U.S. Environmental Protection Agency 

Documentation of OMB Review Under Executive Order 12866 

Title of Action: 

Clean Water Rule: Definition of “Waters of the United States”

Docket#: EPA-HQ-OW-2011-0880 FRL#: FRL-9927-20-OW RIN: 2040-AF30

This action was submitted to the Office of Management and Budget (OMB) for review under Executive Order (E.O.) 

12866, titled Regulatory Planning and Review (58 FR 51735, October 4, 1993). Whenever EPA makes publicly available 

a regulatory action that was reviewed under E.O. 12866, section 6(a)(3)(E) of the E.O. directs the Agency to also: 

(1) Make available to the public a copy of the information that was provided to OMB’s Office of Information and 

Regulatory Affairs (OIRA) for review under the E.O., i.e., the text of the draft regulatory action and, if applicable, 

an assessment of the potential costs and benefits, as well as additional information for those actions that are 

determined to be economically significant under the E.O. (Information requirements are described in sections 

6(a)(3)(B) and (C)). 

(2) Identify for the public any substantive changes between the draft submitted to OIRA and the action that was 

subsequently issued, using a method that is complete, clear, and simple. 

(3) Identify for the public those substantive changes made at the suggestion or recommendation of OIRA.

For this regulatory action, were substantive changes made to information reviewed under E.O. 

12866? [Please check the appropriate answer.]

No. [In the docket, include the information identified in item (1) below.]

Yes. [In the docket, include the information identified in items (1) – (3) below.]

Accordingly, the Agency has included this form and the following information in the public 

docket for this regulatory action: [Please check the appropriate information.]

(1) A copy of the information that was provided to OIRA for review under the E.O. 

(2) Documentation of any substantive changes made to the draft regulatory text that was 

submitted to OIRA when compared with what was subsequently made publicly available.

The documentation is provided on the pages following this form. Changes made at the 

suggestion or recommendation of OIRA, if any, are clearly identified through attribution to 

OIRA. EPA has used one or more of the following methods to note changes: [Select the 

appropriate option(s).]

(a) Redline-Strikeout – A copy of the draft regulatory action submitted, using redlinestrikeout to show the substantive changes that were made.

(b) Hand Markup – A copy of the draft regulatory action submitted, using handwritten notes

to show the substantive changes that were made.

(c) Note to the file - A document that identifies the substantive changes that were made, 

with page and paragraph references to the draft regulatory action that was submitted.

If you have any questions about this regulatory action or this documentation, please call the 

contact:

Name: Donna Downing Email: CWAwaters@epa.gov Phone: 202-566-2428

Revised 05/05/2010 
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EO12866_CWR_2040-AF30_Final_20150403 

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]

Clean Water Rule: Definition of “Waters of the United States” 

AGENCIES: Environmental Protection Agency (EPA); and U.S. Army Corps of Engineers, 

Department of the Army, Department of Defense. 

ACTION: Final rule.

SUMMARY: The Environmental Protection Agency (EPA) and the U.S. Army Corps of 

Engineers (Corps) are publishing a final rule defining the scope of waters protected under the 

Clean Water Act (CWA), in light of the statute, science, Supreme Court decisions 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), and the agencies’ experience 
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and technical expertise. This final rule reflects consideration of the extensive public comments 

received on the proposed rule. The rule will ensure protection for the nation’s public health and 

aquatic resources, and increase CWA program predictability and consistency by clarifying the 

scope of “waters of the United States” protected under the Act.

EFFECTIVE DATE: This rule is effective on [60 days after Federal Register publication]. In 

accordance with Section 509 of the Clean Water Act, review of this action, an “other limitation”

under section 301 of the Act, may be had by any interested person in the Circuit Courts of 

Appeals of the United States within 120 days.

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; e-mail address: CWAwaters@epa.gov. 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: 

USACE_CWA_Rule@usace.army.mil.

SUPPLEMENTARY INFORMATION: 

The final rule does not establish any regulatory requirements. Instead, it is a definitional 

rule that clarifies the scope of “waters of the United States” consistent with the Clean Water Act 

(CWA), Supreme Court precedent, and science. Programs established by the CWA, such as the 

section 402 National Pollution Discharge Elimination System (NPDES) permit program, the 

section 404 permit program for discharge of dredged or fill material, and the section 311 oil spill 
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prevention and clean-up programs, all rely on the definition of “waters of the United States.” 

Entities currently are, and will continue to be, regulated under these programs that protect 

“waters of the United States” from pollution and destruction.

State, tribal, and local governments have well-defined and longstanding relationships 

with the Federal government in implementing CWA programs and these relationships are not 

altered by the final rule. Forty-six states and the U.S. Virgin Islands have been authorized to 

administer the NPDES program under section 402, and two states administer the section 404 

program. All states and forty tribes have developed water quality standards under the CWA for 

waters within their boundaries. 

The scope of regulatory jurisdiction in this rule is narrower than that under the existing 

regulation. Fewer waters will be defined as “waters of the United States” under the rule than 

under the existing regulations, in part because the rule puts important qualifiers on some existing 

categories such as tributaries. In addition, the rule provides greater clarity regarding which

waters are subject to CWA jurisdiction, reducing the instances in which permitting authorities, 

including the states and tribes with authorized section 402 and 404 CWA permitting programs, to 

make jurisdictional determinations on a case-specific basis.

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 Final Rule Issued?

II. Executive Summary

III. Significant Nexus Determinations
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A. The Significant Nexus Standard

B. Science Report

C. Significant Nexus Conclusions

1. Scope of Significant Nexus Analysis 

2. Categories of Waters Determined to Have a Significant Nexus

3. Case-Specific Significant Nexus Determinations

IV. Definition of Waters of the United States

A. Summary of Final Rule

B. Traditional Navigable Waters

C. Interstate Waters

D. Territorial Seas

E. Impoundments

F. Tributaries

G. Adjacent Waters

H. Case-Specific Waters of the United States

I. Waters and Features that Are Not Waters of the United States

V. Economic Impacts

VI. 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
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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. Congressional Review Act

L. Environmental Documentation

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 documents specifically referenced in this action, any public comments received, and other 

information related to this action. The official public docket also includes a Technical Support 

Document that provides additional legal and scientific discussion for issues raised in this rule, 

and the Response to Comments document. Although a part of the official docket, the public 

docket does not include Confidential Business Information 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. 
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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 

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 access EPA Dockets at http://www.regulations.gov to view public comments, 

access the index listing of the contents of the official public docket, and 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.

B. Under What Legal Authority Is This Rule Issued?

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

et seq.

II. Executive Summary

In this final rule, EPA and the Corps clarify the scope of “waters of the United States” 

that are protected under the Clean Water Act (CWA), using the text of the statute, Supreme 

Court decisions, the best available peer-reviewed science, public input, and the agencies’ 

technical expertise and experience in implementing the statute. This rule makes the process of

identifying waters protected under the CWA easier to understand, more predictable, and
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consistent with the law and peer-reviewed science, while protecting the streams and wetlands 

that form the foundation of our nation’s water resources. 

Congress enacted the CWA “to restore and maintain the chemical, physical, and 

biological integrity of the Nation’s waters,” 33 U.S.C. § 1251(a), and to complement statutes that 

protect the navigability of waters, such as Rivers and Harbors Acts. The CWA is the nation’s 

single most important statute for protecting America’s clean water against pollution, degradation,

and destruction. To provide that protection, the Supreme Court has consistently agreed that the 

geographic scope of the CWA reaches beyond waters that are navigable in fact. Peer-reviewed 

science and practical experience demonstrate that upstream waters, including headwaters and 

wetlands, can significantly impact the chemical, physical, and biological integrity of downstream 

waters – playing a crucial role in controlling sediment, filtering pollutants, reducing flooding, 

providing habitat for fish and other aquatic wildlife, and many other vital chemical, physical, and 

biological processes. 

This final rule interprets the CWA to cover those waters that require protection in order 

to restore and maintain the chemical, physical, or biological integrity of traditional navigable 

waters, interstate waters, and the territorial seas. This interpretation is based not only on legal 

precedent and the best available peer-reviewed science, but also on the agencies’ technical 

expertise and extensive experience in implementing the CWA over the past four decades. The 

rule will clarify and simplify implementation of the CWA consistent with its purposes through 

clearer definitions and increased use of bright-line rules. The agencies emphasize that, while the 

CWA establishes permitting requirements for covered waters to ensure protection of water 

quality, these requirements are only triggered when a person discharges a pollutant to the 
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covered water. In the absence of a pollutant discharge that would pollute, degrade, or destroy a

covered water, the CWA does not impose permitting restrictions on the use of such water. 

Additionally, Congress has exempted certain discharges associated with farming, 

ranching, and forestry practices from needing CWA permits. Finally, even where waters are 

covered by the CWA, the agencies have adopted many streamlined regulatory requirements to 

simplify and expedite compliance through the use of measures such as general permits and 

standardized mitigation measures. The agencies will continue to develop general permits and 

simplified procedures, particularly as they affect crossings of ephemeral and intermittent 

tributaries to ensure that projects that offer significant social benefits, such as renewable energy 

development, can proceed with the necessary environmental safeguards while minimizing 

permitting delays. 

The Supreme Court has issued three decisions that provide critical context and guidance 

in determining the appropriate scope of “waters of the United States” covered by the CWA. In 

United States v. Riverside Bayview Homes, 474 U.S. 121 (1985) (Riverside), the Court, in a 

unanimous opinion, 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 
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chose to define the waters covered by the Act broadly.” Id. at 132-33 (citing Senate Report 92-

414). 

In Solid Waste Agency of Northern Cook County v. U.S. Army Corps of Engineers, 531 

U.S. 159 (2001) (SWANCC), the Supreme Court held that the use of “isolated” non-navigable 

intrastate ponds by migratory birds was not by itself a sufficient basis for the exercise of federal 

regulatory authority under the CWA. Although the SWANCC decision did not call into question 

earlier decisions upholding the CWA’s coverage of wetlands or other waters “adjacent” to 

traditional navigable waters, it created uncertainty with regard to the jurisdiction of other waters 

and wetlands that, in many instances, may play an important role in protecting the integrity of the 

nation’s waters. The majority opinion in SWANCC introduced the concept that it was a 

“significant nexus” that informed the Court’s reading of CWA jurisdiction over waters that are 

not navigable in fact. 

Five years later, in Rapanos v. United States, 547 U.S. 715 (2006) (Rapanos), 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. In addition, Justice Kennedy’s opinion 

stated that the critical factor in determining the CWA’s coverage is whether a water has a 

“significant nexus” to downstream traditional navigable waters such that the water is important 

to protecting the chemical, physical, or biological integrity of the navigable water, referring back 

to the Court’s decision in SWANCC. Justice Kennedy’s concurrence in Rapanos stated that to 

constitute a “water of the United States” covered by the CWA, “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). Justice Kennedy concluded that 

wetlands possess the requisite significant nexus if the wetlands “either alone or in combination 
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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.

The agencies’ determination of what constitutes a “significant nexus” is grounded in 

Justice Kennedy’s opinion. At the core of the “significant nexus” analysis, the protection of 

upstream waters must be critical to maintaining the integrity of the downstream waters. These 

upstream waters function as integral parts of the aquatic environment, and if these waters are 

polluted or destroyed there is a significant effect downstream. The agencies assess the 

significance of the nexus in terms of the CWA’s objective to “restore and maintain the chemical, 

physical, and biological integrity of the Nation’s waters.” When the effects are speculative or 

insubstantial, the “significant nexus” would not be present.

The “significant nexus” standard articulated and refined in these Supreme Court opinions 

is the touchstone for the agencies’ interpretation of the CWA’s jurisdictional scope. In response 

to these opinions, the agencies issued guidance in 2003 (post-SWANCC) and 2008 (postRapanos). However, these two guidance documents are not effective in providing the public or 

agency staff with the kind of information needed to ensure timely, consistent, and predictable 

jurisdictional determinations. Many waters are currently subject to case-specific jurisdictional 

analysis to determine whether a “significant nexus” exists, and this time and resource intensive 

process can result in inconsistent interpretation of CWA jurisdiction and perpetuate ambiguity 

over where the CWA applies. As a result of the ambiguity that exists under current regulations 

and practice following these recent decisions, virtually all waters and wetlands across the country 

theoretically could be subject to a case-specific jurisdictional determination. 
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Members of Congress, developers, farmers, state and local governments, energy 

companies, and many others requested new regulations to make the process of identifying waters 

protected under the CWA clearer, simpler, and faster. Chief Justice Roberts’ concurrence in 

Rapanos underscores the value of this rulemaking effort.1 In this final rule, the agencies are 

responding to those requests from across the country to make the process of identifying waters 

protected under the CWA easier to understand, more predictable, and more consistent with the 

law and peer-reviewed science. 

The agencies proposed a rule clarifying the scope of waters of the United States in April, 

2014, and solicited comments for over 200 days. This final rule reflects the over 1 million public 

comments on the proposal, the substantial majority of which supported the proposed rule, as well 

as input provided through the agencies’ extensive public outreach effort, which included over 

400 meetings nationwide with states, small businesses, farmers, academics, miners, energy 

companies, counties, municipalities, environmental organizations, other federal agencies, and 

many others. The agencies sought comment on a number of approaches to specific jurisdictional 

questions, and many of these commenters and stakeholders urged EPA to improve upon the 

April 2014 proposal, by providing more bright lines and simplifying definitions that identify

waters that are protected under the CWA, all for the purpose of minimizing delays and costs, 

making protection of clean water more effective, and improving predictability and consistency 

for landowners and regulated entities. 

 1 Chief Justice Roberts’ concurrence in Rapanos emphasized that “[a]gencies delegated 

rulemaking authority under a statute such as the Clean Water Act are afforded generous leeway 

by the courts in interpreting the statute they are entrusted to administer.” Id. at [758]. Chief 

Justice Roberts made clear that, if the agencies had undertaken such a rulemaking, “the Corps 

and the EPA would have enjoyed plenty of room to operate in developing some notion of an 

outer bound to the reach of their authority.” Id.
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The agencies’ interpretation of the CWA’s scope in this final rule is informed by the best 

available peer-reviewed science – particularly as that science informs the policy judgments and 

legal interpretations as to which waters have a “significant nexus” with traditional navigable 

waters, interstate waters, and the territorial seas. 

The relevant science on the relationship and downstream effects of waters has advanced 

considerably in recent years. A comprehensive report entitled “Connectivity of Streams and 

Wetlands to Downstream Waters: A Review and Synthesis of the Scientific Evidence”2

(hereafter the Science Report) synthesizes the peer-reviewed science. 

The Science Report provides much of the technical basis for the rule. The Science 

Report is based on a review of more than 1,200 publications from the peer-reviewed literature. 

EPA’s Science Advisory Board (SAB) conducted a comprehensive technical review of the 

Science Report and reviewed the adequacy of the scientific and technical basis of the proposed 

rule. The Science Report and the SAB review confirmed that:

• Waters are connected in myriad ways, including physical connections and the hydrologic 

cycle; however, connections occur on a continuum or gradient from highly connected to 

highly isolated.

• These variations in the degree of connectivity are a critical consideration to the ecological 

integrity and sustainability of downstream waters, which are fundamental to meeting the 

Supreme Court’s test of significant nexus.

 2 U.S. Environmental Protection Agency, Connectivity of Streams and Wetlands to Downstream 

Waters: A Review and Synthesis of the Scientific Evidence (Final Report), EPA/600/R-14/475F, 

(Washington, D.C.: U.S. Environmental Protection Agency, (2015)).
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• The critical contribution of upstream waters to the chemical, physical, and biological 

integrity of downstream waters results from the accumulative contribution of similar 

waters in the same watershed and in the context of their functions considered over time.

The Science Report and the SAB review also confirmed that:

• Tributary streams, including perennial, intermittent, and ephemeral streams, are 

chemically, physically, and biologically connected to downstream waters, and influence 

the integrity of downstream waters. 

• Wetlands and open waters in floodplains and riparian areas are chemically, physically, 

and biologically connected with downstream rivers and influence the ecological integrity 

of such rivers. 

• Non-floodplain wetlands and open waters provide many functions that benefit 

downstream water quality and ecological integrity, but their effects on downstream 

waters are difficult to assess based solely on the available science.

Although these conclusions play a critical role in informing the agencies’ interpretation 

of the CWA’s scope, the agencies’ interpretive task in this rule – determining which waters have 

a “significant nexus” – requires the integration of this science with policy judgment and legal 

interpretation. The science demonstrates that waters fall along a gradient of chemical, physical, 

and biological connection to traditional navigable waters, and it is the agencies’ task to 

determine where along that gradient to draw lines of jurisdiction under the CWA. In making this 

determination, the agencies must rely, not only on the science, but also on their technical 
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expertise and practical experience in implementing the CWA during a period of over 40 years. 

In addition, the agencies are guided, in part, by the compelling need for clearer, and more 

consistent, and easily implementable standards to govern administration of the Act, including 

brighter lines where feasible and appropriate.

Major Rule Provisions

In this final rule, the agencies define “waters of the United States” to include eight 

categories of jurisdictional waters. The rule maintains existing exclusions for certain categories 

of waters, and adds additional categorical exclusions that are regularly applied in practice. The 

rule reflects the agencies’ goal of providing simpler, clearer, and more consistent approaches for 

identifying the geographic scope of the CWA. The rule establishes jurisdiction in three basic 

categories: waters that are jurisdictional in all instances, waters that are jurisdictional but only if 

they meet specific definitions in the rule, and a narrowed category of waters subject to casespecific analysis. 

Decisions about waters in each of these categories are based on the law, peer-reviewed 

science, and the agencies’ technical expertise, and were informed by public comments. This rule 

replaces existing procedures that often depend on individual, time-consuming, and often 

inconsistent analyses of the relationship between a particular stream, wetland, lake, or other 

water with downstream navigable waters. The agencies have greatly reduced the extent of 

waters subject to this individual review by carefully incorporating the scientific literature 

characterizing the nature and strength of the chemical, physical, and biological connections 

between upstream and downstream waters. The result of applying this scientific analysis is that 
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the agencies can more effectively focus the rule on identifying waters that are clearly covered by 

the CWA and those that are clearly not covered, making the rule easier to understand, consistent, 

and environmentally more protective.

The jurisdictional categories reflect the current state of the best available science, and are 

based upon the law and Supreme Court decisions. The agencies will continue a transparent 

review of the science, and learn from on-going experience and expertise as the agencies 

implement the rule. If evolving science and the agencies’ experience lead to a need for action to 

alter the jurisdictional categories, any such action will be conducted as part of a rule-making 

process.

The first three categories of jurisdictional waters, traditional navigable waters, interstate 

waters, and the territorial seas, are jurisdictional by rule in all cases. Impoundments of 

jurisdictional waters are also jurisdictional by rule in all cases. The waters in the next two 

categories, “tributaries” and “adjacent” waters, are jurisdictional by rule, as defined, because the 

science confirms that as defined they have a significant nexus to traditional navigable waters, 

interstate waters, or territorial seas. For waters that are jurisdictional by rule, no additional 

analysis is required. 

