes and 
other waters and subsequently downstream traditional navigable 
waters, interstate waters, or the territorial seas. The removal of 
the nutrients nitrogen and phosphorus is a particularly important 
role for riparian waters. Nutrients are necessary to support aquatic 
life, but the presence of excess nutrients can lead to 
eutrophication and the depletion of oxygen nearby waters and in 
waters far downstream. See, e.g., id. at 1-8. Eutrophication is a 
large problem in waters across the United States including such 
significant ecosystems as the Chesapeake Bay and Lake Spokane in 
Washington. W.M. Kemp, et al., ``Eutrophication of Chesapeake Bay: 
Historical Trends and Ecological Interactions,'' Marine Ecology 
Progress Series 303(21):1-29 (2005); D.J. Moore and J. Ross, Spokane 
River and Lake Spokane Dissolved Oxygen Total Maximum Daily Load: 
Water Quality Improvement Report, Publication No. 07-10-073 
(Spokane, WA: Washington State Department of Ecology, 2010); R.R. 
Murphy, et al., ``Long-Term Trends in Chesapeake Bay Seasonal 
Hypoxia, Stratification, and Nutrient Loading,'' Estuaries and 
Coasts 34(6):1293-1309 (2011). Eutrophication is the process by 
which plants and algae grow in waters to such an extent that the 
abundance of vegetation monopolizes the available oxygen, 
detrimentally affecting other aquatic organisms. Id. Oxbow lakes 
also have high mineralization rates, suggesting that similar to 
adjacent wetlands they process and trap nutrients from runoff. 
Report at 5-45 to 5-46 (citing K.O. Winemiller, et al., ``Fish 
Assemblage Structure in Relation to Environmental Variation among 
Brazos River Oxbow Lakes,'' Transactions of the American Fisheries 
Society 129:451-468 (2000)). Protection of these waters therefore 
helps maintain the chemical integrity of the nation's waters.
    The removal of nitrogen is an important function of all waters, 
including wetlands, in the riparian areas. Riparian areas regularly 
remove more than half of dissolved nitrogen found in surface and 
subsurface water by plant uptake and microbial transformation. Id. 
at 5-11 (citing P. Vidon, et al., ``Hot Spots and Hot Moments in 
Riparian Zones: Potential for Improved Water Quality Management,'' 
Journal of the American Water Resources Association 46:278-298 
(2010)). Denitrification in surface and subsurface flows is highest 
where there is high organic matter and/or anoxic conditions. Id. 
Denitrification occurs in wetland soils where there is high organic 
matter, low oxygen, denitrifying microbes, and saturated soil 
conditions, and rates increase with proximity to streams. Id. 
(citing S.V. Gregory, et al., ``An Ecosystem Perspective of Riparian 
Zones: Focus on Links between Land and Water,'' Bioscience 41:540-
551 (1991); P. Vidon, et al., ``Hot Spots and Hot Moments in 
Riparian Zones: Potential for Improved Water Quality Management,'' 
Journal of the American Water Resources Association 46:278-298 
(2010)). Riparian waters are therefore important in maintaining the 
conditions important for denitrification, which in turn protects 
streams, rivers, lakes and other waters from nitrogen pollution.
    Plant uptake of dissolved nitrogen in subsurface flows also 
accounts for large quantities of nitrogen removal. Riparian forests 
have been found to remove 75% of dissolved nitrate transported from 
agricultural fields in Maryland. Id. (citing P. Vidon, et al., ``Hot 
Spots and Hot Moments in Riparian Zones: Potential for Improved 
Water Quality Management,'' Journal of the American Water Resources 
Association 46:278-298 (2010)). Likewise, riparian forests in 
Georgia remove 65% of nitrogen and 30% of phosphorus from 
agricultural sources. Id. at 5-11 to 5-12 (citing Vidon, et al. 
2010). A Pennsylvania forest removed 26% of the nitrate from the 
subsurface. Id. at 5-12 (citing J.D. Newbold, et al., ``Water 
Quality Functions of a 15-Year-Old Riparian Forest Buffer System,'' 
Journal of the American Water Resources Association 46:299-310 
(2010)). The vegetation associated with riparian waters also removes 
nitrogen from subsurface flows. Therefore, the conservation of 
riparian waters helps protect downstream waters from influxes of 
dissolved nitrogen.
    Phosphorus is another potentially harmful nutrient that is 
captured and processed in riparian waters. Id. (citing T.A. Dillaha 
and S.P. Inamdar, ``Buffer Zones as Sediment Traps or Sources,'' in 
N.E. Haycock, T.P. Burt, K.W.T. Goulding, and G. Pinay, ed., Buffer 
Zones: Their Processess and Potential in Water Protection, 
Proceedings of the International Conference on Buffer Zones, 
September 1996 (Hertfordshire, UK: Quest Environmental, 1997), pp. 
33-42; A.N. Sharpley and S. Rekolainen, ``Phosphorus in Agriculture 
and Its Environmental Implications,'' in H. Tunney, et al., ed., 
Phosphorus Losses from Soil to Water (Cambridge, UK: CAB 
International, 1997), pp. 1-54; G.C. Carlyle and A.R. Hill, 
``Groundwater Phosphate Dynamics in a River Riparian Zone: Effects 
of Hydrologic Flowpaths, Lithology, and Redox Chemistry,'' Journal 
of Hydrology 247:151-168 (2001)). Biogeochemical processes, 
sedimentation, and plant uptake account for high rates of removal of 
particulate phosphorus in riparian areas. Id. (citing C.C. Hoffmann, 
et al., ``Phosphorus Retention in Riparian Buffers: Review of Their 
Efficiency,'' Journal of Environmental Quality 38:1942-1955 (2009)). 
The amount of contact the water has with nearby soils determines the 
ability of the riparian area to remove phosphorus. Id. This function 
of upstream riparian waters is crucial for maintaining the chemical 
and biological integrity of the waters to which they are adjacent, 
and for preventing eutrophication in downstream traditional 
navigable waters, interstate waters, and the territorial seas.

[[Page 22239]]

d. Riparian and Floodplain Waters Significantly Affect the Biological 
Integrity of (a)(1) Through (a)(3) Waters

    Waters and wetlands located in both riparian areas and 
floodplains support the biological integrity of downstream (a)(1) 
through (a)(3) waters in a variety of ways. They provide habitat for 
aquatic and water-tolerant plants, invertebrates, and vertebrates, 
and provide feeding, refuge, and breeding areas for invertebrates 
and fish. Seeds, plants, and animals move between waters in the 
riparian zone and floodplains and the adjacent streams, and from 
there colonize or utilize downstream waters, including traditional 
navigable waters.
    Organic matter from adjacent wetlands is critical to aquatic 
food webs, particularly in headwaters, where it is the primary 
source of energy flow due to low light conditions that inhibit 
photosynthesis. Id. at 5-13 (citing J.L. Tank, et al., ``A Review of 
Allochthonous Organic Matter Dynamics and Metabolism in Streams,'' 
Journal of the North American Benthological Society 29:118-146 
(2010)). Headwater streams tend to be located in heavily vegetated 
areas compared to larger waters, so they are more likely to contain 
leaf litter, dead and decaying plants, and other organic matter that 
forms the basis of headwater food webs. The organic matter is 
processed by microbes and insects that make the energy available to 
higher levels of stream life such as amphibians and fish. Studies 
have shown that macroinvertebrates rely on leaf inputs in headwater 
streams and that excluding organic litter from a stream resulted in 
significant changes to the food web at multiple levels. Id. (citing 
G.W. Minshall, ``Role of Allochthonous Detritus in the Tropic 
Structure of a Woodland Springbrook Community,'' Ecology 48:139-149 
(1967); J.B. Wallace, et al., ``Multiple Trophic Levels of a Forest 
Stream Linked to Terrestrial Litter Inputs,'' Science 277:102-104 
(1997); J.L. Meyer, et al., ``Leaf Litter as a Source of Dissolved 
Organic Carbon in Streams,'' Ecosystems 1:240-249 (1998)). Fish and 
amphibian species found in headwaters travel downstream and in turn 
become part of the food web for larger aquatic organisms in rivers 
and other waters. Organic material provided by riparian waters to 
small, headwater streams is therefore important not only to the 
small streams that directly utilize this source of energy to support 
their biological populations but also to the overall biological 
integrity of downstream waters that also benefit from the movement 
of fish and other species that contribute to the food web of larger 
streams and rivers.
    Floodplain water bodies, including oxbow lakes, accumulate 
organic carbon, an important function influenced by the size and 
frequency of floods from adjacent rivers. See, e.g., id. at 5-45 
(citing A. Cabezas, et al., ``Changing Patterns of Organic Carbon 
and Nitrogen Accretion on the Middle Ebro Floodplain (NE Spain),'' 
Ecological Engineering 35:1547-1558 (2009)). These stored chemicals 
are available for exchange with river water when hydrological 
connections form. Organic materials are the basis for the food web 
in stream reaches where photosynthetic production of energy is 
absent or limited, particularly in headwater systems where 
vegetative litter alone makes up the base of the aquatic food web. 
The maintenance of floodplain waters is therefore an important 
component of protecting the biological integrity of downstream 
waters into which the headwaters flow.
    The waters, including wetlands, in the riparian area play an 
important role in the removal of pesticides. Id. at 5-14 (citing P. 
Vidon, et al., ``Hot Spots and Hot Moments in Riparian Zones: 
Potential for Improved Water Quality Management,'' Journal of the 
American Water Resources Association 46:278-298 (2010). Microbes 
near plant roots break down these pesticides. See, e.g., id. (citing 
G. Voos, and P.M. Groffman, ``Relationships between microbial 
biomass and dissipation of 2,4-D and dicamba in soil,'' Biology and 
Fertility of Soils 24:106-110 (1996)). Uptake by aquatic plants has 
also been shown to be an important mechanism of removal of the 
pesticides alachlor and atrazine. Id. (citing K.G. Paterson and J.L. 
Schnoor, ``Fate of Alachlor and Atrazine in a Riparian Zone Field 
Site,'' Water Environment Research 64:274-283 (1992)). Riparian 
waters also trap and hold pesticide contaminated runoff preventing 
it from harming neighboring waters.
    Riparian areas are dynamic places that support a diversity of 
aquatic, amphibious, and terrestrial species adapted to the unique 
habitat created by periodic flooding events. Id. at 5-15 (citing 
W.J. Junk, et al., ``The flood pulse concept in river-floodplain 
systems,'' in D.P. Dodge, ed., Proceedings of the International 
Large River Symposium Ottawa (Ottawa, Canada: Canadian Special 
Publication of Fisheries and Aquatic Sciences 106, 1989), pp. 110-
127; K. Tockner, et al., ``An Extension of the Flood Pulse 
Concept,'' Hydrological Processes 14:2861-2883 (2000); C.T. 
Robinson, et al., ``The Fauna of Dynamic Riverine Landscapes,'' 
Freshwater Biology 47:661-677 (2002)). Plants, invertebrates, and 
vertebrates use waters, including wetlands, in the riparian areas 
for habitat, nutrients, and breeding. As a result, the waters, 
including wetlands, in the riparian areas act as sources of 
organisms, particularly during inundation events, replenishing 
neighboring waters with organisms, seeds, and organic matter. 
Inundation and hydrological connectivity of riparian areas greatly 
increase the area of aquatic habitats and species diversity. Id. at 
5-15 to 5-16 (citing W.J. Junk et al. 1989; R. Jansson, et al., 
``Hydrochory Increases Riparian Plant Species Richness: A Comparison 
between a Free-Flowing and a Regulated River,'' Journal of Ecology 
93:1094-1103 (2005)). Aquatic animals, including amphibians and 
fish, take advantage of the waters present in riparian areas, either 
inhabiting them or moving between the riparian water and neighboring 
waters. Id. at 5-15, 5-17, 5-19 (citing G.H. Copp, ``The habitat 
diversity and fish reproductive function of floodplain ecosystems,'' 
Environmental Biology of Fishes 26:1-27 (1989); L.A. Smock, et al., 
``Lotic macroinvertebrate production in three dimensions: Channel 
surface, hyporheic, and floodplain environments,'' Ecology 73:876-
886 (1992); L.A. Smock, ``Movements of invertebrates between stream 
channels and forested floodplains,'' Journal of the North American 
Benthological Society 13:524-531 (1994); C. T. Robinson, et al., 
``The fauna of dynamic riverine landscapes,'' Freshwater Biology 
47:661-677 (2002); J.S. Richardson, et al., ``Riparian communities 
associated with Pacific Northwest headwater streams: Assemblages, 
processes, and uniqueness,'' Journal of the American Water Resources 
Association 41:935-947 (2005); C. Ilg, et al., ``Long-term reactions 
of plants and macroinvertebrates to extreme floods in floodplain 
grasslands,'' Ecology 89:2392-2398 (2008); D.E. Shoup, and D. H. 
Wahl, ``Fish diversity and abundance in relation to interannual and 
lakespecific variation in abiotic characteristics of floodplain 
lakes of the lower Kaskaskia River, Illinois,'' Transactions of the 
American Fisheries Society 138:1076-1092 (2009)). Likewise, seeds, 
plant fragments, and whole plants move between riparian and 
floodplain waters and the river network. Id. at 5-15 (citing R.L. 
Schneider, and R.R. Sharitz, ``Hydrochory and regeneration in a bald 
cypress water tupelo swamp forest,'' Ecology 69:1055-1063 (1988); B. 
Middleton, ``Hydrochory, seed banks, and regeneration dynamics along 
the landscape boundaries of a forested wetland,'' Plant Ecology 
146:169-184 (2000); C. Nilsson, et al., ``The role of hydrochory in 
structuring riparian and wetland vegetation,'' Biological Reviews 
85:837-858 (2010)).
    Hydrological connections are often drivers of biological 
connections, and flooding events enhance the existing connections 
between floodplain waters and the river network. As a result, waters 
within floodplains have important functions for aquatic health. Many 
species have cycles timed to flooding events, particularly in 
circumstances where flooding is associated with annual spring 
snowmelt or high precipitation. Id. at 5-15 to 5-17, 5-20 (citing 
J.R. Thomas, et al., ``A landscape perspective of the stream 
corridor invasion and habitat characteristics of an exotic 
(Dioscorea oppositifolia) in a pristine watershed in Illinois,'' 
Biological Invasions 8:1103-1113 (2006); L.M. Tronstad, et al., 
``Aerial colonization and growth: Rapid invertebrate responses to 
temporary aquatic habitats in a river floodplain,'' Journal of the 
North American Benthological Society 26:460-471 (2007); A. Gurnell, 
et al., ``Propagule deposition along river margins: Linking 
hydrology and ecology,'' Journal of Ecology 96:553-565 (2008)). 
Waters within floodplains act as sinks of seeds, plant fragments, 
and invertebrate eggs, allowing for cross-breeding and resulting 
gene flow across time. Id. at 5-19 to 5-21 (citing K.M. Jenkins, and 
A.J. Boulton, ``Connectivity in a dryland river: Short-term aquatic 
microinvertebrate recruitment following floodplain inundation,'' 
Ecology 84:2708-2723 (2003); D. Frisch, and S.T. Threlkeld, ``Flood-
mediated dispersal versus hatching: Early recolonisation strategies 
of copepods in floodplain ponds,'' Freshwater Biology 50:323-330 
(2005); B. Vanschoenwinkel, et al., ``Wind mediated dispersal of 
freshwater invertebrates in a rock pool metacommunity: Differences 
in dispersal capacities and modes,'' Hydrobiologia 635:363-372 
(2009)).

[[Page 22240]]

Micro- and macroinvertebrates colonize nutrient rich waters within 
floodplains during periods of inundation, facilitating an increase 
in population and sustaining them though times of limited resources 
and population decline. Id. at 5-19 (citing W.J. Junk, et al., ``The 
flood pulse concept in river-floodplain systems,'' in D.P. Dodge, 
ed., Proceedings of the International Large River Symposium Ottawa 
(Ottawa, Canada: Canadian Special Publication of Fisheries and 
Aquatic Sciences 106, 1989), pp. 110-127; B. Malmqvist, ``Aquatic 
invertebrates in riverine landscapes,'' Freshwater Biology 47:679-
694 (2002); C. Ilg, et al., ``Long-term reactions of plants and 
macroinvertebrates to extreme floods in floodplain grasslands,'' 
Ecology 89:2392-2398 (2008)). Such animals are adapted to high 
floods, desiccation (drying out), or other stresses that come with 
these regular, systemic fluctuations. Id. at 5-20 (citing Jenkins 
and Boulton 2003). Floodplain waters therefore maintain various 
biological populations, which periodically replenish adjacent 
jurisdictional waters, serving to maintain their biological 
integrity.
    Plants and animals use waters, including wetlands, in the 
riparian areas and floodplains for habitat, food, and breeding. 
Oxbow lakes in the floodplain provide critical fish habitat needed 
for feeding and rearing, leading researchers to conclude that the 
entire floodplain should be considered a single functional unit, 
essential to the river's biological integrity. Id. at 5-17 (citing 
D.E. Shoup and D.H. Wahl, ``Fish Diversity and Abundance in Relation 
to Interannual and Lake-Specific Variation in Abiotic 
Characteristics of Floodplain Lakes of the Lower Kaskaskia River, 
Illinois,'' Transactions of the American Fisheries Society 138:1076-
1092 (2009)). Since adjacent ponds are structurally and biologically 
similar to oxbow lakes they serve similar functions relative to the 
nearby river or stream. Waters, including wetlands, in the riparian 
areas also provide food sources for stream invertebrates, which 
colonize during inundation events. Id. at 5-19 (citing W.J. Junk, et 
al., ``The Flood Pulse Concept in River-Floodplain Systems,'' in 
D.P. Dodge, ed., Proceedings of the International Large River 
Symposium Ottawa (Ottawa, Canada: Canadian Special Publication of 
Fisheries and Aquatic Sciences 106, 1989), pp. 110-127; C. Ilg, et 
al., ``Long-term Reactions of Plants and Macroinvertebrates to 
Extreme Floods in Floodplain Grasslands,'' Ecology 89:2392-2398 
(2008)). Riparian waters also form an integral part of the food web, 
linking primary producers and plants to higher animals. Id. (citing 
B. Malmqvist, ``Aquatic Invertebrates in Riverine Landscapes,'' 
Freshwater Biology 47:679-694 (2002); G.U.Y. Woodward and A.G. 
Hildrew, ``Food Web Structure in Riverine Landscapes,'' Freshwater 
Biology 47:777-798 (2002), T.K. Stead, et al., ``Secondary 
Production of a Stream Metazoan Community: Does the Meiofauna Make a 
Difference?,'' Limnology and Oceanography 50:398-403 (2005), D.J. 
Woodford and A.R. McIntosh, ``Evidence of Source-Sink 
Metapopulations in a Vulnerable Native Galaxiid Fish Driven by 
Introduced Trout,'' Ecological Applications 20:967-977 (2010)). 
Likewise, floodplains are important foraging, hunting, and breeding 
sites for fish and amphibians. Id. at 5-15 (citing G.H. Copp, ``The 
Habitat Diversity and Fish Reproductive Function of Floodplain 
Ecosystems,'' Environmental Biology of Fishes 26:1-27 (1989); J.S. 
Richardson, et al., ``Riparian Communities Associated with Pacific 
Northwest Headwater Streams: Assemblages, Processes, and 
Uniqueness,'' Journal of the American Water Resources Association 
41:935-947 (2005)).
    Plants and animals move back and forth between riparian or 
floodplain waters and the river network. This movement is assisted 
in some cases when flooding events create hydrological connections. 
For instance, these floodplain and riparian wetlands provide refuge, 
feeding, and rearing habitat for many fish species. Id. at 5-17 
(citing C.H. Wharton, et al., The Ecology of Bottomland Hardwood 
Swamps of the Southeast: A Community Profile, FWS/OBS-81/37 
(Washington, DC: U.S. Department of the Interior, Fish and Wildlife 
Service, Biological Services Program, 1982); M.P. Matheney and C.F. 
Rabeni, ``Patterns of Movement and Habitat Use by Northern 
Hogsuckers in an Ozark Stream,'' Transactions of the American 
Fisheries Society 124:886-897 (1995); A.A. Pease, et al., ``Habitat 
and Resource Use by Larval and Juvenile Fishes in an Arid-Land River 
(Rio Grande, New Mexico),'' Freshwater Biology 51:475-486 (2006); 
J.A. Henning, et al., ``Use of Seasonal Freshwater Wetlands by 
Fishes in a Temperate River Floodplain,'' Journal of Fish Biology 
71:476-492 (2007); C.A. Jeffres, et al., ``Ephemeral Floodplain 
Habitats Provide Best Growth Conditions for Juvenile Chinook Salmon 
in a California River,'' Environmental Biology of Fishes 83:449-458 
(2008)). Seeds ingested by animals such as carp are dispersed in 
stream channels and associated waters. See, e.g., id. at 5-16 
(citing B.J.A. Pollux, et al., ``Consequences of Intraspecific Seed-
Size Variation in Sparganium emersum for Dispersal by Fish,'' 
Functional Ecology 21:1084-1091 (2007)). Also, phytoplankton move 
between floodplain wetlands and the river network. Id. at 5-17 
(citing D.G. Angeler, et al., ``Phytoplankton community similarity 
in a semiarid floodplain under contrasting hydrological connectivity 
regimes,'' Ecological Research 25:513-520 (2010)). In turn, the 
primary productivity conditions in the floodplain results in large 
populations of phytoplankton that enrich river networks when 
hydrological connections form. Id. (citing P.W. Lehman, et al., 
``The Influence of Floodplain Habitat on the Quantity and Quality of 
Riverine Phytoplankton Carbon Produced During the Flood Season in 
San Francisco Estuary,'' Aquatic Ecology 42:363-378 (2008)). This 
influx of carbon into the river system nourishes the downstream 
waters, for example, supporting fisheries.
    However, even when hydrological connections are absent, some 
organisms can move between riparian waters and their neighboring 
tributaries by overland movement in order to complete their life 
cycle. River-dwelling mammals, such as river otters, move from the 
river to riparian wetlands. Id. at 5-18 (citing D.G. Newman and C.R. 
Griffin, ``Wetland Use by River Otters in Massachusetts,'' Journal 
of Wildlife Management 58:18-23 (1994)). Several species of 
amphibians and reptiles including frogs, snakes and turtles use both 
streams and neighboring waters. Id. at 1-10, 5-4 to 5-5 (Table 5-1), 
5-15 (citing J.S. Richardson, et al., ``Riparian Communities 
Associated with Pacific Northwest Headwater Streams: Assemblages, 
Processes, and Uniqueness,'' Journal of the American Water Resources 
Association 41:935-947 (2005)). Movement between wetlands and the 
river network also occurs by the dispersal of seed and plant 
fragments and the wind dispersal of invertebrates. Id. at 5-15, 5-20 
(citing R.L. Schneider and R.R. Sharitz, ``Hydrochory and 
Regeneration in a Bald Cypress Water Tupelo Swamp Forest,'' Ecology 
69:1055-1063 (1988); B. Middleton, ``Hydrochory, Seed Banks, and 
Regeneration Dynamics Along the Landscape Boundaries of a Forested 
Wetland,'' Plant Ecology 146:169-184 (2000); A.M. Gurnell, 
``Analogies Between Mineral Sediment and Vegetative Particle 
Dynamics in Fluvial Systems,'' Geomorphology 89:9-22 (2007); A. 
Gurnell, et al., ``Propagule Deposition Along River Margins: Linking 
Hydrology and Ecology,'' Journal of Ecology 96:553-565 (2008); C. 
Nilsson, et al., ``The Role of Hydrochory in Structuring Riparian 
and Wetland Vegetation,'' Biological Reviews 85:837-858 (2010); L.M. 
Tronstad, et al., ``Aerial Colonization and Growth: Rapid 
Invertebrate Responses to Temporary Aquatic Habitats in a River 
Floodplain,'' Journal of the North American Benthological Society 
26:460-471 (2007)). Animals, particularly migratory fish, may thus 
move between adjacent waters and (a)(1) through (a)(3) waters. And 
even when some species do not traverse the entire distance from 
adjacent waters to downstream waters, the downstream waters still 
benefit from the ecological integrity that persists because of the 
close relationship that adjacent waters have with nearby waters. 
This is because the chemical and biological properties that arise 
from interactions between adjacent waters and tributaries move 
downstream and support the integrity of (a)(1) through (a)(3) 
waters.
    Biological connections between adjacent waters and river systems 
do not always increase with hydrologic connections. In some cases, 
the lack of connection improves the biological contribution provided 
by riparian waters towards neighboring streams, rivers, and lakes. 
For instance, the periodic hydrologic disconnectedness of oxbow 
lakes is necessary for the accumulation of plankton, an important 
source of carbon more easily assimilated by the aquatic food chain 
than terrestrial forms of carbon. Id. at 5-46 (citing C. Baranyi, et 
al., ``Zooplankton Biomass and Community Structure in a Danube River 
Floodplain System: Effects of Hydrology,'' Freshwater Biology 
47:473-482 (2002); S. Keckeis, et al., ``The Significance of 
Zooplankton Grazing in a Floodplain System of the River Danube,'' 
Journal of Plankton Research 25:243-253 (2003)). Similarly, some 
degree of hydrological disconnectedness is important in increasing 
the number of mollusk species and macroinvertebrate diversity in 
oxbow lakes, which in turn support the diversity of

[[Page 22241]]

mollusks throughout the aquatic system. Id. at 5-46 to 5-47 (citing 
W. Reckendorfer, et al., ``Floodplain Restoration by Reinforcing 
Hydrological Connectivity: Expected Effects on Aquatic Mollusc 
Communities,'' Journal of Applied Ecology 43:474-484 (2006); K. 
Obolewski, et al., ``Effect of Hydrological Connectivity on the 
Molluscan Community Structure in Oxbow Lakes of the Lyna River,'' 
Oceanological and Hydrobiological Studies 38:75-88 (2009).

2. Confined Surface and Shallow Subsurface Hydrologic Connections 
Significantly Affect the Chemical, Physical, or Biological Integrity of 
(a)(1) Through (a)(3) Waters

    Wetlands and open waters, including those outside the riparian 
zone and floodplain, can be connected downstream through 
unidirectional flow from the wetland or open water to a nearby 
tributary. Such connections can occur through a confined surface or 
a shallow subsurface hydrologic connection. Report at 3-7, 5-23. 
Outside of the riparian zone and floodplain, surface hydrologic 
connections between adjacent waters and jurisdictional waters can 
occur via confined flows (e.g. a swale, gully, ditch, or other 
discrete feature). For purposes of this rule, confined surface 
connections are defined as 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 jurisdictional water that at 
times contains water originating in the 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. Id. 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 originate from the adjacent wetland or 
open water, travel to the downstream jurisdictional water, and are 
connected to those downstream waters by swales or other directional 
flowpaths on the surface.
    A confined surface hydrologic connection, which may be 
perennial, intermittent or ephemeral, supports periodic flows 
between the adjacent water and the jurisdictional water. For 
example, wetland seeps are likely to have perennial connections to 
streams that provide important sources of baseflow, particularly 
during summer. Id. at 5-22 (citing T.R. Morley, et al., ``The Role 
of Headwater Wetlands in Altering Streamflow and Chemistry in a 
Maine, USA catchment,'' Journal of the American Water Resources 
Association 47:337-349 (2011)). Other wetlands are connected to 
streams via intermittent or ephemeral conveyances and can contribute 
flow to downstream waters via their surface hydrologic connection. 
Id. at 5-22 (citing M.C. Rains, et al., ``The Role of Perched 
Aquifers in Hydrological Connectivity and Biogeochemical Processes 
in Vernal Pool Landscapes, Central Valley, California,'' 
Hydrological Processes 20:1157-1175 (2006); M.C. Rains, et al., 
``Geological Control of Physical and Chemical Hydrology in 
California Vernal Pools,'' Wetlands 28:347-362 (2008); B.P. Wilcox, 
et al., ``Evidence of Surface Connectivity for Texas Gulf Coast 
Depressional Wetlands,'' Wetlands 31:451-458 (2011)).The surface 
hydrologic connection of the neighboring water to the jurisdictional 
water and the close proximity of the waters enhance the neighboring 
waters substantial effects the waters have on downstream (a)(1) 
through (a)(3) waters. Wetlands and open waters that are connected 
to (a)(1) through (a)(5) waters through a confined surface 
hydrologic connection will have an impact on downstream (a)(1) 
through (a)(3) waters, regardless of whether the outflow is 
permanent, intermittent, or ephemeral. See, e.g., id. at 5-1 to 5-2.
    Wetlands and open waters with confined surface connections can 
affect the physical integrity of waters to which they connect. Such 
waters can provide an important source of baseflow to the streams to 
which they are adjacent, helping to sustain the water levels in the 
nearby streams. Id. at 5-22 (citing T.R. Morley, et al., ``The Role 
of Headwater Wetlands in Altering Streamflow and Chemistry in a 
Maine, USA catchment,'' Journal of the American Water Resources 
Association 47:337-349 (2011); M.C. Rains, et al., ``The Role of 
Perched Aquifers in Hydrological Connectivity and Biogeochemical 
Processes in Vernal Pool Landscapes, Central Valley, California,'' 
Hydrological Processes 20:1157-1175 (2006); M.C. Rains, et al., 
``Geological Control of Physical and Chemical Hydrology in 
California Vernal Pools,'' Wetlands 28:347-362 (2008); B.P. Wilcox, 
et al., ``Evidence of Surface Connectivity for Texas Gulf Coast 
Depressional Wetlands,'' Wetlands 31:451-458 (2011)) and T.M. Lee, 
et al., Effect of Groundwater Levels and Headwater Wetlands on 
Streamflow in the Charlie Creek Basin, Peace River Watershed, West-
Central Florida, U.S. Geological Survey Scientific Investigations 
Report 2010-5189 (Reston, Virginia: U.S. Department of the Interior, 
U.S. Geological Survey, 2010). Waters with a confined surface 
connection to downstream jurisdictional waters can affect streamflow 
by altering baseflow or stormflow through several mechanisms, 
including surface storage and groundwater recharge. Report at 5-25. 
Wetlands effectively store water because the entire aboveground 
portion of the wetland basin is available for water storage, in 
contrast to upland areas where soil particles or rock reduce water 
storage volume for a given volume of that soil or rock (i.e., the 
specific yield). Id. at 5-25 (citing A.I. Johnson, Specific Yield--
Compilation of Specific Yields for Various Materials, USGS Water 
Supply Paper 1662-D (Washington, DC: U.S. Department of the 
Interior, U.S. Geological Survey, 1967)). By storing water, these 
waters can reduce peak streamflow, and thus, downstream flooding. 
Id. at 5-25 (citing A. Bullock, and M. Acreman, ``The Role of 
Wetlands in the Hydrological Cycle,'' Hydrology and Earth System 
Sciences 7:358-389 (2003); P. McEachern, et al., ``Landscape Control 
of Water Chemistry in Northern Boreal Streams of Alberta,'' Journal 
of Hydrology 323:303-324 (2006)). Antecedent moisture conditions, 
available wetland storage, and evaporation rates could impact water 
storage, as some waters connected to jurisdictional waters via 
discrete features may actually reduce flows in the streams they 
neighbor during dry periods. Id. 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)). Thus, 
wetlands and open waters with a confined hydrologic connection to 
jurisdictional waters may function as a sink in dry periods if 
storage capacity is not exceeded and evaporation rates surpass 
groundwater recharge. Id. at 5-26 to 5-27.
    Wetlands and open waters with confined surface connections can 
affect the chemical integrity of waters to which they connect. Such 
waters can affect water quality of jurisdictional waters through 
source and sink functions, often mediated by transformation of 
chemical constituents. The surface hydrologic connections to nearby 
jurisdictional waters provide pathways for materials transformed in 
the wetlands and open waters (such as methylmercury or degraded 
organic matter) to reach and affect the nearby waters and the 
downstream (a)(1) through (a)(3). Id. at 5-27. Functions that occur 
in the wetlands and open waters can affect downstream (a)(1) through 
(a)(3) waters when compounds that are transformed in wetland 
environments move to downstream waters via the surface hydrologic 
connection. Id. at 5-28 (citing T.C. Winter and J.W. LaBaugh, 
``Hydrologic Considerations in Defining Isolated Wetlands,'' 
Wetlands 23:532-540 (2003)). For example, methylmercury (which can 
form in peatlands) can be transported through entrainment with 
organic matter exports, and can move through surface flows from 
peatlands with confined surface connections to downstream waters. 
Id. at 5-28 (citing O. Linqvist, et al., ``Mercury in the Swedish 
Environment--Recent Research on Causes, Consequences, and Remedial 
Measures,'' Water Air and Soil Pollution 55:xi-xiii (1991); G. 
Mierle, and R. Ingram, ``The Role of Humic Substances in the 
Mobilization of Mercury from Watersheds,'' Water Air and Soil 
Pollution 56:349-357 (1991); V.L. St. Louis, et al., ``Importance of 
Wetlands as Sources of Methyl mercury to Boreal Forest Ecosystems,'' 
Canadian Journal of Fisheries and Aquatic Sciences 51:1065-1076 
(1994); C.T. Driscoll, et al., ``The Role of Dissolved Organic 
Carbon in the Chemistry and Bioavailability of Mercury in Remote 
Adirondack Lakes,'' Water Air and Soil Pollution 80:499-508 (1995); 
P. Porvari, and M. Verta, ``Total and Methyl mercury Concentrations 
and Fluxes from Small Boreal Forest Catchments in Finland,'' 
Environmental Pollution 123:181-191 (2003)). The mercury that is 
transported downstream can enter the food chains of the

[[Page 22242]]