The final two categories of jurisdictional waters are those waters subject to case-specific 

analysis to determine whether they have a significant nexus to traditional navigable waters, 

interstate waters, or the territorial seas, either alone or in combination with similarly situated 

waters in the region.

The major elements of the final rule are briefly summarized here.
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Traditional Navigable Waters, Interstate Waters, Territorial Seas, and Impoundments of 

Jurisdictional Waters

Consistent with existing regulations and the April 2014 proposed rule, the final rule 

includes traditional navigable waters, interstate waters, territorial seas, and impoundments of 

jurisdictional waters in the definition of “waters of the United States.” These waters are 

jurisdictional by rule.

Tributaries

Previous definitions of “waters of the United States” regulated all tributaries without 

qualification. This final rule more precisely defines “tributaries” as waters that are characterized 

by the presence of physical indicators of flow – bed and banks and ordinary high water mark –

and concludes that such tributaries are “waters of the United States.” The great majority of 

tributaries as defined by the rule are headwater streams that play an important role in the 

transport of water, sediments, organic matter, nutrients, and organisms to downstream waters. 

The physical indicators of bed and banks and ordinary high water mark demonstrate that there is 

sufficient volume, frequency and flow in such tributaries to a traditional navigable water, 

interstate water, or the territorial seas to establish a significant nexus. “Tributaries” as defined are 

jurisdictional by rule.

The rule covers, as tributaries, only those features that science tells us function as a 

tributary and that meet the significant nexus test articulated by Justice Kennedy. Features not 

meeting this legal and scientific test are not jurisdictional under this rule. The rule continues the 
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current policy of regulating ditches that are constructed in tributaries or are relocated tributaries, 

or that science clearly demonstrates are functioning as a tributary. These waters affect the 

chemical, physical, and biological integrity of downstream waters. The rule further reduces 

existing confusion and inconsistency regarding the regulation of ditches by explicitly excluding 

certain categories of ditches, such as ditches that flow only after precipitation and most roadside 

ditches. This rule appropriately reduces regulatory burdens while minimizing costs for states, 

tribes, and municipalities charged with maintaining the nation’s roads. 

Adjacent Waters

The agencies determined that “adjacent” waters, as defined in the rule, have a significant 

nexus to traditional navigable waters, interstate waters, and the territorial seas based upon their 

hydrological and ecological connections to, and interactions with, those waters. Under the final 

rule, “adjacent” means bordering, contiguous, or neighboring, including waters separated from 

other “waters of the United States” by constructed dikes or barriers, natural river berms, beach 

dunes and the like. Further, waters that connect segments of, or are at the head of, a stream or 

river are “adjacent” to that stream or river. “Adjacent” waters include wetlands, ponds, lakes, 

oxbows, impoundments, and similar water features. “Adjacent” waters do not include waters 

that are subject to established, normal farming, silviculture, and ranching activities (33 U.S.C. § 

1344(f)(1)).

The final rule establishes a definition of “neighboring” for purposes of determining 

adjacency. In the rule, the agencies identify three circumstances under which waters would be 

“neighboring” and therefore “waters of the United States”:
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(1) Waters located in whole or in part within 100 feet of the ordinary high water mark of a 

traditional navigable water, interstate water, the territorial seas, an impoundment of a 

jurisdictional water, or a tributary.

(2) Waters located in whole or in part in the 100-year floodplain (i.e., the area with a one 

percent annual chance of flooding) that are within 1,500 feet of the ordinary high water 

mark of a traditional navigable water, interstate water, the territorial seas, an 

impoundment, or a tributary (“floodplain waters”). 

(3) Waters located in whole or in part within 1,500 feet of the high tide line or the ordinary 

high water mark of a tidally-influenced traditional navigable water, including the Great 

Lakes, or territorial sea.

The agencies emphasize that the rule covers as adjacent waters only those waters that 

currently available science demonstrates possess the requisite connection to downstream waters 

and function as a system to protect the chemical, physical and biological integrity of those 

waters. The agencies recognize that the establishment of “bright line” thresholds in the rule for 

adjacency does not in any way restrict states from considering state specific information and 

concerns, as well as emerging science to evaluate the need to more broadly protect their waters 

under state law. The CWA establishes both national and state roles to ensure that states specificcircumstances are properly considered to complement and reinforce actions taken at the national 

level.

“Adjacent” waters as defined are jurisdictional by rule. The agencies recognize that there are 

individual waters outside of the “neighboring” limits stated above where the science may 
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demonstrate through a case-specific analysis that there exists a significant nexus to a downstream 

traditional navigable water, interstate water, or the territorial seas. However, these waters are not 

determined jurisdictional by rule and will be evaluated through a case-specific analysis. The 

strength of the science and the significance of the nexus will be established on a case-specific 

basis as described below.

Case-Specific Significant Nexus

The rule identifies particular waters that are not jurisdictional by rule but are subject to 

case-specific analysis to determine if a significant nexus exists and the water is a “water of the 

United States.” This category of case-specific waters was determined using available science 

and the law, and in response to public comments that encouraged the agencies to ensure more 

consistent determinations and reduce the complexity of conducting jurisdictional determinations. 

Under the significant nexus standard articulated in the Supreme Court opinions, waters are 

“waters of the United States” if they significantly affect the chemical, physical, or biological 

integrity of traditional navigable waters, interstate waters, or the territorial seas. This 

determination will most typically be made on a water individually, but can when warranted be 

made in combination with other waters where waters operate as a system. 

In this final rule, the agencies have identified by rule, five specific types of waters in 

specific regions that science demonstrates should be subject to a significant nexus analysis and 

are considered similarly situated by rule because they perform similar functions and are located 

sufficiently close together in the watershed to function as a single system in affecting 

downstream waters. These five types of waters are prairie potholes, Carolina and Delmarva bays, 
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pocosins, western vernal pools in California, and Texas coastal prairie wetlands. Supported by 

Justice Kennedy’s opinion in Rapanos, the agencies determined that such waters should be

analyzed “in combination” (as a group, rather than individually) in the watershed that drains to 

the nearest traditional navigable water, interstate water, or the territorial seas when making a 

case-specific analysis of whether these waters have a significant nexus to traditional navigable 

waters, interstate waters, or territorial seas. 

The final rule provides that waters within 4,000 feet of the high tide line or the ordinary 

high water mark of a traditional navigable water, interstate water, the territorial seas, 

impoundments, or covered tributary are subject to case specific significant nexus determinations.

The science available today does not establish that waters beyond those defined as “adjacent” are 

jurisdictional by rule under the CWA, but the agencies’ experience and expertise indicate that 

there are waters out to 4,000 feet where the science demonstrates that they often have a 

significant effect on downstream waters. 

In circumstances where waters within 4,000 feet of the high tide line or ordinary high 

water mark are subject to a case-specific significant nexus analysis and such waters may be 

evaluated as “similarly situated,” it must be first demonstrated that these waters perform similar 

functions and are located sufficiently close to each other to affect the integrity of the downstream 

waters. The significant nexus analysis must then be conducted based on consideration of the 

functions provided by those waters in combination in the point of entry watershed. A “similarly 

situated” analysis is conducted where it is determined that there is a likelihood that there are 

waters that function as a system to affect downstream water integrity. To provide greater clarity 

and transparency in determining what functions will be considered in determining what 
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constitutes a significant nexus, the final rule lists specific functions that the agencies will 

consider. 

The agencies recognize that in establishing the 4,000 feet-foot “bright line” threshold for 

these case-specific significant nexus determinations in the rule, the agencies are carefully

applying the available science. The agencies will work with states to more closely evaluate 

state-specific circumstances that may be present across the country and, as appropriate, 

encourage states to develop rules that reflect their circumstances and emerging science to ensure 

consistent and effective protection for waters in the states. As is the case today, nothing in this 

rule restricts the ability of states to more broadly protect state waters.

Exclusions

All existing exclusions from the definition of “waters of the United States” are retained, 

and several exclusions reflecting longstanding agency practice are added to the regulation for the 

first time. 

Prior converted cropland and waste treatment systems have been excluded from the 

definition of “waters of the United States” definition since 1992 and 1979 respectively, and only 

ministerial changes are made. These two exclusions remain substantively and operationally 

unchanged. The agencies add exclusions for waters and features previously identified as 

generally exempt in preamble language from Federal Register notices by the Corps on 

November 13, 1986, and by EPA on June 6, 1988. This is the first time these exclusions have 

been established by rule. The agencies for the first time also establish by rule that certain ditches 

are excluded from jurisdiction, including ephemeral and intermittent roadside ditches that drain 
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federal, state, county or municipal roads, and that are not a relocated tributary or excavated in a 

tributary. The agencies add exclusions for groundwater and erosional features, as well as 

exclusions for some waters that were identified in public comments as possibly being found 

jurisdictional under proposed rule language where this was never the agencies’ intent, such as 

stormwater control features constructed to convey, treat, or store stormwater, and cooling ponds 

that are created in dry land. These exclusions reflect current agencies’ practice, and their 

inclusion in the rule as specifically excluded furthers the agencies’ goal of providing greater 

clarity over what waters are and are not protected under the CWA.

Role of States and Tribes Under the Clean Water Act

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 CWA sections 402 and 404. Forty-six states and the U.S. 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 (TMDL) programs under section 303, and the section 401 state water quality 

certification process. 
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States and tribes, consistent with the CWA, retain full authority to implement their own 

programs to more broadly and more fully protect the waters in their jurisdiction. Under section 

510 of the CWA, unless expressly stated, nothing in the CWA 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, regulate 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 rule limits or impedes 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 

with authorized section 402 and 404 CWA permitting programs, to make jurisdictional 

determinations on a case-specific basis.

Overview of the Preamble

The remainder of this preamble is organized as follows. Section III (Significant Nexus 

Standard) provides additional background on the rule, including a discussion of Supreme Court 

precedent, the science underpinning the rule, and the agencies’ overall interpretive approach to 

applying the significant nexus standard. Section IV (Definition of Waters of the United States) 

explains the provisions of final rule, including subsections on each of the major elements of the 

rule. Section V summarizes the economic analysis of the rule and Section VI addresses Related 

Acts of Congress, Executive Orders and Agency Initiatives.

III. Significant Nexus Standard
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With this rule, the agencies interpret the scope of the “waters of the United States” for the 

CWA in light of the goals, objectives, and policies of the statute, the Supreme Court caselaw, the 

relevant and available science, and the agencies’ technical expertise and experience. The key to

the agencies’ interpretation of the CWA is the significant nexus standard, as established and 

refined in Supreme Court opinions: waters are “waters of the United States” if they, either alone 

or in combination with similarly situated waters in the region, significantly affect the chemical, 

physical, and biological integrity of traditional navigable waters, interstate waters or the 

territorial seas. The agencies interpret specific aspects of the significant nexus standard in light 

of the science, the law, and the agencies’ technical expertise: the scope of the region to assess 

when making a significant nexus determination; the waters to evaluate in combination with each 

other; and the functions provided by waters and strength of those functions, and when such 

waters significantly affect the chemical, physical, or biological integrity of the downstream 

traditional navigable waters, interstate waters, or the territorial seas.

In the rule, the agencies determine that tributaries, as defined (“covered tributaries”), and 

adjacent waters, as defined (“covered adjacent waters”), have a significant nexus to downstream 

traditional navigable waters, interstate waters, and the territorial seas and therefore are “waters of 

the United States.” In the rule, the agencies also establish that defined sets of additional waters 

may be determined to have a significant nexus on a case-specific basis: (1) five types of waters

that the agencies conclude are “similarly situated” and therefore must be analyzed “in 

combination” in the watershed that drains to the nearest traditional navigable water, interstate 

water, or the territorial seas when making a case-specific significant nexus analysis; and (2) 

waters within 4,000 feet of the high tide line or ordinary high water mark of traditional navigable 
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waters, interstate waters, the territorial seas, impoundments or covered tributaries. The rule 

establishes a definition of significant nexus, based on Supreme Court opinions and the science, to 

use when making these case-specific determinations.

Significant nexus is not a purely a scientific determination and neither is the agencies’ 

interpretation of the scope of “waters of the United States.” Further, the opinions of the Supreme 

Court have noted that as the agencies charged with interpreting the statute, EPA and the Corps 

must develop the outer bounds of the scope of the CWA, while science does not provide bright 

lines with respect to where “water ends” for purposes of the CWA. Therefore, the agencies’ 

interpretation of the CWA is informed by the Science Report and the review and comments of 

the SAB, but not dictated by them. With this context, this section addresses, first, the Supreme 

Court case law and the significant nexus standard, second, the relevant scientific conclusions 

reached by analysis of existing scientific literature, and third, the agencies’ significant nexus 

determinations underpinning the rule. Section IV of the preamble addresses in more detail the 

precise definitions of the covered waters promulgated by the agencies to provide the bright lines 

identifying “waters of the United States.” 

A. The Significant Nexus Standard

Congress enacted the CWA “to restore and maintain the chemical, physical, and 

biological integrity of the Nation’s waters.” 33 U.S.C. § 1251(a). The agencies’ longstanding 

regulations define “waters of the United States” for purposes of the Clean Water Act, and the 

Supreme Court has addressed the scope of “waters of the United States” protected by the CWA 

in three cases. The significant nexus standard evolved through those cases.
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In United States v. Riverside Bayview Homes, 474 U.S. 121 (1985) (Riverside), which 

involved wetlands adjacent to a traditional navigable water in Michigan, the Court, in a 

unanimous opinion, 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). The Court also recognized that “[i]n determining the limits of its power to regulate 

discharges under the Act, the Corps must necessarily choose some point at which water ends and 

land begins. Our common experience tells us that this is often no easy task: the transition from 

water to solid ground is not necessarily or even typically an abrupt one. Rather, between open 

waters and dry land may lie shallows, marshes, mudflats, swamps, bogs — in short, a huge array 

of areas that are not wholly aquatic but nevertheless fall far short of being dry land. Where on 

this continuum to find the limit of ‘waters’ is far from obvious.” Id. The Court then deferred to 

the agencies’ interpretation: “In view of the breadth of federal regulatory authority contemplated 

by the Act itself and the inherent difficulties of defining precise bounds to regulable waters, the 

Corps' ecological judgment about the relationship between waters and their adjacent wetlands 
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provides an adequate basis for a legal judgment that adjacent wetlands may be defined as waters 

under the Act.” Id. at 134.

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” non-navigable 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 any parts of the regulatory definition of “waters of the United 

States.”

Five years after SWANCC, the Court again addressed the term “waters of the United 

States” in Rapanos v. United States, 547 U.S. 715 (2006) (Rapanos). Rapanos involved two 

consolidated cases in which the CWA had been applied to wetlands adjacent to non-navigable 

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 
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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 concurred that the cases should be remanded for further decision

making, and stated 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). Justice Kennedy concluded that 

“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,’ §§ 1311(a), 1362(12).” Id. at 779. 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. 

While Justice Kennedy’s opinion focused on adjacent wetlands in light of the facts of the 

cases before him, his opinion is clear that a significant nexus is the basis for jurisdiction to 

protect non-navigable waters and wetlands under the CWA (id. at 759), and there is no indication 

in his opinion that the analytical framework his opinion provides for determining significant 

nexus for adjacent wetlands is limited to adjacent wetlands. In addition, the four dissenting 

Justices in Rapanos, who would have affirmed the court of appeals’ application of the agencies’ 
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regulation, also 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 opinion invalidated 

any of the current regulatory provisions defining “waters of the United States.”

Chief Justice Roberts’ concurrence in Rapanos emphasized that “[a]gencies delegated 

rulemaking authority under a statute such as the Clean Water Act are afforded generous leeway 

by the courts in interpreting the statute they are entrusted to administer.” Id. at 758. Chief 

Justice Roberts made clear that, if the agencies had undertaken such a rulemaking, “the Corps 

and the EPA would have enjoyed plenty of room to operate in developing some notion of an 

outer bound to the reach of their authority.” Id.

 The agencies utilize the significant nexus standard, as articulated by Justice Kennedy’s 

opinion and informed by the unanimous opinion in Riverside Bayview and the plurality opinion 

in Rapanos which recognize that the Act and the agencies must draw lines “on this continuum to 

find the limit of ‘waters,’” Riverside Bayview at 134, to interpret the scope of the statutory term 

“waters of the United States.” While a significant nexus determination is primarily weighted in 

the scientific evidence and criteria, the agencies also consider the statutory language, the 

statute’s goals, objectives and policies, the case law, and the agencies’ technical expertise and 

experience when interpreting the terms of the CWA.

B. Science Report

EPA’s Office of Research and Development prepared the Science Report, a peerreviewed compilation and analysis of published peer-reviewed scientific literature summarizing 
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the current scientific understanding of the connectivity of and mechanisms by which streams and 

wetlands, singly or in combination, affect the chemical, physical, and biological integrity of 

downstream waters. The final Science Report is available at 

http://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=296414. 

The process for developing the Science Report followed standard information quality 

guidelines for EPA. In September 2013, EPA released a draft of the Science Report for an 

independent SAB review and invited submissions of public comments for consideration by the 

SAB panel. In October 2014, after several public meetings and hearings, the SAB completed its

peer review of the draft Science Report. The SAB was highly supportive of the draft Science 

Report’s conclusions regarding streams, riparian and floodplain wetlands, and open waters, and 

recommended strengthening the conclusion regarding non-floodplain waters to include a more 

definitive statement that reflects how numerous functions of such waters sustain the integrity of 

downstream waters.3 The final peer review report is available on the SAB website, as well as in 

the docket for this rulemaking. EPA revised the draft Science Report based on comments from 

the public and recommendations from the SAB panel. 

The SAB was established in 1978 by the Environmental Research, Development, and 

Demonstration Authorization Act (ERDDAA), to provide independent scientific and technical 

advice to the EPA Administrator on the technical basis for Agency positions and regulations. 

Advisory functions include peer review of EPA’s technical documents, such as the Science 

Report. At the time the peer review was completed, the chartered SAB comprised more than 50 

members from a variety of sectors including academia, non-profit organizations, foundations, 

 

3 U.S. EPA. 2014. SAB review of the draft EPA report Connectivity of Streams and Wetlands to 

Downstream Waters: A Review and Synthesis of the Scientific Evidence. EPA-SAB-15-001, 

U.S. Environmental Protection Agency, Washington, DC. (“SAB 2014a.”) 
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state governments, consulting firms, and industry. To conduct the peer review, EPA’s SAB staff 

formed an ad hoc panel based on nominations from the public to serve as the primary reviewers. 

The panel consisted of 27 technical experts in array of relevant fields, including hydrology, 

wetland and stream ecology, biology, geomorphology, biogeochemistry, and freshwater science. 

Similar to the chartered SAB, the panel members represented sectors including academia, a 

federal government agency, non-profit organizations, and consulting firms. The chair of the 

panel was a member of the chartered SAB.

The SAB process is open and transparent, consistent with the Federal Advisory 

Committee Act, 5 U.S.C., App 2, and agency policies regarding Federal advisory committees. 

Consequently, the SAB has an approved charter, which must be renewed biennially, announces 

its meetings in the Federal Register, and provides opportunities for public comment on issues 

before the Board. The SAB staff announced via the Federal Register that they sought public 

nominations of technical experts to serve on the expert panel: SAB Panel for the Review of the 

EPA Water Body Connectivity Report (via a similar process the public also is invited to 

nominate chartered SAB members). The SAB staff then invited the public to comment on the list 

of candidates for the panel. Once the panel was selected, the SAB staff posted a memo on its

website addressing the formation of the panel and the set of determinations that were necessary 

for its formation (e.g., no conflicts of interest). In the public notice of the first public meetings 

interested members of the public were invited to submit relevant comments for the SAB Panel to 

consider pertaining to the review materials, including the charge to the Panel. Over 133,000 

public comments were received by the Docket. Every meeting was open to the public, noticed in 

the Federal Register, and had time allotted for the public to present their views. In total, the 

Panel held a two-day in-person meeting in Washington, DC, in December 2013, and three four-
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hour public teleconferences in April, May, and June 2014. The SAB Panel also compiled four 

draft versions of its peer review report to inform and assist the meeting deliberations that were 

posted on the SAB website. In September 2014, the chartered SAB conducted a public 

teleconference to conduct the quality review of the Panel’s final draft peer review report. The 

peer review report was approved at that meeting, and revisions were made to reflect the chartered 

SAB’s review. The culmination of that public process was the release of the final peer review 

report in October 2014. All meeting minutes and draft reports are available on the SAB website 

for public access.

The final Science Report states that 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. 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. The scientific literature does not use the term “significant” 

as it is defined in a legal context, but it 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, adjacent waters, and case-specific waters and those downstream 

waters. The scientific literature also 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. 
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The Science Report presents evidence of those connections from various categories of 

waters, evaluated singly or in combination, which affect downstream waters and the strength of 

that effect. The objectives of the Science 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 Science 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 Science Report presents five major conclusions:

Conclusion 1: Streams

The scientific literature unequivocally demonstrates that streams, individually or 

cumulatively, exert a strong influence on the chemical, physical, and biological integrity 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. Streams are the dominant source of water in most rivers, 

and the majority of tributaries are perennial, intermittent, or ephemeral headwater streams. 

Headwater streams also convey water into local storage compartments such as ponds, shallow 

aquifers, and floodplains, and into regional and alluvial aquifers; these local storage 
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compartments are important sources of water for maintaining baseflow in rivers. In addition to 

water, streams transport sediment, wood, organic matter, nutrients, chemical contaminants, and 

many of the organisms found in rivers. The scientific literature provides robust evidence that 

streams are biologically connected to downstream waters by the dispersal and migration of 

aquatic and semiaquatic organisms, including fish, amphibians, plants, microorganisms, 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. In addition to material 

transport and biological connectivity, ephemeral, intermittent, and perennial flows influence 

fundamental biogeochemical processes by connecting channels and shallow groundwater with 

other landscape elements. Chemical, physical, and biological connections between streams and 

downstream waters interact via integrative processes such as nutrient spiraling. This occurs 

when stream communities assimilate and chemically transform large quantities of nitrogen and 

other nutrients that otherwise would be transported directly downstream, thereby increasing 

nutrient loads and associated impairments due to excess nutrients in downstream waters. Science 

Report at xxv.

Conclusion 2: Riparian/Floodplain Wetlands and Open Waters

The scientific literature clearly shows that wetlands and open waters in riparian areas and 

floodplains are chemically, physically, and biologically integrated with rivers via functions that 

improve downstream water quality, including the temporary storage and deposition of channelforming sediment and woody debris, temporary storage of local groundwater that supports 

baseflow in rivers, and transformation and transport of stored organic matter. Riparian/floodplain 

wetlands and open waters improve water quality through the assimilation, transformation, and

sequestration of pollutants, including excess nutrients and chemical contaminants such as 
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pesticides and metals that can degrade downstream water integrity. In addition to providing 

effective buffers to protect downstream waters from point source and nonpoint source pollution, 

these systems form integral components of river food webs, providing nursery habitat for 

breeding fish and amphibians, colonization opportunities for stream invertebrates, and 

maturation habitat for stream insects. Lateral expansion and contraction of the river in its 

floodplain result in an exchange of organic matter and organisms, including fish populations that 

are adapted to use floodplain habitats for feeding and spawning during high water, that are 

critical to river ecosystem function. Riparian/floodplain wetlands and open waters also affect the 

integrity of downstream waters by subsequently releasing (desynchronizing) floodwaters and 

retaining large volumes of stormwater, sediment, and contaminants in runoff that could 

otherwise negatively affect the condition or function of downstream waters. Id.

Conclusion 3: Non-floodplain Wetlands and Open Waters

Wetlands and open waters in non-floodplain landscape settings (“non-floodplain 

wetlands”) provide numerous functions that benefit downstream water integrity. These functions 

include storage of floodwater; recharge of groundwater that sustains river baseflow; retention 

and transformation of nutrients, metals, and pesticides; export of organisms or seeds to 

downstream waters; and habitats needed for stream species. This diverse group of wetlands (e.g., 

many prairie potholes or vernal pools) can be connected to downstream waters through surface

water, shallow subsurface water, and groundwater flows, and through biological and chemical 

connections. 

In general, connectivity of non-floodplain wetlands occurs along a gradient, and can be 

described in terms of the frequency, duration, magnitude, timing, and rate of change of water, 

material, and biotic fluxes to downstream waters. These descriptors are influenced by climate, 
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geology, and terrain, which interact with factors such as the magnitudes of the various functions 

within wetlands (e.g., amount of water storage or carbon export) and their proximity to 

downstream waters to determine where wetlands occur along the connectivity gradient. At one 

end of this gradient, the functions of non-floodplain wetlands clearly affect the condition of 

downstream waters if a visible (e.g., channelized) surface water or a regular shallow subsurfacewater connection to the river network is present. For non-floodplain wetlands lacking a 

channelized surface or regular shallow subsurface connection (i.e., those at intermediate points 

along the gradient of connectivity), generalizations about their specific effects on downstream 

waters from the available literature are difficult because information on both function and 

connectivity is needed. Science Report at xxv-vi.

Conclusion 4: Degrees and Determinants of Connectivity

Connectivity of streams and wetlands to downstream waters occurs along a gradient that 

can be described in terms of the frequency, duration, magnitude, timing, and rate of change of 

water, material, and biotic fluxes to downstream waters. These terms, which we refer to 

collectively as connectivity descriptors, characterize the range over which streams and wetlands 

vary and shift along the connectivity gradient in response to changes in natural and 

anthropogenic factors and, when considered in a watershed context, can be used to predict 

probable effects of different degrees of connectivity over time. The evidence unequivocally 

demonstrates that the stream channels and riparian/floodplain wetlands or open waters that 

together form river networks are clearly connected to downstream waters in ways that 

profoundly influence downstream water integrity. The connectivity and effects of non-floodplain 

wetlands and open waters are more variable and thus more difficult to address solely from 

evidence available in peer-reviewed studies. Science Report at xxvii.
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Conclusion 5: Cumulative Effects

The incremental effects of individual streams and wetlands are cumulative across entire 

watersheds, and therefore, must be evaluated in context with other streams and wetlands. 

Downstream waters are the time-integrated result of all waters contributing to them. For 

example, the amount of water or biomass contributed by a specific ephemeral stream in a given 

year might be small, but the aggregate contribution of that stream over multiple years, or by all 

ephemeral streams draining that watershed in a given year or over multiple years, can have 

substantial consequences on the integrity of the downstream waters. Similarly, the downstream 

effect of a single event, such as pollutant discharge into a single stream or wetland, might be 

negligible but the cumulative effect of multiple discharges could degrade the integrity of 

downstream waters.

When considering the effect of an individual stream or wetland, all contributions and 

functions of that stream or wetland should be evaluated cumulatively. For example, the same 

stream transports water, removes excess nutrients, mitigates flooding, and provides refuge for 

fish when conditions downstream are unfavorable; if any of these functions is ignored, the 

overall effect of that stream would be underestimated. Science Report at xxvii-viii.

SAB Review of the Proposed Rule

In addition to its peer review of the draft Science Report, in a separate effort the SAB 

also reviewed the adequacy of the scientific and technical basis of the proposed rule and 

provided its advice and comments on the proposal in September 2014.4 The same SAB Panel 

 4 U.S. EPA. 2014. SAB Consideration of the Adequacy of the Scientific and Technical Basis of 

the EPA’s Proposed Rule titled “Definition of Waters of the United States under the Clean Water 
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that reviewed the draft Science Report met via two public teleconferences in August 2014 to 

discuss the scientific and technical basis of the proposed rule. The Panel submitted comments to 

the Chair of the chartered SAB. A work group of chartered SAB members considered comments 

provided by panel members, agency representatives, and the public on the adequacy of the 

science informing the rule. This work group then led the September 2014 public teleconference 

discussion of the chartered SAB. The public had an opportunity to submit oral or written 

comments during these two public meetings. The SAB’s final letter to the EPA Administrator 

can be found on the SAB website and in the docket for this rule.

The SAB found that the available science provides an adequate scientific basis for the 

key components of the proposed rule. The SAB noted that although water bodies differ in degree 

of connectivity that affects the extent of influence they exert on downstream waters (i.e., they 

exist on a “connectivity gradient”), the available science supports the conclusion that the types of 

water bodies identified as “waters of the United States” in the proposed rule exert strong 

influence on the chemical, physical, and biological integrity of downstream waters. In particular, 

the SAB expressed support for the proposed rule’s inclusion of tributaries and adjacent waters as

categorical waters of the United States and the inclusion of “other waters” on a case-specific

basis, though noting that certain “other waters” can be determined as a subcategory to be 

similarly situated.

Regarding tributaries, the SAB found, “[t]here is strong scientific evidence to support the 

EPA’s proposal to include all tributaries within the jurisdiction of the Clean Water Act. 

Tributaries, as a group, exert strong influence on the physical, chemical, and biological integrity 

 

Act.” EPA-SAB-14-007, U.S. Environmental Protection Agency, Washington, DC. (“SAB 

2014b.”)
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of downstream waters, even though the degree of connectivity is a function of variation in the 

frequency, duration, magnitude, predictability, and consequences of physical, chemical, and 

biological process.” The Board advised EPA to reconsider the definition of tributaries because 

not all tributaries have ordinary high water marks (e.g., ephemeral streams with arid and semiarid environments or in low gradient landscapes where the flow of water is unlikely to cause an 

ordinary high water mark). The SAB also advised EPA to consider changing the wording in the 

definition to “bed, bank, and other evidence of flow.” SAB 2014b at 2. In addition, the SAB 

suggested that EPA reconsider whether flow-through lentic systems should be included as 

adjacent waters and wetlands, rather than as tributaries.

Regarding adjacent waters and wetlands, the SAB stated, “[t]he available science 

supports the EPA’s proposal to include adjacent waters and wetlands as a waters of the United 

States. ...because [they] have a strong influence on the physical, chemical, and biological 

integrity of navigable waters.” Id. In particular, the SAB noted, “the available science supports 

defining adjacency or determination of adjacency on the basis of functional relationships,” rather

than “solely on the basis of geographical proximity or distance to jurisdictional waters.” Id. at 2-

3.

In the evaluation of “other waters” the SAB found that “scientific literature has 

established that ‘other waters’ can influence downstream waters, particularly when considered in 

aggregate.” Id. at 3. The SAB thus found it “appropriate to define ‘other waters’ as waters of the 

United States on a case-specific basis, either alone or in combination with similarly situated 

waters in the same region.” Id. The SAB found that distance could not be the sole indicator used 

to evaluate the connection of “other waters” to jurisdictional waters. The SAB also expressed

support for language in one of the options discussed in the preamble to the proposed rule. 
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Specifically, the SAB stated there is “also adequate scientific evidence to support a 

determination that certain subcategories and types of ‘other waters’ in particular regions of the 

United States (e.g., Carolina and Delmarva Bays, Texas coastal prairie wetlands, prairie 

potholes, pocosins, western vernal pools) are similarly situated (i.e., they have a similar influence 

on the physical, chemical, and biological integrity of downstream waters and are similarly 

situated on the landscape) and thus could be considered waters of the United States.” Id. The 

Board noted that other sets of wetlands could be identified as “similarly situated” as the science 

continues to develop and that science does not support excluding groups of “other waters” or 

subcategories thereof from jurisdiction.

The exclusions paragraph of the proposed rule generated the most comments from the 

SAB. The SAB noted, “[t]he Clean Water Act exclusions of groundwater and certain other 

exclusions listed in the proposed rule and the current regulation do not have scientific 

justification.” Id. With regard to ditches, the Board found that there is a lack of scientific 

knowledge to determine whether ditches should be categorically excluded. For example, some 

ditches that would be excluded in the Midwest may drain Cowardin wetlands and may provide 

certain ecosystem services, while gullies, rills, and non-wetland swales can be important 

conduits for moving water between jurisdictional waters. The SAB also noted that artificial lakes 

or ponds, or reflection pools, can be directly connected to jurisdictional waters via either shallow 

or deep groundwater. The SAB also recommended that the agencies clarify in the preamble to 

the final rule that “significant nexus” is a legal term, not a scientific one. 

C. Significant Nexus 
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As noted earlier, in the rule, the agencies interpret the scope of “waters of the United 

States” protected under the CWA based on the information and conclusions in the Science 

Report, other relevant scientific literature, the Technical Support Document, the relevant 

Supreme Court decisions, the agencies’ technical expertise and experience, and the objectives 

and requirements of the CWA. In light of this information, the agencies made scientifically and 

technically informed judgments about the nexus between the relevant waters and the significance 

of that nexus and conclude that tributaries and adjacent waters, each as defined by the rule, have 

a significant nexus such that they are “water of the United States” by rule. The agencies also 

determined that additional waters on a case-specific basis may have a significant nexus to 

traditional navigable waters, interstate waters, and the territorial seas, either alone or in 

combination with similarly situated waters. As discussed earlier, significant nexus is not a 

purely scientific determination and neither is the agencies’ interpretation of the scope of “waters 

of the United States;” instead the agencies’ interpretation is informed by the Science Report and 

the review and comments of the SAB, but not dictated by them. The rule reflects the judgment 

of the agencies when balancing the science, the statute, the Supreme Court opinions, the 

agencies’ expertise, and the regulatory goals of providing clarity to the public while protecting 

the environment and public health. 

Since the Rapanos decision, the agencies have extensive experience making significant 

nexus determinations, and that experience and expertise has informed the judgment of the 

agencies as reflected in the provisions of the rule. The agencies, most often the Corps, have 

made more than 500,000 CWA jurisdictional determinations since 2008. Of those, 

approximately 250,000 have been case-specific significant nexus determinations. The agencies 

have made determinations in every state in the country, from the arid West to the tropics of 
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Hawaii, from the Appalachian Mountains in the East to the lush forests of the Northwest. With 

field staff located across 38 Corps District offices and 10 EPA regional offices, the agencies have 

almost a decade of nationwide experience in making significant nexus determinations. Through 

this experience, the agencies developed wide-ranging technical expertise in assessing the 

hydrologic flowpaths along which water and materials are transported and transformed that 

determine the degree of chemical, physical, or biological connectivity, as well as the variations 

in climate, geology, and terrain within and among watersheds and over time that affect the 

functions (such as the removal or transformation of pollutants) performed by streams and 

wetlands for downstream traditional navigable waters, interstate waters or the territorial seas.

In addition, these individual jurisdictional determinations have been for waters ranging 

from an intermittent stream that provides flow to a drinking water source to a group of floodplain 

wetlands in North Dakota that provide important protection from floodwaters to downstream 

communities alongside the Red River to headwater mountain streams that provide high quality 

water that supplies baseflow and reduces the harmful concentrations of pollutants in the 

mainstem river below. The agencies utilized many tools and many sources of information to 

help make these determinations, including U.S. Geological Survey (USGS) and state and local 

topographic maps, aerial photography, soil surveys, watershed studies, scientific literature and 

references, and field work. For example, USGS and state and local stream maps and datasets, 

aerial photography, gage data, watershed assessments, monitoring data, and field observations 

are often used to help assess the contributions of flow of tributary streams, including intermittent 

and ephemeral streams, to downstream traditional navigable waters, interstate waters or the 

territorial seas. Similarly, floodplain and topographic maps of federal, state and local agencies, 

modeling tools, and field observations can be used to assess how wetlands are trapping 
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floodwaters that might otherwise affect downstream waters. Further, the agencies utilize the 

large body of scientific literature regarding the functions of tributary streams, regardless of their 

flow permanence, and of wetlands and open waters to inform their evaluations of significant 

nexus. In addition, the agencies have experience and expertise for decades prior to and since the 

SWANCC and Rapanos decisions with making jurisdictional determinations, and consider 

hydrology, ordinary high water mark, biota, and other technical factors in implementing Clean 

Water Act programs. This immersion in the science along with the practical expertise 

developed through case-specific determinations across the country and in diverse settings is 

reflected in the agencies’ conclusions with respect to waters that have a significant nexus, as well 

as where the agencies have drawn lines demarking where “waters of the United States” end.

1. Scope of Significant Nexus Analysis

Under the significant nexus standard, waters possess the requisite significant nexus 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.’” Rapanos at 780. Several terms in this standard were not defined. In 

this rule the agencies interpret these terms and the scope of “waters of the United States” based 

on the goals, objectives, and policies of the statute, the scientific literature, the Supreme Court 

opinions, and the agencies’ technical expertise and experience. Therefore, for purposes of a 

significant nexus analysis, the agencies have determined (1) which waters are “similarly 

situated,” and thus should be in analyzed in combination in (2) the “region,” for purposes of a 

significant nexus analysis, and (3) the types of functions that should be analyzed to determine if 

waters significantly affect the chemical, physical, and biological integrity of traditional navigable 
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waters, interstate waters and the territorial seas. These determinations underpin many of the key 

elements of the rule and are reflected in the definition of “significant nexus” in the rule. 

a. Similarly situated waters

As reflected in the rule’s definition of “significant nexus,” the agencies determined that it 

is reasonable to consider waters as “similarly situated” where they perform similar functions that 

affect downstream waters and are located within the watershed that drains to the nearest 

traditional navigable water, interstate water, or the territorial sea. Since the focus of the 

significant nexus standard is on protecting and restoring the chemical, physical, and biological 

integrity of the nation’s waters, the agencies interpret the phrase “similarly situated” in terms of 

whether particular waters are providing common, or similar, functions for downstream waters 

such that it is reasonable to consider their effect together. Regarding covered tributaries and 

covered adjacent waters, the agencies define each water type such that the functions provided are

similar and the waters are situated so as to provide those functions together to affect downstream 

traditional navigable waters as a landscape unit.