(a)(1) through (a)(3) waters and negatively impact wildlife 
inhibiting those downstream waters. Id. at 5-28. Export of dissolved 
organic matter from neighboring waters connected via a confined 
surface connection can have potentially negative effects on 
downstream waters because contaminants, such as MeHg and other trace 
metals, can be adsorbed to the organic matter. Id. at 5-28 (citing 
E.M. Thurman, Organic Geochemistry of Natural Waters (Boston, MA: 
Martinus Nijhoff/Dr. W. Junk Publishers, 1985); C.T. Driscoll, et 
al., ``The Role of Dissolved Organic Carbon in the Chemistry and 
Bioavailability of Mercury in Remote Adirondack Lakes,'' Water Air 
and Soil Pollution 80:499-508 (1995)). Dissolved organic matter, 
however, is also an important source of energy for downstream 
aquatic communities. Id. at 5-28 (citing J.E. Hobbie and R.G. 
Wetzel, ``Microbial control of dissolved organic carbon in lakes: 
Research for the future,'' Hydrobiologia 229:169-180 (1992); K.R. 
Reddy and R.D. DeLaune, Biogeochemistry of Wetlands: Science and 
Applications, 774 p. (2008)). Wetlands with confined surface 
hydrologic connections to the stream are connected to jurisdictional 
tributary system and therefore can efficiently transport dissolved 
organic carbon and other dissolved organic matter to the nearby 
jurisdictional water and downstream (a)(1) through (a)(3) waters. 
See, e.g., I.F. Creed, et al., ``Cryptic Wetlands: Integrating 
Hidden Wetlands in Regression Models of the Export of Dissolved 
Organic Carbon from Forested Landscapes,'' Hydrological Processes 
17:3629-3648 (2003). Adjacent waters with a surface hydrologic 
connection to jurisdictional waters can also improve water quality 
through assimilation, transformation, or sequestration of nutrients 
and other pollutants. Report at 5-29 (citing, e.g., K.R. Reddy, and 
R.D. DeLaune, Biogeochemistry of Wetlands: Science and Applications, 
774 p. (2008)). These processes can occur during times of lower 
hydroperiods when water is not present in the surface hydrologic 
connection between the adjacent water and the jurisdictional water. 
Pollutants can be attenuated or retained in such adjacent waters 
through processes including denitrification, ammonia volatilization, 
microbial and plant biomass assimilation, sedimentation, sorption 
and precipitation reactions, biological uptake, and long-term 
storage in plant detritus. Id. at 5-29 (citing K.R. Reddy, et al., 
``Phosphorus Retention in Streams and Wetlands: A Review,'' Critical 
Reviews in Environmental Science and Technology 29:83-146 (1999); 
K.R. Reddy and R.D. DeLaune, Biogeochemistry of Wetlands: Science 
and Applications, 774 p. (2008)). Through retention and mitigation 
of pollutants and other chemical compounds, adjacent waters with a 
surface hydrologic connection to jurisdictional waters can 
substantially improve water quality downstream.
    Wetlands and open waters with confined surface connections can 
affect the biological integrity of waters to which they connect. 
Movement of organisms between these adjacent waters and the nearby 
jurisdictional water is governed by many of the same factors that 
affect movement of organisms between riparian/floodplain waters and 
the river network. Id. at 5-31. Because such waters are at least 
periodically hydrologically connected to the nearby jurisdictional 
tributary network on the surface, dispersal of organisms can occur 
actively through the surface connection or via wind dispersal, 
hitchhiking, walking, crawling, or flying. See, e.g., id. at 5-31. 
For example, waterborne dispersal of aquatic and emergent plants can 
occur between the jurisdictional water and the neighboring water due 
to the periodic hydrologic connection to the tributary system. Id. 
at 5-31 (citing C. Nilsson, et al., ``The Role of Hydrochory in 
Structuring Riparian and Wetland Vegetation,'' Biological Reviews 
85:837-858 (2010)). Fish can also move between the jurisdictional 
water and the neighboring water to which it is connected via a 
surface hydrologic connection during periodic surficial hydrologic 
connections. Id. at 5-32 (citing J.W. Snodgrass, et al., ``Factors 
affecting the occurrence and structure of fish assemblages in 
isolated wetlands of the upper coastal plain, USA,'' Canadian 
Journal of Fisheries and Aquatic Sciences 53:443-454 (1996); K.D. 
Zimmer, et al., ``Effects of fathead minnow colonization and removal 
on a prairie wetland ecosystem,'' Ecosystems 4:346-357 (2001); M.J. 
Baber, et al., ``Controls on fish distribution and abundance in 
temporary wetlands,'' Canadian Journal of Fisheries and Aquatic 
Sciences 59:1441-1450 (2002); M.A. Hanson, et al., ``Biotic 
interactions as determinants of ecosystem structure in prairie 
wetlands: An example using fish,'' Wetlands 25:764-775 (2005);, B.R. 
Herwig, et al., ``Factors influencing fish distributions in shallow 
lakes in prairie and prairie-parkland regions of Minnesota, USA,'' 
Wetlands 30:609-619 (2010)). Mammals and aquatic and semi-aquatic 
amphibians and reptiles that can disperse overland can also 
contribute to connectivity, as can aquatic birds, particularly given 
the close proximity of the neighboring water to the jurisdictional 
water. Mammals and birds can act as transport vectors for 
hitchhikers like algae or aquatic insects. Id. at 5-32 (citing J.P. 
Roscher, ``Alga Dispersal by Muskrat Intestinal Contents,'' 
Transactions of the American Microscopical Society 86:497-498 
(1967)); J. Figuerola and A.J. Green, ``Dispersal of Aquatic 
Organisms by Waterbirds: a Review of Past Research and Priorities 
for Future Studies,'' Freshwater Biology 47:483-494 (2002); J. 
Figuerola, et al., ``Invertebrate Eggs Can Fly: Evidence of 
Waterfowl-Mediated Gene Flow in Aquatic Invertebrates,'' American 
Naturalist 165:274-280 (2005)). Amphibians and reptiles move between 
streams and their adjacent waters to satisfy part of their life-
history requirements. Id.at 5-33, Table 5-2. The hydrologic 
connection between neighboring waters with a surface connection to 
the jurisdictional water allows for that movement to occur either in 
the water or over land. Aquatic insects that use both streams and 
their adjacent waters can move outside of the stream network to the 
nearby wetland or open water to seek suitable habitat for 
overwintering, refuge from adverse conditions, hunting, foraging or 
breeding, and then return to the stream for other life-history 
requirements. Id. at 5-33 (citing D.D. Williams, ``Environmental 
Constraints in Temporary Fresh Waters and Their Consequences for the 
Insect Fauna,'' Journal of the North American Benthological Society 
15:634-650 (1996); A.J. Bohonak and D.G. Jenkins, ``Ecological and 
Evolutionary Significance of Dispersal by Freshwater 
Invertebrates,'' Ecology Letters 6:783-796 (2003)). Neighboring 
waters with a confined surface hydrologic connection to 
jurisdictional waters help to maintain various biological 
populations, which periodically replenish adjacent jurisdictional 
waters, serving to maintain the biological integrity of (a)(1) 
through (a)(3) waters.
    A shallow subsurface hydrologic connection is lateral water flow 
through a shallow subsurface layer, such as can be found in steeply 
sloping areas with shallow soils and soils with a restrictive 
horizon that prevents vertical water flow, or in karst systems. 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). Shallow 
subsurface connections may be found below the ordinary root zone 
(below 12 inches), where other wetland delineation factors may not 
be present. The presence of an aquiclude (impervious layer) near the 
surface leads to shallow subsurface flows through the soil, which 
favors local groundwater flowpaths that connect to nearby wetlands 
or streams. Report at 3-38.
    Wetlands with shallow subsurface connections can affect the 
physical integrity of waters to which they connect. In general, the 
volume and sustainability of streamflow within river networks 
depends on contributions from groundwater, especially in areas with 
shallow groundwater tables and pervious (meaning water can easily 
pass through) subsurfaces. Id. at 3-12 (citing J.J. de Vries, 
``Seasonal Expansion and Contraction of Stream Networks in Shallow 
Groundwater Systems,'' Journal of Hydrology 170:15-26 (1995); T.C. 
Winter, ``The Role of Groundwater in Generating Streamflow in 
Headwater Areas and in Maintaining Base Flow,'' Journal of the 
American Water Resources Association 43:15-25 (2007); G.R. Kish, et 
al., ``A Geochemical Mass-Balance Method for Base-Flow Separation, 
Upper Hillsborough River Watershed, West-Central Florida, 2003-2005 
and 2009,'' USGS Scientific Investigations Report 2010-5092 
(Washington, DC: U.S. Department of the Interior, U.S. Geological 
Survey, 2010). Because wetlands with shallow subsurface connections 
to streams and rivers provide some of these groundwater 
contributions, they influence the flow regime. Wetlands connected 
via shallow subsurface connections also can act as water sinks when 
evapotranspiration is high, but as water sources when 
evapotranspiration is low. Id.

[[Page 22243]]

at 3-25. As a result, these adjacent waters moderate peak flows, 
reduce downstream flooding, and provide runoff to help maintain 
baseflow for streams during times of low flows.
    Wetlands and other waters with shallow subsurface connections 
affect the chemical and biological integrity of downstream waters in 
ways similar to wetlands with surface connections. The distance 
between these wetlands and jurisdictional waters may influence the 
connectivity since wetlands with shorter distances to the stream 
network will have higher hydrological and biological connectivity 
than wetlands located further from the same network. Id. at 3-43. 
The distance between the wetland and water may also influence 
whether waters are connected via surface or shallow subsurface 
hydrologic connections, as wetlands and open waters that are closer 
to rivers and streams will have a higher probability of being 
connected than more distant waters, assuming that conditions 
governing type and quantity of flows (e.g. slope, soil and aquifer 
permeability) are similar. Id at 5-2. For wetlands connected to 
tributaries through groundwater flows, less distant wetlands/waters 
are generally connected through shallower flowpaths, assuming 
similar soil and geologic properties. Id. at 3-11 (Figure 3-5), 3-
42. These shallower subsurface flows have the greatest interchange 
with surface waters and travel between points in the shortest amount 
of time. Id. at 3-42.

3. Adjacent 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 Significantly Affect the Chemical, 
Physical, or Biological Integrity of (a)(1) Through (a)(3) Waters

    The terms earthen dam, dike, berm, and levee are used to 
describe similar structures whose primary purpose is to help control 
flood waters. Such structures vary in scale and size. A levee is an 
embankment whose primary purpose is to furnish flood protection from 
seasonal high water and which is therefore subject to water loading 
for periods of only a few days or weeks a year. Earthen embankments 
that are subject to water loading for prolonged periods (longer than 
normal flood protection requirements) are called earth dams. There 
are a wide variety of types of structures and an even wider set of 
construction methods. These range from a poorly constructed, low 
earthen berm pushed up by a backhoe to a well-constructed, 
impervious core, riprap lined levee that protects houses and 
cropland. Generally, levees are built to detach the floodplain from 
the channel, decreasing overbank flood events. S.B. Franklin, et 
al., ``Complex Effects of Channelization and Levee Construction on 
Western Tennessee Floodplain Forest Function,'' Wetlands 29(2): 451-
464 (2009). The investigation methods to determine the presence or 
absence of the hydrologic connection depend on the type of 
structure, the underlying soils, the presence of groundwater, and 
the depth of the water table. Department of the Army, U.S. Army 
Corps of Engineers, Engineering and Design--Design and Construction 
of Levees, EM 1110-2-1913 (Washington, DC, Department of the Army, 
2000), p. 1-1.
    Man-made berms and the like are fairly common along streams and 
rivers across the United States and often accompany stream 
channelization. S.B. Franklin, et al., ``Complex Effects of 
Channelization and Levee Construction on Western Tennessee 
Floodplain Forest Function,'' Wetlands 29(2): 451-464 (2009). One 
study conducted in Portland, Oregon found that 42% of surveyed 
wetlands had dams, dikes, or berms. M. Kentula, et al., ``Tracking 
Changes in Wetlands with Urbanization: Sixteen Years of Experience 
in Portland, Oregon, USA,'' Wetlands 24(4):734-743 (2004). Likewise, 
over 90% of the tidal freshwater wetlands of the Sacramento-San 
Joaquin Delta have been diked or leveed. C. Simenstad, et al., 
``Preliminary Results from the Sacramento-San Joaquin Delta Breached 
Levee Wetland Study,'' Interagency Ecological Program for the 
Sacramento-San Joaquin Estuary Newsletter 12(4):15-21 (1999). At 
least 40,000 kilometers of levees, floodwalls, embankments, and 
dikes are estimated across the United States, with approximately 
17,000 kilometers of levees in the Upper Mississippi Valley alone. 
SE. Gergel, et al., ``Consequences of Human-altered Floods: Levees, 
Floods, and Floodplain Forests along the Wisconsin River,'' 
Ecological Applications 12(6): 1755-1770 (2002).
    Adjacent waters separated from the tributary network by dikes, 
levees, berms and the like continue to have a hydrologic connection 
to downstream waters. This is because berms and similar features 
typically do not block all water flow. Indeed, even dams, which are 
specifically designed and constructed to impound large amounts of 
water effectively and safely, do not prevent all water flow, but 
rather allow seepage under the foundation of the dam and through the 
dam itself. See, e.g., International Atomic Energy Agency, Factsheet 
on Investigating Leaks through Dams and Reservoirs, http://www.tc.iaea.org/tcweb/publications/factsheets/sheet20dr.pdf; U.S. 
Bureau of Reclamation, Provo Office, Safety of Dams, http://www.usbr.gov/uc/provo/progact/damsafety.html; Federal Energy 
Regulatory Commission (FERC), ``Chapter 14: Dam Safety Performance 
Monitoring Program,'' Engineering Guidelines for the Evaluation of 
Hydropower Projects (FERC, 2005), pp. 14-36 to 14-39.
    Seepage is the flow of a fluid through the soil pores. Seepage 
through a dam, through the embankments, foundations or abutments, or 
through a berm is a normal condition. D.A. Kovacic, et al., 
``Effectiveness of Constructed Wetlands in Reducing Nitrogen and 
Phosphorus Export from Agricultural Tile Drainage,'' Journal of 
Environmental Quality 29(4): 1262-1274 (2000); Federal Energy 
Regulatory Commission (FERC), ``Chapter 14: Dam Safety Performance 
Monitoring Program,'' Engineering Guidelines for the Evaluation of 
Hydropower Projects (FERC, 2005), pp. 14-36 to 14-39. This is 
because water seeks paths of least resistance through the berm or 
dam and its foundation. Michigan Department of Environmental 
Quality, Seepage Through Earth Dams (2002), http://www.michigan.gov/deq/0,1607,7-135-3313_3684_3723-9515-,00.html. All earth and rock-
fill dams are subject to seepage through the embankment, foundation, 
and abutments. Department of the Army, U.S. Army Corps of Engineers, 
Seepage Analysis and Control for Dams, EM 1110-2-1901, (Washington, 
DC: Department of the Army, Original 1986--Revised 1993), Page 1-1; 
Department of the Army, U.S. Army Corps of Engineers, Engineering 
and Design: General Design and Construction Considerations for Earth 
and Rock-filled Dams, EM 1110-2-2300 (Washington, DC: Department of 
the Army, 2004), pp. 6-1 to 6-7. Concrete gravity and arch dams 
similarly are subject to seepage through the foundation and 
abutments. Department of the Army, U.S. Army Corps of Engineers, 
Seepage Analysis and Control for Dams, EM 1110-2-1901 (Washington, 
DC: Department of the Army, Original 1986--Revised 1993), Page 1-1. 
Levees and the like are subject to breaches and breaks during times 
of floods. C. Nilsson, et al., ``Fragmentation and Flow Regulation 
of the World's Large River Systems,'' Science 308(5720):405-408 
(2005). Levees are similarly subject to failure in the case of 
extreme events, such as the extensive levee failures caused by 
Hurricanes Katrina and Rita. J.W. Day, et al., ``Restoration of the 
Mississippi Delta: Lessons from Hurricanes Katrina and Rita,'' 
Science 315(5819): 1679-1684 (2007). In designing levees and similar 
structures, seepage control is necessary to prevent possible failure 
caused by excessive uplift pressures, instability of the downstream 
slope, piping through the embankment and/or foundation, and erosion 
of material by migration into open joints in the foundation and 
abutments. Id.; D.A. Kovacic, et al., ``Effectiveness of Constructed 
Wetlands in Reducing Nitrogen and Phosphorus Export from 
Agricultural Tile Drainage,'' Journal of Environmental Quality 
29(4): 1262-1274 (2000); U.S. Department of the Interior, Bureau of 
Reclamation, Upper Colorado Region, see http://www.usbr.gov/uc/provo/progact/damsafety.html; International Atomic Energy Agency, 
Investigating Leaks through Dams and Reservoirs, see  http://www-tc.iaea.org/tcweb/publications/factsheets/sheet20dr.pdf; California 
Division of Safety of Dams, Embankment Design, see http://damsafety.water.ca.gov/guidelines/embankment.htm.
    The rate at which water moves through the embankment depends on 
the type of soil in the embankment, how well it is compacted, the 
foundation and abutment preparation, and the number and size of 
cracks and voids within the embankment. All but the smallest earthen 
dams are commonly built with internal subsurface drains to intercept 
water seeping from the reservoir (i.e., upstream side) to the 
downstream side. Department of the Army, U.S. Army Corps of 
Engineers, Construction Control for Earth and Rock-filled Dams, EM 
1110-2-1911, September 30, 1995, Washington, DC 20314-1000, Page 1-
1. Where it is not intercepted by a subsurface drain, the seepage 
will emerge downstream from or at the toe of the embankment. 
Michigan Department of Environmental Quality, Seepage Through Earth 
Dams (2002), http://www.michigan.gov/deq/0,1607,7-135-

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3313--3684--3723-9515-,00.html. Seepage may vary in appearance from 
a ``soft,'' wet area to a flowing ``spring.'' It may show up first 
as an area where the vegetation is lush and darker green. Cattails, 
reeds, mosses, and other marsh vegetation may grow in a seepage 
area. Michigan Department of Environmental Quality, Seepage Through 
Earth Dams (2002), http://www.michigan.gov/deq/0,1607,7-135-3313_3684_3723-9515-,00.html.
    Engineered berms are typically designed to interfere with the 
seasonal pattern of water level (hydroperiod) of the area behind the 
berm, reducing the frequency and severity of inundation. Berms are 
not designed to eliminate all hydrologic connection between the 
channel on one side and the area behind the berm on the other. It is 
almost always impracticable to build a berm that will not be 
overtopped by a flood of maximum severity, and most berms are not 
designed to withstand severe floods. See, e.g., Department of the 
Army, U.S. Army Corps of Engineers, Seepage Analysis and Control for 
Dams, EM 1110-2-1901, (Washington, DC: Department of the Army, 
Original 1986--Revised 1993), Page 1-1. Levees are designed to allow 
seepage and are frequently situated on foundations having natural 
covers of relatively fine-grain impervious to semipervious soils 
overlying pervious sands and gravels. Department of the Army, U.S. 
Army Corps of Engineers, Engineering and Design: Design Guidance for 
Levee Underseepage, ELT 1110-2-569, Washington, DC: Department of 
the Army, 2005), pp. 1-9. These surface strata constitute impervious 
or semipervious blankets when considered in connection with seepage. 
Principal seepage control measures for foundation underseepage are 
(a) cutoff trenches, (b) riverside impervious blankets, (c) 
landslide berms, (d) pervious toe trenches, and (e) pressure relief 
wells. Department of the Army, U.S. Army Corps of Engineers, 
Engineering and Design--Design and Construction of Levees, EM 1110-
2-1913 (Washington, DC, Department of the Army, 2000), p. 1-1. 
Overtopping of an embankment dam is very undesirable because the 
embankment materials may be eroded away. Additionally, only a small 
number of concrete dams have been designed to be overtopped. Water 
normally passes through the main spillway or outlet works; it should 
pass over an auxiliary spillway only during periods of high 
reservoir levels and high water inflow. All embankment and most 
concrete dams have some seepage. See, e.g., http://www.damsafety.org/layout/subsection.aspx?groupid=14&contentid=47. 
However, it is important to control the seepage to prevent internal 
erosion and instability. Proper dam construction, and maintenance 
and monitoring of seepage provide control.
    Berm-like landforms known as natural levees occur naturally and 
do not isolate adjacent wetlands from the streams that form them. 
Natural levees and the wetlands and waters behind them are part of 
the floodplain, including along some small streams and streams in 
the Arid West. C.A. Johnston, et al., ``Nutrient Dynamics in 
Relation to Geomorphology of Riverine Wetlands,'' Soil Science 
Society of America Journal 65(2):557-577 (2001). Every flowing 
watercourse transports not only water, but sediment--eroding and 
rebuilding its banks and floodplains continually. Federal 
Interagency Stream Restoration Working Group, Stream Corridor 
Restoration: Principles, Processes and Practices, USDA National 
Engineering Handbook Part 653 (1999). Different deposition patterns 
occur under varying levels of streamflow, with higher flows having 
the most influence on the resulting shape of streambanks and 
floodplains. Id. In relatively flat landscapes drained by low-
gradient streams, this natural process deposits the most sediment on 
the bank immediately next to the stream channel while floodplains 
farther from the channel are usually lower-lying wetlands 
(``backswamps'' or ``backwater wetlands'') that receive less 
sediment. See, e.g., C.A. Johnston, et al., ``The Potential Role of 
Riverine Wetlands as Buffer Zones,'' in N.E. Haycock, et al., ed., 
Buffer Zones Their Processes and Potential in Water Protection 
(Quest International, 1997), pp. 155-170. The somewhat elevated land 
thus built up at streamside is called a natural levee, and this 
entirely natural landform is physically and hydrologically similar 
to narrow, man-made berms. See, e.g., L.B. Leopold, et al., Fluvial 
Processes in Geomorphology (Toronto: General Publishing Co. Ltd., 
1964). Natural levees are discontinuous, which allows for a 
hydrologic connection to the stream or river via openings in the 
levees and thus the periodic mixing of river water and backwater. 
C.A. Johnston, et al., ``Nutrient Dynamics in Relation to 
Geomorphology of Riverine Wetlands,'' Soil Science Society of 
America Journal 65(2): 557-577 (2001). In addition, streams with 
natural levees, in settings with no human interference whatsoever, 
retain hydrologic connection with their wetlands behind the levees 
by periodic flooding during high water and via seepage through and 
under the levee. Similarly, man-made berms are typically 
periodically overtopped with water from the near-by stream, and as 
previously mentioned, are connected via seepage.
    Waters, including wetlands, separated from a stream by a natural 
or man-made berm serve many of the same functions as those discussed 
above on other adjacent waters. Furthermore, even in cases where a 
hydrologic connection may not exist, there are other important 
considerations, such as chemical and biological factors, that result 
in a significant nexus between the adjacent wetlands or waters and 
the nearby ``waters of the United States,'' and (a)(1) through 
(a)(3) waters.
    The movement of surface and subsurface both over berms and 
through soils and berms adjacent to rivers and streams is a 
hydrologic connection between wetlands and flowing watercourses. The 
intermittent connection of surface waters over top of, or around, 
natural and manmade berms further strengthens the evidence of 
hydrologic connection between wetlands and flowing watercourses. 
Both natural and man-made barriers can be topped by occasional 
floods or storm events. See, e.g., R.E. Turner, et al., ``Wetland 
Sedimentation from Hurricanes Katrina and Rita,'' Science 314(5798): 
449-452 (2006); P.A. Keddy, et al., ``The Wetlands of Lakes 
Pontchartrain and Maurepas: Past, Present and Future,'' 
Environmental Reviews 15: 43-77 (2007). When berms are periodically 
overtopped by water, wetlands and waters behind the barriers are 
directly connected to and interacting with the nearby stream and its 
downstream waters. In addition, surface waters move to and from 
adjacent soils (including adjacent wetland soils) continually. Along 
their entire length, streams alternate between effluent (water-
gaining) and influent (water-losing) zones as the direction of water 
exchange with the streambed and banks varies. Federal Interagency 
Stream Restoration Working Group, Stream Corridor Restoration: 
Principles, Processes and Practices, USDA National Engineering 
Handbook Part 653 (1999). The adjacent areas involved in this 
surface water exchange with a stream or river are known as the 
hyporheic zone. Hyporheic zone waters are part of total surface 
waters temporarily moving through soil or sediment. Like within-
channel waters, these waters are oxygenated and support living 
communities of organisms in the hyporheic zone.
    Because a hydrologic connection between adjacent wetlands and 
waters and downstream waters still exists despite the presence of a 
berm or the like, the chemical and biological connections that rely 
on a hydrologic connection also exist. For instance, adjacent waters 
behind berms can still serve important water quality functions, 
serving to filter pollutants and sediment before they reach 
downstream waters. Wetlands behind berms can function to filter 
pollutants before they enter the nearby tributary, with the water 
slowly released to the stream through seepage or other hydrological 
connections. See, e.g., L.L. Osborne and D.A. Kovacic, ``Riparian 
Vegetated Buffer Strips in Water-Quality Restoration and Stream 
Management,'' Freshwater Biology 29(2): 243-258 (1993); D.A. 
Kovacic, et al., ``Effectiveness of Constructed Wetlands in Reducing 
Nitrogen and Phosphorus Export from Agricultural Tile Drainage,'' 
Journal of Environmental Quality 29(4): 1262-1274 (2000). Their 
ability to retain sediment and floodwaters may be enhanced by the 
presence of the berm. For instance, some backwater wetlands in 
floodplain/riparian areas exhibit higher sedimentation rates than 
streamside locations. E.J. Kuenzler, et al., ``Distributions and 
Budgets of Carbon, Phosphorus, Iron and Manganese in a Floodplain 
Swamp Ecosystem,'' Water Resources Research Institute Report 157 
(Chapel Hill, NC: University of North Carolina, 1980); C.A. 
Johnston, et al., ``Nutrient Dynamics in Relation to Geomorphology 
of Riverine Wetlands,'' Soil Science Society of America Journal 
65(2): 557-577 (2001). The presence of manmade levees can actually 
increase denitrification rates, meaning that the adjacent waters can 
more quickly transform nitrogen. SE. Gergel, et al., ``Do Dams and 
Levees Impact Nitrogen Cycling? Simulating the Effects of Flood 
Alterations on Floodplain Denitrification,'' Global Change Biology 
11(8): 1352-1367 (2005). However, the presence of manmade berms does 
limit

[[Page 22245]]

the ability of the river to connect with its adjacent wetlands 
through overbank flooding and thus limits sediment, water and 
nutrients transported from the river to the adjacent waters. Id.; 
J.L. Florsheim and J.F. Mount, ``Changes in Lowland Floodplain 
Sedimentation Processes: Pre-disturbance to Post-rehabilitation, 
Cosumnes River, CA,'' Geomorphology 56(3-4):305-323 (2003). However, 
the presence of a berm does not completely eliminate the transport 
of sediments and water from the river to the nearby adjacent 
wetland, as suspended sediments and water can overflow both natural 
and man-made levees, though the transport is usually more pronounced 
in settings with natural levees. See, e.g., R.E. Turner, et al., 
``Wetland Sedimentation from Hurricanes Katrina and Rita,'' Science 
314(5798):449-452 (2006); P.A. Keddy, et al., ``The Wetlands of 
Lakes Pontchartrain and Maurepas: Past, Present and Future,'' 
Environmental Reviews 15:43-77 (2007). Sediment deposition over 
levees is particularly enhanced by extreme events like hurricanes. 
Id.; D.J. Reed, et al., ``Reducing the Effects of Dredged Material 
Levees on Coastal Marsh Function: Sediment Deposition and Nekton 
Utilization,'' Environmental Management 37(5):671-685 (2006). 
Wetlands behind berms, where the system is extensive, can help 
reduce the impacts of storm surges caused by hurricanes. J.W. Day, 
et al., ``Restoration of the Mississippi Delta: Lessons from 
Hurricanes Katrina and Rita,'' Science 315(5819):1679-1684 (2007).
    Adjacent waters, including wetlands, separated from water bodies 
by berms and the like maintain ecological connection with those 
water bodies. Though a berm may reduce habitat functional value and 
may prevent some species from moving back and forth from the wetland 
to the river, many major species that prefer habitats at the 
interface of wetland and stream ecosystems remain able to utilize 
both habitats despite the presence of such a berm. Additional 
species that are physically isolated in either stream or wetlands 
habitat still interact ecologically with species from the other 
component. Thus, adjacent wetlands with or without small berms can 
retain numerous similarities in ecological function. For example: 
Wetland bird species such as wading birds are able to utilize both 
wetland and adjacent stream/ditch habitats; wetland amphibians would 
be able to bypass the berm in their adult stage; aquatic 
invertebrates and fish would still interact with terrestrial/wetland 
predators and prey in common food web relationships despite the 
presence of a berm. See, e.g., G.S. Butcher, and B. Zimpel, 
``Habitat Value of Isolated Waters to Migratory Birds,'' Prepared by 
Cornell Laboratory of Ornithology and The Cadmus Group, Inc. for 
U.S. Environmental Protection Agency Office of Wetlands Protection, 
(Washington, DC: Cornell and Cadmus, 1991); M.F. Willson and K.C. 
Halupka, ``Anadromous Fish as Keystone Species in Vertebrate 
Communities,'' Conservation Biology 9(3):489-497 (1995); C.J. 
Cederholm, et al., ``Pacific Salmon Carcasses: Essential 
Contributions of Nutrients and Energy for Aquatic and Terrestrial 
Ecosystems,'' Fisheries 24(10):6-15 (1999); S.S. Schwartz and D.G. 
Jenkins, ``Temporary Aquatic Habitats: Constraints and 
Opportunities,'' Aquatic Ecology 34:3-8 (2000); D.T. Bilton, et al., 
``Dispersal in Freshwater Invertebrates,'' Annual Review of Ecology 
and Systematics 32:159-81 (2001).
    One example of adjacent waters behind berms and the like are 
interdunal wetlands located in coastal areas, including some areas 
of the Great Lakes and along barrier islands. Interdunal wetlands 
form in swales or depressions within open dunes or between beach 
ridges along the coast and experience a fluctuating water table 
seasonally and yearly in synchrony with sea or lake level changes. 
W.E. Odum, ``Non-Tidal Freshwater Wetlands in Virginia,'' Virginia 
Journal of Natural Resources Law 7: 421-434 (1988); D.A. Albert, 
Borne of the Wind: An Introduction to the Ecology of Michigan Sand 
Dunes (Lansing, MI: Michigan Natural Features Inventory, 2000), 63 
pp.; D.A. Albert, Between Land and Lake: Michigan's Great Lakes 
Coastal Wetlands, Bulletin E-2902 (East Lansing, MI: Michigan 
Natural Features Inventory, Michigan State University Extension, 
2003), 96 pp; D.A. Albert, Natural Community Abstract for Interdunal 
Wetland (Lansing, MI: Michigan Natural Features Inventory, 2007), 6 
pp. For those along the ocean coast, they are typically formed as a 
result of oceanic processes where the wetlands establish behind 
relict dune ridges (dunes that were formed along a previously 
existing coast line). Wetlands in the interdunal system are in close 
proximity to each other and to the surrounding (a)(1) through (a)(3) 
waters. Their proximity to one another and to the (a)(1) through 
(a)(3) waters indicates a close physical relationship between 
interdunal wetland systems and the traditional navigable waters, 
interstate waters, or the territorial seas. Despite the presence of 
the beach dunes, interdunal wetlands have chemical, physical, or 
biological connections that greatly influence the integrity of the 
nearby (a)(1) through (a)(3) waters. The wetlands are hydrologically 
connected to these (a)(1) through (a)(3) waters through unconfined, 
directional flow and shallow subsurface flow during normal 
precipitation events and extreme events. As previously noted, they 
are linked to the rise and fall of the surrounding tides--the water-
level fluctuations of the nearby (a)(1) through (a)(3) waters are 
important for the dynamics of the wetlands. D.A. Albert, Between 
Land and Lake: Michigan's Great Lakes Coastal Wetlands, Bulletin E-
2902 (East Lansing, MI: Michigan Natural Features Inventory, 
Michigan State University Extension, 2003), 96 pp. The wetlands 
provide floodwater storage and attenuation, retaining and slowly 
releasing floodwaters before they reach the nearby (a)(1) through 
(a)(3) waters. Like other adjacent wetlands, interdunal wetlands 
also have important chemical connections to the nearby (a)(1) 
through (a)(3) waters, as they serve important water quality 
benefits. The wetlands store sediment and pollutants that would 
otherwise reach the surrounding (a)(1) through (a)(3) waters. The 
wetlands are biologically connected to the surrounding (a)(1) 
through (a)(3) waters. For instance, they provide critical habitats 
for species that utilize both the wetlands and the nearby (a)(1) 
through (a)(3) waters, supporting high diversity and structure. 
Habitat uses include basic food, shelter, and reproductive 
requirements. Aquatic insects, amphibians, and resident and 
migratory birds all use interdunal wetlands as critical habitat, and 
the wetlands provide better shelter than the nearby exposed beach. 
D.A. Albert, Borne of the Wind: An Introduction to the Ecology of 
Michigan Sand Dunes (Lansing, MI: Michigan Natural Features 
Inventory, 2000), 63 pp.; S.M. Smith, et al., ``Development of 
Vegetation in Dune Slack Wetlands of Cape Cod National Seashore 
(Massachusetts, USA),'' Plant Ecology 194(2): 243-256 (2008). In 
marine coastal areas, the wetlands are often the only freshwater 
system in the immediate landscape, thus providing critical drinking 
water for the species that utilize both the wetlands and the nearby 
(a)(1) through (a)(3) waters, although some interdunal wetlands are 
brackish in nature. See, e.g., C.M. Heckscher and C.R. Bartlett, 
``Rediscovery and Habitat Associations of Photuris Bethaniensis 
McDermott (Coleoptera: Lampyridae),'' The Coleopterists Bulletin 
58(3): 349-353 (2004).
    Wetlands behind the extensive levee system in the Yazoo Basin 
are an example of adjacent waters behind man-made barriers. A 
regional hydrogeomorphic approach guidebook for the Yazoo Basin of 
the Lower Mississippi River Alluvial Valley assesses the functions 
of these wetlands. R.D. Smith and C.V. Klimas, A Regional Guidebook 
for Applying the Hydrogeomorphic Approach to Assessing Wetland 
Functions of Selected Regional Wetland Subclasses, Yazoo Basin, 
Lower Mississippi River Alluvial Valle, Prepared for the U.S. Army 
Corps of Engineers, ERDC/EL TR-02-4 (2002). An extensive levee 
system was built along the river system to prevent flooding of the 
Mississippi River, resulting in drastic effects to the hydrology of 
the basin. Id. at 47. Despite the alteration of hydrology in the 
basin, extensive wetlands systems still exist behind the man-made 
and natural levees and maintain a hydrologic connection to the river 
system. These wetlands detain floodwater, detain precipitation, 
cycle nutrients, export organic carbon, remove elements and 
compounds, maintain plant communities, and provide fish and wildlife 
habitat. Id. The functions in turn provide numerous and substantial 
benefits to the nearby river.