The science demonstrates that covered tributaries provide many common vital functions 

important to the chemical, physical, and biological integrity of downstream waters, regardless of 

the size of the tributaries. The science also supports the conclusion that sufficient volume, 

duration, and frequency of flow are required to create a bed and banks and ordinary high water 

mark. The agencies conclude that covered tributaries with a bed and banks and ordinary high 

water mark are similarly situated for purposes of the agencies’ significant nexus analysis. 

For covered adjacent waters, the science demonstrates that these waters provide many 

similar vital functions to downstream waters, and the agencies defined adjacent waters with 

distances limitations to ensure that the waters are providing similar functions to downstream 
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waters and that the waters are located comparably in the landscape such that the agencies’

reasonably judged them to be similarly situated.

For waters for which a case-specific significant nexus determination is required the 

agencies have determined that some waters in specific regions are similarly situated; for other 

specified waters, the determination of whether there are any other waters providing similar 

functions in a similar situation in the region must be made as part of a case-specific 

determination. See section IV.H.

Assessing the functions of identified waters in combination is consistent not only with 

Justice Kennedy’s significant nexus standard, but with the science. Scientists routinely combine 

the effects of groups of waters, aggregating the known effect of one water with those of 

ecologically similar waters in a specific geographic area, or to a certain scale. This is because

the chemical, physical, and 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 Science Report consistently 

document 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 ameliorate the potential impacts of flooding and pollutant 

contamination from affecting downstream waters. See Technical Support Document.

For example, excess nutrients discharged into small tributary streams in the aggregate can 

cause algal blooms downstream that reduce dissolved oxygen levels and increase turbidity in 

traditional navigable waters, interstate waters, and the territorial seas. Water low in dissolved 

oxygen cannot support aquatic life. It is widely-recognized and documented that this 

phenomenon known as hypoxia has resulted in the devastation of commercial and recreational 
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fisheries in the northern Gulf of Mexico. In this instance, the cumulative effects of nutrient 

export from the many small headwater streams of the Mississippi River have resulted in largescale ecological and economically harmful impacts hundreds of miles downstream. See 

Technical Support Document. 

In their review of the scientific and technical adequacy of the rule, the SAB panel 

members “generally agreed that aggregating ‘similarly situated’ waters is scientifically justified, 

given that the combined effects of these waters on downstream waters are often only measurable 

in aggregate.”5 As stated in section III.B. above, one of the main conclusions of the Science 

Report is that the incremental contributions of individual streams and wetlands are cumulative 

across entire watersheds, and their effects on downstream waters should be evaluated within the 

context of other streams and wetlands in that watershed. For example, the Science Report finds, 

“[t]he amount of nutrients removed by any one stream over multiple years or by all headwater 

streams in a watershed in a given year can have substantial consequences for downstream 

waters.” Science Report at 1-10. Cumulative effects of streams, wetlands, and open waters across 

a watershed must be considered because “[t]he downstream consequences (e.g., the amount and 

quality of materials that eventually reach a river) are determined by the aggregate effect of 

contributions and sequential alterations that begin at the source waters and function along 

continuous flowpaths to the watershed outlet.” Id. at 1-19.

The agencies conclude that it is appropriate to assess the effects of waters in combination 

based on the similarity of the functions they provide to the downstream water and their location 

 5 September 2, 2014. Memorandum from Dr. Amanda Rodewald to Dr. David Allen. Comments 

to the chartered SAB on the Adequacy of the Scientific and Technical Basis of the EPA’s 

Proposed Rule titled “Definition of ‘Waters of the United States’ under the Clean Water Act.”

(“SAB 2014c.”)
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in the landscape. This is consistent with the science and existing practice, and effectively meets

the goals of the CWA.

b. In the region

Since Justice Kennedy did not define the “region,” the agencies determined that the 

single point of entry watershed is a reasonable and technically appropriate scale for identifying 

“in the region” for purposes of the significant nexus standard. A single point of entry watershed 

is the drainage basin within whose boundaries all precipitation ultimately flows to the nearest 

single traditional navigable water, interstate water, or the territorial sea. The agencies 

determined that because the movement of water from watershed drainage basins to coastal 

waters, 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 

way to identify the scope of waters that together may have an effect on the chemical, physical, or 

biological integrity of a particular traditional navigable water, interstate water, or territorial sea. 

The watershed includes all streams, wetlands, lakes, and open waters within its boundaries. 

Using the watershed that flows to the nearest single traditional navigable water, interstate water, 

or territorial sea is consistent with court decisions that these waters are the ultimate focus of 

CWA protections. Using the single point of entry watershed ensures that any analysis of 

significant nexus is appropriately connected to these touchstone waters. 

Because the movement of water from watershed drainage basins to coastal waters, river 

networks, and lakes shapes the development and function of these systems in a way that is

critical to their integrity, 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. Anthropogenic actions and natural 
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events can have widespread effects within the watershed that collectively impact the integrity 

and quality of the relevant traditional navigable water, interstate water, or the territorial sea. The 

functions of the contributing waters are inextricably linked and have a cumulative effect on the 

integrity of the downstream traditional navigable water, interstate water, or the territorial sea. For 

these reasons, it is more appropriate to conduct a significant nexus analysis at the watershed 

scale than to focus on a specific site, such as an individual stream segment. See proposal 

Appendix A, Scientific Analysis, 79 FR 22246, Science Report, and Technical Support 

Document. 

Concluding that the watershed is the reasonable and appropriate region for purposes of a 

significant nexus analysis is also consistent with the agencies’ longstanding practice and 

experience. To restore or maintain the health of the downstream affected water, the agencies’

standard practice is 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 Corps has used watershed framework 

approaches for water sources, for navigation approaches for more than 100 years, and in the 

regulatory program since its inception. For example, the Corps Districts are generally organized 

based on watersheds. Also, using a watershed framework is consistent with more than two 

decades of practice by EPA and many other governmental, academic, and additional entities that 

recognize that a watershed approach is the most effective framework to address water resource 

challenges. Finally, the watershed that drains to the nearest (i.e., first downstream) traditional 

navigable water, interstate water, or the territorial seas is likely to be of a size commonly 

understood as a “region.” 

In light of the scientific literature, the longstanding approach of the agencies’

implementation of the CWA, and the statutory goals underpinning Justice Kennedy’s significant 
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nexus framework, the watershed draining to the nearest traditional navigable water, interstate 

water, or the territorial sea, is the appropriate “region” for a significant nexus analysis. See the 

proposed rule preamble and Technical Support Document.

c. Significantly affect chemical, physical, or biological integrity

The agencies’ definition of the term “significant nexus” in the rule is consistent with 

language in SWANCC and Rapanos, and with the goals, objectives, and policies of the CWA. 

The definition reflects that not all waters have a requisite connection to traditional navigable 

waters, interstate waters, or the territorial seas sufficient to be determined jurisdictional. Justice 

Kennedy was clear that to be covered, waters 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. The agencies define significant nexus in 

precisely those terms. Under the rule a “significant nexus” is established by a showing of a 

significant chemical, physical, or biological effect. In characterizing the significant nexus 

standard, Justice Kennedy stated: “[t]he 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 is 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 is compromised then that is contrary to the statute’s stated objective. It 

would subvert the objective if the CWA only protected waters upon a showing that they had 

effects on every attribute of the integrity a traditional navigable water, interstate water, or the 

territorial sea.

In the rule’s definition of “significant nexus,” the agencies identify the functions that 

waters provide that can significantly affect the chemical, physical, or biological integrity of 
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traditional navigable waters, interstate waters and the territorial seas. Functions to be considered 

for the purposes of determining significant nexus are sediment trapping; nutrient recycling; 

pollutant trapping, transformation, filtering, and transport; retention and attenuation of 

floodwaters; runoff storage; contribution of flow; export of organic matter; export of food 

resources; and provision of life-cycle dependent aquatic habitat (such as foraging, feeding, 

nesting, breeding, spawning, use as a nursery area) for species located in traditional navigable

waters, interstate waters, or the territorial seas. The effect of an upstream water can be 

significant even when a water, alone or in combination, is providing a subset, or even just one, of 

the functions listed.

Science demonstrates that these aquatic functions provided by smaller streams, ponds, 

wetlands and other waters are important for protecting the chemical, physical, and biological 

integrity of downstream traditional navigable waters, interstate waters, and the territorial seas. 

For example, States identify sediment and nutrients as the primary contaminants in the nation’s 

waters. Sediment storage and export via streams to downstream waters is critical for maintaining 

the river network, including the formation of channel features. Although sediment is essential to 

river systems, excess sediment can impair ecological integrity by filling interstitial spaces, 

reducing channel capacity, blocking sunlight transmission through the water column, and 

increasing contaminant and nutrient concentrations. Streams and wetlands can prevent excess 

deposits of sediment downstream and reduce pollutant concentrations in downstream waters. 

Thus the function of trapping of excess sediment, along with export of sediment, have a 

significant effect on the chemical, physical, and biological integrity of downstream waters

Nutrient recycling results in the uptake and transformation of large quantities of nitrogen 

and other nutrients that otherwise would be transported directly downstream, thereby decreasing
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nutrient loads and associated impairments due to excess nutrients in downstream waters.

Streams, wetlands and open waters improve water quality through the assimilation, 

transformation, or sequestration of pollutants, including excess nutrients and chemical 

contaminants such as pesticides and metals that can degrade downstream water integrity.

Nutrient transport exports nutrients downstream and can degrade water quality and lead to 

stream impairments. Nutrients are necessary to support aquatic life, but excess nutrients lead to 

excessive plant growth and hypoxia, in which over-enrichment causes dissolved oxygen 

concentrations to fall below the level necessary to sustain most aquatic animal life in the 

downstream waters. Nutrient recycling, retention, and export can significantly affect downstream 

chemical integrity by impacting downstream water quality.

The contribution of flow downstream is an important role, as upstream waters can be a 

cumulative source of the majority of the total mean annual flow to bigger downstream rivers and 

waters, including via the recharge of baseflow. Streams, wetlands, and open waters contribute 

surface and subsurface water downstream, and are the dominant sources of water in most rivers. 

Contribution of flow can significantly affect the physical integrity of downstream waters, helping 

to sustain the volume of water in larger waters. 

Small streams and wetlands are particularly effective at retaining and attenuating 

floodwaters. By subsequently releasing (desynchronizing) floodwaters and retaining large 

volumes of stormwater that could otherwise negatively affect the condition or function of 

downstream waters, streams and adjacent wetlands and open waters affect the physical integrity 

of downstream traditional navigable waters, interstate waters, or the territorial seas. This 

function can reduce flood peaks downstream and can also maintain downstream river baseflows 

by recharging alluvial aquifers.
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Streams, wetlands, and open waters supply downstream waters with dissolved and 

particulate organic matter (e.g., leaves, wood), which support biological activity throughout the 

river network. In addition to organic matter, streams, wetlands, and open waters can also export 

other food resources downstream, such as aquatic insects that are the food source for fish in 

downstream waters. The export of organic matter and food resources downstream is important to 

maintaining the food webs and thus the biological integrity of traditional navigable waters, 

interstate waters, and the territorial seas. 

Streams, wetlands, and open waters provide life-cycle dependent aquatic habitat (such as 

foraging, feeding, nesting, breeding, spawning, and use as a nursery area) for species located in 

traditional navigable waters, interstate waters, or the territorial seas. Many species require 

different habitats for different resources (e.g., food, spawning habitat, overwintering habitat), and 

thus move throughout the river network over their life-cycles. For example, headwater streams 

can provide refuge habitat under adverse conditions, enabling fish to persist and recolonize 

downstream areas once conditions have improved. These upstream systems form integral 

components of downstream food webs, providing nursery habitat for breeding fish and 

amphibians, colonization opportunities for stream invertebrates, and maturation habitat for 

stream insects, including for species that are critical to downstream ecosystem function. The 

provision of life-cycle dependent aquatic habitat for species located in downstream waters 

significantly affects the biological integrity of those downstream waters.

Tributaries, adjacent wetlands, and open waters can perform multiple functions, including 

functions that change depending upon the season. For example, the same stream can contribute 

flow when evapotranspiration is low and can retain water when evapotranspiration is high. These 

functions, particularly when considered in aggregate with the functions of similarly situated 
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waters in the region, can significantly affect the chemical, physical, or biological integrity of a 

traditional navigable water, interstate water, or the territorial seas. When considering the effect of 

an individual stream, wetland, or open water, all contributions and functions that the water 

provides should be evaluated cumulatively. For example, the same wetland retains sediment, 

removes excess nutrients, mitigates flooding, and provides habitat for amphibians that also live 

downstream; if any of these functions is ignored, the overall effect of that wetland would be 

underestimated. It is important to note, however, that a water or wetland can provide just one 

function that may significantly affect the chemical, physical or biological integrity of the 

downstream water.

2. Categories of Waters Determined to Have a Significant Nexus

In this rule, the agencies determine that: (1) covered tributaries, in combination with 

other covered tributaries located in a watershed that drains to a traditional navigable water, 

interstate water, or the territorial seas, significantly affect the chemical, physical, and biological 

integrity of that water; and (2) covered adjacent waters, in combination with other covered

adjacent waters located in a watershed that drains to a traditional navigable water, interstate 

water, or the territorial seas, significantly affect the chemical, physical, and biological integrity 

of that water.

a. Covered Tributaries

The agencies determine based on their scientific and technical expertise that waters 

meeting the definition of “tributary” in a single point of entry watershed are similarly situated 

and have a significant nexus because they significantly affect the chemical, physical, and

biological integrity of traditional navigable waters, interstate waters, and the territorial seas. As 
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such, it is appropriate to conclude covered tributaries as a category are “waters of the United 

States.” See Technical Support Document. The agencies limited the tributaries that are “waters 

of the United States” to those that have both a bed and banks and another indicator of ordinary 

high water mark. That limitation served as a reasonable basis to consider covered tributaries 

similarly situated because those physical characteristics indicated sufficient flow that the covered 

tributaries are performing similar functions and located such that they are working together in the 

region to provide those functions to the nearest traditional navigable water, interstate water, or 

the territorial seas. Justice Kennedy opined that the requirement of a perceptible ordinary high 

water mark for tributaries “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. The science supports Justice Kennedy’s 

perception.

The agencies analyzed the Science 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 by rule. Covered tributaries have 

a significant impact on the chemical, physical, and biological integrity of waters into which they 

eventually flow— for CWA purposes, traditional navigable waters, interstate waters, and the 

territorial seas. The great majority of covered 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 waters. Covered 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;
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provide habitat for plants and animals; and sustain the biological productivity of downstream 

rivers, lakes, and estuaries. Such waters have these significant effects whether they are natural, 

modified, or constructed. 

Covered tributaries significantly affect the chemical integrity of traditional navigable 

waters, interstate waters, and the territorial seas. Covered tributaries influence the chemical 

composition of downstream waters, through the transport and removal of chemical elements and 

compounds, such as nutrients, ions, organic matter and pollutants. Ecosystem processes in 

covered 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 transports chemical substances 

downstream, chemical effects are closely related to hydrological connectivity. Within covered

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 

covered tributaries is consumed by downstream organisms. The organic carbon that is exported 

downstream thus supports biological activity throughout the river network. 

Covered tributaries act as both sinks and sources of chemical substances, further affecting 

the chemical integrity of traditional navigable waters, interstate waters, and the territorial seas. 

Covered tributaries 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 traditional navigable waters, interstate 

waters, and the territorial seas as chemicals dissolved in the waters or as chemicals attached to 

suspended sediments.
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Covered tributaries significantly affect the physical integrity of traditional navigable 

waters, interstate waters, and the territorial seas. Physical connections between covered

tributaries and traditional navigable waters, interstate waters, and the territorial seas result from 

the hydrologic transport from covered tributaries to downstream waters of numerous materials, 

including water, sediment and organic matter such as leaves and wood. This transport affects the 

physical characteristics of downstream waters. Covered 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 covered tributaries is 

transporting sediment to downstream waters. Covered tributaries, particularly headwaters, shape 

and maintain river channels by accumulating and gradually or episodically releasing sediment 

and large woody debris into river channels. These effects occur even when the covered

tributaries flow infrequently (such as ephemeral covered tributaries), and even when the covered

tributaries are great distances from the traditional navigable water, interstate water, or the 

territorial sea (such as some headwater covered tributaries). 

Covered tributaries significantly affect the biological integrity of traditional navigable 

waters, interstate waters, and the territorial seas. Covered 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. In addition to providing critical habitat 

for complex life-cycle completion, covered tributaries provide refuge from predators and adverse 

physical conditions in rivers, and are reservoirs of genetic- and species-level diversity. Covered

tributaries contribute materials to downstream food networks and supporting populations for 
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aquatic species, including economically important species such as salmon. These effects occur 

even when the covered tributaries flow infrequently (such as ephemeral covered tributaries), and 

even when the covered tributaries are large distances from the traditional navigable waters, 

interstate waters, and the territorial seas (such as some headwater covered tributaries). 

Similarly, modified and constructed covered tributaries perform the same functions as 

natural tributaries, especially the conveyance of water that carries nutrients, pollutants, and other 

constituents, both good and bad, to traditional navigable waters, interstate waters, and the 

territorial seas. Modified and constructed covered tributaries also provide corridors for 

movement of organisms between headwaters and traditional navigable waters, interstate waters, 

and the territorial seas. The important effect – and thus the significant nexus – between a 

tributary and a traditional navigable water, interstate water, and the territorial sea 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, modified, or constructed, provide 

substantial connectivity between streams and downstream waters. For example, tributary ditches 

quickly move water downstream to traditional navigable waters, interstate waters, and the 

territorial seas due to their often straightened and channelized nature, transporting downstream 

sediment, nutrients, and other materials.

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 covered tributaries of traditional navigable waters, interstate 

waters, and the territorial seas, alone or in combination with other covered tributaries in a 
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watershed, have a significant nexus with those downstream waters. Thus, in the rule the 

agencies assert CWA jurisdiction over all covered tributaries as defined. Those covered

tributaries are “waters of the United States” without the need for further analysis.

b. Covered Adjacent Waters

Based on their review of the scientific literature and the law, the agencies’ determine by 

rule that covered adjacent waters, as defined, have a significant nexus and are “waters of the 

United States.” The scientific literature, including the Science Report, consistently supports the 

conclusion that covered adjacent waters provide similar functions and work together to maintain 

the chemical, physical, and biological integrity of the downstream traditional navigable waters, 

interstate waters, and the territorial seas because of their hydrological and ecological connections 

to, and interactions with, those waters. Science demonstrates that this functional connectivity is 

particularly evident where adjacent waters are located within the floodplain of the traditional 

navigable water, interstate water, the territorial seas, tributary, or impoundment to which they are 

adjacent or are otherwise sufficiently proximate to waters with no floodplain, such as lakes and 

ponds. Location within the floodplain and proximity ensure that the aquatic functions performed

by adjacent waters are effectively and consistently provided to downstream waters. See 

Technical Support Document.

The agencies conclude that all waters meeting the definition of “adjacent” in the rule are 

similarly situated for purposes of analyzing whether they have a significant nexus to a traditional 

navigable water, interstate water, or the territorial sea. Based on a review of the scientific 

literature, the agencies conclude that these bordering, contiguous, or neighboring waters provide 

similar functions and work together to significantly affect the chemical, physical, or biological 

integrity of traditional navigable waters, interstate waters, or the territorial seas. Further, because 
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the definition of “adjacent” focuses on the proximity of the waters (i.e., those that are located 

near traditional navigable waters, interstate waters, the territorial seas, impoundments, and 

covered tributaries), interpreting the term “similarly situated” to include all covered adjacent

waters, as defined in the rule, is reasonable and consistent with the science. The geographic 

proximity of an “adjacent” water relative to the traditional navigable waters, interstate waters,

the territorial seas, impoundments, and covered tributaries 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 supports that waters, including 

wetlands, ponds, lakes, oxbow lakes, and similar waters, that are “adjacent,” as defined in the 

rule, to traditional navigable waters, interstate waters, the territorial seas, impoundments, and 

covered tributaries, 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. 

Covered adjacent waters function together to maintain the chemical, physical, or 

biological health of traditional navigable waters, interstate waters, and the territorial seas to 

which they are directly adjacent or to which they are connected by the tributary system. This 

functional interaction can result from hydrologic connections or because adjacent waters can act 

as water storage areas holding damaging floodwaters or filtering harmful pollutants. These 

chemical, physical, and biological connections affect the integrity of downstream traditional 

navigable waters, interstate waters, and the territorial seas through the temporary storage and 

deposition of channel-forming sediment and woody debris, temporary storage of local 

groundwater sources of baseflow for downstream waters and their tributaries, and transformation 

and transport of organic matter. Covered adjacent waters improve water quality through the 
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assimilation, transformation, or sequestration of pollutants, including excess nitrogen and 

phosphorus and chemical contaminants such as pesticides and metals that can degrade 

downstream water integrity. In addition to providing effective buffers to protect downstream 

waters from pollution, covered adjacent waters form integral components of downstream food 

webs, providing nursery habitat for breeding fish and amphibians, colonization opportunities for 

stream invertebrates, and maturation habitat for stream insects. Covered adjacent waters serve an 

important role in the integrity of traditional navigable waters, interstate waters, and the territorial 

seas by subsequently releasing (desynchronizing) floodwaters and retaining large volumes of 

stormwater, sediment, nutrients, and contaminants that could otherwise negatively impact the 

condition or function of traditional navigable waters, interstate waters, and the territorial seas.

Floodplain areas connect aquatic environments through both surface and hyporheic 

hydrologic flowpaths. Waters in these areas are therefore uniquely situated in watersheds to 

receive and process water that passes over densely vegetated areas and through subsurface zones 

before reaching streams and rivers. When contaminants reach a floodplain water, they can be 

sequestered in sediments, assimilated into wetland plants and animals, transformed into less 

harmful and/or mobile forms or compounds, or lost to the atmosphere. Wetlands located in 

floodplains store large amounts of sediment and organic matter from upstream and upland areas. 

In addition, the primary function of many floodplain wetlands in the Western United States is 

sediment exchange, which can transform materials and compounds temporarily on floodplains.

Wetlands and other similar waters in floodplain areas act as buffers that are among the 

most effective tools for mitigating nonpoint source pollution. The literature shows that 

collectively, wetlands and other similar waters improve water quality through assimilation, 

transformation, or sequestration of nutrients, sediment, and other pollutants―such as pesticides 
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and metals―that can affect downstream water quality. These pollutants enter floodplain 

wetlands from dry and wet atmospheric deposition, runoff from upland agricultural and urban 

areas, spray drift, subsurface water flows, outfalls, pipes, and ditches.

Floodplain waters, including wetlands, can reduce flood peaks by storing and 

desynchronizing floodwaters. They can also maintain river baseflows by recharging alluvial 

aquifers. Many studies have documented the ability of floodplain wetlands to reduce flood 

pulses by storing excess water from streams and rivers. One review of wetland studies reported 

that floodplain wetlands reduced or delayed floods in 23 of 28 studies. For example, peak 

discharges between upstream and downstream gaging stations on the Cache River in Arkansas 

were reduced 10−20 percent primarily due to floodplain water storage. 

Ecosystem function within a river system is driven by interactions between the physical 

environment and the diverse biological communities living within the river system. Wetlands in 

floodplains become important seed sources for the river network, especially if catastrophic 

flooding scours vegetation and seed banks in other parts of the channel. Movements of 

organisms that connect aquatic habitats and their populations, even across different watersheds, 

are 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. The organisms that live within 

the hyporheic zone for these mid- and large-sized river systems have a demonstrated connection 

outward to several miles within the floodplain. General field practice observations further 

indicate that covered adjacent waters with a close proximity have a significant nexus with the 

downstream waters. 
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Waters adjacent to impoundments and covered tributaries are integrally linked to the 

chemical, physical, and biological functions of the waters to which they are adjacent and, 

through those waters, are integrally linked to the chemical, physical, and biological functions of 

the downstream traditional navigable waters, interstate waters, or the territorial seas. Thus, where 

waters are adjacent to impoundments or covered tributaries, they also have a significant nexus to 

the downstream traditional navigable waters, interstate waters, or the territorial seas. The 

important functions that covered adjacent waters perform that impact downstream traditional 

navigable waters, interstate waters, and the territorial seas and their integrated behavior with the 

tributary system demonstrate why all waters adjacent to traditional navigable waters, interstate 

waters, or the territorial seas as well as impoundments and covered tributaries, alone or in 

combination with other covered adjacent wetlands in a watershed have a significant nexus with 

those downstream waters.

Based on the science and technical expertise and experience, the agencies determine it is 

appropriate to protect all adjacent waters as defined in the rule, because those waters are 

functioning as an integrated system with the downstream traditional navigable waters, interstate 

waters, or the territorial seas and significantly affect such downstream waters. Consequently, 

these waters are “adjacent” and therefore “waters of the United States” under the CWA. 

Covered adjacent waters are “waters of the United States” without the need for further analysis. 

3. Case-Specific Significant Nexus Determinations

a. Two exclusive circumstances for case-specific significant nexus 

determinations

The rule identifies two exclusive circumstances under which a significant nexus 

determination is made on a case-specific basis to determine whether the water is a “water of the 
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United States.” First, there are five subcategories of waters – prairie potholes, Carolina and 

Delmarva bays, pocosins, western vernal pools in California, and Texas coastal prairie wetlands 

– that the agencies conclude must be analyzed “in combination” when making a case-specific 

significant nexus analysis. Second, there are waters for which the agencies have made no 

conclusions with respect to which waters are “similarly situated” but for which a case-specific 

significant nexus analyses may be undertaken. The rule establishes that case-specific 

determinations may be made for waters located no more than 4,000 feet from the high tide line or 

the ordinary high water mark of traditional navigable waters, interstate waters, the territorial 

seas, impoundments, or tributaries. 

b. Summary of rationale for “similarly situated” determinations

Based on the agencies’ expertise and experience and available literature and data, the 

agencies have determined that waters in the five subcategories of waters identified in paragraph 

(a)(7) are similarly situated and must be combined with other waters in the same subcategory 

located in the same watershed that drains to the nearest (a)(1) through (a)(3) water. See

Technical Support Document. The scientific literature shows that these subcategories of waters 

are frequently located together in a complex or are otherwise closely co-located and perform 

similar functions. The agencies specifically sought comment in the proposal on options to 

address these five subcategories of waters, including whether waters in these subcategories 

should be found “similarly situated” by rule. 

Based on the body of scientific literature regarding the subcategories of waters specified 

in paragraph (a)(7) and their functions, the agencies determined that waters of the specified 

subcategories are similarly situated because they perform similar functions and they are located 

sufficiently close to each other to be reasonably evaluated in combination with regard to their 
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effects on the integrity of traditional navigable waters, interstate waters, or the territorial seas. 

The specified subcategories of waters perform similar functions as waters of the same 

subcategory in the same single point of entry watershed and collectively function together to 

affect a traditional navigable water, interstate water, or the territorial seas. Among the functions 

and relationships in the landscape the agencies considered to conclude that the subcategories are 

each similarly situated include the physical capacity of the waters to provide flood and sediment 

retention. In determining that the waters in each of the five subcategories were “similarly 

situated,” the agencies concluded that these subcategories of waters were co-located to each 

other or similarly to the tributary system such that they have cumulative and additive effects on 

pollutant removal through parallel, serial, or sequential processing, such as the role of pocosins 

in maintaining water quality in estuaries. The subcategories of waters are sufficiently near each 

other or the tributary system to 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 SAB expressed support for the agencies’ option in the preamble of proposed rule to 

identify certain subcategories of waters as similarly situated and highlighted these same five 

subcategories. It stated, “[t]here is adequate scientific evidence to support a determination that 

certain subcategories and types of ‘other waters’ in particular regions of the United States (e.g., 

Carolina and Delmarva bays, Texas coastal prairie wetlands, prairie potholes, pocosins, western 

vernal pools) are similarly situated (i.e., they have a similar influence on the physical, chemical 

and biological integrity of downstream waters and are similarly situated on the landscape) and 

thus could be considered waters of the United States. Furthermore, as the science continues to 

develop, other sets of wetlands may be identified as ‘similarly situated.’” SAB 2014b at 3.
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The agencies concluded that the specific subcategories of waters listed in paragraph 

(a)(7) are similarly situated for purposes of a case-specific significant nexus based on the 

following:

(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. In the United States, they are found from central Iowa through 

western Minnesota, eastern South Dakota, and North Dakota. Prairie potholes 

demonstrate a wide range of hydrologic permanence; some hold permanent standing 

water and others are wet only in years with high precipitation. This in turn influences 

the diversity and structure of their biological communities. 

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. One of the most noted hydrologic functions of prairie 

potholes is water storage. Because most of the water outflow in potholes is via 

evapotranspiration, potholes can become water sinks, preventing flow to downstream 

waters. 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. 
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Potholes can be highly connected to other portholes via shallow subsurface 

connections and via surface hydrologic connections during the wet season. They can 

also be connected to the stream network via surface and shallow subsurface 

connections. Intense precipitation events or high cumulative precipitation over one or 

more seasons can result in temporary hydrologic connectivity between potholes and 

from potholes to the tributary system via “fill-and-spill” events.

Their density across the landscape varies from region to region as the result of several 

factors, including patterns of glacial movement, topography, and climate. In some 

parts of the region, prairie pothole density is very high. Though their density varies 

across the landscape, prairie potholes often act as a complex. They have similar 

functions that can collectively impact downstream waters. 

Prairie potholes have been determined to be similarly situated based on the

characteristics of prairie pothole wetlands, including their density on the landscape, 

their interaction and formation as a complex of wetlands and open waters, their 

connections to each other and the tributary network, and their similar functions. In 

addition, their chemical, physical, and biological connections to downstream waters 

and the strength of their effects on the chemical, physical, or biological integrity of a 

traditional navigable water, interstate water, or the territorial seas support this 

determination that prairie potholes are similarly situated by rule.
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(B) Carolina and Delmarva bays are ponded depressional wetlands that occur along the 

Atlantic coastal plain from northern Florida to New Jersey. Though Carolina and 

Delmarva bays are from the same category of wetland and perform similar functions, 

they are located in different parts of the Atlantic coastal plain and thus have unique 

names. Carolina bays are most abundant in North Carolina and South Carolina, while 

Carolina bays found in the Delmarva Peninsula are commonly referred to as 

Delmarva bays or Delmarva potholes. 

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 streams, providing for hydrologic connections to each other and to downstream 

waters in large rain events via overland flow or shallow subsurface connections. 

Some Delmarva bays have surface water connections to the Chesapeake Bay. In 

addition, human channeling and ditching of the bays are widespread and create 

surface connections to other waters, including the tributary system and estuaries. 

These ditches commonly connect the surface water of bays to other bays that are 

lower on the landscape, and ultimately, to streams. 

The hydrology in bays allow for denitrification, which could reduce the amount of 

nitrate in both groundwater and downstream surface waters. Because bays are 

frequently connected chemically to downstream waters through ditches, they can be 

sources of sediment and nutrients to downstream waters. Where they are not 
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connected via confined surface connections, bays can act as sediment and nutrient 

sinks.

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 feet 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 downstream waters and allowing transfer of nutrients, 

sediment, and other pollutants, such as methylmercury. 

Carolina and Delmarva bays can occur in high density on the landscape and can act as 

a wetlands complex. Bays have similar functions to other bays and cumulatively these 

functions can impact downstream waters. 

The agencies conclude that Carolina and Delmarva bays are similarly situated based 

on their close proximity to each other and the tributary network, their hydrologic 

connections to each other and the tributary network, their density on the landscape, 

and their similar functions.

(C) 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 
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Virginia to northern Florida, but mainly in North Carolina. Typically, 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 water is slowly released to 

downstream waters and estuaries, where it helps to maintain the proper salinity, 

nutrients, and acidity. 

Because pocosins are the topographic high areas on the regional landscape, they serve 

as the source of water for downstream waters. Pocosins often have seasonal 

connections to drainageways leading to estuaries or are contiguous with other 

wetlands draining into perennial streams or estuaries. Other pocosins have been 

ditched and are directly connected to streams. The draining of pocosins and decreased 

salinity in estuaries may be having a negative effect on brown shrimp in North 

Carolina. 

The agencies conclude that pocosins are similarly situated based on their close 

proximity to each other and the tributary network, their hydrologic connections to 

each other and the tributary network, their density on the landscape, and their similar 

functions.
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(D)Western vernal pools are shallow, seasonal wetlands that accumulate water during 

colder, wetter months and gradually dry up during warmer, drier months. Western 

vernal pools are seasonal wetlands from the Pacific Northwest to northern Baja 

California, Mexico associated with topographic depressions, soils with poor drainage, 

mild, wet winters and hot, dry summers. The agencies have determined that western 

vernal California pools in California are “similarly situated.”

Because their hydrology and ecology are so tightly coupled with the local and 

regional geological processes that formed them, western vernal pools in California

typically occur within “vernal pool landscapes,” or complexes of pools in which 

swales connect pools to each other and to seasonal streams. 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, contain 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. Animals and other organisms can move between western 

vernal pool complexes and streams. Insects and zooplankton can be flushed from 
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vernal pools into streams and other waterbodies during periods of overflow, carried 

by animal vectors (including humans), or dispersed by wind.

The agencies conclude that western vernal pools are similarly situated based on their 

close proximity to each other and the tributary network, their interaction and 

arrangement as a complex of wetlands, their hydrologic connections to each other and 

the tributary network, their density on the landscape, and their similar functions.

(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. 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. The term Texas coastal prairie wetlands is not used uniformly 

in the scientific literature but encompasses Texas prairie pothole (freshwater 

depressional wetlands) and marsh wetlands that are described in some studies that 

occur on the Lissie and Beaumont Geological Formations, and the Ingleside Sand. 

Texas coastal prairie wetlands are locally abundant and in close proximity to other 

coastal prairie wetlands and function together cumulatively. Collectively as a 

complex, Texas coastal prairie wetlands can be geographically and hydrologically 

connected to each other via swales and connected to downstream waters, contributing 

flow to those downstream waters. Cumulatively, these wetlands can control nutrient 
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release levels and rates to downstream waters, as they capture, store, transform, and 

pulse releases of nutrients to those waters. 

The agencies conclude that Texas coastal prairie wetlands are similarly situated based 

on their close proximity to each other and the tributary network, their hydrologic 

connections to each other and the tributary network, their interaction and formation as 

a complex of wetlands, their density on the landscape, and their similar functions.

IV. Definition of Waters of the United States

A. Summary of the Rule

The rule revises the existing definition of “waters of the United States” consistent with 

the CWA, science, the agencies’ technical expertise and experience, and Supreme Court cases. 

The final rule establishes categories of waters that are jurisdictional and other categories of 

waters that are excluded, as well as categories of waters and wetlands that require a case-specific 

significant nexus evaluation to determine if they are “waters of the United States” and covered 

by the CWA. The rule also provides definitions for key terms used in the regulation. The final 

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. All existing exclusions 

from the definition of “waters of the United States” are retained, and several exclusions 

reflecting longstanding agencies’ practice are added to the regulation for the first time. 

The agencies define “waters of the United States” in paragraph (a) of the rule for all 

sections of the CWA to include the traditional navigable waters (a)(1), interstate waters (a)(2), 
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the territorial seas (a)(3), impoundments of jurisdictional waters (a)(4), and covered tributaries 

(a)(5) and covered adjacent waters (a)(6) as defined. Waters in these categories are jurisdictional 

“waters of the United States” by rule – no additional analysis is required. This eliminates the 

need to make a case-specific significant nexus determination for covered tributaries or for 

covered adjacent waters because the agencies determined that these waters have a significant 

nexus and thus are “waters of the United States.” The agencies emphasize that the finding of 

jurisdiction for these covered 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 other of these covered tributaries or adjacent waters in the 

watershed, is significant.

The agencies exclude specified waters from the definition of “waters of the United 

States” in paragraph (b) of the rule. The rule makes no substantive change to the existing 

exclusion for waste treatment systems designed consistent with the requirements of the CWA

and makes no change to the existing exclusion for prior converted cropland. The rule excludes 

certain waters and features over which the agencies have generally not asserted CWA 

jurisdiction, as well as groundwater, which the agencies have never interpreted to be a “water of 

the United States” under the CWA. Codifying these longstanding practices supports the 

agencies’ goals of providing greater clarity, certainty, and predictability for the regulated public 

and regulators, and makes rule implementation clear and practical. The final rule provides clear 

exclusions for certain types of ditches. The final rule also expressly excludes stormwater control 

features created in dry land and certain wastewater recycling structures created in dry land. 

Waters and features that are excluded under paragraph (b) of the rule cannot be determined to be 

jurisdictional under any of the categories in the rule under paragraph (a).
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In addition to waters that are categorically “waters of the United States” or categorically 

excluded under paragraphs (a) and (b), the rule identifies that certain waters that can be “waters 

of the United States” only where a case-specific determination has found a significant nexus 

between the water and traditional navigable waters, interstate waters, or the territorial seas. First, 

paragraph (a)(7) of the rule specifies five types of waters (prairie potholes, Delmarva and 

Carolina bays, pocosins, western vernal pools in California, and Texas coastal prairie wetlands) 

that the agencies have determined to be “similarly situated,” and thus are to be considered in 

combination in a significant nexus analysis. Second, the rule specifies in paragraph (a)(8) that 

waters located no more than 4,000 feet from the high tide line or the ordinary high water mark of 

traditional navigable waters, interstate waters, the territorial seas, impoundments, or covered

tributaries may be found to have a significant nexus on a case specific basis, but the agencies 

have not made a determination that the waters are “similarly situated.” As a result, a significant 

nexus analysis for these waters will include a case-specific assessment of whether there are any

similarly situated waters, as well as whether the water, alone or in combination with any waters 

determined to be similarly situated, has a significant nexus to a traditional navigable water, 

interstate water, or territorial sea. The rule outlines at (c)(5)(A)-(I) functions relevant to these 

case-specific significant nexus analyses.