4. Conclusions Regarding Adjacent Waters

    The scientific literature documents that waters which are 
adjacent to (a)(1) through (a)(5) waters, including wetlands, oxbow 
lakes and adjacent ponds, are integral parts of tributary networks 
to (a)(1) through (a)(3) waters because they are directly connected 
to streams via permanent surface features that concentrate, mix, 
transform, and transport water and other materials, including food 
resources, downstream to larger rivers. Adjacent wetlands and other 
adjacent waters filter pollutants before they enter the tributary 
system, they attenuate flow during flood events, they regulate flow 
rate and timing, they trap sediment, and they input organic material 
into rivers and streams, providing the basic building blocks for 
their

[[Page 22246]]

healthy functioning. These waters also are biologically connected to 
downstream waters by providing habitat and refuge to many species, 
and storing and releasing food sources. The scientific literature 
demonstrates that adjacent waters in a watershed together exert a 
strong influence on the character and functioning of rivers, streams 
and lakes.
    Adjacent waters, as defined, alone or in combination with other 
adjacent waters in a watershed, significantly affect the chemical, 
physical, or biological integrity of traditional navigable waters, 
interstate waters, and the territorial seas. Based on studies of 
waters in riparian areas, flood plains, and their hydrologic 
connections through the tributary system there is sufficient 
scientific evidence regarding the important functions of these 
adjacent wetlands to demonstrate that, alone or in combination with 
similarly situated waters in the region, wetlands and open waters 
adjacent to any tributary have a significant effect on the chemical, 
physical, or biological integrity of traditional navigable waters, 
interstate waters, or the territorial seas. The reviewed scientific 
literature supports the conclusion that adjacent waters generally 
play a larger role in the ecological condition of smaller tributary 
systems, which, in turn, determines the effects on the chemical, 
physical, and biological health of larger downstream waters.

iii. ``Other Waters''

    The Report includes a focused evaluation of the connections and 
effects to downstream waters for several regional types of streams 
and wetlands: Prairie streams, southwest intermittent and ephemeral 
streams, oxbow lakes, Carolina and Delmarva bays, prairie potholes, 
and vernal pools. These regional types were chosen for evaluation 
because they represent a broad geographic area as well as a 
diversity of water types based on their origin, landscape setting, 
hydrology, and other factors. Most prairie streams and southwest 
intermittent and ephemeral streams are likely to be considered 
tributaries to (a)(1) through (a)(3) waters (with the exception of 
streams, for example, located in closed basins, which lack an (a)(1) 
through (a)(3) water or a connection thereto); similarly, most oxbow 
lakes are likely to be considered adjacent to (a)(1) through (a)(5) 
waters. Carolina and Delmarva bays, prairie potholes, and vernal 
pools may or may not be considered adjacent to (a)(1) through (a)(5) 
waters. Where waters are not considered tributaries (e.g. waters in 
a solely intrastate closed basin that does not contain a traditional 
navigable water, interstate water, or a territorial sea, or a 
connection thereto) or where waters, including wetlands, do not meet 
the proposed regulatory definition of adjacent, they should be 
evaluated to determine whether they are (a)(7) waters. The agencies 
seek comment on establishing such categories, as well as on other 
options for addressing ``other waters.''
    The term ``other waters'' refers to waters that cannot be 
considered ``adjacent'' to downstream jurisdictional waters and that 
are not tributaries of such waters. ``Other waters'' are found 
outside the riparian zone and the floodplain, as waters within these 
areas are considered to be ``adjacent.'' As such, wetlands that are 
``other waters'' typically will have unidirectional flow. As 
mentioned in Part II, section 2.B. above, many unidirectional 
wetlands are considered adjacent and interact with downstream 
jurisdictional waters through channels, shallow subsurface flow, or 
by providing additional functions such as storage and mitigating 
peak flows. Unidirectional wetlands that lack a confined surface 
connection or a shallow subsurface connection to downstream waters 
and are surrounded by uplands will typically fall under the 
definition of ``other waters,'' and are often referred to in 
scientific literature and policy as ``geographically isolated 
waters.'' The term ``geographically isolated'' should not be used to 
implicate the lack of connectivity to downstream waters, as these 
wetlands are often connected to downstream waters through deeper 
groundwater connections, biological connections, or spillage. The 
degree of connectivity of such wetlands will vary depending on 
landscape features such as distance from downstream waters and 
proximity to other wetlands of similar nature that as a group 
connect to jurisdictional downstream waters. Report at 3-43, 5-2.
    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 
each of the elements of Justice Kennedy's significant nexus standard 
in the definition of ``significant nexus.''

A. In the Region

    The agencies have 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 interpretation of Justice Kennedy's 
standard. See, e.g., D.R. Montgomery, ``Process Domains and the 
River Continuum,'' Journal of the American Water Resources 
Association 35:397-410 (1999).
    Using a watershed as the framework for conducting significant 
nexus evaluations is scientifically supportable. Watersheds are 
generally regarded as the most appropriate spatial unit for water 
resource management. See, e.g., J.M. Omernik and R.G. Bailey, 
``Distinguishing Between Watersheds and Ecoregions,'' Journal of the 
American Water Resources Association 33.5: 939-40 (1997); D.R. 
Montgomery, ``Process Domains and the River Continuum,'' Journal of 
the American Water Resources Association 35: 397-410 (1999); T.C. 
Winter ``The Concept of Hydrologic Landscapes,'' Journal of the 
American Water Resources Association 37: 335-49 (2001); J.S. Baron, 
et al., ``Meeting Ecological and Societal Needs for Freshwater,'' 
Ecological Applications 12: 1247-60 (2002); J.D. Allan, ``Landscapes 
and Riverscapes: The Influence of Land Use on Stream Ecosystems,'' 
Annual Review of Ecology Evolution and Systematics 35: 257-84 
(2004); United States, EPA 841-B-08-002: U.S. Environmental 
Protection Agency, Handbook for Developing Watershed Plans to 
Restore and Protect Our Waters: Planning & Implementation Steps 
(Washington D.C.: U.S. EPA, March 2008); P.J. Wigington, et al., 
``Oregon Hydrologic Landscapes: A Classification Framework,'' 
Journal of the American Water Resources Association 49.1:163-82 
(2013). Anthropogenic actions and natural events can have widespread 
effects within the watershed that collectively impact the quality of 
the relevant traditional navigable water, interstate water or 
territorial sea. United States, U.S. EPA and USDA/ARS Southwest 
Watershed Research Center, EPA/600/R-08/134, ARS/2330462008: The 
Ecological and Hydrological Significance of Ephemeral and 
Intermittent Streams in the Arid and Semi-arid American Southwest 
(Washington, D.C.: U.S. EPA and USDA/ARS Southwest Watershed 
Research Center, Levick et al., 2008) (Levick, et. al.). For these 
reasons, it is more appropriate to conduct a significant nexus 
determination at the watershed scale than to focus on a specific 
site, such as an individual stream segment. The watershed size 
reflects the specific water management objective, and is scaled up 
or down as is appropriate to meet that objective. If the objective 
is to manage the water quality in a particular receiving water body 
(the ``target'' water body), the watershed should include all those 
waters that are contributing to that target water since they will 
primarily determine the quality of the receiving water.
    The watershed that drains to the single point of entry to a 
traditional navigable water, interstate water or territorial sea is 
a logical spatial framework for the evaluation of the nexus. This is 
because, from a water quality management perspective, the (a)(1), 
(a)(2) or (a)(3) water is the downstream affected water whose 
quality is dependent on the condition of the contributing upstream 
waters, including streams, lakes, and wetlands. To restore or 
maintain the health of the downstream affected water, it is standard 
practice to evaluate the condition of the waters that are in the 
contributing watersheds and to develop a plan to address the issues 
of concern. The functions of the contributing waters are 
inextricably linked and have a cumulative effect on the integrity of 
the downstream traditional navigable water, interstate water or 
territorial sea. The size of that watershed can be determined by 
identifying the geographic area that drains to the nearest 
traditional navigable water, interstate water or the territorial 
seas, and then using that point of entry watershed to conduct a 
significant nexus evaluation. P.E. Black, ``Watershed Functions,'' 
Journal of the American Water Resources Association 33.1:1-11 
(1997).
    The Corps is organized based on watersheds and has used 
watershed framework approaches for water sources, navigation 
approaches for over 100 years, and in the regulatory program since 
its inception. Also, using a watershed framework is consistent with 
over two decades of practice by EPA and many other governmental, 
academic, and other entities which recognize that a watershed 
approach is the most effective framework to address water resource 
challenges. U.S. Environmental Protection Agency, The

[[Page 22247]]

Watershed Protection Approach Framework (Oct. 1991). The agencies 
both recognize the importance of the watershed approach by investing 
in opportunities to advance watershed protection and in developing 
useful watershed tools and services. For example, EPA is allowing 
states that are reorganizing programs to function on a watershed 
basis to have short-term backlogs on CWA section 402 National 
Pollution Discharge Elimination System (NPDES) permit review--
without penalty. This flexibility gives states time to synchronize 
the reissuance of major and minor permits within a watershed. By 
managing NPDES permits on a watershed basis, all the permits for 
discharges to the water body can be coordinated and the most 
efficient and equitable allocation of pollution control 
responsibility can be made. U.S. Environmental Protection Agency, 
Why Watersheds?, EPA 800-F-96-001 (February 1996). Applying a 
watershed approach continues to be a priority of EPA, and is one of 
the three key strategies the agency is using to drive progress 
toward the Agency's health and environmental goals over the next 
five years. U.S Environmental Protection Agency, FY 2011-2015 
Strategic Plan: Achieving Our Vision, 2010.

B. Similarly Situated

    Scientists routinely aggregate the effects of groups of waters, 
multiplying the known effect of one water by the number of similar 
waters in a specific geographic area, or to a certain scale. This 
kind of functional aggregation of non-adjacent (and other types of 
waters) is well-supported in the scientific literature. See, e.g., 
R.J. Stevenson and F.R. Hauer, ``Integrating Hydrogeomorphic and 
Index of Biotic Integrity Approaches for Environmental Assessment of 
Wetlands,'' Journal of the North American Benthological Society 
21(3): 502-513 (2002); S.G. Leibowitz, ``Isolated Wetlands and Their 
Functions: An Ecological Perspective,'' Wetlands 23:517-531 (2003); 
D. Gamble, et al., An Ecological and Functional Assessment of Urban 
Wetlands in Central Ohio, Ohio EPA Technical Report WET/2007-3B 
(Columbus, OH: Ohio Environmental Protection Agency, 2007); C.R. 
Lane and E. D'Amico, ``Calculating the Ecosystem Service of Water 
Storage in Isolated Wetlands using LiDAR in North Central Florida, 
USA,'' Wetlands 30:967-977 (2010); B.P. Wilcox, et al., ``Evidence 
of Surface Connectivity for Texas Gulf Coast Depressional 
Wetlands,'' Wetlands 31(3):451-8 (2011). Similarly, streams and 
rivers are routinely aggregated by scientists to estimate their 
combined effect on downstream waters in the same watershed. This is 
because chemical, physical, or biological integrity of downstream 
waters is directly related to the aggregate contribution of upstream 
waters that flow into them, including any tributaries and connected 
wetlands. As a result, the scientific literature and the Report 
consistently documents that the health of larger downstream waters 
is directly related to the aggregate health of waters located 
upstream, including waters such as wetlands that may not be 
hydrologically connected but function together to prevent 
floodwaters and contaminants from reaching downstream waters.
    In the aggregate, similarly situated wetlands may have 
significant effects on the quality of water many miles away, 
particularly in circumstances where numerous similarly situated 
waters are located in the region and are performing like functions 
that combine to influence downstream waters. See, e.g., A. Jansson 
et al., ``Quantifying the Nitrogen Retention Capacity of Natural 
Wetlands in the Large-Scale Drainage Basin of the Baltic Sea,'' 
Landscape Ecology 13:249-262 (1998); W.J. Mitsch et al., ``Reducing 
Nitrogen Loading to the Gulf of Mexico from the Mississippi River 
Basin: Strategies to Counter a Persistent Ecological Problem,'' 
BioScience 51(5): 373-388 (2001); M.G. Forbes, et al., ``Nutrient 
Transformation and Retention by Coastal Prairie Wetlands, Upper Gulf 
Coast, Texas,'' Wetlands 32(4):705-15 (2012). Cumulatively, many 
small wetlands can hold a large amount of snowmelt and 
precipitation, reducing the likelihood of flooding downstream. 
Report at 5-25 (citing D.E. Hubbard and R.L. Linder, ``Spring Runoff 
Retention in Prairie Pothole Wetlands,'' Journal of Soil and Water 
Conservation 41(2):122-125 (1986)).
    Scientists can and do routinely classify similar waters and 
wetlands into groups for a number of different reasons; because of 
their inherent physical characteristics, because they provide 
similar functions, because they were formed by similar geomorphic 
processes, and by their level of biological diversity, for example. 
Classifying wetlands based on their functions is also the basis for 
the U.S. Army Corps of Engineers hydrogeomorphic (HGM) 
classification of wetlands. M.M. Brinson, A Hydrogeomorphic 
Classification for Wetlands (Washington, D.C.: U.S. Army Corps of 
Engineers, 1993). The HGM method is a wetlands assessment approach 
pioneered by the Corps in the 1990s, and extensively applied via 
regional handbooks since then. The Corps HGM method uses a 
conceptual framework for identifying broad wetland classes based on 
common structural and functional features, which includes a method 
for using local attributes to further subdivide the broad classes 
into regional subclasses. Assessment methods like the HGM provide a 
basis for determining if waters provide similar functions based on 
their structural attributes and indicator species. Scientists also 
directly measure attributes and processes taking place in particular 
types of waters during in-depth field studies that provide reference 
information that informs the understanding of the functions 
performed by many types of aquatic systems nationwide.
    These waters, primarily depressional wetlands, small open waters 
and peatlands, are known to have important hydrologic, water 
quality, and habitat functions which vary as a result of the diverse 
settings in which they exist across the country. 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)). Some of the important factors which 
influence the variability of their functions and connectivity 
include the topography, geology, soil features, antecedent moisture 
conditions, and seasonal position of the water table relative to the 
wetland. Report at 5-25.
    When proposing that ``other waters'' are sufficiently close and 
should be considered similarly situated, it is recognized that they 
are more likely to have similar influence with regard to their 
effect on the chemical, physical, or biological integrity of a 
downstream water identified in paragraphs (a)(1) through (a)(3). If 
a water is a great distance from a group of similar ``other 
waters,'' it may be performing some of the same functions as those 
in the group, but their distance from each other or from downstream 
(a)(1) through (a)(3) waters will decrease the probability that it 
has some kind of chemical, physical, or biological connectivity to 
the downstream water, assuming that conditions governing the type 
and quantity of flows (e.g. slope, soil, and aquifer permeability, 
etc.) are similar. Id. at 5-2, 5-41.
    Consideration of the aggregate effects of wetlands and other 
waters often gives the most complete information about how such 
waters influence the chemical, physical, or biological integrity of 
downstream waters. In many watersheds, wetlands have a 
disproportionate effect on water quality relative to their surface 
area because wetland plants slow down water flow, allowing suspended 
sediments, nutrients, and pollutants to settle out. They filter 
these materials out of the water received from large areas, 
absorbing or processing them, and then releasing higher quality 
water. National Research Council, Wetlands: Characteristics and 
Boundaries (Washington, D.C.: National Academy Press, 1995), p. 38. 
For an individual wetland, this is most pronounced where it lies 
immediately upstream of a drinking water intake, for example. See, 
e.g., C.A. Johnston, et al., ``The Cumulative Effect of Wetlands on 
Stream Water Quality and Quantity,'' Biogeochemistry 10:105-141 
(1990).
    The structure and function of a river are highly dependent on 
the constituent materials that are stored in, or transported through 
the river. Most of the materials found in rivers originate outside 
of them. Thus, the fundamental way that ``other waters'' are able to 
affect river structure and function is by providing or altering the 
materials delivered to the river. Report at 1-13. Since the 
alteration of material fluxes depends on the functions within these 
waters and the degree of connectivity, it is appropriate to consider 
both these factors for purposes of significant nexus under this 
provision.
    Numerous factors affect chemical, physical, and biological 
connectivity, operating at multiple spatial and temporal scales, and 
interacting with each other in complex ways, to determine where 
components of aquatic systems fall on the connectivity-isolation 
gradient at a given time. Some of these factors include climate, 
watershed characteristics, spatial distribution

[[Page 22248]]

patterns, biota, and human activities and alterations. Id. at 3-33. 
Recognizing the limits on the ability to observe or document all of 
these interacting factors, it is reasonable to look for visible 
patterns in the landscape and waters that are often indicative of 
the connectivity factors, in determining what waters to aggregate. 
Due to relative similarity of soils, topography, or groundwater 
connections, for example, there may be a group of wetlands scattered 
throughout a watershed, at similar distances from the tributaries in 
the watershed and performing similar functions. It is appropriate to 
assess the significance of the nexus of those waters in the 
aggregate, consistent with Justice Kennedy's standard.

C. Significant Nexus

    The scientific literature regarding ``other waters'' documents 
their functions, including the chemical, physical, and biological 
impact they can have downstream. Available literature indicates that 
``other waters'' have important hydrologic, water quality, and 
habitat functions that have the ability to affect downstream waters 
if and when a connection exists between the ``other water'' and 
downstream waters. Report at 6-1. ``Other waters'' generally fit 
into the category of unidirectional waters as described in the 
Report. However, there are some unidirectional waters that are in 
fact adjacent under (a)(6) to (a)(1) through (a)(5) waters (e.g., 
neighboring waters that are outside of the riparian area and/or 
floodplain but that have a surface or shallow subsurface hydrologic 
connection to (a)(1) through (a)(5) waters). Connectivity of ``other 
waters'' to downstream waters that do not meet the definition of 
adjacent will vary within a watershed and over time, which is why a 
case-specific significant nexus determination for ``other waters'' 
is necessary under (a)(7). See, e.g., id. at 6-2. The types of 
chemical, physical, and biological connections between ``other 
waters'' and downstream waters are described below for illustrative 
purposes. As described in the preamble above, when the agencies are 
conducting a case-specific determination for significant nexus under 
(a)(7), they examine the connections between the water (including 
any similarly situated waters in the region) and downstream waters 
and determine if those connections significantly affect the 
chemical, physical, or biological integrity of the downstream water, 
using any available site-information and field observations where 
available, relevant scientific studies or data, or other relevant 
jurisdictional determinations that have been made on similar 
resources in the region.
    The hydrologic connectivity of ``other waters'' to downstream 
waters occurs on a gradient and can include waters that have 
groundwater or occasional surface water connections (through 
overland flow) to the tributary network and waters that have no 
hydrologic connection to the tributary network. Id. at 5-1. The 
connectivity of ``other waters'' to downstream waters will vary 
within a watershed as a function of local factors (e.g. position, 
topography, and soil characteristics). Id. at 3-41 to 3-43. 
Connectivity also varies over time, as the tributary network and 
water table expand and contract in response to local climate. Id. at 
3-31 to 3-33. Lack of connection does not necessarily translate to 
lack of impact; even when lacking connectivity, waters can still 
impact chemical, physical, and biological conditions downstream. Id. 
at 3-29, 3-31.
    The physical effect that ``other waters'' have downstream is 
less obvious than the physical connections of waters that are 
adjacent or waters that are tributary, due to the physical distance 
of ``other waters'' from the stream network. Despite this physical 
distance, they are frequently connected in some degree through 
either surface water or groundwater systems; over time, impacts in 
one part of the hydrologic system will be felt in other parts. T.C. 
Winter and J.W. LaBaugh, ``Hydrologic Considerations in Defining 
Isolated Wetlands,'' Wetlands 23:532-540 (2003) at 538. For example, 
``other waters'' that overspill into downstream water bodies during 
times of abundant precipitation are connected over the long term. 
Id. at 539. Wetlands that lack surface connectivity in a particular 
season or year can, nonetheless, be highly connected in wetter 
seasons or years. Report at 5-22 to 5-25. Many ``other waters'' 
interact with groundwater, either by receiving groundwater discharge 
(flow of groundwater to the ``other water''), contributing to 
groundwater recharge (flow of water from the ``other water'' to the 
groundwater), or both. Id. at 5-23 (citing R.F. Lide, et al., 
``Hydrology of a Carolina Bay Located on the Upper Coastal Plain of 
Western South Carolina,'' Wetlands 15:47-57 (1995); K.J. Devito, et 
al., ``Groundwater Surface-Water Interactions in Headwater Forested 
Wetlands of the Canadian Shield,'' Journal of Hydrology 181:127-47 
(1996); R.K. Matheney and P.J. Gerla, ``Environmental Isotopic 
Evidence for the Origins of Ground and Surface Water in a Prairie 
Discharge Wetland,'' Wetlands 16:109-120 (1996); D.O. Rosenberry and 
T.C. Winter, ``Dynamics of Water-Table Fluctuations in an Upland 
between Two Prairie-Pothole Wetlands in North Dakota,'' Journal of 
Hydrology 191:266-289 (1997); J.E. Pyzoha, et al., ``A Conceptual 
Hydrologic Model for a Forested Carolina Bay Depressional Wetland on 
the Coastal Plain of South Carolina, USA,'' Hydrological Processes 
22:2689-2698 (2008)). Factors that determine whether a water 
recharges groundwater or is a site of groundwater discharge include 
topography, geology, soil features, and seasonal position of the 
water table relative to the water. Id. at 5-24 (citing P.J. Phillips 
and R.J. Shedlock, ``Hydrology and Chemistry of Groundwater and 
Seasonal Ponds in the Atlantic Coastal-Plain in Delaware, USA,'' 
Journal of Hydrology 141:157-78 (1993); R.J. Shedlock, et al., 
``Interactions between Ground-Water and Wetlands, Southern Shore of 
Lake-Michigan, USA,'' Journal of Hydrology 141:127-55 (1993); D.O. 
Rosenberry and T.C. Winter, ``Dynamics of Water-Table Fluctuations 
in an Upland Between two Prairie-Pothole Wetlands in North Dakota,'' 
Journal of Hydrology 191:266-89 (1997); J.E. Pyzoha, et al., ``A 
Conceptual Hydrologic Model for a Forested Carolina Bay Depressional 
Wetland on the Coastal Plain of South Carolina, USA,'' Hydrological 
Processes 22: 2689-98 (2008)). Similarly, the magnitude and transit 
time of groundwater flow from an ``other water'' to downstream 
waters depend on several factors, including the intervening distance 
and the properties of the rock or unconsolidated sediments between 
the water bodies (i.e., the hydraulic conductivity of the material). 
Id. at 5-24. Surface and groundwater hydrological connections are 
those generating the capacity for ``other waters'' to affect 
downstream waters, as water from the ``other water'' may contribute 
to baseflow or stormflow through groundwater recharge. Id. at 5-25. 
Contributions to baseflow are important for maintaining conditions 
that support aquatic life in downstream waters. As discussed further 
below, even in cases where waters lack a connection to downstream 
waters, they can influence downstream water through water storage 
and mitigation of peak flows. Id. at 5-36.
    The chemical effects that ``other waters'' have on downstream 
waters are linked to their hydrologic connection downstream, though 
a surface connection is not needed for a water to influence the 
chemical integrity of the downstream water. Because the majority of 
``other waters'' are hydrologically connected to downstream waters 
via surface or groundwater connections, most ``other waters'' can 
affect water quality downstream (although these connections do not 
meet the definition of adjacency). D.F. Whigham and T. E. Jordan, 
``Isolated Wetlands and Water Quality,'' Wetlands 23:541-549 (2003) 
at 542. ``Other waters'' can act as sinks and transformers for 
nitrogen and phosphorus, metals, pesticides, and other contaminants 
that could otherwise negatively impact downstream waters. Report at 
5-30 (citing R.R. Brooks, et al., ``Cobalt and Nickel Uptake by the 
Nyssaceae,'' Taxon 26:197-201 (1977); H.F. Hemond, ``Biogeochemistry 
of Thoreau's Bog, Concord, Massachusetts,'' Ecological Monographs 
50:507-526 (1980); C.B. Davis, et al., ``Prairie Pothole Marshes as 
Traps for Nitrogen and Phosphorus in Agricultural Runoff,'' in B. 
Richardson, ed., Selected Proceedings of the Midwest Conference on 
Wetland Values and Management, June 17-19, 1981, St. Paul, MN, (St. 
Paul, MN: The Freshwater Society, 1981), pp. 153-163; H.F. Hemond, 
``The Nitrogen Budget of Thoreau's Bog,'' Ecology 64:99-109 (1983); 
K.C. Ewel and H.T. Odum, ed., Cypress Swamps, (Gainesville, Florida: 
University of Florida Press, 1984); J.T. Moraghan, ``Loss and 
Assimilation of 15N-nitrate Added to a North Dakota Cattail Marsh,'' 
Aquatic Botany 46:225-234 (1993); C.M. Kao, et al., ``Non-point 
Source Pesticide Removal by a Mountainous Wetland,'' Water Science 
and Technology 46:199-206 (2002); P.I. Boon, ``Biogeochemistry and 
Bacterial Ecology of Hydrologically Dynamic Wetlands,'' in D.P. 
Batzer and R.R. Sharitz, ed., Ecology of Freshwater and Estuarine 
Wetlands (Berkeley, CA: University of California Press, 2006), pp. 
115-176; E.J. Dunne, et al., ``Phosphorus Release and Retention by 
Soils of Natural Isolated Wetlands,'' International Journal of 
Environment and Pollution 28:496-516 (2006); T.E. Jordan, et al., 
``Comparing Functional Assessments of Wetlands to Measurements of 
Soil Characteristics and Nitrogen Processing,'' Wetlands 27:479-497

[[Page 22249]]

(2007); S.L. Whitmire and S.K. Hamilton, ``Rates of Anaerobic 
Microbial Metabolism in Wetlands of Divergent Hydrology on a Glacial 
Landscape,'' Wetlands 28:703-714 (2008)). Also see, e.g., T.M. 
Isenhart, Transformation and Fate of Nitrate in Northern Prairie 
Wetlands, Ph.D. Dissertation (Ames, Iowa: Iowa State University, 
1992). The body of published scientific literature and the Report 
indicate that sink removal of nutrients and other pollutants by 
``other waters'' is significant and geographically widespread. 
Report at 5-30. Water quality characteristics of ``other waters'' 
are highly variable, depending primarily on the sources of water, 
characteristics of the substrate, and land uses within the 
watershed. D.F. Whigham and T.E. Jordan, ``Isolated Wetlands and 
Water Quality,'' Wetlands 23:541-549 (2003) at 541. These variables 
inform whether an ``other water'' has a significant nexus to an 
(a)(1) through (a)(3) water. For instance, some prairie potholes may 
improve water quality and may efficiently retain nutrients that 
might otherwise cause water quality problems downstream; in such 
systems it may be their lack of a direct hydrologic connection that 
enables the prairie potholes to more effectively retain nutrients. 
Id. at 543.
    ``Other waters'' can be biologically connected to each other and 
to downstream waters through the movement of seeds, 
macroinvertebrates, amphibians, reptiles, birds, and mammals. Report 
at 5-31 to 5-33; S.G. Leibowitz, ``Isolated Wetlands and Their 
Functions: An Ecological Perspective,'' Wetlands 23:517-531 (2003) 
at 519. The movement of organisms between ``other waters'' and 
downstream waters is governed by many of the same factors that 
affect movement of organisms between adjacent wetlands and 
downstream waters (See Part II Section 2.A.d.). Report at 5-31. 
Generally, ``other waters'' are further away from stream channels 
than adjacent waters, making hydrologic connectivity less frequent, 
and increasing the number and variety of landscape barriers over 
which organisms must disperse. Id. Plants, though non-mobile, have 
evolved many adaptations to achieve dispersal over a variety of 
distances, including water-borne dispersal during periodic 
hydrologic connections, ``hitchhiking'' on or inside highly mobile 
animals, and more typically via wind dispersal of seeds and/or 
pollen. Id. at 5-31 (citing S.M. Galatowitsch and A.G. van der Valk, 
``The Vegetation of Restored and Natural Prairie 
Wetlands,''Ecological Applications 6:102-112 (1996); H.R. Murkin and 
P.J. Caldwell, ``Avian Use of Prairie Wetlands,'' in H.R. Murkin, et 
al., ed., Prairie Wetland Ecology: The Contribution of the Marsh 
Ecology Research Program, (Ames, IA: Iowa State University Press, 
2000), pp. 249-286; J.M. Amezaga, et al., ``Biotic Wetland 
Connectivity--Supporting a New Approach for Wetland Policy,'' Acta 
Oecologica-International Journal of Ecology 23:213-222 (2002); J. 
Figuerola and A.J. Green, ``Dispersal of Aquatic Organisms by 
Waterbirds: a Review of Past Research and Priorities for Future 
Studies,'' Freshwater Biology 47:483-494 (2002); M.B. Soons and G.W. 
Heil, ``Reduced Colonization Capacity in Fragmented Populations of 
Wind-Dispersed Grassland Forbs,'' Journal of Ecology 90:1033-1043 
(2002); M.B. Soons, ``Wind Dispersal in Freshwater Wetlands: 
Knowledge for Conservation and Restoration,'' Applied Vegetation 
Science 9:271-278 (2006); C. Nilsson, et al., ``The Role of 
Hydrochory in Structuring Riparian and Wetland Vegetation,'' 
Biological Reviews 85:837-858 (2010)). Mammals that disperse 
overland can also contribute to connectivity and can act as 
transport vectors for hitchhikers such as algae. Id. at 5-32 (citing 
C.E. Shanks and G.C. Arthur, ``Muskrat Movements and Population 
Dynamics in Missouri Farm Ponds and Streams,'' Journal of Wildlife 
Management 16:138-148 (1952); J.P. Roscher, ``Alga Dispersal by 
Muskrat Intestinal Contents,'' Transactions of the American 
Microscopical Society 86:497-498 (1967); W.R. Clark, ``Ecology of 
Muskrats in Prairie Wetlands,'' in H. R. Murkin, et al., ed., 2000, 
pp. 287-313)). Invertebrates also utilize birds and mamals to 
hitchhike, and these hitchhikers can be an important factor 
structuring invertebrate metapopulations in ``other waters'' and in 
aquatic habitats separated by hundreds of kilometers. Id. (citing J. 
Figuerola and A.J. Green, ``Dispersal of Aquatic Organisms by 
Waterbirds: A Review of Past Research and Priorities for Future 
Studies,'' Freshwater Biology 47:483-494 (2002); J. Figuerola, et 
al., ``Invertebrate Eggs Can Fly: Evidence of Waterfowl-Mediated 
Gene Flow in Aquatic Invertebrates,'' American Naturalist 165:274-
280 (2005); M.R. Allen, ``Measuring and Modeling Dispersal of Adult 
Zooplankton,'' Oecologia 153:135-143 (2007); D. Frisch, et al., 
``High Dispersal Capacity of a Broad Spectrum of Aquatic 
Invertebrates Via Waterbirds,'' Aquatic Sciences 69:568-574 (2007)). 
Numerous flight-capable insects use both ``other waters'' and 
downstream waters; these insects move outside the tributary network 
to find suitable habitat for overwintering, refuge from adverse 
conditions, hunting, foraging, or breeding, and then can return back 
to the tributary network for other lifecycle needs. Id. at 5-33 
(citing D.D. Williams, ``Environmental Constraints in Temporary 
Fresh Waters and Their Consequences for the Insect Fauna,'' Journal 
of the North American Benthological Society 15:634-650 (1996); A.J. 
Bohonak and D.G. Jenkins, ``Ecological and Evolutionary Significance 
of Dispersal by Freshwater Invertebrates,'' Ecology Letters 6:783-
796 (2003)). Amphibians and reptiles also move between ``other 
waters'' and downstream waters to satisfy part of their life history 
requirements. Id. at 5-33. Alligators in the Southeast, for 
instance, can move from tributaries to shallow, seasonal limesink 
wetlands for nesting, and also use these wetlands as nurseries for 
juveniles; sub-adults then shift back to the tributary network 
through overland movements. Id. (citing A.L. Subalusky, et al., 
``Ontogenetic Niche Shifts in the American Alligator Establish 
Functional Connectivity between Aquatic Systems,'' Biological 
Conservation 142:1507-1514 (2009); A.L. Subalusky, et al., 
``Detection of American Alligators in Isolated, Seasonal Wetlands,'' 
Applied Herpetology 6:199-210 (2009)). Similarly, amphibians and 
small reptile species, such as frogs, toads, and newts, commonly use 
both tributaries and ``other waters,'' during one or more stages of 
their life cycle, and can at times disperse over long distances. Id. 
(citing V.S. Lamoureux and D.M. Madison, ``Overwintering Habitats of 
Radio-Implanted Green Frogs, Rana clamitans,'' Journal of 
Herpetology 33:430-435 (1999); K.J. Babbitt, et al., ``Patterns of 
Larval Amphibian Distribution along a Wetland Hydroperiod 
Gradient,'' Canadian Journal of Zoology-Revue Canadienne De Zoologie 
81:1539-1552 (2003); S.B. Adams, et al., ``Instream Movements by 
Boreal Toads (Bufo boreas boreas),'' Herpetological Review 36:27-33 
(2005); D.M. Green, ``Bufo americanus, American Toad,'' in M. 
Lannoo, ed., Amphibian Declines: The Conservation Status of the 
United States Species (Berkeley, CA: University of California Press, 
2005), pp. 692-704; T.W. Hunsinger and M. J. Lannoo, ``Notophthalmus 
viridescens, Eastern Newt,'' in M. Lannoo, ed., 2005, pp. 912-914; 
J.W. Petranka and C.T. Holbrook, ``Wetland Restoration for 
Amphibians: Should Local Sites Be Designed to Support 
Metapopulations or Patchy Populations?,'' Restoration Ecology 
14:404-411 (2006)).
    Even when a surface or groundwater hydrologic connection between 
a water and a downstream water is visibly absent, many waters still 
have the ability to substantially influence the integrity of 
downstream waters. However, such circumstances would be uncommon. 
Id. at 5-22 to 5-25. Aquatic systems that may seem disconnected 
hydrologically are often connected but at irregular timeframes or 
through subsurface flow, and perform important functions that can be 
vital to the chemical, physical, or biological integrity of 
downstream waters. Some wetlands that are not adjacent may be 
hydrologically disconnected most of the time but connected to the 
stream network during rare high-flow events. The lack of a 
hydrologic connection also allows for water storage in ``other 
waters,'' attenuating peak streamflows, and, thus, downstream 
flooding, and also reducing nutrient and soil pollution in 
downstream waters. Report at 5-25 to 5-26, 5-36. Prairie potholes a 
great distance from any tributary, for example, are thought to store 
significant amounts of runoff. Id. at 5-36 (citing R.P. Novitzki, 
``Hydrologic Characteristics of Wisconsin's Wetlands and Their 
Influence on Floods,'' in P. Greeson, et al., ed., Wetland Functions 
and Values: The Status of Our Understanding, Proceedings of the 
National Symposium on Wetlands (Minneapolis, MN: American Water 
Resources Association, 1979), pp. 377-388; D.E. Hubbard and R.L. 
Linder, ``Spring Runoff Retention in Prairie Pothole Wetlands,'' 
Journal of Soil and Water Conservation 41:122-125 (1986); J. Jacques 
and D.L. Lorenz, ``Techniques for Estimating the Magnitude and 
Frequency of Floods in Minnesota,'' Water Resources Investigations 
Report 87-4170, (St. Paul, MN: U.S. Geological Survey, 1988); K.C. 
Vining, ``Simulation of Streamflow and Wetland Storage, Starkweather 
Coulee Subbasin, North Dakota, Water Years 1981-98,'' Water-
Resources Investigations Report 02-4113 (Bismarck, North Dakota: 
U.S. Geological

[[Page 22250]]

Survey, 2002); R.A. Gleason, et al., Estimating Water Storage 
Capacity of Existing and Potentially Restorable Wetland Depressions 
in a Subbasin of the Red River of the North, U.S. Geological Survey 
Open-File Report 2007-1159 (Reston, VA: U.S. Geological Survey, 
2007); D.L. Lorenz, et al., ``Techniques for Estimating the 
Magnitude and Frequency of Peak Flows on Small Streams in Minnesota 
Based on Through Water Year 2005,'' USGS Scientific Investigations 
Report 2009-5250, (Reston, VA: U.S. Geological Survey, 2010)). 
Filling wetlands reduces water storage capacity in the landscape and 
causes runoff from rainstorms to overwhelm the remaining available 
water conveyance system. See, e.g., C.A. Johnston, et al., ``The 
Cumulative Effect of Wetlands on Stream Water Quality and 
Quantity,'' Biogeochemistry 10:105-141 (1990); A.L. Moscrip and D.R. 
Montgomery, ``Urbanization, Flood Frequency, and Salmon Abundance in 
Puget Lowland Streams,'' Journal of the American Water Resources 
Association 33:1289-1297 (1997); N.E. Detenbeck, et al., 
``Evaluating Perturbations and Developing Restoration Strategies for 
Inland Wetlands in the Great Lakes Basin,'' Wetlands 19(4): 789-820 
(1999); N.E. Beck, et al., ``Relationship of Stream Flow Regime in 
the Western Lake Superior Basin to Watershed Type Characteristics,'' 
Journal of Hydrology 309(1-4): 258-276 (2005). Wetlands, even when 
lacking a hydrologic connection downstream, improve downstream water 
quality by accumulating nutrients, trapping sediments, and 
transforming a variety of substances. See, e.g., National Research 
Council, Wetlands: Characteristics and Boundaries (Washington, DC: 
National Academy Press, 1995), p. 38.
    Under today's proposal, on a case-specific basis, ``other 
waters'' that have a significant nexus to an (a)(1) through (a)(3) 
water are ``waters of the United States'' under (a)(7). The 
scientific literature and data in the Report and elsewhere support 
that some ``other waters'' (including some of those in the case 
studies), along with other similarly situated waters in the region, 
do greatly affect the chemical, physical, or biological integrity of 
(a)(1) through (a)(3) waters, and thus would be jurisdictional under 
(a)(7).
    Though much of the literature cited in the Report relates to 
``other waters'' that are wetlands, the Report indicates that non-
wetland waters that are not (a)(1) through (a)(6) waters also can 
have chemical, physical, or biological connections that 
significantly impact downstream waters. For instance, non-adjacent 
ponds or lakes that are not part of the tributary network can still 
be connected to downstream waters through chemical, physical, and 
biological connections. Lake storage has been found to attenuate 
peak streamflows in Minnesota. Id. at 5-25 (citing J. Jacques and 
D.L. Lorenz, Techniques for Estimating the Magnitude and Frequency 
of Floods of Ungauged Streams in Minnesota, USGS Water-Resources 
Investigations Report 84-4170 (Washington, DC: U.S. Geological 
Survey, 1988); D.L. Lorenz, et al., Techniques for Estimating the 
Magnitude and Frequency of Peak Flows on Small Streams in Minnesota 
Based on Data through Water Year 2005, U.S. Geological Survey 
Scientific Investigations Report 2009-5250 (Reston, VA: U.S. 
Geological Survey, 2010)). Similar to wetlands, ponds are often used 
by invertebrate, reptile, and amphibian species that also utilized 
downstream waters for various life history requirements, 
particularly because many ponds, particularly temporary ponds, are 
free of predators, such as fish, that prey on larvae. The American 
toad and Eastern newt are widespread habitat generalists that can 
move among streams, wetlands, and ponds to take advantage of each 
aquatic habitat, feeding on aquatic invertebrate prey, and avoiding 
predators. See, e.g., Id. at 5-33 (citing K.J. Babbitt et al., 
``Patterns of Larval Amphibian Distribution along a Wetland 
Hydroperiod Gradient,'' Canadian Journal of Zoology-Revue Canadienne 
De Zoologie 81:1539-1552 (2003); D.M. Green, ``Bufo americanus, 
American Toad,'' in M. Lannoo, ed., Amphibian Declines: The 
Conservation Status of United States Species, (Berkeley, CA: 
University of California Press, 2005), pp. 692-704; T.W. Hunsinger 
and M.J. Lannoo, ``Notophthalmus viridescens, Eastern Newt,'' in M. 
Lannoo, ed., Amphibian Declines: The Conservation Status of United 
States Species, (Berkeley, CA: University of California Press, 
2005), pp. 912-914; J.W. Petranka and C.T. Holbrook, ``Wetland 
Restoration for Amphibians: Should Local Sites Be Designed to 
Support Metapopulations or Patchy Populations?,'' Restoration 
Ecology 14:404-411 (2006)). Additionally, stream networks that are 
not part of the tributary system (e.g., streams in closed basins 
without an (a)(1) through (a)(3) water or losing streams and other 
streams that cease to flow before reaching downstream (a)(1) through 
(a)(3) waters) may likewise have a significant impact on the 
chemical, physical, or biological integrity of downstream waters. 
Non-tributary streams may be connected via groundwater to downstream 
waters. Such streams may also provide habitat to insect, amphibian, 
and reptile species that also use the tributary network.

i. Additional Request for Public Comment on ``Other Waters''

    The agencies are considering whether to determine by rule that 
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. 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). These waters would not 
require a case-by-case analysis. At the same time, the agencies 
could determine by rule that playa lakes, and perhaps other 
categories of waters, do not have a significant nexus and are not 
jurisdictional. These waters would not be subject to a case-by-case 
analysis of significant nexus. As the science develops, the agencies 
may determine that additional categories of ``other waters'' have a 
significant nexus and are thus categorically jurisdictional. The 
specific categories of ``other waters'' for which there is currently 
evidence of a significant nexus are discussed below:
    a. Prairie potholes are a complex of glacially formed wetlands, 
usually occurring in depressions that lack permanent natural 
outlets, that are found in the central United States and Canada. 
Report at 5-57. The vast area they occupy is variable in many 
aspects, including climatically, topographically, geologically, and 
in terms of land use and alteration, which imparts variation on the 
potholes themselves. Prairie potholes demonstrate a wide range of 
hydrologic permanence, from holding permanent standing water to 
wetting only in years with high precipitation, which in turn 
influences the diversity and structure of their biological 
communities. Owing in large part to their spatial and temporal 
variability, individual prairie potholes span the entire continuum 
of connectivity to and isolation from the river network and other 
bodies of water. Potholes generally accumulate and retain water 
effectively due to the low permeability of their underlying soil, 
which can modulate flow characteristics of nearby streams and 
rivers. Potholes also can accumulate chemicals in overland flow, 
thereby reducing chemical loading to other bodies of water. When 
potholes are artificially connected to streams and lakes through 
drainage, isolation is eliminated and they become sources of water 
and chemicals. Potholes also support a community of highly mobile 
organisms, from plants to invertebrates that move among potholes and 
that can biologically connect the entire complex to the river 
network. Based on these connections and the strength of their 
effects, individually or in combination with other prairie potholes 
in the watershed, on the chemical, physical, or biological integrity 
of an (a)(1) through (a)(3) water, the agencies could conclude by 
rule that prairie potholes have a significant nexus and are 
jurisdictional. The agencies' determination will be informed by the 
final version of the Report and other available scientific 
information.
    b. Carolina and Delmarva bays are ponded depressional wetlands 
that occur along the Atlantic coastal plain from northern Florida to 
New Jersey. Id. at 5-49. Most bays receive water through 
precipitation, lose water through evapotranspiration, and lack 
natural surface outlets. Both mineral-based and peat-based bays have 
shown connections to shallow groundwater. Bays typically are in 
proximity to each other or to open waters, providing the potential 
for surface water connections in large rain events via overland 
flow. Fish are reported in bays that are known to dry out, 
indirectly demonstrating surficial connections. Amphibians and 
reptiles use bays extensively for breeding and for rearing young. 
These animals can disperse many meters on the landscape and can 
colonize, or serve as a food source to, downstream waters. 
Similarly, bays foster abundant insects that have the potential to 
become part of the downstream food chain. Humans have ditched and 
channelized a high percentage of bays, creating new surface 
connections to ``other waters'' and allowing

[[Page 22251]]

transfer of nutrients, sediment, and other pollutants such as 
methylmercury. Based on these connections and the strength of their 
effects, individually or in combination with other Carolina or 
Delmarva bays in the watershed, on the chemical, physical, or 
biological integrity of an (a)(1) through (a)(3) water, the agencies 
could conclude by rule that Carolina and Delmarva bays have a 
significant nexus and are jurisdictional. The agencies' 
determination will be informed by the final version of the Report 
and other available scientific information.
    c. Vernal pools are shallow, seasonal wetlands that accumulate 
water during colder, wetter months and gradually dry up during 
warmer, drier months. Id. at 5-66. Western vernal pools are seasonal 
wetlands associated with topographic depressions, soils with poor 
drainage, mild, wet winters and hot, dry summers in western North 
America from southeastern Oregon to northern Baja California, Mexico 
(Id. at 5-67, citing E.T. Bauder and S. McMillan, ``Current 
Distribution and Historical Extent of Vernal Pools in Southern 
California and Northern Baja California, Mexico,'' pp. 56-70 in C.W. 
Witham, et al., editors, Ecology, Conservation, and Management, 
1998). Because their hydrology and ecology are so tightly coupled 
with the local and regional geological processes that formed them, 
western vernal pools typically occur within ``vernal pool 
landscapes,'' or complexes of pools in which swales connect pools to 
each other and to seasonal streams (Id. at 5-67 to 5-68, citing W.A. 
Weitkamp, et al., ``Pedogenesis of a Vernal Pool Entisol-Alfisol-
Vertisol Catena in Southern California,'' Soil Science Society of 
America Journal 60:316323 (1996); D.W. Smith and W.L. Verrill, 
``Vernal Pool-Soil-Landform Relationships in the Central Valley, 
California,'' pp. 15-23 in C.W. Witham, et al., editors, Ecology, 
Conservation, and Management of Vernal Pool Ecosystems--Proceedings 
from a 1996 Conference (California Native Plant Society, Sacramento, 
CA,1998); M.C. Rains, et al., ``The Role of Perched Aquifers in 
Hydrological Connectivity and Biogeochemical Processes in Vernal 
Pool Landscapes, Central Valley, California,'' Hydrological 
Processes 20:1157-1175 (2008)). Despite differences in geology, 
climate, and biological communities, some common findings about the 
hydrologic connectivity of vernal pools in different regions, 
including Western vernal pools, include evidence for temporary or 
permanent outlets, frequent filling and spilling of higher pools 
into lower elevation swales and stream channels, and conditions 
supporting subsurface flows through pools without perched aquifers 
to nearby streams. Non-glaciated vernal pools in western states are 
reservoirs of biodiversity and can be connected genetically to other 
locations and aquatic habitats through wind- and animal-mediated 
dispersal. Based on these connections and the strength of their 
effects, individually or in combination with other western vernal 
pools in the watershed, on the chemical, physical, or biological 
integrity of an (a)(1) through (a)(3) water, the agencies could 
conclude by rule that western vernal pools have a significant nexus 
and are jurisdictional. The agencies' determination will be informed 
by the final version of the Report and other available scientific 
information. The jurisdictional status of vernal pools located in 
other areas will be determined on a case-by-case significant nexus 
analysis with any similar situated waters in the single point of 
entry watershed. For example, insects and amphibians that can live 
in streams or permanent pools opportunistically use glaciated vernal 
pools in the Northeast and Midwest as alternative breeding habitat, 
refuge from predators or environmental stressors, hunting or 
foraging habitat, or stepping-stone corridors for dispersal and 
migration.
    d. The word pocosin comes from the Algonquin Native American 
word for ``swamp on a hill,'' and these evergreen shrub and tree 
dominated landscapes are found from Virginia to northern Florida, 
but mainly in North Carolina. (C.J. Richardson, ``Pocosins: 
Hydrologically Isolated or Integrated Wetlands on the Landscape?,'' 
Wetlands 23(3):563-576 (2003)). Usually, there is no standing water 
present in these peat-accumulating wetlands, but a shallow water 
table leaves the soil saturated for much of the year. They range in 
size from less than an acre to several thousand acres. The slow 
movement of water through the dense organic matter in pocosins 
removes excess nutrients deposited by rainwater. The same organic 
matter also acidifies the water. This pure water is slowly released 
to downstream waters and estuaries, where it helps to maintain the 
proper salinity, nutrients, and acidity. (Id.) Because pocosins are 
the topographic high areas on the regional landscape, they serve as 
the source of water for downstream areas. Pocosins often have 
seasonal connections to drainageways leading to estuaries or are 
contiguous with other wetlands draining into perennial streams or 
estuaries. (R.W. Tiner, ``Geographically Isolated Wetlands of the 
United States,'' Wetlands 23(3):494-516 (2003)). Other pocosins have 
been ditched and are directly connected to streams. (Id.) The 
draining of pocosins and decreased salinity in estuaries may be 
having a negative effect on brown shrimp in North Carolina. (Id.) 
Based on these connections and the strength of their effects, 
individually or in combination with other pocosins in the watershed, 
on the chemical, physical, or biological integrity of an (a)(1) 
through (a)(3) water, the agencies could conclude by rule pocosins 
have a significant nexus and are jurisdictional. The agencies' 
determination will be informed by the final version of the Report 
and other available scientific information.
    e. Along the Gulf of Mexico from western Louisiana to south 
Texas, freshwater wetlands occur as a mosaic of depressions, ridges, 
intermound flats, and mima mounds. (M.G. Forbes, et al., ``Nutrient 
Transformation and Retention by Coastal Prairie Wetlands, Upper Gulf 
Coast, Texas,'' Wetlands 32(4): 705-715 (2012)). These coastal 
prairie wetlands were formed thousands of years ago by ancient 
rivers and bayous and once occupied almost a third of the landscape 
around Galveston Bay, Texas. Texas coastal prairie wetlands are 
locally abundant and in close proximity to other coastal prairie 
wetlands and function together cumulatively. (N. Enwright, et al., 
``Using Geographic Information Systems (GIS) to Inventory Coastal 
Prairie Wetlands Along the Upper Gulf Coast, Texas,'' Wetlands 
31:687-697 (2011)). Collectively as a complex, Texas coastal prairie 
wetlands may be geographically and hydrologically connected to each 
other via swales and connected to downstream waters, contributing 
flow to those downstream waters. (B.P. Wilcox, et al., ``Evidence of 
Surface Connectivity for Texas Gulf Coast Depressional Wetlands,'' 
Wetlands 31(3):451-458 (2011)). Cumulatively, these wetlands can 
control nutrient release levels and rates to downstream waters, as 
they capture, store, transform and pulse releases of nutrients to 
those waters. (M.G. Forbes, et al., ``Nutrient Transformation and 
Retention by Coastal Prairie Wetlands, Upper Gulf Coast, Texas,'' 
Wetlands 32(4): 705-715 (2012)). Based on these connections and the 
strength of their effects, individually or in combination with other 
coastal prairie wetlands in the watershed, on the chemical, 
physical, or biological integrity of an (a)(1) through (a)(3) water, 
the agencies could conclude by rule Texas coastal prairie wetlands 
have a significant nexus and are jurisdictional. The agencies' 
determination will be informed by the final version of the Report 
and other available scientific information.
    The agencies could also conclude that playa lakes in the Great 
Plains even in combination with other playa lakes in a single point 
of entry watershed always lack a significant nexus and therefore are 
not jurisdictional. Playa lakes are round, shallow wetlands found 
primarily in the High Plains, a subregion of the Great Plains in the 
western and Midwestern United States. (D.A. Haukos, and L.M. Smith, 
``Past and Future Impacts of Wetland Regulations on Playas,'' 
Wetlands 23(3):577-589 (2003); R.W. Tiner, ``Geographically Isolated 
Wetlands of the United States,'' Wetlands 23(3):494-516 (2003)). 
Each playa typically occurs within a closed or terminal watershed, 
where all water in the watershed drains to the playa. (D.A. Haukos, 
and L.M. Smith, ``Past and Future Impacts of Wetland Regulations on 
Playas,'' Wetlands 23(3):577-589 (2003)). As such, playas typically 
do not drain to an (a)(1) through (a)(3) water. Most playas are fed 
by precipitation and associated runoff, though a few are fed by 
groundwater. (R.W. Tiner, ``Geographically Isolated Wetlands of the 
United States,'' Wetlands 23(3):494-516 (2003)). Most playas fill 
with water only after spring rainstorms when freshwater collects in 
the round depressions of the otherwise flat landscape of west Texas, 
Oklahoma, New Mexico, Colorado, and Kansas. Although playas play a 
role in groundwater recharge of the Ogallala Aquifer, in local 
floodwater storage, and in provision of wildlife habitat, available 
scientific literature indicates that their chemical, physical, or 
biological connections to and effects on (a)(1) through (a)(3) 
waters are of a limited and tenuous nature.
    The agencies seek comment, data, and information on whether 
there are

[[Page 22252]]

subcategories of ``other waters'' or specific combinations of 
characteristics that are ``likely, in the majority of cases, to 
perform important functions for an aquatic ecosystem incorporating 
navigable waters,'' and, thus, should be per se jurisdictional. For 
example, if there are additional studies addressing the connectivity 
of prairie potholes in the Red River Valley, including the factors 
influencing that connectivity and how it is important to particular 
downstream waters, that would be relevant information.

Appendix B

Legal Analysis

Background

    Congress enacted the Federal Water Pollution Control Act 
Amendments of 1972, Public Law 92-500, 86 Stat. 816, as amended, (33 
U.S.C. 1251 et seq.) (Clean Water Act or CWA) ``to restore and 
maintain the chemical, physical, and biological integrity of the 
Nation's waters.'' 33 U.S.C. 1251(a).\9\ The U.S. Supreme Court 
first addressed the scope of ``waters of the United States'' 
protected by the CWA in United States v. Riverside Bayview Homes, 
474 U.S. 121 (1985), which involved wetlands adjacent to a 
traditional navigable water in Michigan. In a unanimous opinion, the 
Court deferred to the Corps' ecological judgment that adjacent 
wetlands are ``inseparably bound up'' with the waters to which they 
are adjacent, and upheld the inclusion of adjacent wetlands in the 
regulatory definition of ``waters of the United States.'' Id. at 
134. The Court observed that the broad objective of the CWA to 
restore and maintain the integrity of the Nation's waters 
``incorporated a broad, systemic view of the goal of maintaining and 
improving water quality. . . . Protection of aquatic ecosystems, 
Congress recognized, demanded broad federal authority to control 
pollution, for `[w]ater moves in hydrologic cycles and it is 
essential that discharge of pollutants be controlled at the source.' 
In keeping with these views, Congress chose to define the waters 
covered by the Act broadly.'' Id. at 132-33 (citing Senate Report 
92-414).
---------------------------------------------------------------------------

    \9\ The 1972 legislation extensively amended the Federal Water 
Pollution Control Act (FWPCA), which was originally enacted in 1948. 
Further amendments to the FWPCA enacted in 1977 acknowledged the 
popular name of the statute as the Clean Water Act. See Public Law 
95-217, 91 Stat. 1566; 33 U.S.C. 1251 note.
---------------------------------------------------------------------------

    The issue of CWA jurisdiction over ``waters of the United 
States'' was addressed again by the Supreme Court in Solid Waste 
Agency of Northern Cook County v. U.S. Army Corps of Engineers, 531 
U.S. 159 (2001) (SWANCC). In SWANCC, the Court (in a 5-4 opinion) 
held that the use of ``isolated'' nonnavigable intrastate ponds by 
migratory birds was not by itself a sufficient basis for the 
exercise of Federal regulatory authority under the CWA. The SWANCC 
Court noted that in Riverside it had ``found that Congress' concern 
for the protection of water quality and aquatic ecosystems indicated 
its intent to regulate wetlands `inseparably bound up' with the 
`waters of the United States' '' and that ``it was the significant 
nexus between the wetlands and `navigable waters' that informed our 
reading of the CWA'' in that case. Id. at 167. SWANCC did not 
invalidate (a)(3) or other parts of the regulatory definition of 
``waters of the United States.''
    Five years after SWANCC, the Court again addressed the CWA term 
``waters of the United States'' in Rapanos v. United States, 547 
U.S. 715 (2006). Rapanos involved two consolidated cases in which 
the CWA had been applied to wetlands adjacent to nonnavigable 
tributaries of traditional navigable waters. All Members of the 
Court agreed that the term ``waters of the United States'' 
encompasses some waters that are not navigable in the traditional 
sense. A four-Justice plurality in Rapanos interpreted the term 
``waters of the United States'' as covering ``relatively permanent, 
standing or continuously flowing bodies of water . . . ,'' id. at 
739, that are connected to traditional navigable waters, id. at 742, 
as well as wetlands with a ``continuous surface connection . . .'' 
to such water bodies, id. (Scalia, J., plurality opinion). The 
Rapanos plurality noted that its reference to ``relatively 
permanent'' waters did ``not necessarily exclude streams, rivers, or 
lakes that might dry up in extraordinary circumstances, such as 
drought,'' or ``seasonal rivers, which contain continuous flow 
during some months of the year but no flow during dry months . . . 
.'' Id. at 732 n.5 (emphasis in original). Justice Kennedy's 
concurring opinion took a different approach. Justice Kennedy 
concluded 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.'' 
Id. at 759 (citing SWANCC, 531 U.S. at 167, 172). He concluded that 
wetlands possess the requisite significant nexus 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. Justice Kennedy's opinion notes 
that such a relationship with navigable waters must be more than 
``speculative or insubstantial.'' Id. at 780. In Rapanos, the four 
dissenting Justices, who would have affirmed the court of appeals' 
application of the pertinent regulatory provisions, concluded that 
the term ``waters of the United States'' encompasses, inter alia, 
all tributaries and wetlands that satisfy either the plurality's 
standard or that of Justice Kennedy. Id. at 810 & n.14 (Stevens, J., 
dissenting). Neither the plurality nor the Kennedy opinions 
invalidated any of the regulatory provisions defining ``waters of 
the United States.''
    The Circuit Courts of Appeals are not uniform as to the 
controlling standard for ``waters of the United States'' under 
Rapanos. The First, Third and Eighth Circuits have concluded that 
CWA jurisdiction exists if either Justice Kennedy's standard or the 
plurality's standard is met. United States v. Johnson, 467 F.3d 56, 
66 (1st Cir. 2006), cert. denied, 552 U.S. 948 (2007); U.S. v. 
Donovan, 661 F.3d. 174, 176 (3rd Cir. 2011), cert. denied, 132 S.Ct. 
2409 (2012); U.S. v. Bailey, 571 F.3d 791, 798-99 (8th Cir. 2009). 
The Seventh and Ninth Circuits limited their holdings that the 
Kennedy standard applied to the facts of the cases before them, and 
did not foreclose the possibility that in some cases the plurality's 
standard might apply. N. Cal. River Watch v. City of Healdsburg, 496 
F.3d 993, 999-1000 (9th Cir. 2007), cert. denied, 552 U.S. 1180 
(2008); United States v. Gerke Excavating, Inc., 464 F.3d 723, 725 
(7th Cir. 2006), cert. denied, 552 U.S. 810 (2007). The Fifth and 
Sixth Circuits did not choose a controlling standard because the 
waters at issue satisfied both standards. United States v. Lucas, 
516 F.3d 316, 326-27 (5th Cir. 2008), cert. denied, 555 U.S. 822 
(2008); United States v. Cundiff, 555 F.3d 200, 210-13 (6th Cir. 
2009), cert. denied, 558 U.S. 818 (2009). The Eleventh Circuit has 
held that only the Kennedy standard determines jurisdiction. United 
States v. Robison, 505 F.3d 1208 (11th Cir. 2007), cert. denied sub 
nom United States v. McWane and McWane v. United States, 555 U.S. 
1045 (2008). No Circuit Court has held that only the plurality 
standard applies.

Traditional Navigable Waters

    EPA and the Corps are proposing no changes to the existing 
regulation related to traditional navigable waters and at paragraph 
(a)(1) will continue to assert jurisdiction over all waters which 
are currently used, or were used in the past, or may be susceptible 
to use in interstate or foreign commerce, including all waters which 
are subject to the ebb and flow of the tide. See e.g., 33 CFR 
328.3(a)(1); 40 CFR 230.3(s)(1); 40 CFR 122.2 (``waters of the 
U.S.'')). These ``(a)(1) waters'' are the ``traditional navigable 
waters.'' These (a)(1) waters include all of the waters defined in 
33 CFR part 329, which implements sections 9 and 10 of the Rivers 
and Harbors Act, and by numerous decisions of the Federal courts, 
plus all other waters that are navigable-in-fact (e.g., the Great 
Salt Lake, UT and Lake Minnetonka, MN).
    To determine whether a water body constitutes an (a)(1) water 
under the regulations, relevant considerations include Corps 
regulations, prior determinations by the Corps and by the Federal 
courts, and case law. Corps districts and EPA regions would 
determine whether a particular water body is a traditional navigable 
water based on application of those considerations to the specific 
facts in each case.
    As noted above, the (a)(1) waters include, but are not limited 
to, waters that meet any of the tests set forth in 33 CFR part 329 
(e.g., the water body is (a) subject to the ebb and flow of the 
tide, and/or (b) the water body is presently used, or has been used 
in the past, or may be susceptible for use (with or without 
reasonable improvements) to transport interstate or foreign 
commerce). The Corps districts have made determinations in the past 
under these regulations for purposes of asserting jurisdiction under 
sections 9 and 10 of the Rivers and Harbors Act of 1899 (33 U.S.C. 
401 and 403). Pursuant to 33 CFR 329.16, the Corps maintains lists 
of final determinations of navigability for purposes of Corps 
jurisdiction under the Rivers and Harbors Act of 1899. While absence 
from the list should not be taken as an indication that the water is 
not navigable (Sec.  329.16(b)), Corps districts and EPA Regions 
rely on any final Corps

[[Page 22253]]

determination that a water body meets any of the tests set forth in 
part 329.
    If the Federal courts have determined that a water body is 
navigable-in-fact under Federal law for any purpose, that water body 
qualifies as a ``traditional navigable water'' subject to CWA 
jurisdiction under 33 CFR 328.3(a)(1) and 40 CFR 230.3(s)(1). Corps 
districts and EPA regions are guided by the relevant opinions of the 
Federal courts in determining whether such water bodies are 
``currently used, or were used in the past, or may be susceptible to 
use in interstate or foreign commerce'' (33 CFR 328.3(a)(1); 40 CFR 
230.3(s)(1)) or ``navigable-in-fact.''
    The definition of ``navigable-in-fact'' derives from a long line 
of cases originating with The Daniel Ball, 77 U.S. 557 (1870). The 
Supreme Court stated:

Those rivers must be regarded as public navigable rivers in law 
which are navigable in fact. And they are navigable in fact when 
they are used, or are susceptible of being used, in their ordinary 
condition, as highways for commerce, over which trade and travel are 
or may be conducted in the customary modes of trade and travel on 
water.

The Daniel Ball, 77 U.S. at 563.
    In The Montello, the Supreme Court clarified that ``customary 
modes of trade and travel on water'' encompasses more than just 
navigation by larger vessels:

The capability of use by the public for purposes of transportation 
and commerce affords the true criterion of the navigability of a 
river, rather than the extent and manner of that use. If it be 
capable in its natural state of being used for purposes of commerce, 
no matter in what mode the commerce may be conducted, it is 
navigable in fact, and becomes in law a public river or highway.

The Montello, 87 U.S. 430, 441-42 (1874). In that case, the Court 
held that early fur trading using canoes sufficiently showed that 
the Fox River was a navigable water of the United States. The Court 
was careful to note that the bare fact of a water's capacity for 
navigation alone is not sufficient; that capacity must be indicative 
of the water's being ``generally and commonly useful to some purpose 
of trade or agriculture.'' Id. at 442.
    In Economy Light & Power, the Supreme Court held that a waterway 
need not be continuously navigable; it is navigable even if it has 
``occasional natural obstructions or portages'' and even if it is 
not navigable ``at all seasons . . . or at all stages of the 
water.'' Economy Light & Power Co. v. U.S., 256 U.S. 113, 122 
(1921).
    In United States v. Holt State Bank, 270 U.S. 49 (1926), the 
Supreme Court summarized the law on navigability as of 1926 as 
follows:

The rule long since approved by this court in applying the 
Constitution and laws of the United States is that streams or lakes 
which are navigable in fact must be regarded as navigable in law; 
that they are navigable in fact when they are used, or are 
susceptible of being used, in their natural and ordinary condition, 
as highways for commerce, over which trade and travel are or may be 
conducted in the customary modes of trade and travel on water; and 
further that navigability does not depend on the particular mode in 
which such use is or may be had--whether by steamboats, sailing 
vessels or flatboats--nor on an absence of occasional difficulties 
in navigation, but on the fact, if it be a fact, that the stream in 
its natural and ordinary condition affords a channel for useful 
commerce.

Holt State Bank, 270 U.S. at 56.
    In U.S. v. Utah, 283 U.S. 64 (1931) and U.S. v. Appalachian 
Elec. Power Co, 311 U.S. 377 (1940), the Supreme Court held that so 
long as a water is susceptible to use as a highway of commerce, it 
is navigable-in-fact, even if the water has never been used for any 
commercial purpose. U.S. v. Utah, at 81-83 (``The question of that 
susceptibility in the ordinary condition of the rivers, rather than 
of the mere manner or extent of actual use, is the crucial 
question.''); U.S. v. Appalachian Elec. Power Co., 311 U.S. at 416 
(``Nor is lack of commercial traffic a bar to a conclusion of 
navigability where personal or private use by boats demonstrates the 
availability of the stream for the simpler types of commercial 
navigation.'') Appalachian Power further held that a water is 
navigable-in-fact even if it is not navigable and never has been but 
may become so by reasonable improvements. 311 U.S. at 407-08.
    In 1971, in Utah v. United States, 403 U.S. 9 (1971), the 
Supreme Court held that the Great Salt Lake, an intrastate water 
body, was navigable under Federal law even though it ``is not part 
of a navigable interstate or international commercial highway.'' Id. 
at 10. In doing so, the Supreme Court stated that the fact that the 
Lake was used for hauling of animals by ranchers rather than for the 
transportation of ``water-borne freight'' was an ``irrelevant 
detail.'' Id. at 11. ``The lake was used as a highway and that is 
the gist of the federal test.'' Id.
    Most recently, the Supreme Court explained:

The Daniel Ball formulation has been invoked in considering the 
navigability of waters for purposes of assessing federal regulatory 
authority under the Constitution, and the application of specific 
federal statutes, as to the waters and their beds. See, e.g., ibid.; 
The Montello, 20 Wall. 430, 439, 22 L.Ed. 391 (1874); United States 
v. Appalachian Elec. Power Co., 311 U.S. 377, 406, and n. 21, 61 
S.Ct. 291, 85 L.Ed. 243 (1940) (Federal Power Act); Rapanos v. 
United States, 547 U.S. 715, 730-731, 126 S.Ct. 2208, 165 L.Ed.2d 
159 (2006) (plurality opinion) (Clean Water Act); id., at 761, 126 
S.Ct. 2208 (KENNEDY, J., concurring in judgment) (same). It has been 
used as well to determine questions of title to water beds under the 
equal-footing doctrine. See Utah, supra, at 76, 51 S.Ct. 438; 
Oklahoma v. Texas, 258 U.S. 574, 586, 42 S.Ct. 406, 66 L.Ed. 771 
(1922); Holt State Bank, supra, at 56, 46 S.Ct. 197. It should be 
noted, however, that the test for navigability is not applied in the 
same way in these distinct types of cases.