Paragraph (c) of the rule provides definitions for key terms used in the regulation. Some 

of these are unchanged from the current regulations, including the definitions for “wetlands” at 

(c)(4), “ordinary high water mark” at (c)(6) and “high tide line” at (c)(7), although the latter two 

are existing, unchanged Corps’ definitions added to EPA’s regulations for the first time. The 

rule also defines for the first time “tributary” and “tributaries” at (c)(3), “neighboring” (an aspect 

of adjacency) at (c)(2), and “significant nexus” at (c)(5).
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This rule is effective on [60 days after Federal Register publication]. Under existing 

Corps’ regulations and guidance, Corps’ approved jurisdictional determinations generally are 

valid for five years. The agencies do not intend to reopen existing approved jurisdictional 

determinations unless requested to do so by the applicant. All jurisdictional determinations made 

after [60 days after Federal Register publication] will be made consistent with this rule.

B. Traditional Navigable Waters

The 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 

paragraph of the regulation encompasses those waters that are often referred to as “traditional 

navigable waters.” The rule does not make any changes to this paragraph of the regulation. 

For purposes of CWA jurisdiction, waters will be considered traditional navigable waters, 

and jurisdictional under (a)(1) of the rule, if they: 

• are subject to section 9 or 10 of the Rivers and Harbors Appropriations Act of 1899; 

• have been determined by a Federal court to be navigable-in-fact under Federal law; 

• are waters currently being used for commercial navigation, including commercial 

waterborne recreation (for example, boat rentals, guided fishing trips, or water ski 

tournaments); 

• have historically been used for commercial navigation, including commercial waterborne 

recreation; or
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• are susceptible to being used in the future for commercial navigation, including 

commercial waterborne recreation. 

See Technical Support Document; “U.S. Army Corps of Engineers Jurisdictional Determination 

Form Instructional Guidebook Appendix D, ‘Traditional Navigable Waters,’” available at: 

http://www.usace.army.mil/Portals/2/docs/civilworks/regulatory/cwa_guide/app_d_traditional_n

avigable_waters.pdf. 

The agencies received several comments on the scope of traditional navigable waters. 

Some commenters observed that “traditional navigable waters” as a jurisdictional category is not 

based in science. The agencies note that the Supreme Court concluded that Congress enacted the 

CWA to protect “traditional navigable waters.” Several commenters thought that the final rule 

should specify considerations to be taken into account when determining if a water is susceptible 

to being used in future commercial navigation. The agencies have not revised the regulation to 

address susceptibility, but observe that caselaw has provided a number of considerations and 

examples that are described further in the Technical Support Document and are reflected in 

longstanding agencies’ practice. A number of commenters expressed concern that the revised 

definition of “waters of the United States” would alter the scope of waters subject to state and 

tribal permitting upon assumption of the section 404 permitting program under CWA section 

404(g). The rule does not affect the scope of waters subject to assumption under section 404(g) 

of the CWA. See CWA section 404(g). 

C. Interstate Waters
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The existing regulations define “waters of the United States” to include interstate waters, 

including interstate wetlands. The rule does not change that provision of the regulations. 

Therefore, interstate waters are “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 covered by the CWA, the rule protects impoundments of interstate 

waters, tributaries to interstate waters, waters adjacent to interstate waters, and waters adjacent to 

covered tributaries of interstate waters because they have a significant nexus to interstate waters.

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 subjected interstate waters and their tributaries to Federal jurisdiction. The text of the 

CWA, specifically CWA section 303 which 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.

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 
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jurisdictional requirements on interstate waters. For additional discussion of the agencies’ 

interpretation of the CWA with respect to interstate waters, see Appendix B of the proposed rule

and the Technical Support Document.

It is reasonable to assert jurisdiction over tributaries, adjacent wetlands, and 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 that 

Congress intended to subject to Federal jurisdiction are indeed covered, 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 rule also protects 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. 

The agencies received a number of comments on interstate waters. Some commenters

asserted that interstate waters required a significant nexus to a traditional navigable water in 

order to be jurisdictional after Rapanos. The agencies disagree for the reasons described above 

and in Appendix B to the proposed rule and the Technical Support Document. 

D. Territorial Seas
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The CWA and its existing regulations include “the territorial seas” as a “water of the 

United States.” The rule makes no changes to that provision of the regulation other than to 

change the ordering 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 clearly covered by the 

CWA (they are also traditional navigable waters), it is reasonable to use Justice Kennedy’s 

significant nexus framework to protect the integrity of the territorial seas. The rule reflects this

by protecting the tributaries and adjacent waters that flow into the territorial seas.

Although some comments addressed the definition of “territorial seas” provided in the 

CWA suggesting that the distance thresholds be revised to reflect other resource statutes, the 

agencies do not have authority to revise statutory language. 

E. Impoundments

The existing regulations provide that impoundments of “waters of the United States”

remain “waters of the United States” and the rule does not make any changes to the existing 

regulatory language. 

Impoundments are jurisdictional because 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 traditional navigable waters, interstate waters, and the territorial seas. The Supreme 
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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 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. The agencies will analyze the stream 

network, above and below the impoundment, for connection to downstream traditional navigable 

waters, interstate waters, or the territorial seas. Scientific literature, as well as the agencies’ 

scientific and technical expertise and experience confirm that impoundments have chemical, 

physical, and biological effects on downstream waters. See Technical Support Document.

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-infact and covered under paragraph (a)(1) of the rule.

Impoundments also may be one of the waters through which tributaries indirectly 

contribute flow to a traditional navigable water, interstate water, or territorial sea. As a matter of 

law and science, an impoundment does not cut off a connection between upstream tributaries and 

a downstream traditional navigable water, interstate water, or territorial sea, so covered

tributaries above the impoundment are still considered tributary to a downstream traditional 

navigable waters, interstate waters, or the territorial seas even where the flow of water might be
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impeded due to the impoundment. See (a)(5). 

The agencies received comments on impoundments, which generally explored the 

impacts of impoundments on connectivity to downstream waters. For the reasons described 

above and in the Technical Support Document, the agencies concluded that impoundments of 

“waters of the United States” remain “waters of the United States.”

F. Tributaries

Previous definitions of “waters of the United States” regulated all tributaries without 

qualification. The final rule protects only waters that have a significant effect on the integrity of 

traditional navigable waters, interstate waters, or the territorial seas. The rule establishes a

definition of “tributary,” and provides that all waters meeting the definition of tributary, unless a 

water is excluded under paragraph (b), are “waters of the United States” without the need for a 

separate case-specific significant nexus evaluation. As explained in Section III. above, covered

tributaries and the 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, or the territorial seas. See also Technical Support Document. 

This section describes the provisions of the rule addressing tributaries and changes made to the 

provisions in the proposed rule based on public comments. 

1. What Are the Provisions in the Rule?

The rule defines “tributary” by emphasizing the physical characteristics created by 

sufficient volume, frequency and duration of flow, and that the water contributes flow, either 

directly or through another water, to a traditional navigable water, interstate water, or the 
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territorial seas. This definition is based on the best available science, intent of the CWA, and 

caselaw, and is consistent with current practice. As mentioned above in Section III, the Science 

Report concludes that “[t]he scientific literature unequivocally demonstrates that streams, 

individually or cumulatively, exert a strong influence on the integrity of downstream waters.” 

Science Report at ES-2. 

First, to meet the rule’s definition of “tributary,” a water must flow directly or to another 

water or waters which eventually flow into a traditional navigable water, interstate water, or the 

territorial seas. Waters through which a tributary may contribute flow indirectly include, for 

example, impoundments, wetlands, lakes, and other tributaries. This limitation on what 

constitutes a tributary for purposes of this rule is fundamental. If a water is not part of the 

tributary system of a traditional navigable water, interstate water, or the territorial seas, it does 

not meet the definition of “tributary” and is not jurisdictional under this provision of the rule. 

For example, an intermittent stream that exists wholly within one state, is not itself a traditional 

navigable water, and whose flows eventually ends without connecting to a traditional navigable 

water, interstate water, or the territorial seas is not a “water of the United States” as a “tributary” 

for purposes of this rule. To determine whether a water meets this aspect of the definition, the 

connection can be traced using direct observation, U.S. Geological Survey (USGS) data, stream 

datasets such as the National Hydrography Dataset, aerial photography or other reliable remote 

sensing information, or other appropriate information.

Under the rule, flow in the tributary may be perennial, intermittent, or ephemeral. 

Longstanding agencies’ practice considers perennial streams as those with flowing water yearround during a typical year, with groundwater or contributions of flow from higher in the stream 

or river network as primary sources of water for stream flow. Intermittent streams are those that 
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have both precipitation and groundwater providing part of the stream’s flow, and flow 

continuously only during certain times of the year (e.g., during certain seasons such as the rainy 

season). Ephemeral streams have flowing water only in response to precipitation events in a 

typical year, and are always above the water table. Precipitation can include rainfall as well as 

snowmelt. Science shows that tributaries regardless of flow permanence are very effective at 

transporting pollutants downstream, such as excess nutrients and sediment, which impact the 

integrity and character of traditional navigable waters, interstate waters, and the territorial seas.

See Technical Support Document. 

Second, the rule requires two physical indicators of flow: there must be a bed and banks 

and an additional indicator of ordinary high water mark. This definition of “tributary” includes

only those waters the agencies have concluded are the type of waters that the CWA was intended 

to protect and which either individually or in combination with other covered tributaries in the 

watershed have a significant nexus to a traditional navigable water, interstate water, or the 

territorial seas. Thus, the agencies are not defining “waters of the United States” to include all 

streams that might be considered “tributaries” in the general scientific literature. To provide 

additional clarity and for ease of use for the public, the agencies are including the Corps’ existing 

definition of ordinary high water mark in EPA’s regulations as well. Under that existing Corps 

regulation, ordinary high water mark indicators include characteristics such as shelving, scour, 

changes in soil characteristics, and destruction of terrestrial vegetation, among others. 

A bed and banks and other indicators of ordinary high water mark are physical indicators 

of water flow and are only created by sufficient and regular intervals of flow. These physical 

indicators can be created by perennial, intermittent, and ephemeral flows. See Technical Support 

Document. For purposes of the rule, “bed and banks” means the substrate and sides of a channel 
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between which flow is confined. The banks constitute a break in slope between the edge of the 

bed and the surrounding terrain, and may vary from steep to gradual. Existing Corps regulations 

define ordinary high water mark 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 the rule and is added to EPA’s 

regulations. 

Bed and banks are themselves an indicator of ordinary high water mark, and the definition 

of “tributary” also requires another indicator of ordinary high water mark. In many tributaries, 

the bed is that part of the channel below the ordinary high water mark, and the banks often 

extend above the ordinary high water mark. For other tributaries, such as those that are incised, 

changes in vegetation, changes in sediment characteristics, staining, or other ordinary high water 

mark indicators may be found within the banks. In concrete-lined channels, the concrete serves 

as the bed and banks and can have other ordinary high water mark indicators such as staining and 

debris deposits. Indicators of an ordinary high water mark may vary from region to region 

across the country. See Technical Support Document.

Other evidence, besides direct field observation, may establish the presence of bed and 

banks and another indicator of ordinary high water mark. The agencies currently use many tools 

in identifying tributaries and will continue to rely on their experience and expertise in identifying

the presence of a bed and banks and ordinary high water mark. For example, several reliable, 

well-established remote sensing sources of information or mapping can assist to establish the 

presence of water that contributes flow to an (a)(1) through (a)(3) water and provide evidence 
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regarding the presence of a bed and banks and another indicator of ordinary high water mark.

Among the types of remote sensing or mapping information that can assist in establishing the 

presence of water are USGS topographic data, the USGS National Hydrography Dataset (NHD), 

Natural Resources Conservation Service (NRCS) Soil Surveys, and State or local stream maps, 

as well as the analysis of aerial photographs, and light detection and ranging (also known as 

LIDAR) data, and desktop tools that provide for the hydrologic estimation of a discharge 

sufficient to create an ordinary high water mark, such as a regional regression analysis or 

hydrologic modeling. These sources of information can sometimes be used independently to 

infer the presence of a bed and banks and another indicator of ordinary high water mark, or 

where they correlate, can be used to reasonably conclude the presence of a bed and banks and 

ordinary high water mark.

Both the USGS topographic data and the NHD data assist to delineate tributaries to (a)(1)

through (a)(3) waters. Where one or both of these sources have indicated a “blue line stream” 

there is an indication that the tributary could exhibit a bed and banks and another indicator of

ordinary high water mark. Where this information is combined with stream order,6 more 

certainty can result. For example, a water that is a second-order stream will be more likely to 

exhibit a bed and banks and another indicator of ordinary high water mark as compared to a firstorder stream. This information will vary in validity in different parts of the country, so care must 

be taken to evaluate additional information prior to reasonably concluding a bed and banks or

 6 Stream order is a method for stream classification based on relative position within a river 

network, when streams lacking upstream tributaries (i.e., headwater streams) are first-order 

streams and the junction of two streams of the same order results in an increase in stream order 

(i.e., two first-order streams join to form a second-order stream, and so on). When streams of 

different orders join, the order of the larger stream is retained. See Science Report and Technical 

Support Document.
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other indicators of ordinary high water mark are associated with the stream. This will be 

particularly true for first-order streams and for many streams in the arid portions of the country. 

Supporting information that can be used to conclude the presence of a bed and banks and another 

indicator of ordinary high water mark would be the presence of USGS stream data on the NRCS 

county Soil Survey or local stream maps which are mapped independently of the USGS, aerial 

photography interpretation, or digital terrain depictions created from LIDAR. See Technical 

Support Document. 

Tributaries are observable in aerial photography by their topographic expression, 

characteristic linear and curvilinear patterns, dark photographic tones, and the presence and 

pattern of riparian vegetation. The characteristic linear and curvilinear patterns and dark 

photographic tones observed on aerial photography can be caused by shadow cast from the banks 

of an incised stream or from water in the stream channel itself. In some cases stream channel 

morphology is visible, providing evidence of scour, materials sorting, and deposition, all 

characteristics of an ordinary high water mark. Visible persistent water (e.g., multiple dates of 

aerial photography showing visible water) provides strong evidence of the sufficient frequency 

and duration of surface flow to create a bed and banks and other indicators of ordinary high 

water mark. Visible indicators of running water such as rapids, riffles, and pools all indicate the 

presence of a bed and banks and other indicators of ordinary high water mark. Other physical 

characteristics of an ordinary high water mark that may be visible on aerial photography include 

the destruction of terrestrial vegetation and the absence of vegetation in a channel. These 

indicators gleaned from aerial photography interpretation can be correlated with the presence of 

USGS streams data in reasonably concluding that a bed and banks and another indicator of

ordinary high water mark are present. See Technical Support Document.
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Additional desktop tools can assist in the identification of bed and banks and other 

indicators of ordinary high water mark. For instance, field staff use other methods for estimating 

ordinary high water mark, including, but not limited to, lake and stream gage data, flood 

predictions, historic records of water flow, and statistical evidence. Some desktop tools, such as a 

regional regression analysis and the Hydrologic Modeling System (HEC-HMS), provide for the 

hydrologic estimation of stream discharge sufficient to create an ordinary high water mark in 

tributaries under regional conditions. Such desktop tools are particularly useful for identifying 

presence of bed and banks and another indicator of ordinary high water mark when supported by 

additional remote sensing tools that indicate the presence of such physical features. 

LIDAR is powerful tool to analyze the characteristics of the land surface, including 

tributary identification and characterization. LIDAR data are becoming more and more 

widespread for engineering and land use planning purposes. Where LIDAR data have been 

processed to create a bare earth model, detailed depictions of the land surface are available. Bare 

earth models reveal subtle elevation changes and can clearly show a tributary’s bed and banks

and channel morphology. In many cases LIDAR can help delineate tributaries that would exhibit 

a bed and banks and another indicator of an ordinary high water mark in greater detail than aerial 

photography interpretation alone can. Visible linear and curvilinear incisions on a bare earth 

model are strong evidence that a tributary with a bed and banks and another indicator of an 

ordinary high water mark is present. LIDAR-indicated tributaries can be correlated with aerial 

photography interpretation and USGS stream data, to reasonable conclude the presence of a bed 

and banks and another indicator of an ordinary high water mark in the absence of a field visit. 

See Technical Support Document. The agencies have been using such remote sensing and 
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desktop tools to delineate tributaries for many years where data from the field are unavailable or 

a field visit is not possible. 

In addition, such desktop tools are critical in circumstances where physical characteristics 

of bed and banks and another indicator of ordinary high water mark are absent in the field, often 

due to unpermitted alteration of streams. In such cases where physical characteristics of bed and 

banks and another indicator of ordinary high water mark no longer exist, they may be determined

by using other appropriate means that consider the characteristics of the surrounding areas. Such 

reliable methods that can indicate prior existence of bed and banks and other indicators of

ordinary high water mark include, but are not limited to, lake and stream gage data, elevation 

data, spillway height, historic water flow records, flood predictions, statistical evidence, the use 

of reference conditions, or through the remote sensing and desktop tools described above.

The upper limit of the tributary is the point where a bed and banks and another indicator of 

ordinary high water mark cease to be identifiable. The ordinary high water mark establishes the 

lateral limits of a water, and its absence generally determines when a tributary’s channel or bed 

and banks has ended, representing the upper limit of the tributary. However, a natural or 

constructed break in bed and banks or other indicator of ordinary high water mark does not 

constitute the upper limit of a tributary where bed and banks or other indicator ordinary high 

water mark can be found farther upstream. Note that waters, including wetlands, which are 

adjacent to a tributary at the upper limit of the channel are jurisdictional as adjacent waters.

The definition of “tributary” includes tributaries that flow directly or indirectly through 

impoundments that are jurisdictional under (a)(4) of the rule. Tributaries to impoundments of 

“waters of the United States” are jurisdictional for the same reasons the impoundments 

themselves are jurisdictional. As discussed in section IV. E., under case law, an impoundment of 
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a “water of the United States” remains a “water of the United States,” and scientific literature 

demonstrates that impoundments continue to significantly affect the chemical, physical, or 

biological integrity of downstream waters traditional navigable waters, interstate waters, and the 

territorial seas. Therefore, tributaries to such impoundments continue to have a significant 

nexus, alone or in combination with other covered tributaries in the watershed, to the 

downstream traditional navigable water, interstate water, or the territorial seas.