Among the differences in application are the following. For state 
title under the equal-footing doctrine, navigability is determined 
at the time of statehood, see Utah, supra, at 75, 51 S.Ct. 438, and 
based on the ``natural and ordinary condition'' of the water, see 
Oklahoma, supra, at 591, 42 S.Ct. 406. In contrast, admiralty 
jurisdiction extends to water routes made navigable even if not 
formerly so, see, e.g., Ex parte Boyer, 109 U.S. 629, 631-632, 3 
S.Ct. 434, 27 L.Ed. 1056 (1884) (artificial canal); and federal 
regulatory authority encompasses waters that only recently have 
become navigable, see, e.g., Philadelphia Co. v. Stimson, 223 U.S. 
605, 634-635, 32 S.Ct. 340, 56 L.Ed. 570 (1912), were once navigable 
but are no longer, see Economy Light & Power Co. v. United States, 
256 U.S. 113, 123-124, 41 S.Ct. 409, 65 L.Ed. 847 (1921), or are not 
navigable and never have been but may become so by reasonable 
improvements, see Appalachian Elec. Power Co., supra, at 407-408, 61 
S.Ct. 291. With respect to the federal commerce power, the inquiry 
regarding navigation historically focused on interstate commerce. 
See The Daniel Ball, 1229*1229 supra, at 564. And, of course, the 
commerce power extends beyond navigation. See Kaiser Aetna v. United 
States, 444 U.S. 164, 173-174, 100 S.Ct. 383, 62 L.Ed.2d 332 (1979). 
In contrast, for title purposes, the inquiry depends only on 
navigation and not on interstate travel. See Utah, supra, at 76, 51 
S.Ct. 438. This list of differences is not exhaustive. Indeed, 
``[e]ach application of [the Daniel Ball] test . . . is apt to 
uncover variations and refinements which require further 
elaboration.'' Appalachian Elec. Power Co., supra, at 406, 61 S.Ct. 
291.

PPL Montana v. Montana, 565 U.S. ------(2012).
    Also of note are two decisions from the courts of appeals. In 
FPL Energy Marine Hydro, a case involving the Federal Power Act, the 
D.C. Circuit reiterated the fact that ``actual use is not necessary 
for a navigability determination'' and repeated earlier Supreme 
Court holdings that navigability and capacity of a water to carry 
commerce could be shown through ``physical characteristics and 
experimentation.'' FPL Energy Marine Hydro LLC v. FERC, 287 F.3d 
1151, 1157 (D.C. Cir. 2002). In that case, the D.C. Circuit upheld a 
FERC navigability determination that was based upon three 
experimental canoe trips taken specifically to demonstrate the 
river's navigability. Id. at 1158-59.
    The 9th Circuit has also implemented the Supreme Court's holding 
that a water need only be susceptible to being used for waterborne 
commerce to be navigable-in-fact. Alaska v. Ahtna, Inc., 891 F.2d 
1404 (9th Cir. 1989). In Ahtna, the 9th Circuit held that current 
use of an Alaskan river for commercial recreational boating was 
sufficient evidence of the water's capacity to carry waterborne 
commerce at the time that Alaska became a state. Id. at 1405. It was 
found to be irrelevant whether or not the river was actually being 
navigated or being used for commerce at the time, because current 
navigation showed that the river always had the capacity to support 
such navigation. Id. at 1404.
    In summary, when determining whether a water body qualifies as a 
``traditional navigable water'' (i.e., an (a)(1) water), relevant 
considerations include whether the water body meets any of the tests 
set forth in Part 329, or a Federal court has determined that the 
water body is

[[Page 22254]]

``navigable-in-fact'' under Federal law for any purpose, or the 
water body is ``navigable-in-fact'' under the standards that have 
been used by the Federal courts.

Interstate Waters

1. Interstate Waters

    The agencies' proposal today makes no change to the interstate 
waters section of the existing regulations and the agencies would 
continue to assert jurisdiction over interstate waters, including 
interstate wetlands. The language of the CWA is clear that Congress 
intended the term ``navigable waters'' to include interstate waters, 
and the agencies' interpretation, promulgated contemporaneously with 
the passage of the CWA, is consistent with the statute and 
legislative history. The Supreme Court's decisions in SWANCC and 
Rapanos did not address the interstate waters provision of the 
existing regulation.

A. The Language of the Clean Water Act, the Statute as a Whole, and the 
Statutory History Demonstrate Congress' Clear Intent To Include 
Interstate Waters as ``Navigable Waters'' Subject to the Clean Water 
Act

    While as a general matter, the scope of the terms ``navigable 
waters'' and ``waters of the United States'' is ambiguous, the 
language of the CWA, particularly when read as a whole, demonstrates 
that Congress clearly intended to continue to subject interstate 
waters to Federal regulation. The statutory history of Federal water 
pollution control places the terms of the CWA in context and 
provides further evidence of Congressional intent to include 
interstate waters within the scope of the ``navigable waters'' 
protected by the Act. Congress clearly intended to subject 
interstate waters to CWA jurisdiction without imposing a requirement 
that they be water that is navigable for purposes of Federal 
regulation under the Commerce Clause themselves or be connected to 
water that is navigable for purposes of Federal regulation under the 
Commerce Clause.\10\ The CWA itself is clear that interstate waters 
that were previously subject to Federal regulation remain subject to 
Federal regulation. The text of the CWA, specifically the CWA's 
provision with respect to interstate waters and their water quality 
standards, in conjunction with the definition of navigable waters, 
provides clear indication of Congress' intent. Thus, interstate 
waters are ``navigable waters'' protected by the CWA.
---------------------------------------------------------------------------

    \10\ For purposes of the CWA, EPA and the Corps have interpreted 
the term ``traditional navigable waters'' to include all of the 
``navigable waters of the United States,'' defined in 33 CFR part 
329 and by numerous decisions of the Federal courts, plus all other 
waters that are navigable-in-fact (e.g., the Great Salt Lake, UT and 
Lake Minnetonka, MN). This section explains why EPA and the Corps do 
not interpret the CWA or the Supreme Court's decisions in Solid 
Waste Agency of Northern Cook County (SWANCC) v. U.S. Army Corps of 
Engineers, 531 U.S. 159 (2001) and Rapanos v. United States, 547 
U.S. 715 (2006), to restrict CWA jurisdiction over interstate waters 
to only those interstate waters that are traditional navigable 
waters or that connect to traditional navigable waters.
---------------------------------------------------------------------------

(1) The Plain Language of the Clean Water Act and the Statute as a 
Whole Clearly Indicate Congress' Intent to Include Interstate Waters 
Within the Scope of ``Navigable Waters'' for Purposes of the Clean 
Water Act

    Under well settled principles, the phrase ``navigable waters'' 
should not be read in isolation from the remainder of the statute. 
As the Supreme Court has explained:

The definition of words in isolation, however, is not necessarily 
controlling in statutory construction. A word in a statute may or 
may not extend to the outer limits of its definitional 
possibilities. Interpretation of a word or phrase depends upon 
reading the whole statutory text, considering the purpose and 
context of the statute, and consulting any precedents or authorities 
that inform the analysis.

Dolan v. U.S. Postal Service, 546 U.S. 481, 486 (2006); see also 
United States Nat'l. Bank of Oregon v. Indep. Ins. Agents of Am., 
Inc., 508 U.S. 439, 455 (1993).
    While the term ``navigable waters'' is, in general, ambiguous, 
interstate waters are waters that are clearly covered by the plain 
language of the definition of ``navigable waters.'' \11\ Congress 
defined ``navigable waters'' to mean ``the waters of the United 
States, including the territorial seas.'' Interstate waters are 
waters of the several States and, thus, the United States. While the 
1972 Act was clearly not limited to interstate waters, it was 
clearly intended to include interstate waters.
---------------------------------------------------------------------------

    \11\ The Supreme Court has found that the term ``waters of the 
United States'' is ambiguous in some respects. Rapanos, 547 U.S. at 
752 (plurality opinion), 804 (dissent).
---------------------------------------------------------------------------

    Furthermore, the CWA does not simply define ``navigable 
waters.'' Other provisions of the statute provide additional textual 
evidence of the scope of this term of the Act. Most importantly, 
there is a specific provision in the 1972 CWA establishing 
requirements for those interstate waters which were subject to the 
prior Water Pollution Control Acts.
    The CWA requires states to establish water quality standards for 
navigable waters and submit them to the Administrator for 
review.\12\ Under section 303(a) of the Act, in order to carry out 
the purpose of this Act, any water quality standard applicable to 
interstate waters which was adopted by any State and submitted to, 
and approved by, or is awaiting approval by, the Administrator 
pursuant to this Act as in effect immediately prior to the date of 
enactment of the Federal Water Pollution Control Act Amendments of 
1972, shall remain in effect unless the Administrator determined 
that such standard is not consistent with the applicable 
requirements of the Act as in effect immediately prior to the date 
of enactment of the Federal Water Pollution Control Act Amendments 
of 1972. If the Administrator makes such a determination he shall, 
within three months after the date of enactment of the Federal Water 
Pollution Control Act Amendments of 1972, notify the State and 
specify the changes needed to meet such requirements. If such 
changes are not adopted by the State within ninety days after the 
date of such notification, the Administrator shall promulgate such 
changes in accordance with subsection (b). CWA section 303(a)(1) 
(emphasis added).
---------------------------------------------------------------------------

    \12\ Section 303 of the Act requires the states to submit 
revised and new water quality standards to the Administrator for 
review. CWA section 303(c)(2)(A). Such revised or new water quality 
standards ``shall consist of the designated uses of the navigable 
waters involved and the water quality criteria for such waters.'' 
Id. If the Administrator determines that a revised or new standard 
is not consistent with the Act's requirements, or determines that a 
revised or new standard is necessary to meet the Act's requirements, 
and the state does not make required changes, ``[t]he Administrator 
shall promptly prepare and publish proposed regulations setting 
forth a revised or new water quality standard for the navigable 
waters involved.'' CWA section 303(c)(4).
---------------------------------------------------------------------------

    Under the 1965 Act, as discussed in more detail below, states 
were directed to develop water quality standards establishing water 
quality goals for interstate waters. By the early 1970s, all the 
states had adopted such water quality standards. Advanced Notice of 
Proposed Rulemaking, Water Quality Standards Regulation, 63 FR 
36742, 36745, July 7, 1998. In section 303(a), Congress clearly 
intended for existing Federal regulation of interstate waters to 
continue under the amended CWA. Water quality standards for 
interstate waters were not merely to remain in effect, but EPA was 
required to actively assess those water quality standards and even 
promulgate revised standards for interstate waters if states did not 
make necessary changes. By the plain language of the statute, these 
water quality standards for interstate waters were to remain in 
effect ``in order to carry out the purpose of this Act.'' The 
objective of the Act is ``to restore and maintain the chemical, 
physical, and biological integrity of the Nation's waters.'' CWA 
section 101(a). It would contravene Congress' clearly stated intent 
for a court to impose an additional jurisdictional requirement on 
all rivers, lakes, and other waters that flow across, or form a part 
of, state boundaries (``interstate waters'' as defined by the 1948 
Act, Sec.  10, 62 Stat. 1161), such that interstate waters that were 
previously protected were no longer protected because they lacked a 
connection to a water that is navigable for purposes of Federal 
regulation under the Commerce Clause. Nor would all the existing 
water quality standards be ``carry[ing] out the purpose of this 
Act,'' if the only water quality standards that could be implemented 
through the Act (through, for example, National Pollutant Discharge 
Elimination System permits under section 402) were those water 
quality standards established for interstate waters that are also 
waters that are navigable for purposes of Federal regulation under 
the Commerce Clause or that connect to waters that are navigable for 
purposes of Federal regulation under the Commerce Clause. Nowhere in 
section 303(a) does Congress make such a distinction.

(2) The Federal Water Pollution Control Statute That Became the Clean 
Water Act Covered Interstate Waters

    In 1972, when Congress rewrote the law governing water 
pollution, two Federal statutes addressed discharges of pollutants 
into interstate waters and water that is

[[Page 22255]]

navigable for purposes of Federal regulation under the Commerce 
Clause, and tributaries of each: The Water Pollution Control Act of 
1948, as amended, and section 13 of the Rivers and Harbors Act of 
1899 (known as the ``Refuse Act''). Of the two, the Water Pollution 
Control Act extended Federal authority over interstate waters and 
their tributaries. In contrast, the Refuse Act extended Federal 
jurisdiction over the ``navigable waters of the United States'' and 
their tributaries. These two separate statutes demonstrate that 
Congress recognized that interstate waters and ``navigable waters of 
the United States'' were independent lawful bases of Federal 
jurisdiction.

a. The Federal Water Pollution Control Act Prior to 1972

    From the outset, and through all the amendments pre-dating the 
1972 Amendments, the Federal authority to abate water pollution 
under the Water Pollution Control Act, and the Federal Water 
Pollution Control Act (FWPCA) as it was renamed in 1956, extended to 
interstate waters. In addition, since first enacted in 1948, and 
throughout all the amendments, the goals of the Act have been, inter 
alia, to protect public water supplies, propagation of fish and 
aquatic life, recreation, agricultural, industrial, and other 
legitimate uses. See 62 Stat. 1155 and 33 U.S.C. 466 (1952), 33 
U.S.C. 466 (1958), 33 U.S.C. 466 (1964), 33 U.S.C. 1151 (1970).
    In 1948, Congress enacted the Water Pollution Control Act in 
connection with the exercise of jurisdiction over the waterways of 
the Nation and in the consequence of the benefits to public health 
and welfare by the abatement of stream pollution. See Pub. L. No. 
80-845, 62 Stat. 1155 (June 30, 1948). The Act authorized technical 
assistance and financial aid to states for stream pollution 
abatement programs, and made discharges of pollutants into 
interstate waters and their tributaries a nuisance, subject to 
abatement and prosecution by the United States. See section 
2(d)(1),(4), 62 Stat. at 1156-1157 (section 2(d)(1) of the Water 
Pollution Control Act of 1948, 62 Stat. at 1156, stated that the 
``pollution of interstate waters'' in or adjacent to any State or 
States (whether the matter causing or contributing to such pollution 
is discharged directly into such waters or reaches such waters after 
discharge into a tributary of such waters), which endangers the 
health or welfare of persons in a State other than that in which the 
discharge originates, is declared to be a public nuisance and 
subject to abatement as provided by the Act. (emphasis added)); 
Sec.  2(a), 62 Stat. 1155 (requiring comprehensive programs for 
``interstate waters and tributaries thereof''); Sec.  5, 62 Stat. 
1158 (authorizing loans for sewage treatment to abate discharges 
into ``interstate waters or into a tributary of such waters''). 
Under the statute, ``interstate waters'' were defined as all rivers, 
lakes, and other waters that flow across, or form a part of, state 
boundaries. Section 10, 62 Stat. 1161.
    In 1956, Congress strengthened measures for controlling 
pollution of interstate waters and their tributaries. Public Law 84-
660, 70 Stat. 498 (1956) (directing further cooperation between the 
Federal and State Governments in development of comprehensive 
programs for eliminating or reducing ``the pollution of interstate 
waters and tributaries'' and improving the sanitary condition of 
surface and underground waters, and authorizing the Surgeon General 
to make joint investigations with States into the conditions of and 
discharges into ``any waters of any State or States.'').
    In 1961, Congress amended the FWPCA to substitute the term 
``interstate or navigable waters'' for ``interstate waters.'' See 
Public Law 87-88, 75 Stat. 208 (1961). Accordingly, beginning in 
1961, the provisions of the FWPCA applied to all interstate waters 
and navigable waters and the tributaries of each, see 33 U.S.C. 
466a, 466g(a) (1964).\13\
---------------------------------------------------------------------------

    \13\ Congress did not define the term ``navigable waters'' in 
the 1961 Amendments, or in subsequent FWPCA Amendments, until 1972.
---------------------------------------------------------------------------

    In 1965, Congress approved a second set of major legislative 
changes, requiring each state to develop water quality standards for 
interstate waters within its boundaries by 1967. Public Law 89-234, 
79 Stat. 908 (1965).\14\ Failing establishment of adequate standards 
by the state, the Act authorized establishment of water quality 
standards by Federal regulation. Id. at 908. The 1965 Amendments 
provided that the discharge of matter ``into such interstate waters 
or portions thereof,'' which reduces the quality of such waters 
below the water quality standards established under this subsection 
(whether the matter causing or contributing to such reduction is 
discharged directly into such waters or reaches such waters after 
discharge into tributaries of such waters), is subject to abatement 
through procedures specified in the Act, including (after 
conferences and negotiations and consideration by a Hearing Board) 
legal action in the courts. Id. at 909.\15\
---------------------------------------------------------------------------

    \14\ In 1967, the state of Arizona created the Water Quality 
Control Council (Council) to implement the requirements of the 1965 
FWPCA. The Council adopted water quality standards for those waters 
that were considered ``interstate waters'' pursuant to the existing 
Federal law. The Council identified the Santa Cruz River as an 
interstate water and promulgated water quality standards for the 
river in accordance with Federal law.
    \15\ The 1966 Amendments authorized civil fines for failing to 
provide information about an alleged discharge causing or 
contributing to water pollution. Public Law 89-753, 80 Stat. 1250 
(1966); see also S. Rep. No. 414, 92d Congress, 1st Sess. 10 (1972) 
(describing the history of the FWPCA).
---------------------------------------------------------------------------

 b. The Refuse Act

    Since its original enactment in 1899, the Refuse Act has 
prohibited the discharge of refuse matter ``into any navigable water 
of the United States, or into any tributary of any navigable 
water.'' Ch. 425, 30 Stat. 1152 (1899). It also has prohibited the 
discharge of such material on the bank of any tributary where it is 
liable to be washed into a navigable water. Id. Violators are 
subject to fines and imprisonment. Id. at 1153 (codified at 33 
U.S.C. 412). In 1966, the Supreme Court upheld the Corps' 
interpretation of the Refuse Act as prohibiting discharges that 
pollute the navigable waters, and not just those discharges that 
obstruct navigation. United States v. Standard Oil Co., 384 U.S. 
224, 230 (1966). In 1970, President Nixon signed an Executive Order 
directing the Corps (in consultation with the Federal Water 
Pollution Control Administration \16\) to implement a permit program 
under section 13 of the RHA ``to regulate the discharge of 
pollutants and other refuse matter into the navigable waters of the 
United States or their tributaries and the placing of such matter 
upon their banks.'' E.O. 11574, 35 FR 19627, Dec. 25, 1970. In 1971, 
the Corps promulgated regulations establishing the Refuse Act Permit 
Program. 36 FR 6564, 6565, April 7, 1971. The regulations made it 
unlawful to discharge any pollutant (except those flowing from 
streets and sewers in a liquid state) into a navigable waterway or 
tributary, except pursuant to a permit. Under the permit program, 
EPA advised the Corps regarding the consistency of a proposed 
discharge with water quality standards and considerations, and the 
Corps evaluated a permit application for impacts on anchorage, 
navigation, and fish and wildlife resources. Id. at 6566.
---------------------------------------------------------------------------

    \16\ In December 1970, administration of the Federal Water 
Pollution Control Administration was transferred from the Secretary 
of the Interior to EPA. S. Rep. No. 414, 92d Congress, 1st Sess. 
(1972).
---------------------------------------------------------------------------

 c. The Federal Water Pollution Control Act Amendments of 1972

    When Congress passed the Federal Water Pollution Control Act 
Amendments of 1972 (referred to hereinafter as the CWA or CWA), it 
was not acting on a blank slate. It was amending existing law that 
provided for a Federal/State program to address water pollution. The 
Supreme Court has recognized that Congress, in enacting the CWA in 
1972, ``intended to repudiate limits that had been placed on federal 
regulation by earlier water pollution control statutes and to 
exercise its powers under the Commerce Clause to regulate at least 
some waters that would not be deemed `navigable' under the classical 
understanding of that term.'' Riverside Bayview Homes, 474 U.S. at 
133; see also International Paper Co. v. Ouellette, 479 U.S. 481, 
486, n.6 (1987).
    The amendments of 1972 defined the term ``navigable waters'' to 
mean ``the waters of the United States, including the territorial 
seas.'' 33 U.S.C. 1362(7). While earlier versions of the 1972 
legislation defined the term to mean ``the navigable waters of the 
United States,'' the Conference Committee deleted the word 
``navigable'' and expressed the intent to reject prior geographic 
limits on the scope of Federal water-protection measures. Compare S. 
Conf. Rep. No. 1236, 92d Cong., 2d Sess. 144 (1972), with H.R. Rep. 
No. 911, 92 Cong., 2d Sess. 356 (1972) (bill reported by the House 
Committee provided that ``[t]he term `navigable waters' means the 
navigable waters of the United States, including the territorial 
seas''); see also S. Rep. No. 414, 92d Cong., 1st Sess. 77 
(``Through a narrow interpretation of the definition of interstate 
waters the implementation of the 1965 Act was severely limited. . . 
. Therefore, reference to the control requirements must be made to 
the navigable waters, portions thereof, and their tributaries.''). 
Thus, Congress intended the scope of the 1972 Act to include, at a

[[Page 22256]]

minimum, the waters already subject to Federal water pollution 
control law--both interstate waters and waters that are navigable 
for purposes of Federal regulation under the Commerce Clause. Those 
statutes covered interstate waters, defined interstate waters 
without requiring that they be a traditional navigable water or be 
connected to water that is a traditional navigable water, and 
demonstrated that Congress knew that there are interstate waters 
that are not navigable for purposes of Federal regulation under the 
Commerce Clause.
    In fact, Congress amended the Federal Water Pollution Control 
Act in 1961 to substitute the term ``interstate or navigable 
waters'' for ``interstate waters,'' demonstrating that Congress 
wanted to be very clear that it was asserting jurisdiction over both 
types of waters: interstate waters even if they were not navigable 
for purposes of Federal regulation under the Commerce Clause, and 
traditional navigable waters even if they were not interstate 
waters. At no point were the interstate waters already subject to 
Federal water pollution control authority required to be navigable 
or to connect to a traditional navigable water. Further, as 
discussed above, the legislative history clearly demonstrates that 
Congress was expanding jurisdiction--not narrowing it--with the 1972 
amendments. Thus, it is reasonable to conclude that by defining 
``navigable waters'' as ``the waters of the United States'' in the 
1972 amendments, Congress included not just traditionally navigable 
waters, but all waters previously regulated under the Federal Water 
Pollution Control Act, including non-navigable interstate waters.
    Based on the statutory definition of navigable waters, the 
requirement of section 303(a) for water quality standards for 
interstate waters to remain in effect, the purposes of the Act, and 
the more than three decades of Federal water pollution control 
regulation that provides a context for reading those provisions of 
the statute, the intent of Congress is clear that the term 
``navigable waters'' includes ``interstate waters'' as an 
independent basis for CWA jurisdiction, whether or not they 
themselves are traditional navigable waters or are connected to a 
traditional navigable water.

B. Supreme Court Precedent Supports CWA Jurisdiction Over 
Interstate Waters Without Respect to Navigability

    In two seminal decisions, the Supreme Court established that 
resolving interstate water pollution issues was a matter of Federal 
law and that the CWA was the comprehensive regulatory scheme for 
addressing interstate water pollution. Illinois v. Milwaukee, 406 
U.S. 91 (1972); City of Milwaukee v. Illinois, 451 U.S. 304 (1981). 
In both of these decisions, the Court held that Federal law applied 
to interstate waters. Moreover, these cases analyzed the applicable 
Federal statutory schemes and determined that the provisions of the 
Federal Water Pollution Control Act and the CWA regulating water 
pollution applied generally to interstate waters. The holdings of 
these cases recognized the Federal interest in interstate water 
quality pollution; and City of Milwaukee recognized that CWA 
jurisdiction extends to interstate waters without regard to 
navigability.
    In Illinois v. Milwaukee, the Court considered a public nuisance 
claim brought by the State of Illinois against the city of Milwaukee 
to address the adverse effects of Milwaukee's discharges of poorly 
treated sewage into Lake Michigan, ``a body of interstate water.'' 
406 U.S. at 93. In relevant part, the Court held that the Federal 
common law of nuisance was an appropriate mechanism to resolve 
disputes involving interstate water pollution. 406 U.S. at 107 
(``federal courts will be empowered to appraise the equities of 
suits alleging creation of a public nuisance by water pollution''). 
The Court further noted that in such actions the Court could 
consider a state's interest in protecting its high water quality 
standards from ``the more degrading standards of a neighbor.'' Id.
    In reaching this conclusion, the Court examined in detail the 
scope of the Federal regulatory scheme as it existed prior to the 
October, 1972 FWPCA amendments. In its April, 1972 decision, the 
Court concluded that the Federal Water Pollution Control Act ``makes 
clear that it is federal, not state, law that in the end controls 
the pollution of interstate or navigable waters.'' 406 U.S. at 102 
(emphasis added). The Court, in this case, concluded that the 
regulatory provisions of the Federal Water Pollution Control Act did 
not address the right of a state to file suit to protect water 
quality. However, this was not because this statute did not reach 
interstate waters. The Court specifically noted that section 10(a) 
of the Federal Water Pollution Control Act ``makes pollution of 
interstate or navigable waters subject `to abatement' '' 406 U.S. at 
102 (emphasis added). Rather, the Court noted that the plaintiff in 
this action was seeking relief outside the scope of the Federal 
Water Pollution Control Act and that statute explicitly provided 
that independent ``state and interstate action to abate pollution of 
interstate or navigable waters shall be encouraged and shall not . . 
. be displaced by Federal enforcement action.'' 406 U.S. at 104 
(citing section 10(b) of the Federal Water Pollution Control Act).
    In addition, in Illinois v. Milwaukee, the Court acknowledged 
that it was essential for Federal law to resolve interstate water 
pollution disputes, citing with approval the following discussion 
from Texas v. Pankey:

Federal common law and not the varying common law of the individual 
states is, we think, entitled and necessary to be recognized as a 
basis for dealing in uniform standard with the environmental rights 
of a State against improper impairment by sources outside its 
domain. . . . Until the field has been made the subject of 
comprehensive legislation or authorized administrative standards, 
only a federal common law basis can provide an adequate means for 
dealing with such claims as alleged federal rights.

406 U.S. at 107 n. 9, citing Texas v. Pankey, 441 F.2d 236, 241-242.
    In City of Milwaukee, the Court revisited this dispute and 
addressed the expanded statutory provisions of the CWA regulating 
water pollution. The scope of the CWA amendments led the Court to 
reverse its decision in Illinois v. Milwaukee. In reaching this 
result, the Court concluded that Congress had elected to exercise 
its authority under Federal law to occupy the field of water 
pollution regulation. As a result, the Court concluded that there 
was no basis for maintaining a Federal common law of nuisance.

Congress has not left the formulation of appropriate federal 
standards to the courts through application of often vague and 
indeterminate nuisance concepts and maxims of equity jurisprudence, 
but rather has occupied the field through the establishment of a 
comprehensive regulatory program supervised by an expert 
administrative agency. The 1972 Amendments to the Federal Water 
Pollution Control Act were not merely another law ``touching 
interstate waters''. . . Rather, the Amendments were viewed by 
Congress as a ``total restructuring'' and ``complete rewriting'' of 
the existing water pollution legislation considered in that case.

451 U.S. at 317.
    The Court's analysis in Illinois v. Milwaukee made clear that 
Federal common law was necessary to protect ``the environmental 
rights of States against improper impairment by sources outside its 
domain.'' 406 U.S. at 107, n. 9. In the context of interstate water 
pollution, nothing in the Court's language or logic limits the reach 
of this conclusion to only navigable interstate waters. In City of 
Milwaukee, the Court found that the CWA was the ``comprehensive 
regulatory program'' that ``occupied the field'' (451 U.S. 317) with 
regard to interstate water pollution, eliminating the basis for an 
independent common law of nuisance to address interstate water 
pollution. Since the Federal common law of nuisance (as well as the 
statutory provisions regulating water pollution in the Federal Water 
Pollution Control Act) applied to interstate waters whether 
navigable or not, the CWA could only occupy the field of interstate 
water pollution if it too extended to non-navigable as well as 
navigable interstate waters.
    With regard to the specifics of interstate water pollution, the 
City of Milwaukee Court noted that, in Illinois v. Milwaukee, it had 
been concerned that Illinois did not have a forum in which it could 
protect its interests in abating water pollution from out of state, 
absent the recognition of Federal common law remedies. 451 U.S. at 
325. The Court then went on to analyze in detail the specific 
procedures created by the CWA ``for a State affected by decisions of 
a neighboring State's permit-granting agency to seek redress.'' 451 
U.S. at 326. The Court noted that ``any State whose waters may be 
affected by the issuance of a permit'' is to receive notice and the 
opportunity to comment on the permit. Id. (citing to CWA section 
402(b)(3)(5). In addition the Court noted provisions giving EPA the 
authority to veto and issue its own permits ``if a stalemate between 
an issuing and objecting state develops.'' Id. (citing to CWA 
sections 402(d)(2)(A),(4)). In light of these protections for states 
affected by interstate water pollution, the court concluded that


[[Page 22257]]


[t]he statutory scheme established by Congress provides a forum for 
the pursuit of such claims before expert agencies by means of the 
permit-granting process. It would be quite inconsistent with this 
scheme if federal courts were in effect to ``write their own 
ticket'' under the guise of federal common law after permits have 
already been issued and permittees have been planning and operating 
in reliance on them.

451 U.S. at 326.

    Nothing in the language or the reasoning of this discussion 
limits the applicability of these protections of interstate waters 
to navigable interstate waters or interstate waters connected to 
navigable waters. If these protections only applied to navigable 
interstate waters, a downstream state would be unable to protect 
many of its waters from out of state water pollution. This would 
hardly constitute a comprehensive regulatory scheme that occupied 
the field of interstate water pollution.
    For these reasons, the holdings and the reasoning of these 
decisions establish that the regulatory reach of the CWA extends to 
all interstate waters without regard to navigability.\17\
---------------------------------------------------------------------------

    \17\ Nothing in subsequent Supreme Court case law regarding 
interstate waters in any way conflicts with the agencies' 
interpretation. See International Paper v. Ouellette, 479 U.S. 481 
(1987); Arkansas v. Oklahoma, 503 U.S. 91 (1992). In both of these 
cases, the Court detailed how the CWA had supplanted the Federal 
common law of nuisance to establish the controlling statutory scheme 
for addressing interstate water pollution disputes. Nothing in 
either decision limits the applicability of the CWA to interstate 
water pollution disputes involving navigable interstate waters or 
interstate waters connected to navigable waters.
---------------------------------------------------------------------------

C. The Supreme Court's Decisions in SWANCC and Rapanos Do Not Limit 
or Constrain Clean Water Act Jurisdiction Over Non-Navigable 
Interstate Waters

    As noted above, the Supreme Court recognized that Congress, in 
enacting the CWA, ``intended to repudiate limits that had been 
placed on federal regulation by earlier water pollution control 
statutes and to exercise its powers under the Commerce Clause to 
regulate at least some waters that would not be deemed `navigable' 
under the classical understanding of that term.'' Riverside Bayview, 
474 U.S. at 133; see also International Paper Co. v. Ouellette, 479 
U.S. 481, 486 n.6, (1987). In Riverside Bayview, and subsequently in 
SWANCC and Rapanos, the Court addressed the construction of the CWA 
terms ``navigable waters'' and ``the waters of the United States.'' 
In none of these cases did the Supreme Court address interstate 
waters, nor did it overrule prior Supreme Court precedent which 
addressed the interaction between the CWA and Federal common law to 
address pollution of interstate waters. Therefore, the statute, even 
in light of SWANCC and Rapanos, does not impose an additional 
requirement that interstate waters must be water that is navigable 
for purposes of Federal regulation under the Commerce Clause or 
connected to water that is navigable for purposes of Federal 
regulation under the Commerce Clause to be jurisdictional waters for 
purposes of the CWA.
    At the outset, it is worth noting that neither SWANCC nor 
Rapanos dealt with the jurisdictional status of interstate waters. 
Repeatedly in the SWANCC decision the Court emphasized that the 
question presented concerned the jurisdiction status of nonnavigable 
intrastate waters located in two Illinois counties. SWANCC 531 U.S. 
at 165-166, 171 (``we thus decline to . . . hold that isolated 
ponds, some only seasonal, wholly located within two Illinois 
counties fall under Sec.  404(a) definition of navigable waters . . 
.'') (emphasis added). Nowhere in Justice Rehnquist's majority 
opinion in SWANCC does the Court discuss the Court's interstate 
water case law.\18\ The Court does not even discuss the fact that 
CWA jurisdictional regulations identify interstate waters as 
regulated ``waters of the United States.'' In fact, the repeated 
emphasis on the intrastate nature of the waters at issue can be read 
as an attempt to distinguish SWANCC from the Court's interstate 
water jurisprudence.
---------------------------------------------------------------------------

    \18\ It is worth noting the Justice Rehnquist was also the 
author of City of Milwaukee.
---------------------------------------------------------------------------

    In Rapanos, the properties at issue were located entirely within 
the State of Michigan. 547 U.S. 715, 762-764. Thus, the Court had no 
occasion to address the text of the CWA with respect to interstate 
waters or the agencies' regulatory provisions concerning interstate 
waters. In addition, neither Justice Kennedy nor the plurality 
discusses the impact of their opinions on the Court's interstate 
waters jurisprudence. The plurality decision acknowledges that CWA 
jurisdictional regulations include interstate waters. 547 U.S. 715, 
724. However, the plurality did not discuss in any detail its views 
as to the continued vitality of regulations concerning such waters.
    Moreover, one of the analytical underpinnings of the SWANCC and 
Rapanos decisions is irrelevant to analysis of regulations asserting 
jurisdiction over interstate waters. In SWANCC, the Court declined 
to defer to agency regulations asserting jurisdiction over isolated 
waters because

[w]here an administrative interpretation of a statute invokes the 
outer limits of Congress' power, we expect a clear indication that 
Congress intended that result. . . .This requirement stems from our 
prudential desire not to needlessly reach constitutional issues and 
our assumption that Congress does not casually authorize 
administrative agencies to interpret a statute to push the limit of 
Congressional authority. . . . This concern is heightened where the 
administrative interpretation alerts the federal-state framework by 
permitting federal encroachment upon a traditional state power.

531 U.S. at 172-173 (citations omitted).
    However, the Court's analysis in Illinois v. Milwaukee and City 
of Milwaukee makes clear that Congress has broad authority to create 
Federal law to resolve interstate water pollution disputes. As 
discussed above, the Court in Illinois v. Milwaukee, invited further 
Federal legislation to address interstate water pollution, and in so 
doing concluded that State law was not an appropriate basis for 
addressing interstate water pollution issues. 406 U.S. at 107 n. 9 
(citing Texas v. Pankey, 441 F.2d 236, 241-242). In City of 
Milwaukee, the Court indicated that central to its holding in 
Illinois v. Milwaukee was its concern ``that Illinois did not have 
any forum to protect its interests [in the matters involving 
interstate water pollution].'' 451 U.S. 325. As discussed above, the 
Court cited with approval the statutory provisions of the CWA 
regulating water pollution as an appropriate means to address that 
concern.
    The City of Milwaukee and Illinois v. Milwaukee decisions make 
clear that assertion of Federal authority to resolve disputes 
involving interstate waters does not alter ``the Federal-State 
framework by permitting Federal encroachment on a traditional State 
power.'' 531 U.S. at 173. ``Our decisions concerning interstate 
waters contain the same theme. Rights in interstate streams, like 
questions of boundaries, have been recognized as presenting Federal 
questions.'' Illinois v. Milwaukee, 406 U.S. at 105 (internal 
quotations and citations omitted).
    The Supreme Court's analysis in SWANCC and Rapanos materially 
altered the criteria for analyzing CWA jurisdictional issues for 
wholly intrastate waters. However, these decisions by their terms 
did not affect the body of case law developed to address interstate 
waters. The holdings in the Supreme Court's interstate waters 
jurisprudence, in particular City of Milwaukee, apply CWA 
jurisdiction to interstate waters without regard to, or discussion 
of, navigability. In City of Milwaukee, the Court held that the CWA 
provided a comprehensive statutory scheme for addressing the 
consequences of interstate water pollution. Based on this analysis, 
the Court expressly overruled its holding in Illinois v. Milwaukee 
that the Federal common law of nuisance would apply to resolving 
interstate water pollution disputes. Instead, the Court held that 
such disputes would now be resolved through application of the 
statutory provisions of the CWA regulating water pollution.
    It would be unreasonable to interpret SWANCC or Rapanos as 
overruling City of Milwaukee with respect to CWA jurisdiction over 
non-navigable interstate waters. Such an interpretation would result 
in no law to apply to water pollution disputes with regard to such 
waters, unless one were to assume that the Court intended (without 
discussion or analysis) to restore the Federal common law of 
nuisance as the law to apply in such matters. Moreover, SWANCC and 
Rapanos acknowledge that CWA regulatory jurisdiction extends to at 
least some non-navigable waters. See, e.g., 547 U.S. at 779 
(Kennedy, J.). Neither the SWANCC Court nor the plurality or Kennedy 
opinions in Rapanos purports to set out the complete boundaries of 
CWA jurisdiction. See, e.g., 547 U.S. at 731 (``[w]e need not decide 
the precise extent to which the qualifiers `navigable' and `of the 
United States' restrict the coverage of the Act.'') (plurality 
opinion).
    In addition, as the Supreme Court has repeatedly admonished, if 
a Supreme Court precedent has direct application in a case yet 
appears to rest on a rationale rejected in some other line of 
decisions, lower courts should follow the case which directly 
controls,

[[Page 22258]]

leaving to the Supreme Court the prerogative of overruling its 
precedents. Agostino v. Felton, 521 U.S. 203, 237 (1997); United 
States v. Hatter, 532 U.S. 557, 566-567 (1981). Moreover, when the 
Supreme Court overturns established precedent, it is explicit. See, 
Lawrence v. Texas, 539 U.S. 558, 578 (``Bowers was not correct when 
it was decided, and it is not correct today. It ought not to remain 
binding precedent. Bowers v. Hardwick should be and now is 
overruled.'').

D. The Agencies' Longstanding Interpretation of the Term 
``Navigable Waters'' To Include ``Interstate Waters''

    EPA, the agency charged with implementing the CWA, has always 
interpreted the 1972 Act to cover interstate waters. Final Rules, 38 
FR 13528, May 22, 1973 (the term ``waters of the United States'' 
includes ``interstate waters and their tributaries, including 
adjacent wetlands''). While the Corps of Engineers initially limited 
the scope of coverage for purposes of section 404 of the CWA to 
those waters that were subject to the Rivers and Harbors Act of 
1899, after a lawsuit, the Corps amended its regulations to provide 
for the same definition of ``waters of the United States'' that 
EPA's regulations had always established. In 1975, the Corps' 
revised regulations defined ``navigable waters'' to include 
``[i]nterstate waters landward to their ordinary high water mark and 
up to their headwaters.'' In their final rules promulgated in 1977, 
the Corps adopted EPA's definition and included within the 
definition of ``waters of the United States'' ``interstate waters 
and their tributaries, including adjacent wetlands.'' The preamble 
provided an explanation for the inclusion of interstate waters:

The affects [sic] of water pollution in one state can adversely 
affect the quality of the waters in another, particularly if the 
waters involved are interstate. Prior to the FWPCA amendments of 
1972, most federal statutes pertaining to water quality were limited 
to interstate waters. We have, therefore, included this third 
category consistent with the Federal government's traditional role 
to protect these waters from the standpoint of water quality and the 
obvious effects on interstate commerce that will occur through 
pollution of interstate waters and their tributaries.

Final Rules, 42 FR 37122, July 19, 1977.

    The legislative history similarly provides support for the 
agencies' interpretation. Congress in 1972 concluded that the 
mechanism for controlling discharges and, thereby abating pollution, 
under the FWPCA and Refuse Act ``has been inadequate in every vital 
aspect.'' S. Rep. No. 414, 92d Cong., 1st Sess. 7 (1972). The Senate 
Committee on Public Works reported that development of water quality 
standards, assigned to the states under the 1965 FWPCA Amendments, 
``is lagging'' and the ``1948 abatement procedures, and the almost 
total lack of enforcement,'' prompted the search for ``more direct 
avenues of action against water polluters and water pollution.'' Id. 
at 5. The Committee further concluded that although the Refuse Act 
permit program created in 1970 ``seeks to establish this direct 
approach,'' it was too weak because it applied only to industrial 
polluters and too unwieldy because the authority over each permit 
application was divided between two Federal agencies. See id. at 5; 
see also id. at 70-72 (discussing inadequacies of Refuse Act 
program).
    In light of the poor success of those programs, the Committee 
recommended a more direct and comprehensive approach which, after 
amendment in conference, was adopted in the 1972 Act. The text, 
legislative history and purpose of the 1972 Amendments all show an 
intent--through the revisions--to broaden, improve and strengthen, 
not to curtail, the Federal water pollution control program that had 
existed under the Refuse Act and FWPCA.\19\ The 1972 FWPCA 
Amendments were ``not merely another law `touching interstate 
waters' '' but were ``viewed by Congress as a `total restructuring' 
and `complete rewriting' of the existing water pollution 
legislation.'' \20\
---------------------------------------------------------------------------

    \19\ See id. at 9 (``The scope of the 1899 Refuse Act is 
broadened; the administrative capability is strengthened.''); id. at 
43 (``Much of the Committee's time devoted to this Act centered on 
an effort to resolve the existing water quality program and the 
separate pollution program developing under the 1899 Refuse Act.''). 
Congress made an effort ``to weave'' the Refuse Act permit program 
into the 1972 Amendments, id. at 71, as the statutory text shows. 
See 33 U.S.C. 1342(a) (providing that each application for a permit 
under 33 U.S.C. 407, pending on October 18, 1972, shall be deemed an 
application for a permit under 33 U.S.C. 1342(a)).
    \20\ City of Milwaukee v. Illinois, 451 U.S. at 317; see also 
id. at 318 (holding that the CWA precluded Federal common-law claims 
because ``Congress' intent in enacting the [CWA] was clearly to 
establish an all-encompassing program of water pollution 
regulation''); Middlesex County Sewerage Auth. v. National Sea 
Clammers Ass'n, 453 U.S. 1, 22 (1981) (existing statutory scheme 
``was completely revised'' by enactment of the CWA).
---------------------------------------------------------------------------

    As the legislative history of the 1972 Act confirms, Congress' 
use of the term ``waters of the United States'' was intended to 
repudiate earlier limits on the reach of Federal water pollution 
efforts: ``The conferees fully intend that the term `navigable 
waters' be given the broadest possible constitutional interpretation 
unencumbered by agency determinations which have been made or may be 
made for administrative purposes.'' See S. Conf. Rep. No. 1236, 92d 
Cong., 2d Sess. 144 (1972). The House and Senate Committee Reports 
further elucidate the Conference Committee's rationale for removing 
the word ``navigable'' from the definition of ``navigable waters,'' 
in 33 U.S.C. 1362(7). The Senate report stated:

    The control strategy of the Act extends to navigable waters. The 
definition of this term means the navigable waters of the United 
States, portions thereof, tributaries thereof, and includes the 
territorial seas and the Great Lakes. Through a narrow 
interpretation of the definition of interstate waters the 
implementation of the 1965 Act was severely limited. Water moves in 
hydrologic cycles and it is essential that discharge of pollutants 
be controlled at the source. Therefore, reference to the control 
requirements must be made the navigable waters, portions thereof, 
and their tributaries.

See S. Rep. 414, 92d Cong., 1st Sess. 77 (1971); see also H.R. Rep. 
No. 911, 92d Cong., 2d Sess. 131 (1972) (``The Committee fully 
intends that the term ``navigable waters'' be given the broadest 
possible constitutional interpretation unencumbered by agency 
determinations which have been made or may be made for 
administrative purposes.''). These passages strongly suggest that 
Congress intended to expand Federal protection of waters. There is 
no evidence that Congress intended to exclude interstate waters 
which were protected under Federal law if they were not water that 
is navigable for purposes of Federal regulation under the Commerce 
Clause or connected to water that is navigable for purposes of 
Federal regulation under the Commerce Clause. Such an exclusion 
would be contrary to all the stated goals of Congress in enacting 
the sweeping amendments which became the CWA.
    The CWA was enacted in 1972. EPA's contemporaneous regulatory 
definition of ``waters of the United States,'' promulgated in 1973, 
included interstate waters. The definition has been EPA's 
interpretation of the geographic jurisdictional scope of the CWA for 
approximately 40 years. Congress has also been aware of and has 
supported the Agency's longstanding interpretation of the CWA. 
``Where `an agency's statutory construction has been fully brought 
to the attention of the public and the Congress, and the latter has 
not sought to alter that interpretation although it has amended the 
statute in other respects, then presumably the legislative intent 
has been correctly discerned.' '' North Haven Board of Education v. 
Bell, 102 456 U.S. 512, 535 (1982) (quoting United States v. 
Rutherford, 442 U.S. 544 n. 10 (1979) (internal quotes omitted)).
    The 1977 amendments to the CWA were the result of Congress' 
thorough analysis of the scope of CWA jurisdiction in light of EPA 
and Corps regulations. The 1975 interim final regulations 
promulgated by the Corps in response to NRDC v. Callaway,\21\ 
aroused considerable congressional interest. Hearings on the subject 
of section 404 jurisdiction were held in both the House and the 
Senate.\22\ An amendment to limit the geographic reach of section 
404 to waters that are navigable for purposes of Federal regulation 
under the Commerce Clauses and their adjacent wetlands was passed by 
the House, 123 Cong. Rec. 10434 (1977), defeated on the floor of the 
Senate, 123 Cong. Rec. 26728 (1977), and eliminated by the 
Conference Committee, H.R. Conf. Rep. 95-830, 95th Cong., 1st Sess. 
97-105 (1977). Congress rejected the proposal to limit the 
geographic reach of section 404 because it wanted a permit system 
with ``no gaps'' in its protective sweep. 123 Cong. Rec. 26707 
(1977) (remarks of Sen. Randolph). Rather than alter the geographic 
reach of section

[[Page 22259]]

404, Congress amended the statute by exempting certain activities--
most notably certain agricultural and silvicultural activities--from 
the permit requirements of section 404. See 33 U.S.C. 1344(f).
---------------------------------------------------------------------------

    \21\ 40 FR 31320, 31324 (July 25, 1975).
    \22\ Section 404 of the Federal Water Pollution Control Act 
Amendments of 1972: Hearings Before the Senate Comm. on Public 
Works, 94th Cong., 2d Sess. (1976); Development of New Regulations 
by the Corps of Engineers, Implementing Section 404 of the Federal 
Water Pollution Control Act Concerning Permits for Disposal of 
Dredge or Fill Material: Hearings Before the Subcomm. on Water 
Resources of the House Comm. on Public Works and Transportation, 
94th Cong., 1st Sess. (1975).
---------------------------------------------------------------------------

    Other evidence abounds to support the conclusion that when 
Congress rejected the attempt to limit the geographic reach of 
section 404, it was well aware of the jurisdictional scope of EPA 
and the Corps' definition of ``waters of the United States.'' For 
example, Senator Baker stated (123 Cong. Rec. 26718 (1977)):

Interim final regulations were promulgated by the [C]orps [on] July 
25, 1975.* * * Together the regulations and [EPA] guidelines 
established a management program that focused the decisionmaking 
process on significant threats to aquatic areas while avoiding 
unnecessary regulation of minor activities. On July 19, 1977, the 
[C]orps revised its regulations to further streamline the program 
and correct several misunderstandings. * * *
Continuation of the comprehensive coverage of this program is 
essential for the protection of the aquatic environment. The once 
seemingly separable types of aquatic systems are, we now know, 
interrelated and interdependent. We cannot expect to preserve the 
remaining qualities of our water resources without providing 
appropriate protection for the entire resource.
Earlier jurisdictional approaches under the [Rivers and Harbors Act] 
established artificial and often arbitrary boundaries. . . .

    This legislative history leaves no room for doubt that Congress 
was aware of the agencies' definition of navigable waters. While 
there was controversy over the assertion of jurisdiction over all 
adjacent wetlands and some non-adjacent wetlands, the agencies' 
assertion of CWA jurisdiction over interstate waters was 
uncontroversial.
    Finally, the constitutional concerns which led the Supreme Court 
to decline to defer to agency regulations in SWANCC and Rapanos are 
not present here where the agency is asserting jurisdiction over 
interstate waters. In SWANCC, the Court declined to defer to agency 
regulations asserting jurisdiction over non-adjacent, non-navigable, 
intrastate waters because the Court felt such an interpretation of 
the statute invoked the outer limits of Congress' power. The Court's 
concern ``is heightened where the administrative interpretation 
alters the federal-state framework by permitting federal 
encroachment upon a traditional state power.'' 531 U.S. at 172-173 
(citations omitted). Authority over interstate waters is squarely 
within the bounds of Congress' Commerce Clause powers.\23\ Further, 
the Federal Government is in the best position to address issues 
which may arise when waters cross state boundaries, so this 
interpretation does not disrupt the Federal-State framework in the 
manner the Supreme Court feared that the assertion of jurisdiction 
over a non-adjacent, non-navigable, intrastate body of water based 
on the presence of migratory birds did. The Supreme Court's analysis 
in Illinois v. Milwaukee and City of Milwaukee makes clear that 
Congress has broad authority to create Federal law to resolve 
interstate water pollution disputes. Therefore, as discussed in 
Section II.B above, it is appropriate for the agencies to adopt an 
interpretation of the extent of CWA jurisdiction over interstate 
waters that gives full effect to City of Milwaukee unless and until 
the Supreme Court elects to revisit its holding in that case.
---------------------------------------------------------------------------

    \23\ In Illinois v. Milwaukee, the Supreme Court noted that 
``Congress has enacted numerous laws touching interstate waters.'' 
406 U.S. at 101.
---------------------------------------------------------------------------

    Thus, based on the language of the statute, the statutory 
history, the legislative history, and the caselaw, the agencies' 
continue their longstanding interpretation of ``navigable waters'' 
to include interstate waters.

Tributaries

    In Rapanos, Justice Kennedy reasoned that Riverside Bayview and 
SWANCC ``establish the framework for'' determining whether an 
assertion of regulatory jurisdiction constitutes a reasonable 
interpretation of ``navigable waters''--``the connection between a 
non-navigable water or wetland and a navigable water may be so 
close, or potentially so close, that the Corps may deem the water or 
wetland a `navigable water' under the Act;'' and ``[a]bsent a 
significant nexus, jurisdiction under the Act is lacking.'' 547 U.S. 
at 767. ``The required nexus must be assessed in terms of the 
statute's goals and purposes. Congress enacted the law to `restore 
and maintain the chemical, physical, and biological integrity of the 
Nation's waters,' 33 U.S.C. 1251(a), and it pursued that objective 
by restricting dumping and filling in `navigable waters,' sections 
1311(a), 1362(12).'' Id. at 779. ``Justice Kennedy concluded that 
the term ``waters of the United States'' encompasses wetlands and 
other waters that ``possess a `significant nexus' to waters that are 
or were navigable in fact or that could reasonably be so made.'' Id. 
at 759. He further concluded that wetlands possess the requisite 
significant nexus: ``if the wetlands, either alone or in combination 
with similarly situated [wetlands] in the region, significantly 
affect the chemical, physical, and biological integrity of other 
covered waters more readily understood as `navigable.' '' Id. at 
780.
    While Justice Kennedy's opinion focused on adjacent wetlands in 
light of the facts of the cases before him, the agencies determined 
it was reasonable and appropriate to undertake a detailed 
examination of the scientific literature to determine whether 
tributaries, as a category and as the agencies propose to define 
them, significantly affect the chemical, physical, or biological 
integrity of downstream navigable waters, interstate waters, or 
territorial seas into which they flow. Based on this extensive 
analysis, the agencies concluded that tributaries with bed and 
banks, and ordinary high water marks, alone or in combination with 
other tributaries, as defined by the proposed regulation, in the 
watershed perform these functions and should be considered, as a 
category, to be ``waters of the United States.''
    The assertion of jurisdiction over this category of waters is 
fully consistent with Justice Kennedy's opinion in Rapanos. 
``Justice Kennedy concluded that the term ``waters of the United 
States'' encompasses wetlands and other waters that ``possess a 
`significant nexus' to waters that are or were navigable in fact or 
that could reasonably be so made.'' Id. at 759. With respect to 
tributaries, Justice Kennedy rejected the plurality's approach that 
only ``relatively permanent'' tributaries are within the scope of 
CWA jurisdiction. He stated that the plurality's requirement of 
``permanent standing water or continuous flow, at least for a period 
of `some months' . . . makes little practical sense in a statute 
concerned with downstream water quality.'' Id. at 769. Instead, 
Justice Kennedy concluded that ``Congress could draw a line to 
exclude irregular waterways, but nothing in the statute suggests it 
has done so;'' in fact, he stated that Congress has done ``[q]uite 
the opposite . . ..'' Id. at 769. Further, Justice Kennedy 
concluded, based on ``a full reading of the dictionary definition'' 
of ``waters,'' that ``the Corps can reasonably interpret the Act to 
cover the paths of such impermanent streams.'' Id. at 770 (emphasis 
added).
    Moreover, Justice Kennedy's opinion did not reject the agencies' 
existing regulations governing tributaries. The consolidated cases 
in Rapanos involved discharges into wetlands adjacent to 
nonnavigable tributaries and, therefore, Justice Kennedy's analysis 
focused on the requisite showing for wetlands. Justice Kennedy 
described the Corps' standard for asserting jurisdiction over 
tributaries: ``the Corps deems a water a tributary if it feeds into 
a traditional navigable water (or a tributary thereof) and possesses 
an ordinary high water mark . . ..'' Id. at 781, see also id at 761. 
He acknowledged that this requirement of a perceptible ordinary high 
water mark for ephemeral streams, 65 FR 12828, March 9, 2000, 
``[a]ssuming it is subject to reasonably consistent application, . . 
. may well provide a reasonable measure of whether specific minor 
tributaries bear a sufficient nexus with other regulated waters to 
constitute navigable waters under the Act.'' 547 U.S. at 781, see 
also id. at 761. With respect to wetlands, Justice Kennedy concluded 
that the breadth of this standard for tributaries precluded use of 
adjacency to such tributaries as the determinative measure of 
whether wetlands adjacent to such tributaries ``are likely to play 
an important role in the integrity of an aquatic system comprising 
navigable waters as traditionally understood.'' Id. at 781. He did 
not, however, reject the Corps' use of ``ordinary high water mark'' 
to assert regulatory jurisdiction over tributaries themselves. Id.
    In the foregoing passage regarding the existing regulatory 
standard for ephemeral streams, Justice Kennedy also provided a 
``but see'' citation to a 2004 U.S. General Accounting Office (now 
the U.S. Government Accountability Office) (GAO) report ``noting 
variation in results among Corps district offices.'' Id. In 2005, 
the Corps issued a regulatory guidance letter (RGL 05-05) to Corps 
districts on OHWM identification that was designed to ensure more 
consistent practice. The Corps has also issued documents to provide 
additional technical assistance for problematic OHWM delineations. 
See, e.g., R.W. Lichvar and S.M.

[[Page 22260]]

McColley, U.S. Army Corps of Engineers, A Field Guide to the 
Identification of the Ordinary High Water Mark (OHWM) in the Arid 
West Region of the Western United States: A Delineation Manual, 
ERDC/CRREL TR-08-12 (2008). Moreover, the agencies propose today for 
the first time a regulatory definition of ``tributary.'' The 
definition expressly addresses some of the issues with respect to 
identification of an OHWM that caused many of the inconsistencies 
reported by the GAO. For example, this proposed regulation clearly 
provides that a water that otherwise meets the proposed definition 
of tributary remains a jurisdictional tributary even if there are 
natural or man-made breaks in the OHWM. The proposed definition also 
provides a non-exclusive list of examples of breaks in the OHWM to 
assist in clearly and consistently determining what meets the 
definition of tributary.
    Most fundamentally, the agencies believe that the scientific 
literature demonstrates that tributaries, as a category and as the 
agencies propose to define them, play a critical role in the 
integrity of aquatic systems comprising traditional navigable waters 
and interstate waters, and therefore are ``waters of the United 
States'' within the meaning of the Clean Water Act.

Adjacent Waters

    The CWA explicitly establishes authority over adjacent wetlands. 
Under section 404(g), states are authorized to assume responsibility 
for administration of the section 404 permitting program with 
respect to ``navigable waters (other than those waters which are 
presently used, or are susceptible to use in their natural condition 
or by reasonable improvement as a means to transport interstate or 
foreign commerce shoreward to their ordinary high water mark, 
including all waters which are subject to the ebb and flow of the 
tide shoreward to their mean high water mark, or mean higher high 
water mark on the west coast, including wetlands adjacent 
thereto).'' 33 U.S.C. 1344(g)(1) (emphasis added). While this 
provision mainly serves as a limitation on the scope of waters for 
which states may be authorized to issue permits, it also shows that 
Congress was concerned with the protection of adjacent wetlands and 
recognized their important role in protecting downstream traditional 
navigable waters. Indeed, the existing definition of adjacency was 
developed in recognition of the integral role wetlands play in 
broader aquatic ecosystems:

The regulation of activities that cause water pollution cannot rely 
on . . . artificial lines . . . but must focus on all waters that 
together form the entire aquatic system. Water moves in hydrologic 
cycles, and the pollution of this part of the aquatic system, 
regardless of whether it is above or below an ordinary high water 
mark, or mean high tide line, will affect the water quality of the 
other waters within that aquatic system. For this reason, the 
landward limit of Federal jurisdiction under Section 404 must 
include any adjacent wetlands that form the border of or are in 
reasonable proximity to other waters of the United States, as these 
wetlands are part of this aquatic system.

42 FR 37128, July 19, 1977.
    As the Supreme Court found in United States v. Riverside Bayview 
Homes, Inc., ``the evident breadth of congressional concern for 
protection of water quality and aquatic ecosystems suggests that it 
is reasonable for the Corps to interpret the term `waters' to 
encompass wetlands adjacent to waters as more conventionally 
defined.'' 474 U.S. at 133.
    In upholding the Corps' judgment about the relationship between 
waters and their adjacent wetlands, the Supreme Court in Riverside 
Bayview acknowledged that the agencies' regulations take into 
account functions provided by wetlands in support of this 
relationship. ``[A]djacent wetlands may `serve significant natural 
biological functions, including food chain production, general 
habitat, and nesting, spawning, rearing and resting sites for 
aquatic . . . species.' '' Id. at 133 (citing Sec.  320.4(b)(2)(i)). 
The Court further stated that the Corps had reasonably concluded 
that ``wetlands adjacent to lakes, rivers, streams, and other bodies 
of water may function as integral parts of the aquatic environment 
even when the moisture creating the wetlands does not find its 
source in the adjacent bodies of water.'' 474 U.S. at 135.
    Two decades later, a majority of justices in Rapanos concluded 
that the agencies' regulatory definition of adjacent wetlands 
reasonable. Justice Kennedy stated:

As the Court noted in Riverside Bayview, `the Corps has concluded 
that wetlands may serve to filter and purify water draining into 
adjacent bodies of water, 33 CFR 320.4(b)(2)(vii)(1985), and to slow 
the flow of surface runoff into lakes, rivers, and streams and thus 
prevent flooding and erosion, see Sec.  320.4(b)(2)(iv) and (v).' 
Where wetlands perform these filtering and runoff-control functions, 
filling them may increase downstream pollution, much as a discharge 
of toxic pollutants would.. . . In many cases, moreover, filling in 
wetlands separated from another water by a berm can mean that flood 
water, impurities, or runoff that would have been stored or 
contained in the wetlands will instead flow out to major waterways. 
With these concerns in mind, the Corps' definition of adjacency is a 
reasonable one, for 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.

547 U.S. at 775 (citations omitted).
The four dissenting justices similarly concluded:

The Army Corps has determined that wetlands adjacent to tributaries 
of traditionally navigable waters preserve the quality of our 
Nation's waters by, among other things, providing habitat for 
aquatic animals, keeping excessive sediment and toxic pollutants out 
of adjacent waters, and reducing downstream flooding by absorbing 
water at times of high flow. The Corps' resulting decision to treat 
these wetlands as encompassed within the term `waters of the United 
States' is a quintessential example of the Executive's reasonable 
interpretation of a statutory provision.

Id. at 778 (citing Chevron U.S.A. Inc. v. Natural Resources Defense 
Council, Inc., 467 U.S. 837, 842-845 (1984)).
    For those wetlands adjacent to traditional navigable waters, 
Justice Kennedy concluded 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 other adjacent waters, including adjacent 
wetlands, Justice Kennedy's significant nexus standard provides 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 lands in the region, significantly affect the 
chemical, physical, and biological integrity of other covered waters 
more readily understood as `navigable.' '' Id. at 780. Next, Justice 
Kennedy stated that ``[t]hrough regulation or adjudication, the 
Corps may choose to identify categories of tributaries that, due to 
their volume of flow (either annually or on average), their 
proximity to navigable waters, or other relevant considerations, are 
significant enough that wetlands adjacent to them are likely, in the 
majority of cases, to perform important functions for an aquatic 
system incorporating navigable waters.'' Id. at 780-81.
    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 a touchstone for CWA jurisdiction. The agencies 
have determined that adjacent waters as defined in today's proposed 
rule, alone or in combination with other adjacent waters in the 
region that drains to a traditional navigable water, interstate 
water or the territorial seas, significantly affect the chemical, 
physical, and biological integrity of those waters. As explained in 
more detail in Section H, below, the proposed rule interprets the 
phrase ``in the region'' to mean the watershed that drains to the 
nearest traditional navigable water or interstate water through a 
single point of entry. The agencies have 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 reflection of Congressional 
intent.
    The agencies have concluded that all waters that meet the 
proposed definition of ``adjacent'' are similarly situated for 
purposes of analyzing whether they, in the majority of cases, have a 
significant nexus to an (a)(1) through (a)(3) water. Based on the 
agencies' review of the scientific literature, we have concluded 
that these waters, when bordering, contiguous or located in the 
floodplain or riparian area, or when otherwise meeting the 
definition of ``adjacent,'' provide many similar functions that 
significantly affect the chemical, physical, or biological integrity 
of traditional navigable waters, interstate waters, or the 
territorial seas. Further, because the proposed definition generally

[[Page 22261]]

focuses on the location of the waters (i.e., those that are located 
near (a)(1) through (a)(5) waters), interpreting the term 
``similarly situated'' to include all adjacent waters, as defined in 
the proposed rule, is reasonable and consistent with the science. 
The geographic position of an ``adjacent'' water relative to the 
tributary is indicative of the relationship to it, with many of its 
defining characteristics resulting from the movement of materials 
and energy between the categories of waters. The scientific 
literature documents that 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 
downstream traditional navigable waters, interstate waters, and 
territorial seas into which those waters flow, are an integrated 
ecological system, and discharges of pollutants, including 
discharges of dredged or fill material, into any component of that 
ecological system, must be regulated under the CWA to restore and 
maintain the chemical, physical, or biological integrity of these 
waters.
    Based on the science, as summarized below, the agencies have 
concluded that wetlands and waters adjacent to all tributaries that 
meet the proposed definition of ``tributary'' provide vital 
functions for downstream traditional navigable waters, interstate 
waters, or the territorial seas. In particular, the scientific 
literature supports the conclusion that waters adjacent to all 
tributaries as defined in section (a)(5) have a significant nexus to 
waters described in paragraphs (a)(1) through (a)(3). Because 
smaller streams, whether perennial, intermittent, or ephemeral, are 
much more common than larger streams, the volume of a stream's flow 
is not the best measure of its contribution to the chemical, 
physical, or biological integrity of downstream waters. Report at 4-
2, 4-3. As discussed in more detail in Appendix A, small streams 
cumulatively exert a strong influence on downstream waters, partly 
by collectively providing a substantial amount of the river's water, 
id. at 4-3, 4-4 to 4-5, but also by playing unique roles that large 
streams typically do not, including providing habitat for aquatic 
macroinvertebrates which help maintain the health of the downstream 
water. Waters adjacent to those small tributary streams, therefore, 
also significantly affect (a)(1) through (a)(3) waters through the 
movement of energy and materials between adjacent waters and those 
tributaries, resulting ultimately in significant downstream effects 
on the chemical, physical, and biological integrity of the (a)(1) 
through (a)(3) waters.

``Other Waters''

    In Rapanos, Justice Kennedy provides an approach for determining 
what constitutes a ``significant nexus'' that can serve as a basis 
for defining ``waters of the United States'' through regulation. 
Justice Kennedy concluded 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.'' Id. at 759 (citing SWANCC, 531 U.S. at 167, 
172). Again, the four justices who signed on to Justice Stevens' 
opinion would have upheld jurisdiction under the agencies' existing 
regulations and stated that they would uphold jurisdiction under 
either the plurality or Justice Kennedy's opinion. Justice Kennedy 
stated that 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 [wetlands] in the region, significantly 
affect the chemical, physical, and biological integrity of other 
covered waters more readily understood as `navigable.' '' Id. at 
780. In light of Rapanos and SWANCC, the ``significant nexus'' 
standard for CWA jurisdiction that Justice Kennedy's opinion applied 
to adjacent wetlands also can reasonably be applied to other waters 
such as ponds, lakes, and non-adjacent wetlands that may have a 
significant nexus to a traditional navigable water, an interstate 
water, or the territorial seas.
    The proposed rule includes a definition of significant nexus 
that is consistent with Justice Kennedy's significant nexus 
standard. In characterizing the significant nexus standard, Justice 
Kennedy stated: ``The required nexus must be assessed in terms of 
the statute's goals and purposes. Congress enacted the [CWA] to 
`restore and maintain the chemical, physical, and biological 
integrity of the Nation's waters' . . ..'' 547 U.S. at 779. It clear 
that Congress intended the CWA to ``restore and maintain'' all three 
forms of ``integrity,'' 33 U.S.C. 1251(a), so if any one form is 
compromised then that is contrary to the statute's stated objective. 
It would subvert the intent if the CWA only protected waters upon a 
showing that they had effects on every attribute of a traditional 
navigable water, interstate water, or territorial sea. Therefore, a 
showing of a significant chemical, physical, or biological affect 
should satisfy the significant nexus standard.
    Justice Kennedy's opinion provides guidance pointing to many 
functions of waters that might demonstrate a significant nexus, such 
as sediment trapping, nutrient recycling, pollutant trapping and 
filtering, retention or attenuation of flood waters, and runoff 
storage. See 547 U.S. at 775, 779-80. Furthermore, Justice Kennedy 
recognized that a hydrologic connection is not necessary to 
establish a significant nexus, because in some cases the absence of 
a hydrologic connection would show the significance of a water to 
the aquatic system, such as retention of flood waters or pollutants 
that would otherwise flow downstream to the traditional navigable 
water or interstate water. Id. at 775. Finally, Justice Kennedy was 
clear that the requisite nexus must be more than ``speculative or 
insubstantial'' in order to be significant. Id. at 780. Justice 
Kennedy's standard is consistent with basic scientific principles 
about how to restore and maintain the integrity of aquatic 
ecosystems.