Waters that meet the rule definition of tributary remain tributaries even if there is a 

manmade or natural break at some point along the connection to the traditional navigable water, 

interstate water, or the territorial seas. In many tributaries, there are often natural or constructed

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. Many 

tributaries lose their ordinary high water mark when adjacent wetlands are contiguous with the 

stream channel. The definition of “tributary” addresses these circumstances and states that waters 

that meet the definition of tributary remain tributaries even if such breaks occur, so long as bed 

and banks and an ordinary high water mark are present upstream of the break. Under the rule, 

when a covered tributary flows through a wetland into another tributary (sometimes called a 

“run-of-stream” wetland), the covered tributary remains jurisdictional even though it lost its 

ordinary high water mark through the wetland. By looking to the presence of a bed and banks 

and an ordinary high water mark upstream, the rule ensures that a mere break in the ordinary 

high water mark does not render tributaries with a significant nexus to downstream waters not 

jurisdictional. Other breaks that do not sever jurisdiction include constructed breaks such as 

bridges, culverts, pipes, dams, or waste treatment systems, or natural breaks such as debris piles, 
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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. 

The rule also clarifies that a water meets the definition of tributary if the water contributes 

flow through an excluded feature such as an ephemeral ditch. While the water above and below 

the excluded feature is jurisdictional if it meets the definition of tributary, the excluded feature 

does not become jurisdictional. A water also continues to meet the definition of tributary if at 

some point the water contributes flow through a jurisdictional water that is not a tributary, such 

as an adjacent wetland or impoundment. 

The agencies’ longstanding interpretation of the CWA has included tributaries that are

natural, modified, or constructed waters. While this rule at paragraph (b) excludes specific types 

of constructed waters from jurisdiction, it continues to interpret constructed tributaries as 

jurisdictional unless expressly excluded in paragraph (b). Natural, modified, and constructed

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, modified, or constructed. See discussion 

in section III.C. above and the Technical Support Document. 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 modified

or constructed. For example, tributaries that have been channelized in concrete or otherwise have 

been modified may still meet the definition of tributaries under the rule so long as they have bed 

and banks and an ordinary high water mark, contribute flow to a traditional navigable water, 

interstate water, or the territorial seas, and are not excluded under paragraph (b). The important 
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consideration for a modified or constructed water is whether it meets the definition of “tributary” 

and is not excluded under paragraph (b).

Ditches are one important example of constructed features that in many instances can 

meet the definition of tributary. Ditches are jurisdictional under the rule only if they both meet 

the definition of “tributary” and are not are not excluded under paragraph (b)(3) in the rule. Not 

all ditches meet the definition of a tributary, and others – as discussed in Section I – are 

expressly excluded from jurisdiction.

Ditches protected by the rule must meet the definition of tributary, having a bed and 

banks and ordinary high water mark, and contributing flow directly or indirectly through another 

water to a traditional navigable water, interstate water, or the territorial seas. Jurisdictional 

ditches may include ditches such as the following: 

• Ditches that have perennial flow, including roadside ditches,

• Ditches with intermittent flow, not including roadside ditches (unless they are a relocated 

tributary or excavated in a tributary),

• Ditches, regardless of flow, that are excavated in or relocate a tributary.

The definition of tributary includes natural, undisturbed waters and those that have been 

man-altered or constructed, but which science shows function as a tributary. In addition, natural 

streams and rivers that are altered or modified for purposes as flood control, erosion control, and 

other reasons does not convert the tributary to a ditch. A stream or river that has been 

channelized or straightened because its natural sinuosity has been altered, cutting off the 

meanders, is not a ditch. A stream that has banks stabilized through use of concrete or rip-rap 

(e.g., rocks or stones) is not a ditch. The Los Angeles River, for example, is a “water of the 

United States” (and, indeed, a traditional navigable water) and remains a “water of the United 
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States” and is not a excluded under paragraph (b)(3) even where it has been ditched, channelized, 

concreted and runs alongside a road.

Where an excluded roadside or ephemeral ditch is excavated in or relocates a covered 

tributary, only the segment of the ditch actually excavated in or relocating the covered tributary 

would be considered jurisdictional. For example, an entire roadside ditch does not become 

subject to jurisdiction because a portion of it is excavated in or relocates a tributary. The 

opposite is also true though - a tributary does not lose its jurisdictional status for its entire length 

simply because a portion of it is excluded under paragraph (b)(3). This approach reasonably 

balances the exclusion with the need to ensure that covered tributaries, and the significant 

functions they provide, are preserved. A ditch that relocates a stream is not an excluded ditch 

under paragraph (b)(3) and a stream is relocated either when at least a portion of its original 

channel has been physically moved, or when the majority of its flow has been redirected. A 

ditch that is a relocated stream is distinguishable from a ditch that withdraws water from a stream 

without changing the stream’s aquatic character. The latter type of ditch may be excluded from 

jurisdiction where it meets the listed characteristics of excluded ditches under paragraph 

(b)(3). Agency staff can determine historical presence of tributaries using a variety of resources, 

such as historical maps, historic aerial photographs, local surface water management plans, street 

maintenance data, wetlands and conservation programs and plans, as well as functional 

assessments and monitoring efforts.

Evidence, such as current or historic photographs, prior delineations, or USGS and state 

and local topographic maps, may be used to determine whether a ditch is an excluded ditch. 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 
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fashion with little sinuosity and may not connect to another “water of the United States.” 

Ditches created by relocating natural waters would be considered “waters of the United States,” 

so long as they contribute flow to another jurisdictional water. Further, these ditches are 

jurisdictional from the point of natural water modification to their downstream intersection with 

another water.

2. What Changes Did the Agencies Make from the Proposed Rule Based on 

Public Comments? 

The rule’s definition of “tributary” retains many elements from the proposed rule, but 

reflects public comments in several important ways. In particular, the rule emphasizes flow. 

The rule defines “tributary” by emphasizing physical characteristics created by water flow and 

requiring that the water contributes flow, either directly or through another water, to a traditional 

navigable water, interstate water, or the territorial seas. The rule also is clearer regarding the 

jurisdictional status of certain ditches, and clarifies that wetlands and waters such as ponds and 

lakes that contribute flow to a traditional navigable water, interstate water, or the territorial seas 

but typically lack a bed and banks and ordinary high water mark are considered “adjacent” but 

not tributary.

A number of commenters suggested that the agencies should exclude ephemeral streams 

from the definition of tributary, expressing concern that ephemeral waters that flow very rarely

would be considered a jurisdictional tributary. The rule definition of “tributary” requires that 

flow must be of sufficient volume, frequency, and duration to create the physical characteristics 

of bed and banks and an ordinary high water mark. If a water lacks sufficient flow to create such 

characteristics, it is not considered “tributary” under this rule. While some commenters 
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expressed concern that a feature that flowed very infrequently could meet the proposed definition 

of “tributary,” it is the agencies’ judgment that such a feature is not a tributary under the rule 

because it would not form the physical indicators required under the definitions of “ordinary high 

water mark” and “tributary.” To further emphasize this point, the rule expressly indicates in 

paragraph (b) that ephemeral reaches that do not meet the definition of tributary are not “waters 

of the United States.” 

The rule includes ephemeral streams that meet the definition of tributary as “waters of the 

United States” because the agencies determined that such streams provide important functions 

for downstream waters, and in combination with other covered tributaries in a watershed 

significantly affect the chemical, physical, and biological integrity of traditional navigable 

waters, interstate waters, and the territorial seas. As noted by the SAB, and consistent with the 

scientific literature, tributaries as a group exert strong influence on the chemical, physical, and 

biological integrity of downstream waters, even though the degree of connectivity is a function 

of variation in the frequency, duration, magnitude, predictability, and consequences of chemical, 

physical, and biological processes. See, e.g., SAB 2014b. These significant effects on traditional 

navigable waters, interstate waters, and the territorial seas occur even when the tributary is small, 

intermittent, or ephemeral. 

In addition, the Science Report concludes that, “[a]lthough less abundant, the evidence 

for connectivity and downstream effects of ephemeral streams was strong and compelling, 

particularly in context with the large body of evidence supporting the physical connectivity and 

cumulative effects of channelized flows that form and maintain stream networks.” Science 

Report at 6-13. For example, ephemeral headwater streams shape river channels in traditional 

navigable or interstate waters by accumulating and gradually or episodically releasing stored 
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materials such as sediment and large woody debris. These materials help structure traditional 

navigable and interstate river channels by slowing the flow of water through channels and 

providing substrate and habitat for aquatic organisms. 

Moreover, the agencies have historically considered ephemeral tributaries to be “waters 

of the United States.” For example, for many years EPA has reviewed and approved state water 

quality standards for ephemeral waters under CWA section 303(c), several Corps’ Nationwide 

Permits under CWA section 404 address discharges of dredged or fill material into ephemeral 

waters, and the agencies’ definition of “waters of the United States” prior to this rule included all 

tributaries without reference to flow regime.

Numerous commenters asked that the final rule define “bed and banks,” which are 

physical characteristics called for under the definition of tributary. Such commenters 

emphasized the importance of a definition of “bed and banks,” and some suggested definitional 

language. To increase clarity, the preamble in IV.F.1. above includes a definition of bed and 

banks adapted largely from longstanding agencies’ practice as well as comments. Several 

commenters suggested that the rule should add a definition of “ordinary high water mark.” In 

response and to increase clarity, the rule adds the Corps’ existing regulatory ordinary high water 

mark definition to EPA’s regulations. Corps technical manuals are available to help identify 

ordinary high water mark, referenced above. Several commenters suggested that the agencies 

not require a tributary to have both bed and banks and ordinary high water mark, because bed 

and banks are themselves an indicator of ordinary high water mark, and because ordinary high 

water mark alone is an appropriate criterion for many streams in the arid west where the 

characteristic of bed and banks is less common. The agencies based their significant nexus 

determination for the covered tributaries in part on the amount of flow indicated where a 
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tributary had both a bed banks and another indicator of ordinary high water mark, so the rule 

continues to require both physical indicators with the preamble at IV.F.1. above clarifying the 

means to conclude that those indicators exist. 

Several commenters suggested that the rule exclude all constructed waters from the 

definition of “waters of the United States.” While the rule does exclude several types of 

constructed waters from jurisdiction, it continues to consider constructed tributaries as 

jurisdictional unless expressly excluded in paragraph (b) for the reasons described in section 

IV.I. and the Technical Support Document.

The agencies received extensive comments on ditches, addressing circumstances where 

commenters thought ditches should be jurisdictional and where they should not. Many 

comments asserted that some, if not all, roadside ditches should be non-jurisdictional in light of 

their importance to highway safety and the need to not discourage maintenance of roadside 

ditches. In light of those comments, the rule includes perennial roadside ditches and roadside 

ditches that are a relocated tributary or excavated in a tributary as “waters of the United States,” 

while paragraph (b) of the rule expressly excludes from jurisdiction intermittent and ephemeral 

roadside ditches that are not a relocated tributary or excavated in a tributary where they drain 

Federal, state, tribal, county, or municipal roads. See Section I for additional discussion of 

excluded ditches. 

Many comments recommended that wetlands, ponds, and lakes that contribute flow to a 

traditional navigable water, interstate water, or the territorial seas but lack a bed and banks and 

ordinary high water mark not be considered tributary, because of the importance of those 

physical characteristics to the definition. Wetlands typically lack bed and banks and ordinary 

high water mark, while lakes and ponds typically have an ordinary high water mark and a bed 
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but may lack banks. The proposed rule expressly sought comment on whether such waters 

should be considered tributary or as adjacent waters, recognizing that it might add an element of 

uncertainty to the definition of “tributary” to include waters that lacked the physical features 

called for in the definition. In addition, the SAB commented that tributaries are not typically 

defined to include lentic systems (still waters), and suggested that the agencies reconsider 

including ponds, lakes, and wetlands as adjacent waters instead of tributaries. SAB 2014b at 2. In

response, the rule does not consider these waters to be tributaries, but defines adjacent waters to 

include wetlands, lakes, and ponds that connect segments of tributaries or are at the head of the 

tributary system. See section G for further discussion.

G. Adjacent Waters 

Section III above explains the basis for the agencies’ conclusion that covered adjacent

waters have a significant nexus with traditionally navigable waters, interstate waters, or the 

territorial seas. The adjacency provision is based on the best available science, intent of the 

CWA, and caselaw, and is consistent with the experience of the agencies in making case-specific 

significant nexus determinations. As discussed above in Section III, the SAB concludes, “[t]he 

available science supports [the agencies’] proposal to include adjacent waters and wetlands as 

waters of the United States.” SAB 2014b at 2. This section describes the provisions of the rule 

governing adjacent waters, changes made to the adjacent waters provision based on comments on 

the proposed rule, and, finally, how science and the law support the agencies’ conclusions in the 

final rule.

1. What Are the Provisions of the Rule?
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Under the rule, “adjacent” means bordering, contiguous, or neighboring, including waters 

separated from other “waters of the United States” by constructed dikes or barriers, natural river 

berms, beach dunes, and the like. Waters adjacent to a traditional navigable water, interstate 

water, territorial sea, impoundment, or tributary, are “waters of the United States.” For purposes 

of determining adjacency, a water that includes wetlands within or abutting its ordinary high 

water mark is considered a single water. Adjacency is not limited to waters located laterally to a 

traditional navigable water, interstate water, the territorial seas, an impoundment, or a tributary. 

Therefore, waters that connect segments of a traditional navigable water, interstate water, the 

territorial seas, an impoundment, or a tributary or are located at the head of a traditional 

navigable water, interstate water, the territorial seas, an impoundment, or a tributary may be 

determined to be bordering, contiguous, or neighboring, and thus adjacent. “Adjacent waters” 

include wetlands, ponds, lakes, oxbows, impoundments, and similar water features. “Adjacent 

waters” do not include any water excluded under paragraph (b) of the rule. Note also that a 

water that does not meet the definition of “adjacent waters” may be determined to be a “water of 

the United States” on a case-specific basis under paragraph (a)(8) of the rule.

Within the definition of “adjacent,” the terms bordering and contiguous are well 

understood, and for continuity and clarity the agencies continue to interpret and implement those 

terms consistent with the current policy and practice. Waters separated by a berm or other similar 

feature remain “adjacent” under the definition. 

Some waters included under the definition of “tributary” in the proposed rule, after 

consideration of public comment, are “adjacent” in the final rule. Specifically, waters that 

connect segments of, or are at the head of, a traditional navigable water, interstate water, the 

territorial seas, an impoundment, or a tributary are adjacent to that water. For example, a pond 
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that is the source water to a tributary and borders the tributary at its uppermost reach is 

jurisdictional as an adjacent water. Further, if there is a fringe wetland abutting that pond that is 

the source water to a tributary, that wetland is considered part of the pond under the rule and 

such pond as a whole, including any abutting wetlands, is jurisdictional as an adjacent water. 

For purposes of adjacency, including all three provisions of the definition of 

“neighboring,” the entire water is adjacent if any part of the water is bordering, contiguous or 

neighboring. Therefore, the entire wetland is “adjacent” if any part of it is within the distance 

thresholds established in the definition of “neighboring.” For example, if a tributary has a 1,000 

foot wide 100-year floodplain, then a water that is located within 1,000 feet of the ordinary high 

water mark of a covered tributary and extends to 2,000 feet is jurisdictional in its entirety as 

“neighboring.” In addition, for purposes of determining whether a water is “adjacent” artificial 

features (such as roads) do not divide a water; rather, the water is treated as one entire water. 

The definition of “adjacent” in the rule does not include those waters that are subject to 

established, normal farming, silviculture, and ranching activities. Wetlands and farm ponds being 

used for normal farming activities, as those terms are used in the Clean Water Act and its 

implementing regulations, are not jurisdictional under the Act as an “adjacent” water. Waters 

subject to normal farming, silviculture, and ranching activities instead will continue to be subject 

to case-specific review, as they are today. Recognizing the vital role of farmers in providing the 

nation with food and fiber, the Clean Water Act in Section 404(f)(1) (33 U.S.C. § 1344(f)(1)) 

exempts many normal farming activities such as seeding, harvesting, cultivating, planting, soil 

and water conservation practices, and other activities from the Section 404 permitting 

requirement. “Normal” farming, silviculture, and ranching is clarified in the agencies’ 

implementing regulations (40 C.F.R § 232.3(c)(1)) to mean established and ongoing activities to 
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distinguish from activities needed to convert an area to farming, silviculture, or ranching and 

activities that convert a water to a non-water. The rule reflects this framework by clarifying the 

waters subject to the activities Congress exempted under Section 404(f)(1) are not jurisdictional 

by rule as “adjacent.” It is important to recognize that “tributaries,” including those ditches that 

meet the tributary definition, are not “adjacent waters” and are jurisdictional by rule.

This provision interprets the intent of Congress and reflects the intent of the agencies to 

minimize potential regulatory burdens on the nation’s agriculture community, and recognizes the 

work of farmers to protect and conserve natural resources and water quality on agricultural lands. 

While waters subject to normal farming, silviculture, or ranching practices may be determined to 

significantly affect the chemical, physical, or biological integrity of downstream navigable 

waters, the agencies believe that such determination should be made based on a case-specific 

basis instead of by rule. The agencies also recognize that waters subject to normal farming, 

silviculture, or ranching practices are often associated with modifications and alterations 

including drainage, changes to vegetation, and other disturbances the agencies believe should be 

specifically considered in making a significant nexus determination. 

The rule establishes a definition of “neighboring” for purposes of determining adjacency. 

In the rule, the agencies identify three circumstances under which waters would be 

“neighboring” and therefore “waters of the United States.” 

First, the term “neighboring” includes all waters located in whole or in part within 100 

feet of the ordinary high water mark of a traditional navigable water, interstate water, the 

territorial seas, an impoundment, or a covered tributary. 

 Second, the term “neighboring” includes all waters within the 100-year floodplain (i.e., 

the area with a one percent annual chance of flooding) of a traditional navigable water, interstate 
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water, the territorial seas, an impoundment, or a covered tributary that is located in whole or in 

part within 1,500 feet of the ordinary high water mark of that jurisdictional water. If the 100-

year floodplain is greater than 1,500 feet from the ordinary high water mark, only those waters 

that are located in whole or in part within 1,500 feet of the ordinary high water mark meet this 

provision. In addition, if the 100-year floodplain is less than 1,500 feet from the ordinary high 

water mark, only those waters within the floodplain are “neighboring” under this provision. 

Third, the rule defines “neighboring” to include all waters located in whole or in part 

within 1,500 feet of the high tide line of a traditional navigable water, interstate water, or the 

territorial seas, and within 1,500 feet of the ordinary high water mark of the Great Lakes. This 

provision defines waters that begin within 1,500 feet of a tidally-influence traditional navigable 

water, interstate water or the territorial seas as “waters of the United States.” To provide clarity 

for this aspect of the definition, the agencies incorporated the Corps’ existing definition of high 

tide line into EPA’s regulations at paragraph (c)(7) in the rule. The Great Lakes are tidally 

influenced but the Corps in practice uses the ordinary high water mark to define their lateral 

limits. Therefore, this provision includes waters within 1,500 feet of the ordinary high water 

mark of the Great Lakes.