Similarly Situated

    For purposes of analyzing the significant nexus of tributaries 
and adjacent waters, tributaries that meet the proposed definition 
of ``tributary'' in a watershed draining to an (a)(1) through (a)(3) 
water are similarly situated, and adjacent waters that meet the 
proposed definition of ``adjacent'' in a watershed draining to an 
(a)(1) through (a)(3) water are similarly situated. That is 
reasonable because the agencies are identifying characteristics of 
these waters through the regulation and documenting the science that 
demonstrates that these defined tributaries and defined adjacent 
waters provide similar functions in the watershed. As stated above, 
the functions of the tributaries are inextricably linked and have a 
cumulative effect on the integrity of the downstream traditional 
navigable water or interstate water. There is also an obvious 
locational relationship between the (a)(1), (a)(2) or (a)(3) water 
and the streams, lakes, and wetlands that meet the definition of 
tributaries and the definition of adjacent waters; these waters have 
a clear linear relationship resulting from the simple existence of 
the channel itself and the direction of flow. See Appendix A, 
Scientific Evidence.
    ``Other waters,'' on the other hand, constitute a broad range of 
different types of waters performing different functions. In light 
of the range and degree of functions performed by waters that are 
neither tributaries nor adjacent waters under today's proposed rule, 
the agencies propose a definition of similarly situated which takes 
into account similarity of functions provided and situation in the 
landscape. Since the focus of the significant nexus standard is on 
protecting the chemical, physical, and biological integrity of the 
nation's waters, the agencies propose to interpret the phrase 
``similarly situated'' in terms of whether the functions provided by 
the particular ``other waters'' are similar and, therefore, whether 
such ``other waters'' are collectively influencing the chemical, 
physical, or biological integrity of downstream waters. There are 
many functions of waters that might demonstrate a significant nexus, 
such as sediment trapping, nutrient recycling, pollutant trapping 
and filtering, retention or attenuation of flood waters, runoff 
storage, and provision of habitat. See 547 U.S. at 775, 779-80. This 
approach is consistent not only with the significant nexus standard, 
but with the science of aquatic systems.
    The absence of a hydrologic connection between ``other waters'' 
and traditional navigable waters, interstate waters, or the 
territorial seas may demonstrate the presence of a significant nexus 
between such waters, as Justice Kennedy recognized in his opinion. 
``Other waters'' frequently function alone or cumulatively with 
similarly situated ``other waters'' in the region to capture runoff, 
rain water, or snowmelt and thereby protect the integrity of 
downstream waters by reducing potential flooding or trapping 
pollutants that would otherwise reach a traditional navigable water 
or interstate water. See id. at 775. Such waters can be crucial in 
controlling flooding as well as in maintaining water quality by 
trapping or transforming

[[Page 22262]]

pollutants such as excess nutrients or sediment, for example, or 
retaining precipitation or snow melt, thereby reducing contamination 
or flooding of traditional navigable waters, interstate waters, or 
the territorial seas.

Significant Nexus

    The agencies propose to define the term ``significant nexus'' 
consistent with language in SWANCC and Rapanos. The proposed 
definition of ``significant nexus'' at (c)(7) relies most 
significantly on Justice Kennedy's Rapanos opinion which recognizes 
that not all waters have this requisite connection to waters covered 
by paragraphs (a)(1) through (a)(3) of the proposed regulations. 
Justice Kennedy was clear that the requisite nexus must be more than 
``speculative or insubstantial. . ., '' Rapanos, 547 U.S. at 780, in 
order to be significant and the proposed rule defines significant 
nexus in precisely those terms. In Rapanos, Justice Kennedy stated 
that in both the consolidated cases before the Court the record 
contained evidence suggesting the possible existence of a 
significant nexus according to the principles he identified. See id. 
at 783. 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.'' Id. Justice Kennedy remanded the cases 
because neither the agency nor the reviewing courts properly applied 
the controlling legal standard--whether the wetlands at issue had a 
significant nexus. See id. Justice Kennedy was clear however, that 
``[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. at 784.
    With respect to one of the wetlands at issue in the consolidated 
Rapanos cases, Justice Kennedy stated:

    In Carabell, No. 04-1384, the record also contains evidence 
bearing on the jurisdictional inquiry. The Corps noted in deciding 
the administrative appeal that ``[b]esides the effects on wildlife 
habitat and water quality, the [district office] also noted that the 
project would have a major, long-term detrimental effect on 
wetlands, flood retention, recreation and conservation and overall 
ecology. . . . The Corps' evaluation further noted that by 
`eliminat[ing] the potential ability of the wetland to act as a 
sediment catch basin,'' the proposed project ``would contribute to 
increased runoff and . . . accretion along the drain and further 
downstream in Auvase Creek.' . . . And it observed that increased 
runoff from the site would likely cause downstream areas to ``see an 
increase in possible flooding magnitude and frequency.''

Id. at 785-86. Justice Kennedy also expressed concern that ``[t]he 
conditional language in these assessments--`potential ability,' 
`possible flooding'--could suggest an undue degree of speculation.'' 
Id.at 786.
    Justice Kennedy's observations regarding the above case provide 
guidance as to what it means for a nexus to be more than merely 
speculative or insubstantial and inform the proposed definition of 
``significant nexus.'' It is important to note, however, that where 
Justice Kennedy viewed the language ``more than speculative or 
insubstantial'' to suggest an undue degree of speculation, 
scientists do not equate certain conditional language (such as 
``may'' or ``could'') with speculation, but rather with the rigorous 
and precise language of science necessary when applying specific 
findings in another individual situation or more broadly across a 
variety of situations. Certain terms used in a scientific context do 
not have the same implications that they have in a legal or policy 
context. Scientists use cautionary language, such as ``may'' or 
``could,'' when applying specific findings on a broader scale to 
avoid the appearance of overstating their research results and to 
avoid inserting bias into their findings (such that the reader may 
think the results of one study are applicable in all related 
studies). Words like ``potential'' are commonly used in the 
biological sciences, but when viewed under a legal and policy veil, 
may seem to mean the same as ``speculative'' or ``insubstantial.'' 
Instead, potential in scientific terms means ability or capability. 
For example, when the term ``potential'' is used to describe how a 
wetland has the potential to act as a sink for floodwater and 
pollutants, scientists mean that wetlands in general do indeed 
perform those functions, but whether a particular wetland performs 
that function is dependent upon the circumstances that would create 
conditions for floodwater or pollutants in the watershed to reach 
that particular wetland to retain and transform. That does not mean, 
however, that this nexus to downstream waters is ``speculative;'' 
indeed the wetland would be expected to provide these functions 
under the proper circumstances.

    Definition of ``Waters of the United States'' Under the Clean Water 
Act.

List of Subjects

33 CFR Part 328

    Environmental protection, Administrative practice and procedure, 
Intergovernmental relations, Navigation, Water pollution control, 
Waterways.

40 CFR Part 110

    Environmental protection, Water pollution control.

40 CFR Part 112

    Environmental protection, Water pollution control.

40 CFR Part 116

    Environmental protection, Water pollution control.

40 CFR Part 117

    Environmental protection, Water pollution control.

40 CFR Part 122

    Environmental protection, Water pollution control.

40 CFR Part 230

    Environmental protection, Water pollution control.

40 CFR Part 232

    Environmental protection, Water pollution control.

40 CFR Part 300

    Environmental protection, Water pollution control.

40 CFR Part 302

    Environmental protection, Water pollution control.

40 CFR Part 401

    Environmental protection, Water pollution control.

    Dated: March 25, 2014.
Gina McCarthy,
Administrator, Environmental Protection Agency.
    Dated: March 24, 2014.
Jo Ellen Darcy,
Assistant Secretary of the Army (Civil Works), Department of the Army.

Title 33--Navigation and Navigable Waters

    For the reasons set out in the preamble, title 33, chapter I of the 
Code of Federal Regulations is proposed to be amended as follows:

PART 328--DEFINITION OF WATERS OF THE UNITED STATES

0
1. The authority citation for part 328 continues to read as follows:

    Authority:  The Clean Water Act, 33 U.S.C. 1251 et seq.

0
2. Section 328.3 is amended by removing the introductory text and 
revising paragraphs (a), (b), and (c) to read as follows:


Sec.  328.3  Definitions.

    (a) For purposes of all sections of the Clean Water Act, 33 U.S.C. 
1251 et. seq. and its implementing regulations, subject to the 
exclusions in paragraph (b) of this section, the term ``waters of the 
United States'' means:
    (1) All waters which are currently used, were used in the past, or 
may be susceptible to use in interstate or foreign commerce, including 
all waters which are subject to the ebb and flow of the tide;
    (2) All interstate waters, including interstate wetlands;
    (3) The territorial seas;
    (4) All impoundments of waters identified in paragraphs (a)(1) 
through (3) and (5) of this section;
    (5) All tributaries of waters identified in paragraphs (a)(1) 
through (4) of this section;

[[Page 22263]]

    (6) All waters, including wetlands, adjacent to a water identified 
in paragraphs (a)(1) through (5) of this section; and
    (7) On a case-specific basis, other waters, including wetlands, 
provided that those waters alone, or in combination with other 
similarly situated waters, including wetlands, located in the same 
region, have a significant nexus to a water identified in paragraphs 
(a)(1) through (3) of this section.
    (b) The following are not ``waters of the United States'' 
notwithstanding whether they meet the terms of paragraphs (a)(1) 
through (7) of this section--
    (1) Waste treatment systems, including treatment ponds or lagoons, 
designed to meet the requirements of the Clean Water Act.
    (2) Prior converted cropland. Notwithstanding the determination of 
an area's status as prior converted cropland by any other Federal 
agency, for the purposes of the Clean Water Act the final authority 
regarding Clean Water Act jurisdiction remains with EPA.
    (3) Ditches that are excavated wholly in uplands, drain only 
uplands, and have less than perennial flow.
    (4) Ditches that do not contribute flow, either directly or through 
another water, to a water identified in paragraphs (a)(1) through (4) 
of this section.
    (5) The following features:
    (i) Artificially irrigated areas that would revert to upland should 
application of irrigation water to that area cease;
    (ii) 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;
    (iii) Artificial reflecting pools or swimming pools created by 
excavating and/or diking dry land;
    (iv) Small ornamental waters created by excavating and/or diking 
dry land for primarily aesthetic reasons;
    (v) Water-filled depressions created incidental to construction 
activity;
    (vi) Groundwater, including groundwater drained through subsurface 
drainage systems; and
    (vii) Gullies and rills and non-wetland swales.
    (c) Definitions--
    (1) Adjacent. 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.''
    (2) Neighboring. The term neighboring, for purposes of the term 
``adjacent'' in this section, includes waters located within the 
riparian area or floodplain of a water identified in paragraphs (a)(1) 
through (5) of this section, or waters with a shallow subsurface 
hydrologic connection or confined surface hydrologic connection to such 
a jurisdictional water.
    (3) Riparian area. 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.
    (4) Floodplain. 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.
    (5) Tributary. The term tributary means a water physically 
characterized by the presence of a bed and banks and ordinary high 
water mark, as defined at 33 CFR 328.3(e), which contributes flow, 
either directly or through another water, to a water identified in 
paragraphs (a)(1) through (4) of this section. In addition, wetlands, 
lakes, and ponds are tributaries (even if they lack a bed and banks or 
ordinary high water mark) if they contribute flow, either directly or 
through another water to a water identified in paragraphs (a)(1) 
through (3) of this section. A water that otherwise qualifies as a 
tributary under this definition does not lose its status as a tributary 
if, for any length, there are one or more man-made breaks (such as 
bridges, culverts, pipes, or dams), or one or more natural breaks (such 
as wetlands at the head of or along the run of a stream, debris piles, 
boulder fields, or a stream that flows underground) so long as a bed 
and banks and an ordinary high water mark can be identified upstream of 
the break. A tributary, including wetlands, can be a natural, man-
altered, or man-made water and includes waters such as rivers, streams, 
lakes, ponds, impoundments, canals, and ditches not excluded in 
paragraph (b)(3) or (4) of this section.
    (6) Wetlands. The term wetlands means those areas that are 
inundated or saturated by surface or groundwater at a frequency and 
duration sufficient to support, and that under normal circumstances do 
support, a prevalence of vegetation typically adapted for life in 
saturated soil conditions. Wetlands generally include swamps, marshes, 
bogs and similar areas.
    (7) Significant nexus. The term significant nexus means 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 (3) 
of this section), significantly affects the chemical, physical, or 
biological integrity of a water identified in paragraphs (a)(1) through 
(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 (3) of this section.
* * * * *

Title 40--Protection of Environment

    For the reasons set out in the preamble, title 40, chapter I of the 
Code of Federal Regulations is proposed to be amended as follows:

PART 110--DISCHARGE OF OIL

0
3. The authority citation for part 110 continues to read as follows:

    Authority:  The Clean Water Act, 33 U.S.C. 1321 et seq.

0
4. Section 110.1 is amended by revising the definition of ``navigable 
waters'' to read as follows:


Sec.  110.1  Definitions.

* * * * *
    Navigable waters means the waters of the United States, including 
the territorial seas.
    (1) For purposes of all sections of the Clean Water Act, 33 U.S.C. 
1251 et. seq. and its implementing regulations, subject to the 
exclusions in paragraph (2) of this definition, the term ``waters of 
the United States'' means:
    (i) All waters which are currently used, were used in the past, or 
may be susceptible to use in interstate or foreign commerce, including 
all waters which are subject to the ebb and flow of the tide;
    (ii) All interstate waters, including interstate wetlands;
    (iii) The territorial seas;
    (iv) All impoundments of waters identified in paragraphs (1)(i) 
through (iii) and (v) of this definition;

[[Page 22264]]

    (v) All tributaries of waters identified in paragraphs (1)(i) 
through (iv) of this definition;
    (vi) All waters, including wetlands, adjacent to a water identified 
in paragraphs (1)(i) through (v) of this definition; and
    (vii) On a case-specific basis, other waters, including wetlands, 
provided that those waters alone, or in combination with other 
similarly situated waters, including wetlands, located in the same 
region, have a significant nexus to a water identified in paragraphs 
(1)(i) through (iii) of this definition.
    (2) The following are not ``waters of the United States'' 
notwithstanding whether they meet the terms of paragraphs (1)(i) 
through (vii) of this definition--
    (i) Waste treatment systems, including treatment ponds or lagoons, 
designed to meet the requirements of the Clean Water Act.
    (ii) Prior converted cropland. Notwithstanding the determination of 
an area's status as prior converted cropland by any other Federal 
agency, for the purposes of the Clean Water Act the final authority 
regarding Clean Water Act jurisdiction remains with EPA.
    (iii) Ditches that are excavated wholly in uplands, drain only 
uplands, and have less than perennial flow.
    (iv) Ditches that do not contribute flow, either directly or 
through another water, to a water identified in paragraphs (1)(i) 
through (iv) of this definition.
    (v) The following features:
    (A) Artificially irrigated areas that would revert to upland should 
application of irrigation water to that area cease;
    (B) 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;
    (C) Artificial reflecting pools or swimming pools created by 
excavating and/or diking dry land;
    (D) Small ornamental waters created by excavating and/or diking dry 
land for primarily aesthetic reasons;
    (E) Water-filled depressions created incidental to construction 
activity;
    (F) Groundwater, including groundwater drained through subsurface 
drainage systems; and
    (G) Gullies and rills and non-wetland swales.
    (3) Definitions--
    (i) Adjacent. 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.''
    (ii) Neighboring. The term neighboring, for purposes of the term 
``adjacent'' in this section, includes waters located within the 
riparian area or floodplain of a water identified in paragraphs (1)(i) 
through (v) of this definition, or waters with a shallow subsurface 
hydrologic connection or confined surface hydrologic connection to such 
a jurisdictional water.
    (iii) Riparian area. 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.
    (iv) Floodplain. 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.
    (v) Tributary. The term tributary means a water physically 
characterized by the presence of a bed and banks and ordinary high 
water mark, as defined at 33 CFR 328.3(e), which contributes flow, 
either directly or through another water, to a water identified in 
paragraphs (1)(i) through (iv) of this definition. In addition, 
wetlands, lakes, and ponds are tributaries (even if they lack a bed and 
banks or ordinary high water mark) if they contribute flow, either 
directly or through another water to a water identified in paragraphs 
(1)(i) through (iii) of this definition. A water that otherwise 
qualifies as a tributary under this definition does not lose its status 
as a tributary if, for any length, there are one or more man-made 
breaks (such as bridges, culverts, pipes, or dams), or one or more 
natural breaks (such as wetlands at the head of or along the run of a 
stream, debris piles, boulder fields, or a stream that flows 
underground) so long as a bed and banks and an ordinary high water mark 
can be identified upstream of the break. A tributary, including 
wetlands, can be a natural, man-altered, or man-made water and includes 
waters such as rivers, streams, lakes, ponds, impoundments, canals, and 
ditches not excluded in paragraph (2)(iii) or (iv) of this definition.
    (vi) Wetlands. The term wetlands means those areas that are 
inundated or saturated by surface or groundwater at a frequency and 
duration sufficient to support, and that under normal circumstances do 
support, a prevalence of vegetation typically adapted for life in 
saturated soil conditions. Wetlands generally include swamps, marshes, 
bogs and similar areas.
    (vii) Significant nexus. The term significant nexus means 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 (1)(i) through 
(iii) of this definition), significantly affects the chemical, 
physical, or biological integrity of a water identified in paragraphs 
(1)(i) through (iii) of this definition. 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 (1)(i) through (iii) of this definition.
* * * * *

PART 112--OIL POLLUTION PREVENTION

0
5. The authority citation for part 112 continues to read as follows:

    Authority:  The Clean Water Act, 33 U.S.C. 1321 et seq.

0
6. Section 112.2 is amended by revising the definition of ``navigable 
waters'' to read as follows:


Sec.  112.2  Definitions.

* * * * *
    Navigable waters means the waters of the United States, including 
the territorial seas.
    (1) For purposes of all sections of the Clean Water Act, 33 U.S.C. 
1251 et. seq. and its implementing regulations, subject to the 
exclusions in paragraph (b) of this section, the term ``waters of the 
United States'' means:
    (i) All waters which are currently used, were used in the past, or 
may be susceptible to use in interstate or foreign commerce, including 
all waters which are subject to the ebb and flow of the tide;
    (ii) All interstate waters, including interstate wetlands;
    (iii) The territorial seas;
    (iv) All impoundments of waters identified in paragraphs (1)(i) 
through (iii) and (v) of this definition;

[[Page 22265]]

    (v) All tributaries of waters identified in paragraphs (1)(i) 
through (iv) of this definition;
    (vi) All waters, including wetlands, adjacent to a water identified 
in paragraphs (1)(i) through (v) of this definition; and
    (vii) On a case-specific basis, other waters, including wetlands, 
provided that those waters alone, or in combination with other 
similarly situated waters, including wetlands, located in the same 
region, have a significant nexus to a water identified in paragraphs 
(1)(i) through (iii) of this definition.
    (2) The following are not ``waters of the United States'' 
notwithstanding whether they meet the terms of paragraphs (1)(i) 
through (vii) of this definition ----
    (i) Waste treatment systems, including treatment ponds or lagoons, 
designed to meet the requirements of the Clean Water Act.
    (ii) Prior converted cropland. Notwithstanding the determination of 
an area's status as prior converted cropland by any other Federal 
agency, for the purposes of the Clean Water Act the final authority 
regarding Clean Water Act jurisdiction remains with EPA.
    (iii) Ditches that are excavated wholly in uplands, drain only 
uplands, and have less than perennial flow.
    (iv) Ditches that do not contribute flow, either directly or 
through another water, to a water identified in paragraphs (1)(i) 
through (iv) of this definition.
    (v) The following features:
    (A) Artificially irrigated areas that would revert to upland should 
application of irrigation water to that area cease;
    (B) 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;
    (C) Artificial reflecting pools or swimming pools created by 
excavating and/or diking dry land;
    (D) Small ornamental waters created by excavating and/or diking dry 
land for primarily aesthetic reasons;
    (E) Water-filled depressions created incidental to construction 
activity;
    (F) Groundwater, including groundwater drained through subsurface 
drainage systems; and
    (G) Gullies and rills and non-wetland swales.
    (3) Definitions--
    (i) Adjacent. 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.''
    (ii) Neighboring. The term neighboring, for purposes of the term 
``adjacent'' in this section, includes waters located within the 
riparian area or floodplain of a water identified in paragraphs (1)(i) 
through (v) of this definition, or waters with a shallow subsurface 
hydrologic connection or confined surface hydrologic connection to such 
a jurisdictional water.
    (iii) Riparian area. 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.
    (iv) Floodplain. 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.
    (v) Tributary. The term tributary means a water physically 
characterized by the presence of a bed and banks and ordinary high 
water mark, as defined at 33 CFR 328.3(e), which contributes flow, 
either directly or through another water, to a water identified in 
paragraphs (1)(i) through (iv) of this definition. In addition, 
wetlands, lakes, and ponds are tributaries (even if they lack a bed and 
banks or ordinary high water mark) if they contribute flow, either 
directly or through another water to a water identified in paragraphs 
(1)(i) through (iii) of this definition. A water that otherwise 
qualifies as a tributary under this definition does not lose its status 
as a tributary if, for any length, there are one or more man-made 
breaks (such as bridges, culverts, pipes, or dams), or one or more 
natural breaks (such as wetlands at the head of or along the run of a 
stream, debris piles, boulder fields, or a stream that flows 
underground) so long as a bed and banks and an ordinary high water mark 
can be identified upstream of the break. A tributary, including 
wetlands, can be a natural, man-altered, or man-made water and includes 
waters such as rivers, streams, lakes, ponds, impoundments, canals, and 
ditches not excluded in paragraph (2)(iii) or (iv) of this definition.
    (6) Wetlands. The term wetlands means those areas that are 
inundated or saturated by surface or groundwater at a frequency and 
duration sufficient to support, and that under normal circumstances do 
support, a prevalence of vegetation typically adapted for life in 
saturated soil conditions. Wetlands generally include swamps, marshes, 
bogs and similar areas.
    (7) Significant nexus. The term significant nexus means 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 (1)(i) through 
(iii) of this definition), significantly affects the chemical, 
physical, or biological integrity of a water identified in paragraphs 
(1)(i) through (iii) of this definition. 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 (1)(i) through (iii) of this definition.
* * * * *

PART 116--DESIGNATION OF HAZARDOUS SUBSTANCE

0
7. The authority citation for part 116 continues to read as follows:

    Authority: The Clean Water Act, 33 U.S.C. 1251 et seq.

0
8. Section 116.3 is amended by revising the definition of ``navigable 
waters'' to read as follows:


Sec.  116.3  Definitions.

* * * * *
    Navigable waters is defined in section 502(7) of the Act to mean 
``waters of the United States, including the territorial seas.''
    (1) For purposes of all sections of the Clean Water Act, 33 U.S.C. 
1251 et seq. and its implementing regulations, subject to the 
exclusions in paragraph (2) of this definition, the term ``waters of 
the United States'' means:
    (i) All waters which are currently used, were used in the past, or 
may be susceptible to use in interstate or foreign commerce, including 
all waters which are subject to the ebb and flow of the tide;
    (ii) All interstate waters, including interstate wetlands;
    (iii) The territorial seas;
    (iv) All impoundments of waters identified in paragraphs (1)(i) 
through (iii) and (v) of this definition;.

[[Page 22266]]

    (v) All tributaries of waters identified in paragraphs (1)(i) 
through (iv) of this definition;
    (vi) All waters, including wetlands, adjacent to a water identified 
in paragraphs (1)(i) through (v) of this definition; and
    (vii) On a case-specific basis, other waters, including wetlands, 
provided that those waters alone, or in combination with other 
similarly situated waters, including wetlands, located in the same 
region, have a significant nexus to a water identified in paragraphs 
(1)(i) through (iii) of this definition.
    (2) The following are not ``waters of the United States'' 
notwithstanding whether they meet the terms of paragraphs (1)(i) 
through (viii) of this definition--
    (i) Waste treatment systems, including treatment ponds or lagoons, 
designed to meet the requirements of the Clean Water Act.
    (ii) Prior converted cropland. Notwithstanding the determination of 
an area's status as prior converted cropland by any other Federal 
agency, for the purposes of the Clean Water Act the final authority 
regarding Clean Water Act jurisdiction remains with EPA.
    (iii) Ditches that are excavated wholly in uplands, drain only 
uplands, and have less than perennial flow.
    (iv) Ditches that do not contribute flow, either directly or 
through another water, to a water identified in paragraphs (1)(i) 
through (iv) of this section.
    (v) The following features:
    (A) Artificially irrigated areas that would revert to upland should 
application of irrigation water to that area cease;
    (B) 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;
    (C) Artificial reflecting pools or swimming pools created by 
excavating and/or diking dry land;
    (D) Small ornamental waters created by excavating and/or diking dry 
land for primarily aesthetic reasons;
    (E) Water-filled depressions created incidental to construction 
activity;
    (F) Groundwater, including groundwater drained through subsurface 
drainage systems; and
    (G) Gullies and rills and non-wetland swales.
    (3) Definitions--
    (i) Adjacent. 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.''
    (ii) Neighboring. The term neighboring, for purposes of the term 
``adjacent'' in this section, includes waters located within the 
riparian area or floodplain of a water identified in paragraphs (1)(i) 
through (v) of this definition, or waters with a shallow subsurface 
hydrologic connection or confined surface hydrologic connection to such 
a jurisdictional water.
    (iii) Riparian area. 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.
    (4) Floodplain. 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.
    (5) Tributary. The term tributary means a water physically 
characterized by the presence of a bed and banks and ordinary high 
water mark, as defined at 33 CFR 328.3(e), which contributes flow, 
either directly or through another water, to a water identified in 
paragraphs (1)(i) through (iv) of this definition. In addition, 
wetlands, lakes, and ponds are tributaries (even if they lack a bed and 
banks or ordinary high water mark) if they contribute flow, either 
directly or through another water to a water identified in paragraphs 
(1)(i) through (iii) of this definition. A water that otherwise 
qualifies as a tributary under this definition does not lose its status 
as a tributary if, for any length, there are one or more man-made 
breaks (such as bridges, culverts, pipes, or dams), or one or more 
natural breaks (such as wetlands at the head of or along the run of a 
stream, debris piles, boulder fields, or a stream that flows 
underground) so long as a bed and banks and an ordinary high water mark 
can be identified upstream of the break. A tributary, including 
wetlands, can be a natural, man-altered, or man-made water and includes 
waters such as rivers, streams, lakes, ponds, impoundments, canals, and 
ditches not excluded in paragraph (2)(iii) or (iv) of this definition.
    (vi) Wetlands. The term wetlands means those areas that are 
inundated or saturated by surface or groundwater at a frequency and 
duration sufficient to support, and that under normal circumstances do 
support, a prevalence of vegetation typically adapted for life in 
saturated soil conditions. Wetlands generally include swamps, marshes, 
bogs and similar areas.
    (vii) Significant nexus. The term significant nexus means 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 (1)(i) through 
(iii) of this definition), significantly affects the chemical, 
physical, or biological integrity of a water identified in paragraphs 
(1)(i) through (iii) of this definition. 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 (1)(i) through (iii) of this definition.
* * * * *

PART 117--DETERMINATION OF REPORTABLE QUANTITIES FOR HAZARDOUS 
SUBSTANCES

0
9. The authority citation for part 117 continues to read as follows:

    Authority:  The Clean Water Act, 33 U.S.C. 1251 et seq.

0
10. Section 117.1 is amended by revising the definition of ``navigable 
waters'' to read as follows:


Sec.  117.1  Definitions.

* * * * *
    (i) Navigable waters means ``waters of the United States, including 
the territorial seas.''
    (1) For purposes of all sections of the Clean Water Act, 33 U.S.C. 
1251 et. seq. and its implementing regulations, subject to the 
exclusions in paragraph (i)(2) of this section, the term ``waters of 
the United States'' means:
    (i) All waters which are currently used, were used in the past, or 
may be susceptible to use in interstate or foreign commerce, including 
all waters which are subject to the ebb and flow of the tide;
    (ii) All interstate waters, including interstate wetlands;
    (iii) The territorial seas;
    (iv) All impoundments of waters identified in paragraphs (i)(1)(i) 
through (iii) and (v) of this section;

[[Page 22267]]

    (v) All tributaries of waters identified in paragraphs (i)(1)(i) 
through (iv) of this section;
    (vi) All waters, including wetlands, adjacent to a water identified 
in paragraphs (i)(1)(i) through (v) of this section; and
    (vii) On a case-specific basis, other waters, including wetlands, 
provided that those waters alone, or in combination with other 
similarly situated waters, including wetlands, located in the same 
region, have a significant nexus to a water identified in paragraphs 
(i)(1)(i) through (iii) of this section.
    (2) The following are not ``waters of the United States'' 
notwithstanding whether they meet the terms of paragraphs (i)(1)(i) 
through (vii) of this section--
    (i) Waste treatment systems, including treatment ponds or lagoons, 
designed to meet the requirements of the Clean Water Act.
    (ii) Prior converted cropland. Notwithstanding the determination of 
an area's status as prior converted cropland by any other Federal 
agency, for the purposes of the Clean Water Act the final authority 
regarding Clean Water Act jurisdiction remains with EPA.
    (iii) Ditches that are excavated wholly in uplands, drain only 
uplands, and have less than perennial flow.
    (iv) Ditches that do not contribute flow, either directly or 
through another water, to a water identified in paragraphs (i)(1)(i) 
through (iv) of this section.
    (v) The following features:
    (A) Artificially irrigated areas that would revert to upland should 
application of irrigation water to that area cease;
    (B) 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;
    (C) Artificial reflecting pools or swimming pools created by 
excavating and/or diking dry land;
    (D) Small ornamental waters created by excavating and/or diking dry 
land for primarily aesthetic reasons;
    (E) Water-filled depressions created incidental to construction 
activity;
    (F) Groundwater, including groundwater drained through subsurface 
drainage systems; and
    (G) Gullies and rills and non-wetland swales.
    (3) Definitions--
    (i) Adjacent. 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.''
    (ii) Neighboring. The term neighboring, for purposes of the term 
``adjacent'' in this section, includes waters located within the 
riparian area or floodplain of a water identified in paragraphs 
(i)(1)(i) through (v) of this section, or waters with a shallow 
subsurface hydrologic connection or confined surface hydrologic 
connection to such a jurisdictional water.
    (iii) Riparian area. 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.
    (iv) Floodplain. 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.
    (v) Tributary. The term tributary means a water physically 
characterized by the presence of a bed and banks and ordinary high 
water mark, as defined at 33 CFR 328.3(e), which contributes flow, 
either directly or through another water, to a water identified in 
paragraphs (i)(1)(i) through (iv) of this section. In addition, 
wetlands, lakes, and ponds are tributaries (even if they lack a bed and 
banks or ordinary high water mark) if they contribute flow, either 
directly or through another water to a water identified in paragraphs 
(i)(1)(i) through (iii) of this section. A water that otherwise 
qualifies as a tributary under this definition does not lose its status 
as a tributary if, for any length, there are one or more man-made 
breaks (such as bridges, culverts, pipes, or dams), or one or more 
natural breaks (such as wetlands at the head of or along the run of a 
stream, debris piles, boulder fields, or a stream that flows 
underground) so long as a bed and banks and an ordinary high water mark 
can be identified upstream of the break. A tributary, including 
wetlands, can be a natural, man-altered, or man-made water and includes 
waters such as rivers, streams, lakes, ponds, impoundments, canals, and 
ditches not excluded in paragraph (i)(2)(iii) or (iv) of this section.
    (vi) Wetlands. The term wetlands means those areas that are 
inundated or saturated by surface or groundwater at a frequency and 
duration sufficient to support, and that under normal circumstances do 
support, a prevalence of vegetation typically adapted for life in 
saturated soil conditions. Wetlands generally include swamps, marshes, 
bogs and similar areas.
    (vii) Significant nexus. The term significant nexus means 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 (i)(1)(i) through 
(iii) of this section), significantly affects the chemical, physical, 
or biological integrity of a water identified in paragraphs (i)(1)(i) 
through (iii) 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 
(i)(1)(i) through (iii) of this section.
* * * * *

PART 122--EPA ADMINISTERED PERMIT PROGRAMS: THE NATIONAL POLLUTANT 
DISCHARGE ELIMINATION SYSTEM

0
11. The authority citation for part 122 continues to read as follows:

    Authority:  The Clean Water Act, 33 U.S.C. 1251 et seq.

0
12. Section 122.2 is amended by revising the definition of ``Waters of 
the United States'' and removing the note and editorial note at the end 
of the section.
    The revision reads as follows:


Sec.  122.2  Definitions.

* * * * *
    Waters of the United States or waters of the U.S. means:
    (a) For purposes of all sections of the Clean Water Act, 33 U.S.C. 
1251 et seq. and its implementing regulations, subject to the 
exclusions in paragraph (b) of this definition, the term ``waters of 
the United States'' means:
    (1) All waters which are currently used, were used in the past, or 
may be susceptible to use in interstate or foreign commerce, including 
all waters which are subject to the ebb and flow of the tide;
    (2) All interstate waters, including interstate wetlands;
    (3) The territorial seas;

[[Page 22268]]

    (4) All impoundments of waters identified in paragraphs (a)(1) 
through (3) and (5) of this definition;
    (5) All tributaries of waters identified in paragraphs (a)(1) 
through (4) of this definition;
    (6) All waters, including wetlands, adjacent to a water identified 
in paragraphs (a)(1) through (5) of this definition; and
    (7) On a case-specific basis, other waters, including wetlands, 
provided that those waters alone, or in combination with other 
similarly situated waters, including wetlands, located in the same 
region, have a significant nexus to a water identified in paragraphs 
(a)(1) through (3) of this definition.
    (b) The following are not ``waters of the United States'' 
notwithstanding whether they meet the terms of paragraphs (a)(1) 
through (7) of this definition--
    (1) Waste treatment systems, including treatment ponds or lagoons, 
designed to meet the requirements of the Clean Water Act. This 
exclusion applies only to manmade bodies of water which neither were 
originally created in waters of the United States (such as disposal 
area in wetlands) nor resulted from the impoundment of waters of the 
United States.\1\
    (2) Prior converted cropland. Notwithstanding the determination of 
an area's status as prior converted cropland by any other Federal 
agency, for the purposes of the Clean Water Act the final authority 
regarding Clean Water Act jurisdiction remains with EPA.
    (3) Ditches that are excavated wholly in uplands, drain only 
uplands, and have less than perennial flow.
    (4) Ditches that do not contribute flow, either directly or through 
another water, to a water identified in paragraphs (a)(1) through (4) 
of this definition.
    (5) The following features:
    (i) Artificially irrigated areas that would revert to upland should 
application of irrigation water to that area cease;
    (ii) 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;
    (iii) Artificial reflecting pools or swimming pools created by 
excavating and/or diking dry land;
    (iv) Small ornamental waters created by excavating and/or diking 
dry land for primarily aesthetic reasons;
    (v) Water-filled depressions created incidental to construction 
activity;
    (vi) Groundwater, including groundwater drained through subsurface 
drainage systems; and
    (vii) Gullies and rills and non-wetland swales.
    (c) Definitions--
    (1) Adjacent. 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.''
    (2) Neighboring. The term neighboring, for purposes of the term 
``adjacent'' in this section, includes waters located within the 
riparian area or floodplain of a water identified in paragraphs (a)(1) 
through (5) of this section, or waters with a shallow subsurface 
hydrologic connection or confined surface hydrologic connection to such 
a jurisdictional water.
    (3) Riparian area. 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.
    (4) Floodplain. 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.
    (5) Tributary. The term tributary means a water physically 
characterized by the presence of a bed and banks and ordinary high 
water mark, as defined at 33 CFR 328.3(e), which contributes flow, 
either directly or through another water, to a water identified in 
paragraphs (a)(1) through (4) of this definition. In addition, 
wetlands, lakes, and ponds are tributaries (even if they lack a bed and 
banks or ordinary high water mark) if they contribute flow, either 
directly or through another water to a water identified in paragraphs 
(a)(1) through (3) of this definition. A water that otherwise qualifies 
as a tributary under this definition does not lose its status as a 
tributary if, for any length, there are one or more man-made breaks 
(such as bridges, culverts, pipes, or dams), or one or more natural 
breaks (such as wetlands at the head of or along the run of a stream, 
debris piles, boulder fields, or a stream that flows underground) so 
long as a bed and banks and an ordinary high water mark can be 
identified upstream of the break. A tributary, including wetlands, can 
be a natural, man-altered, or man-made water and includes waters such 
as rivers, streams, lakes, ponds, impoundments, canals, and ditches not 
excluded in paragraphs (b)(3) or (4) of this definition.
    (6) Wetlands. The term wetlands means those areas that are 
inundated or saturated by surface or groundwater at a frequency and 
duration sufficient to support, and that under normal circumstances do 
support, a prevalence of vegetation typically adapted for life in 
saturated soil conditions. Wetlands generally include swamps, marshes, 
bogs and similar areas.
    (7) Significant nexus. The term significant nexus means 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 (3) 
of this definition), significantly affects the chemical, physical, or 
biological integrity of a water identified in paragraphs (a)(1) through 
(3) of this definition. 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 (3) of this definition.
* * * * *
    \1\At 45 FR 48620, July 21, 1980, the Environmental Protection 
Agency suspended until further notice in Sec.  122.2, the last 
sentence, beginning ``This exclusion applies . . .'' in the definition 
of ``Waters of the United States.'' This revision (48 FR 14153, Apr. 1, 
1983) continues that suspension.

PART 230--SECTION 404(b)(1) GUIDELINES FOR SPECIFICATION OF 
DISPOSAL SITES FOR DREDGED OR FILL MATERIAL

0
13. The authority citation for part 230 continues to read as follows:

    Authority:  The Clean Water Act, 33 U.S.C. 1251 et seq.

0
14. Section 230.3 is amended by revising paragraphs (s) and (t) and 
adding paragraph (u) to read as follows:


Sec.  230.3  Definitions.

* * * * *
    (s) For purposes of all sections of the Clean Water Act, 33 U.S.C. 
1251 et seq.

[[Page 22269]]

and its implementing regulations, subject to the exclusions in 
paragraph (t) of this section, the term ``waters of the United States'' 
means:
    (1) All waters which are currently used, were used in the past, or 
may be susceptible to use in interstate or foreign commerce, including 
all waters which are subject to the ebb and flow of the tide;
    (2) All interstate waters, including interstate wetlands;
    (3) The territorial seas;
    (4) All impoundments of waters identified in paragraphs (s)(1) 
through (3) and (5) of this section;
    (5) All tributaries of waters identified in paragraphs (s)(1) 
through (4) of this section;
    (6) All waters, including wetlands, adjacent to a water identified 
in paragraphs (s)(1) through (5) of this section; and
    (7) On a case-specific basis, other waters, including wetlands, 
provided that those waters alone, or in combination with other 
similarly situated waters, including wetlands, located in the same 
region, have a significant nexus to a water identified in paragraphs 
(s)(1) through (3) of this section.
    (t) The following are not ``waters of the United States'' 
notwithstanding whether they meet the terms of paragraphs (s)(1) 
through (7) of this section--
    (1) Waste treatment systems, including treatment ponds or lagoons, 
designed to meet the requirements of the Clean Water Act.
    (2) Prior converted cropland. Notwithstanding the determination of 
an area's status as prior converted cropland by any other Federal 
agency, for the purposes of the Clean Water Act the final authority 
regarding Clean Water Act jurisdiction remains with EPA.
    (3) Ditches that are excavated wholly in uplands, drain only 
uplands, and have less than perennial flow.
    (4) Ditches that do not contribute flow, either directly or through 
another water, to a water identified in paragraphs (s)(1) through (4) 
of this section.
    (5) The following features:
    (i) Artificially irrigated areas that would revert to upland should 
application of irrigation water to that area cease;
    (ii) 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;
    (iii) Artificial reflecting pools or swimming pools created by 
excavating and/or diking dry land;
    (iv) Small ornamental waters created by excavating and/or diking 
dry land for primarily aesthetic reasons;
    (v) Water-filled depressions created incidental to construction 
activity;
    (vi) Groundwater, including groundwater drained through subsurface 
drainage systems; and
    (vii) Gullies and rills and non-wetland swales.
    (u) Definitions--
    (1) Adjacent. 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.''
    (2) Neighboring. The term neighboring, for purposes of the term 
``adjacent'' in this section, includes waters located within the 
riparian area or floodplain of a water identified in paragraphs (s)(1) 
through (5) of this section, or waters with a shallow subsurface 
hydrologic connection or confined surface hydrologic connection to such 
a jurisdictional water.
    (3) Riparian area. 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.
    (4) Floodplain. 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.
    (5) Tributary. The term tributary means a water physically 
characterized by the presence of a bed and banks and ordinary high 
water mark, as defined at 33 CFR 328.3(e), which contributes flow, 
either directly or through another water, to a water identified in 
paragraphs (s)(1) through (4) of this section. In addition, wetlands, 
lakes, and ponds are tributaries (even if they lack a bed and banks or 
ordinary high water mark) if they contribute flow, either directly or 
through another water to a water identified in paragraphs (s)(1) 
through (3) of this section. A water that otherwise qualifies as a 
tributary under this definition does not lose its status as a tributary 
if, for any length, there are one or more man-made breaks (such as 
bridges, culverts, pipes, or dams), or one or more natural breaks (such 
as wetlands at the head of or along the run of a stream, debris piles, 
boulder fields, or a stream that flows underground) so long as a bed 
and banks and an ordinary high water mark can be identified upstream of 
the break. A tributary, including wetlands, can be a natural, man-
altered, or man-made water and includes waters such as rivers, streams, 
lakes, ponds, impoundments, canals, and ditches not excluded in 
paragraph (t)(3) or (4) of this section.
    (6) Wetlands. The term wetlands means those areas that are 
inundated or saturated by surface or groundwater at a frequency and 
duration sufficient to support, and that under normal circumstances do 
support, a prevalence of vegetation typically adapted for life in 
saturated soil conditions. Wetlands generally include swamps, marshes, 
bogs and similar areas.
    (7) Significant nexus. The term significant nexus means 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 (s)(1) through (3) 
of this section), significantly affects the chemical, physical, or 
biological integrity of a water identified in paragraphs (s)(1) through 
(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 (s)(1) 
through (3) of this section.

PART 232--404 PROGRAMS DEFINITIONS; EXEMPT ACTIVITIES NOT REQUIRING 
404 PERMITS

0
15. The authority citation for part 232 continues to read as follows:

    Authority:  The Clean Water Act, 33 U.S.C. 1251 et seq.

0
16. Section 232.2 is amended by revising the definition of ``Waters of 
the United States'' to read as follows:


Sec.  232.2  Definitions,

* * * * *
    Waters of the United States or waters means:
    (1) For purposes of all sections of the Clean Water Act, 33 U.S.C. 
1251 et. seq. and its implementing regulations, subject to the 
exclusions in paragraph (2) of this definition, the term ``waters of 
the United States'' means:

[[Page 22270]]

    (i) All waters which are currently used, were used in the past, or 
may be susceptible to use in interstate or foreign commerce, including 
all waters which are subject to the ebb and flow of the tide;
    (ii) All interstate waters, including interstate wetlands;
    (iii) The territorial seas;
    (iv) All impoundments of waters identified in paragraphs (1)(i) 
through (iii) and (v) of this definition;
    (v) All tributaries of waters identified in paragraphs (1)(i) 
through (iv) of this section;
    (vi) All waters, including wetlands, adjacent to a water identified 
in paragraphs (1)(i) through (v) of this definition; and
    (vii) On a case-specific basis, other waters, including wetlands, 
provided that those waters alone, or in combination with other 
similarly situated waters, including wetlands, located in the same 
region, have a significant nexus to a water identified in paragraphs 
(1)(i) through (iii) of this definition.
    (2) The following are not ``waters of the United States'' 
notwithstanding whether they meet the terms of paragraphs (1)(i) 
through (vii) of this definition--
    (i) Waste treatment systems, including treatment ponds or lagoons, 
designed to meet the requirements of the Clean Water Act.
    (ii) Prior converted cropland. Notwithstanding the determination of 
an area's status as prior converted cropland by any other Federal 
agency, for the purposes of the Clean Water Act the final authority 
regarding Clean Water Act jurisdiction remains with EPA.
    (iii) Ditches that are excavated wholly in uplands, drain only 
uplands, and have less than perennial flow.
    (iv) Ditches that do not contribute flow, either directly or 
through another water, to a water identified in paragraphs (1)(i) 
through (iv) of this section.
    (v) The following features:
    (A) Artificially irrigated areas that would revert to upland should 
application of irrigation water to that area cease;
    (B) 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;
    (C) Artificial reflecting pools or swimming pools created by 
excavating and/or diking dry land;
    (D) Small ornamental waters created by excavating and/or diking dry 
land for primarily aesthetic reasons;
    (E) Water-filled depressions created incidental to construction 
activity;
    (F) Groundwater, including groundwater drained through subsurface 
drainage systems; and
    (G) Gullies and rills and non-wetland swales.
    (3) Definitions--
    (i) Adjacent. 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.''
    (ii) Neighboring. The term neighboring, for purposes of the term 
``adjacent'' in this section, includes waters located within the 
riparian area or floodplain of a water identified in paragraphs (1)(i) 
through (v) of this definition, or waters with a shallow subsurface 
hydrologic connection or confined surface hydrologic connection to such 
a jurisdictional water.
    (iii) Riparian area. 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.
    (iv) Floodplain. 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.
    (v) Tributary. The term tributary means a water physically 
characterized by the presence of a bed and banks and ordinary high 
water mark, as defined at 33 CFR 328.3(e), which contributes flow, 
either directly or through another water, to a water identified in 
paragraphs (1)(i) through (iv) of this definition. In addition, 
wetlands, lakes, and ponds are tributaries (even if they lack a bed and 
banks or ordinary high water mark) if they contribute flow, either 
directly or through another water to a water identified in paragraphs 
(1)(i) through (iii) of this definition. A water that otherwise 
qualifies as a tributary under this definition does not lose its status 
as a tributary if, for any length, there are one or more man-made 
breaks (such as bridges, culverts, pipes, or dams), or one or more 
natural breaks (such as wetlands at the head of or along the run of a 
stream, debris piles, boulder fields, or a stream that flows 
underground) so long as a bed and banks and an ordinary high water mark 
can be identified upstream of the break. A tributary, including 
wetlands, can be a natural, man-altered, or man-made water and includes 
waters such as rivers, streams, lakes, ponds, impoundments, canals, and 
ditches not excluded in paragraph (2)(iii) or (iv) of this definition.
    (vi) Wetlands. The term wetlands means those areas that are 
inundated or saturated by surface or groundwater at a frequency and 
duration sufficient to support, and that under normal circumstances do 
support, a prevalence of vegetation typically adapted for life in 
saturated soil conditions. Wetlands generally include swamps, marshes, 
bogs and similar areas.
    (vii) Significant nexus. The term significant nexus means 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 (1)(i) through 
(iii) of this definition), significantly affects the chemical, 
physical, or biological integrity of a water identified in paragraphs 
(1)(i) through (iii) of this definition. 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 (1)(i) through (iii) of this definition.

PART 300--NATIONAL OIL AND HAZARDOUS SUBSTANCES POLLUTION 
CONTINGENCY PLAN

0
17. The authority citation for part 300 continues to read as follows:

    Authority:  The Clean Water Act, 33 U.S.C. 1251 et seq.

0
18. Section 300.5 is amended by revising the definition of ``navigable 
waters'' to read as follows:


Sec.  300.5  Definitions.

* * * * *
    Navigable waters as defined by 40 CFR 110.1, means the waters of 
the United States, including the territorial seas.
    (1) For purposes of all sections of the Clean Water Act, 33 U.S.C. 
1251 et seq. and its implementing regulations, subject to the 
exclusions in paragraph (2) of this definition, the term ``waters of 
the United States'' means:

[[Page 22271]]

    (i) All waters which are currently used, were used in the past, or 
may be susceptible to use in interstate or foreign commerce, including 
all waters which are subject to the ebb and flow of the tide;
    (ii) All interstate waters, including interstate wetlands;
    (iii) The territorial seas;
    (iv) All impoundments of waters identified in paragraphs (1)(i) 
through (iii) and (v) of this definition;
    (v) All tributaries of waters identified in paragraphs (1)(i) 
through (iv) of this definition;
    (vi) All waters, including wetlands, adjacent to a water identified 
in paragraphs (1)(i) through (v) of this definition; and
    (vii) On a case-specific basis, other waters, including wetlands, 
provided that those waters alone, or in combination with other 
similarly situated waters, including wetlands, located in the same 
region, have a significant nexus to a water identified in paragraphs 
(1)(i) through (iii) of this definition.
    (2) The following are not ``waters of the United States'' 
notwithstanding whether they meet the terms of paragraphs (1)(i) 
through (vii) of this definition--
    (i) Waste treatment systems, including treatment ponds or lagoons, 
designed to meet the requirements of the Clean Water Act.
    (ii) Prior converted cropland. Notwithstanding the determination of 
an area's status as prior converted cropland by any other Federal 
agency, for the purposes of the Clean Water Act the final authority 
regarding Clean Water Act jurisdiction remains with EPA.
    (iii) Ditches that are excavated wholly in uplands, drain only 
uplands, and have less than perennial flow.
    (iv) Ditches that do not contribute flow, either directly or 
through another water, to a water identified in paragraphs (1)(i) 
through (iv) of this definition.
    (v) The following features:
    (A) Artificially irrigated areas that would revert to upland should 
application of irrigation water to that area cease;
    (B) 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;
    (C) Artificial reflecting pools or swimming pools created by 
excavating and/or diking dry land;
    (D) Small ornamental waters created by excavating and/or diking dry 
land for primarily aesthetic reasons;
    (E) Water-filled depressions created incidental to construction 
activity;
    (F) Groundwater, including groundwater drained through subsurface 
drainage systems; and
    (G) Gullies and rills and non-wetland swales.
    (3) Definitions--
    (i) Adjacent. 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.''
    (ii) Neighboring. The term neighboring, for purposes of the term 
``adjacent'' in this section, includes waters located within the 
riparian area or floodplain of a water identified in paragraphs (1)(i) 
through (v) of this definition, or waters with a shallow subsurface 
hydrologic connection or confined surface hydrologic connection to such 
a jurisdictional water.
    (iii) Riparian area. 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.
    (iv) Floodplain. 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.
    (v) Tributary. The term tributary means a water physically 
characterized by the presence of a bed and banks and ordinary high 
water mark, as defined at 33 CFR 328.3(e), which contributes flow, 
either directly or through another water, to a water identified in 
paragraphs (1)(i) through (iv) of this definition. In addition, 
wetlands, lakes, and ponds are tributaries (even if they lack a bed and 
banks or ordinary high water mark) if they contribute flow, either 
directly or through another water to a water identified in paragraphs 
(1)(i) through (iii) of this definition. A water that otherwise 
qualifies as a tributary under this definition does not lose its status 
as a tributary if, for any length, there are one or more man-made 
breaks (such as bridges, culverts, pipes, or dams), or one or more 
natural breaks (such as wetlands at the head of or along the run of a 
stream, debris piles, boulder fields, or a stream that flows 
underground) so long as a bed and banks and an ordinary high water mark 
can be identified upstream of the break. A tributary, including 
wetlands, can be a natural, man-altered, or man-made water and includes 
waters such as rivers, streams, lakes, ponds, impoundments, canals, and 
ditches not excluded in paragraph (2)(iii) or (iv) of this definition.
    (vi) Wetlands. The term wetlands means those areas that are 
inundated or saturated by surface or groundwater at a frequency and 
duration sufficient to support, and that under normal circumstances do 
support, a prevalence of vegetation typically adapted for life in 
saturated soil conditions. Wetlands generally include swamps, marshes, 
bogs and similar areas.
    (vii) Significant nexus. The term significant nexus means 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 (1)(i) through 
(iii) of this definition), significantly affects the chemical, 
physical, or biological integrity of a water identified in paragraphs 
(1)(i) through (iii) of this definition. 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 (1)(i) through (iii) of this definition.
* * * * *
0
19. In appendix E to part 300, section 1.5 Definitions is amended by 
revising the definition of ``navigable waters'' to read as follows:

Appendix E to Part 300--Oil Spill Response.

    1.5 Definitions. * * *
    Navigable waters as defined by 40 CFR 110.1, means the waters of 
the United States, including the territorial seas.
    (1) For purposes of all sections of the Clean Water Act, 33 
U.S.C. 1251 et seq. and its implementing regulations, subject to the 
exclusions in paragraph (2) of this definition, the term ``waters of 
the United States'' means:
    (i) All waters which are currently used, were used in the past, 
or may be susceptible to use in interstate or foreign commerce, 
including all waters which are subject to the ebb and flow of the 
tide;
    (ii) All interstate waters, including interstate wetlands;
    (iii) The territorial seas;

[[Page 22272]]

    (iv) All impoundments of waters identified in paragraphs (1)(i) 
through (iii) and (v) of this definition;
    (v) All tributaries of waters identified in paragraphs (1)(i) 
through (iv) of this definition;
    (vi) All waters, including wetlands, adjacent to a water 
identified in paragraphs (1)(i) through (v) of this definition; and
    (vii) On a case-specific basis, other waters, including 
wetlands, provided that those waters alone, or in combination with 
other similarly situated waters, including wetlands, located in the 
same region, have a significant nexus to a water identified in 
paragraphs (1)(i) through (iii) of this definition.
    (2) The following are not ``waters of the United States'' 
notwithstanding whether they meet the terms of paragraphs (1)(i) 
through (vii) of this definition--
    (i) Waste treatment systems, including treatment ponds or 
lagoons, designed to meet the requirements of the Clean Water Act.
    (ii) Prior converted cropland. Notwithstanding the determination 
of an area's status as prior converted cropland by any other Federal 
agency, for the purposes of the Clean Water Act the final authority 
regarding Clean Water Act jurisdiction remains with EPA.
    (iii) Ditches that are excavated wholly in uplands, drain only 
uplands, and have less than perennial flow.
    (iv) Ditches that do not contribute flow, either directly or 
through another water, to a water identified in paragraphs (1)(i) 
through (iv) of this definition.
    (v) The following features:
    (A) Artificially irrigated areas that would revert to upland 
should application of irrigation water to that area cease;
    (B) 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;
    (C) Artificial reflecting pools or swimming pools created by 
excavating and/or diking dry land;
    (D) Small ornamental waters created by excavating and/or diking 
dry land for primarily aesthetic reasons;
    (E) Water-filled depressions created incidental to construction 
activity;
    (F) Groundwater, including groundwater drained through 
subsurface drainage systems; and
    (G) Gullies and rills and non-wetland swales.
    (3) Definitions--
    (i) Adjacent. 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.''
    (ii) Neighboring. The term neighboring, for purposes of the term 
``adjacent'' in this section, includes waters located within the 
riparian area or floodplain of a water identified in paragraphs 
(1)(i) through (v) of this definition, or waters with a shallow 
subsurface hydrologic connection or confined surface hydrologic 
connection to such a jurisdictional water.
    (iii) Riparian area. 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.
    (iv) Floodplain. 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.
    (v) Tributary. The term tributary means a water physically 
characterized by the presence of a bed and banks and ordinary high 
water mark, as defined at 33 CFR 328.3(e), which contributes flow, 
either directly or through another water, to a water identified in 
paragraphs (1)(i) through (iv) of this definition. In addition, 
wetlands, lakes, and ponds are tributaries (even if they lack a bed 
and banks or ordinary high water mark) if they contribute flow, 
either directly or through another water to a water identified in 
paragraphs (1)(i) through (iii) of this definition. A water that 
otherwise qualifies as a tributary under this definition does not 
lose its status as a tributary if, for any length, there are one or 
more man-made breaks (such as bridges, culverts, pipes, or dams), or 
one or more natural breaks (such as wetlands at the head of or along 
the run of a stream, debris piles, boulder fields, or a stream that 
flows underground) so long as a bed and banks and an ordinary high 
water mark can be identified upstream of the break. A tributary, 
including wetlands, can be a natural, man-altered, or man-made water 
and includes waters such as rivers, streams, lakes, ponds, 
impoundments, canals, and ditches not excluded in paragraph (2)(iii) 
or (iv) of this definition.
    (vi) Wetlands. The term wetlands means those areas that are 
inundated or saturated by surface or groundwater at a frequency and 
duration sufficient to support, and that under normal circumstances 
do support, a prevalence of vegetation typically adapted for life in 
saturated soil conditions. Wetlands generally include swamps, 
marshes, bogs and similar areas.
    (vii) Significant nexus. The term significant nexus means 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 (1)(i) through 
(iii) of this definition), significantly affects the chemical, 
physical, or biological integrity of a water identified in 
paragraphs (1)(i) through (iii) of this definition. 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 (1)(i) through (iii) of this 
definition.
* * * * *

PART 302--DESIGNATION, REPORTABLE QUANTITIES, AND NOTIFICATION

0
20. The authority citation for part 302 continues to read as follows:

    Authority:  The Clean Water Act, 33 U.S.C. 1251 et seq.

0
21. Section 302.3 is amended by revising the definition of ``navigable 
waters'' to read as follows:


Sec.  302.3  Definitions.

* * * * *
    Navigable waters means the waters of the United States, including 
the territorial seas.
    (1) For purposes of all sections of the Clean Water Act, 33 U.S.C. 
1251 et. seq. and its implementing regulations, subject to the 
exclusions in paragraph (2) of this definition, the term ``waters of 
the United States'' means:
    (i) All waters which are currently used, were used in the past, or 
may be susceptible to use in interstate or foreign commerce, including 
all waters which are subject to the ebb and flow of the tide;
    (ii) All interstate waters, including interstate wetlands;
    (iii) The territorial seas;
    (iv) All impoundments of waters identified in paragraphs (1)(i) 
through (iii) and (v) of this definition;
    (v) All tributaries of waters identified in paragraphs (1)(i) 
through (iv) of this definition;
    (vi) All waters, including wetlands, adjacent to a water identified 
in paragraphs (1)(i) through (v) of this definition; and
    (vii) On a case-specific basis, other waters, including wetlands, 
provided that those waters alone, or in combination with other 
similarly situated waters, including wetlands, located in the same 
region, have a significant nexus to a water identified in paragraphs 
(1)(i) through (iii) of this definition.
    (2) The following are not ``waters of the United States'' 
notwithstanding whether they meet the terms of paragraphs (1)(i) 
through (vii) of this definition--
    (i) Waste treatment systems, including treatment ponds or lagoons, 
designed to meet the requirements of the Clean Water Act.
    (ii) Prior converted cropland. Notwithstanding the determination of 
an area's status as prior converted cropland by any other Federal 
agency, for the purposes of the Clean Water Act the final authority 
regarding Clean Water Act jurisdiction remains with EPA.

[[Page 22273]]

    (iii) Ditches that are excavated wholly in uplands, drain only 
uplands, and have less than perennial flow.
    (iv) Ditches that do not contribute flow, either directly or 
through another water, to a water identified in paragraphs (1)(i) 
through (iv) of this definition.
    (v) The following features:
    (A) Artificially irrigated areas that would revert to upland should 
application of irrigation water to that area cease;
    (B) 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;
    (C) Artificial reflecting pools or swimming pools created by 
excavating and/or diking dry land;
    (D) Small ornamental waters created by excavating and/or diking dry 
land for primarily aesthetic reasons;
    (E) Water-filled depressions created incidental to construction 
activity;
    (F) Groundwater, including groundwater drained through subsurface 
drainage systems; and
    (G) Gullies and rills and non-wetland swales.
    (3) Definitions--
    (i) Adjacent. 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.''
    (ii) Neighboring. The term neighboring, for purposes of the term 
``adjacent'' in this section, includes waters located within the 
riparian area or floodplain of a water identified in paragraphs (1)(i) 
through (v) of this definition, or waters with a shallow subsurface 
hydrologic connection or confined surface hydrologic connection to such 
a jurisdictional water.
    (iii) Riparian area. 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.
    (iv) Floodplain. 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.
    (v) Tributary. The term tributary means a water physically 
characterized by the presence of a bed and banks and ordinary high 
water mark, as defined at 33 CFR 328.3(e), which contributes flow, 
either directly or through another water, to a water identified in 
paragraphs (1)(i) through (iv) of this definition. In addition, 
wetlands, lakes, and ponds are tributaries (even if they lack a bed and 
banks or ordinary high water mark) if they contribute flow, either 
directly or through another water to a water identified in paragraphs 
(1)(i) through (iii) of this definition. A water that otherwise 
qualifies as a tributary under this definition does not lose its status 
as a tributary if, for any length, there are one or more man-made 
breaks (such as bridges, culverts, pipes, or dams), or one or more 
natural breaks (such as wetlands at the head of or along the run of a 
stream, debris piles, boulder fields, or a stream that flows 
underground) so long as a bed and banks and an ordinary high water mark 
can be identified upstream of the break. A tributary, including 
wetlands, can be a natural, man-altered, or man-made water and includes 
waters such as rivers, streams, lakes, ponds, impoundments, canals, and 
ditches not excluded in paragraph (2)(iii) or (iv) of this definition.
    (vi) Wetlands. The term wetlands means those areas that are 
inundated or saturated by surface or groundwater at a frequency and 
duration sufficient to support, and that under normal circumstances do 
support, a prevalence of vegetation typically adapted for life in 
saturated soil conditions. Wetlands generally include swamps, marshes, 
bogs and similar areas.
    (vii) Significant nexus. The term significant nexus means 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 (1)(i) through 
(iii) of this definition), significantly affects the chemical, 
physical, or biological integrity of a water identified in paragraphs 
(1)(i) through (iii) of this definition. 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 (1)(i) through (iii) of this definition.
* * * * *

PART 401--GENERAL PROVISIONS

0
22. The authority citation for part 401 continues to read as follows:

    Authority:  The Clean Water Act, 33 U.S.C. 1251 et seq.

0
23. Section 401.11 is amended by revising paragraph (l) to read as 
follows:


Sec.  401.11  General definitions.

* * * * *
    (l) The term navigable waters means the waters of the United 
States, including the territorial seas.
    (1) For purposes of all sections of the Clean Water Act, 33 U.S.C. 
1251 et. seq. and its implementing regulations, subject to the 
exclusions in paragraph (l)(2) of this section, the term ``waters of 
the United States'' means:
    (i) All waters which are currently used, were used in the past, or 
may be susceptible to use in interstate or foreign commerce, including 
all waters which are subject to the ebb and flow of the tide;
    (ii) All interstate waters, including interstate wetlands;
    (iii) The territorial seas;
    (iv) All impoundments of waters identified in paragraphs (l)(1)(i) 
through (iii) and (v) of this section;
    (v) All tributaries of waters identified in paragraphs (l)(1)(i) 
through (iv) of this section;
    (vi) All waters, including wetlands, adjacent to a water identified 
in paragraphs (l)(1)(i) through (v) of this section; and
    (vii) On a case-specific basis, other waters, including wetlands, 
provided that those waters alone, or in combination with other 
similarly situated waters, including wetlands, located in the same 
region, have a significant nexus to a water identified in paragraphs 
(l)(1)(i) through (iii) of this section.
    (2) The following are not ``waters of the United States'' 
notwithstanding whether they meet the terms of paragraphs (l)(1)(i) 
through (vii) of this section--
    (i) Waste treatment systems, including treatment ponds or lagoons, 
designed to meet the requirements of the Clean Water Act.
    (ii) Prior converted cropland. Notwithstanding the determination of 
an area's status as prior converted cropland by any other Federal 
agency, for the purposes of the Clean Water Act the final authority 
regarding Clean Water Act jurisdiction remains with EPA.
    (iii) Ditches that are excavated wholly in uplands, drain only 
uplands, and have less than perennial flow.
    (iv) Ditches that do not contribute flow, either directly or 
through another

[[Page 22274]]

water, to a water identified in paragraphs (l)(1)(i) through (iv) of 
this section.
    (v) The following features:
    (A) Artificially irrigated areas that would revert to upland should 
application of irrigation water to that area cease;
    (B) 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;
    (C) Artificial reflecting pools or swimming pools created by 
excavating and/or diking dry land;
    (D) Small ornamental waters created by excavating and/or diking dry 
land for primarily aesthetic reasons;
    (E) Water-filled depressions created incidental to construction 
activity;
    (F) Groundwater, including groundwater drained through subsurface 
drainage systems; and
    (G) Gullies and rills and non-wetland swales.
    (3) Definitions--
    (i) Adjacent. 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.''
    (ii) Neighboring. The term neighboring, for purposes of the term 
``adjacent'' in this section, includes waters located within the 
riparian area or floodplain of a water identified in paragraphs 
(l)(1)(i) through (v) of this section, or waters with a shallow 
subsurface hydrologic connection or confined surface hydrologic 
connection to such a jurisdictional water.
    (iii) Riparian area. 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.
    (iv) Floodplain. 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.
     (v) Tributary. The term tributary means a water physically 
characterized by the presence of a bed and banks and ordinary high 
water mark, as defined at 33 CFR 328.3(e), which contributes flow, 
either directly or through another water, to a water identified in 
paragraphs (l)(1)(i) through (iv) of this section. In addition, 
wetlands, lakes, and ponds are tributaries (even if they lack a bed and 
banks or ordinary high water mark) if they contribute flow, either 
directly or through another water to a water identified in paragraphs 
(l)(1)(i) through (iii) of this section. A water that otherwise 
qualifies as a tributary under this definition does not lose its status 
as a tributary if, for any length, there are one or more man-made 
breaks (such as bridges, culverts, pipes, or dams), or one or more 
natural breaks (such as wetlands at the head of or along the run of a 
stream, debris piles, boulder fields, or a stream that flows 
underground) so long as a bed and banks and an ordinary high water mark 
can be identified upstream of the break. A tributary, including 
wetlands, can be a natural, man-altered, or man-made water and includes 
waters such as rivers, streams, lakes, ponds, impoundments, canals, and 
ditches not excluded in paragraph (l)(2)(iii) or (iv) of this section.
    (vi) Wetlands. The term wetlands means those areas that are 
inundated or saturated by surface or groundwater at a frequency and 
duration sufficient to support, and that under normal circumstances do 
support, a prevalence of vegetation typically adapted for life in 
saturated soil conditions. Wetlands generally include swamps, marshes, 
bogs and similar areas.
    (vii) Significant nexus. The term significant nexus means 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 (l)(1)(i) through 
(iii) of this section), significantly affects the chemical, physical, 
or biological integrity of a water identified in paragraphs (l)(1)(i) 
through (iii) 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 
(l)(1)(i) through (iii) of this section.
* * * * *
[FR Doc. 2014-07142 Filed 4-18-14; 8:45 am]
BILLING CODE 6560-50-P