As noted above, the rule provides that with respect to the distance limitations for adjacent 

waters the entire water is jurisdictional as long as the water is at least partially located within the 

distance threshold, and the agencies interpret the rule to apply to any single waterbody or 

wetland that may straddle a distance threshold. Low-centered polygonal tundra and patterned 

ground bogs (also called strangmoor, string bogs, or patterned ground fens) are considered a 

single water for purposes of the rule because their small, intermingled wetland and non-wetland 

components are physically and functionally integrated. These areas often have complex micro-
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topography with repeated small changes in elevation occurring over short distances. Science 

demonstrates that these wetlands function as a single wetland matrix having clearly hydrophytic 

vegetation, hydric soils, and wetland hydrology. As a result, the agencies will continue to 

evaluate these wetlands as a single water under the rule. Where any portion of these wetland 

types is bordering, contiguous or neighboring, the entire wetland is a “water of the United 

States.” Similarly, for purposes of a case-specific determination under (a)(8), wetlands of these 

types constitute a single water when making a significant nexus determination. Other wetlands 

may also have intermingled wetland and non-wetland components that are so physically and 

functionally integrated they can be considered a single water for purposes of the rule. Groups of 

wetlands that are simply part of a complex of wetlands would not be considered a single water 

for purposes of the rule.

The final rule also makes some ministerial changes to the definition of “adjacent.” The 

existing regulation defined “adjacent” to mean “bordering, contiguous, or neighboring,” and had 

a second sentence that clarified that wetlands separated by berms and the like remain adjacent 

wetlands. The final rule combines those sentences without changing the scope of adjacency. 

When determining the jurisdictional limits under the CWA for adjacent waters, the 

agencies will rely on published Federal Emergency Management Agency (FEMA) Flood Zone 

Maps to identify the location and extent of the 100-year floodplain. https://msc.fema.gov/portal. 

These maps are publicly available and provide a readily accessible and transparent tool for the 

public and agencies to use in locating the 100-year floodplain. It is important to recognize, 

however, that much of the United States has not been mapped by FEMA and, in some cases, a 

particular map may be out of date and may not accurately represent existing circumstances on 

the ground, such as streams or rivers moving out of their channels with associated changes in the 
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location of the floodplain. In the absence of applicable FEMA maps, or in circumstances where 

an existing FEMA map is clearly out of date, the agencies will rely on other available tools to 

identify the 100-year floodplain, including other Federal, State, or local floodplain maps, Natural 

Resources Conservation Service (NRCS) Soil Surveys (Flooding Frequency Classes), tidal gage 

data, and site-specific modeling (e.g., Hydrologic Engineering Centers River System Analysis 

System or HEC-RAS). http://websoilsurvey.sc.egov.usda.gov/App/HomePage.htm and HECRAS and http://www.hec.usace.army.mil/software/hec-ras/. Additional supporting information 

can include historical evidence, such as photographs, prior delineations, topographic maps, and 

existing site characteristics. Because identifying the 100-year floodplain is an important aspect 

of establishing jurisdiction under the rule and the reliable and appropriate tools for identifying 

the 100-year floodplain may vary, the agencies will coordinate with other federal and state 

agencies to develop additional information for EPA and Corps field staff to further improve tools 

for identifying the 100-year floodplain in a consistent, predictable, and scientifically valid 

manner.

When determining the outer threshold of an “adjacent water” the line is drawn 

perpendicular to the ordinary high water mark or high tide line of the (a)(1) through (a)(5) water 

and extended landward from that point. If there are breaks in the ordinary high water mark, the 

line should be extrapolated from the point where the ordinary high water mark is observed on the 

downstream side to the point where the ordinary high water mark is lost on the upstream side. 

Therefore, waters may meet the definition of neighboring even where, for example, a tributary 

temporarily flows underground. 

Additionally, the agencies emphasize that they fully support efforts by States and tribes to 

protect under their own laws any additional waters, including locally special waters that may not 
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be within the Federal interests of the CWA as the agencies have interpreted its scope in this 

rule. In promulgating the adjacent water limits, the agencies have balanced protection and 

clarity, scientific uncertainties and regulatory experience, and established lines that are, in their 

judgment, reasonable and consistent with the statute and its goals and objectives.

If waters identified in this section are determined to be adjacent, no case specific 

significant nexus evaluation is required. 

2. What Changes Did the Agencies Make from the Proposed Rule Based on 

Public Comments? 

In the proposal, the agencies sought comment on a number of ways to address and clarify 

jurisdiction over adjacent waters, including establishing a floodplain interval and providing 

clarity on reasonable proximity as a foundational aspect of adjacency. In light of the comments, 

the science, the agencies’ experience, and the Supreme Court’s consistent recognition of the 

agencies’ discretion to interpret the bounds of CWA jurisdiction, the agencies have made some 

revisions in the final rule designed to more clearly establish limits on the scope of “adjacent 

waters.”

Under the proposal and the final rule, “adjacent waters” are jurisdictional based on the 

conclusion that they have a significant nexus and there is no need for additional analysis. Some 

commenters wanted a case-specific analysis for all adjacent waters as they believed that the 

waters would not individually have a significant nexus to an adjacent “water of the United 

States,” while others noted that their functional relationship to the downstream traditional 

navigable waters, interstate waters, or the territorial seas warranted the conclusion that they were 

all jurisdictional. Based on a review of the science, the agencies’ expertise and experience, and 

the law, the agencies determined that adjacent waters, as defined, alone or in combination with 
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other covered adjacent waters in a watershed have a significant nexus to a traditional navigable 

water, interstate water or the territorial seas and therefore are “waters of the United States" 

without the need for any additional analysis. However, the rule also provides for case-specific 

analysis of some waters that do not meet the definition of “neighboring” established by the rule. 

See section IV.H.

 The proposal included wetlands, ponds, lakes, and impoundments that contribute flow, 

directly or indirectly, to the downstream traditional navigable waters, interstate waters, or the 

territorial seas in the definition of “tributary.” Some commenters expressed concern that since 

such waters generally do not have both an ordinary high water mark and a bed and banks, the 

definition of tributary was contradictory and confusing. The agencies sought comment on 

whether to treat these waters as adjacent waters instead of tributaries, since they not only 

contribute flow, but they also border or are contiguous to the waters to which they contribute 

flow. The SAB in particular commented that the agencies “may want to consider whether flowthrough lentic systems should be included as adjacent waters and wetlands, rather than as 

tributaries.” SAB 2014b at 2. In light of the comments and to provide additional clarity, the 

agencies revised the definitions of “adjacent” and “tributary” to include these waters as 

“adjacent.”

Under the existing rule, there is no definition for the term “neighboring” and the public 

commented that not having a definition created a lack of clarity and inconsistent field practices 

across the nation. In the proposal, “neighboring” was defined to include waters located within 

the riparian area or floodplain of a traditional navigable water, interstate water, territorial sea, 

impoundment, or tributary; waters with a shallow subsurface hydrologic connection to a 

jurisdictional water; and waters with a confined surface hydrologic connection to a jurisdictional 
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water. Although the definitions were scientifically-based for the terms “riparian area” and 

“floodplain” to define the lateral reach of the term “neighboring,” some commenters indicated 

that the proposed definitions to clarify neighboring were not clear. Those commenters requested

that a specific floodplain interval or other limitation should be established to more clearly 

identify the outer limit of neighboring. Some commenters stated that the proposed definition of 

“neighboring” was unclear, while other commenters found the definition helped clarify CWA 

jurisdiction and were supportive of including a broad definition, based on ecological 

interconnectedness. 

Some commenters stated that the proposed definitions of “riparian area” and “floodplain” 

were vague or ambiguous, broad or effectively limitless, beyond the agencies’ authority or

difficult or impossible to implement in the field. Other commenters were supportive of using the 

riparian area as a basis for adjacency. Some commenters asked why the agencies were proposing 

a new definition of “floodplain” that was inconsistent with the definition used by other Federal 

agencies like NRCS or FEMA. Some commenters suggested that if the agencies use floodplains 

as a means to define “neighboring,” it should be limited to the area inundated by the 2-year, 5-

year, 10-year, or 20-year flood, while other commenters supported the use of the 100-year 

floodplain as a component of “neighboring.” Some commenters supported including all 

wetlands and other waters in the 100-year floodplain as categorically jurisdictional. Other 

commenters requested that floodplain size be based on tributary size, while others suggested that 

it should be based on soil and geologic features, and some suggested the use of the FEMA flood 

zone maps. Some commenters stated that “reasonable proximity” was neither defined nor 

clarified adjacency, noting that adjacency should not apply to waters separated from a “water of 

the United States” by great distances. 
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In response to comments and to provide greater clarity and consistency, in the rule the 

agencies establish a definition of neighboring which provides additional specificity requested by 

some commenters, including establishing a floodplain interval and providing specific distance 

limits from traditional navigable waters, interstate waters, the territorial seas, impoundments, and 

tributaries. As recommended by the public and based on science, the agencies defining limits for 

“neighboring” are primarily based on the reliance of a 100-year floodplain. The agencies 

concluded that the use of the riparian area was unnecessarily complicated and that as a general 

matter, waters in the riparian area will also be in the 100-year floodplain. Further, should the 

riparian area on occasion extend beyond the 100-year floodplain, the agencies have the ability to 

perform a case-specific significant nexus analysis on a water out 4,000 feet from the ordinary 

high water mark or high tide line of a traditional navigable water, interstate water, the territorial 

sea, impoundment, or tributary. The agencies have drawn these lines based on their technical 

expertise and experience in order to provide a rule that is practical to understand and implement 

and protects those waters that significantly affect the chemical, physical, or biological integrity 

of traditional navigable waters, interstate waters or the territorial seas. Because science indicates 

that connectivity is on a gradient, the agencies have also identified limited circumstances in 

which waters that do not meet the definition of “neighboring” may be determined on a casespecific basis to have a significant nexus. See section IV.I. 

First, the rule establishes as “neighboring” waters that occur within 100 feet from

traditional navigable waters, interstate waters, the territorial seas, impoundments, and tributaries. 

Second, the rule utilizes a specific floodplain and also establishes maximum distances for 

purposes of “neighboring.” Studies have found that waters within the floodplain are dynamically 

connected and frequently interact with the downstream traditional navigable water, interstate 
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water, territorial sea, impoundment or tributary. Some commenters indicated that a specific 

floodplain or other designation should be set to define the outer limit of “neighboring.” Further, 

some commenters requested that the 100-year floodplain designation be used to define the outer 

limit of adjacency because the public understands this concept. Several commenters 

recommended that FEMA or NRCS maps be used to support the analysis as these maps are 

easily accessible to the public. Because FEMA maps exist for many areas of the country and the 

NRCS Soil Survey maps do as well, the agencies decided that defining “neighboring” based in 

part on a particular floodplain or recurrence interval was a reasonable means of ensuring the 

consistency and certainty that is important to the public and for implementation of the CWA. In 

drawing lines, the agencies chose the 100-year floodplain because FEMA and NRCS together 

have generally covered large portions of the United States, and these maps are publicly available, 

well-known and well-understood. 

Because the 100-year floodplain can be extremely wide in some areas of the country, 

particularly near large rivers, the agencies chose to provide increased clarity and certainty while 

ensuring that waters that provide important functions significantly affecting the chemical, 

physical, and biological integrity of the downstream traditional navigable waters, interstate 

waters, or the territorial seas are protected by establishing a 1,500-foot maximum distance for 

neighboring waters in the rule. Waters within the 100-year floodplain to a maximum of 1,500 

feet of the ordinary high water mark are adjacent without regard to the presence of berms or 

other barriers. 

The rule also establishes a separate bright line for including as jurisdictional those waters 

that occur within 1,500 feet of tidally-influenced (a)(1) or (a)(3) waters.
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The proposal defined “neighboring” to include waters with a surface connection to 

jurisdictional waters and some commenters recommended eliminating surface hydrologic 

connectivity as a basis for adjacency. The definition of neighboring does not include a provision 

defining “neighboring” based on a surface hydrologic connection. However, waters with 

confined surface hydrologic connections are considered adjacent where they are bordering, 

contiguous, or neighboring an (a)(1) through (a)(5) water. For example, a water with a confined 

surface hydrologic connection to a traditional navigable water that is 1,200 feet from the high 

tide line of that water would meet the definition of neighboring and be considered an adjacent 

water. In circumstances where a water does not meet the definition of neighboring but is located 

within 4,000 feet of a jurisdictional water, a confined surface hydrologic connection may be an 

important factor in evaluating a case-specific significant nexus under (a)(8). See H. below.

The proposal defined “neighboring” to include waters connected with a shallow 

subsurface connection, and some commenters recommended eliminating subsurface hydrologic 

connectivity as a basis for adjacency. For example, some commenters asserted that, because the 

CWA does not apply to groundwater, the agencies do not have the authority to assert jurisdiction 

over waters connected to other “waters of the United States” via a shallow subsurface hydrologic 

connection. Some commenters were concerned that the distinction between “groundwater” and a 

“shallow subsurface connection” was unclear and questioned whether using a shallow subsurface 

connection as a basis for adjacency is contradictory to excluding groundwater—including 

groundwater drained through subsurface drainage systems—as a “water of the United States.” 

Some commenters supported use of shallow subsurface connectivity for adjacency, since the 

significant nexus test would be employed to make the determination of jurisdiction. Several 

commenters suggested that the rule should protect groundwater and shallow subsurface flow, due 
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to its connectivity to other “waters of the United States” and particularly since altering it could 

affect the downstream waters. A few commenters simply requested clarifications regarding 

issues such as how to determine whether a subsurface connection exists; the meaning of 

“shallow;” distinguishing between “shallow” and “deep;” whether there were any distance limits 

on adjacency via hydrologic connectivity; and determining whether the connection was 

“sufficient” to establish adjacency. In order to provide more certainty to the public, the rule does 

not include a provision defining neighboring based on shallow subsurface flow, though such 

flow may be an important factor in evaluating a water on a case-specific basis under paragraph 

(a)(8), as appropriate.

Some commenters expressed concern that the agencies’ proposed definition of 

“neighboring,” “riparian area,” and “floodplain” would mean that all land within the floodplain 

or riparian area would become regulated. In fact, only waters, not land, in the floodplain or 

riparian area would have been considered adjacent under the proposed rule. Similarly, under the 

final rule, only waters, not land, are adjacent. In response, the agencies have deleted the 

definitions of floodplain and riparian area and have provided a definition of neighboring which is 

clear that only waters in specified circumstances may be “waters of the United States.”

The agencies also deleted a 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 a nonjurisdictional wetland. Such waters do not meet the definition of "adjacent" under the rule since 

waters must be adjacent to an (a)(1) through (a)(5) water, so the phrase is unnecessary and 

confusing. With this change, the agencies are protecting all waters that meet the definition of 

“adjacent” as “waters of the United States," and eliminating confusion caused by the 
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parenthetical. For example, where the 100-year floodplain is greater than 1,500 feet, all wetlands 

within 1,500 feet of the tributary's ordinary high water mark are jurisdictional because they are 

“neighboring” to the tributary, regardless of the wetlands’ position relative to each other.

3. How Do Science and Law Support the Rule? 

Based on a review of the scientific literature and the law, the agencies’ determined that 

waters that are bordering, contiguous or, within the limits established in the definition of 

“neighboring,” waters within 100 feet of a jurisdictional water, waters in the 100-year floodplain 

within 1,500 feet of a jurisdictional water, and tidally-influenced waters (such as the territorial 

seas and the Great Lakes). Based on a review of the scientific literature, the agencies’ expertise 

and experience, and the law, the agencies determined that the categories of waters discussed 

below are integrally linked to the chemical, physical, or biological functions of waters to which 

they are adjacent and downstream to the traditional navigable waters, interstate waters or the 

territorial seas. Therefore, the agencies determined that the waters defined as adjacent have a 

significant nexus with traditional navigable waters, interstate waters or the territorial seas and are 

thus “waters of the United States.” Additional information, including citations, can be found in 

section III of the preamble, the Science Report, the proposed rule preamble, and the Technical 

Support Document for the rule. 

a. Waters that are bordering or contiguous

As discussed in section III above, wetlands, ponds, lakes, oxbows, impoundments, and 

similar water features that are bordering or contiguous perform a myriad of critical chemical and 

biological functions associated with the downstream traditional navigable waters, interstate 

waters, or the territorial seas. Such waters are integrally linked with the jurisdictional waters to 
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which they are adjacent. Because of their close physical proximity to nearby jurisdictional 

waters, bordering or contiguous waters readily exchange their waters through the saturated soils 

surrounding the (a)(1) through (a)(5) water 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, which in turn can significantly affect downstream 

traditional navigable waters, interstate waters, or the territorial seas. The close proximity also 

allows for the direct exchange of biological materials, including organic matter that serves as 

part of the food web of downstream traditional navigable waters, interstate waters, or the 

territorial seas. Waters that are bordering or contiguous are often located on the floodplain or 

within the riparian area of the waters to which they are adjacent. Bordering or contiguous waters 

include those that directly abut an (a)(1) through (a)(5) water. The Science Report, the proposed 

rule preamble, and the Technical Support Document demonstrate that such waters are physically, 

chemically, and biologically integrated with downstream traditional navigable waters, interstate 

waters, or the territorial seas and significantly affect their integrity. 

b. Waters separated from other “waters of the United States” by 

constructed dikes or barriers, natural river berms, beach dunes and the 

like

Adjacent waters separated from (a)(1) through (a)(5) waters by dikes, levees, berms and 

the like continue to have a significant effect on downstream traditional navigable waters, 

interstate waters, or the territorial seas, either alone or in combination with other adjacent waters. 

Such waters continue to have a hydrologic connection to downstream waters. This is because 

berms and similar features typically do not block all water flow. This hydrologic connection can 

occur via seepage, or the flow of water through the soil pores, or via over-topping, where water 
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from the nearby (a)(1) through (a)(5) water periodically overtops the berm or other similar 

feature. 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. 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. Man-made levees and similar structures also do not isolate adjacent waters. 

Waters, including wetlands, separated from a jurisdictional water by a natural or man-made berm 

serve many of the same functions as other adjacent waters. Furthermore, even in cases where a 

hydrologic connection may not exist, there are other important considerations, such as chemical 

and biological functions, that result in a significant nexus between the adjacent wetlands or 

waters and the nearby “waters of the United States,” and traditional navigable waters, interstate 

waters, or the territorial seas. Indeed, Justice Kennedy was clear that the absence of hydrologic 

connection could establish a significant nexus. 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 and open waters behind berms, where the system is 

extensive, can help reduce the impacts of storm surges caused by hurricanes. Such adjacent 

waters, including wetlands, separated from waters by berms and the like maintain ecological 

connection with those waters. Waters behind berms and the like can significantly affect the 

chemical, physical, and biologic integrity of traditional navigable waters, interstate waters, or the 

territorial seas.

c. Waters within 100 feet 

All wetlands, ponds, lakes, oxbows, impoundments, and similar water features that are 

located in whole or in part within 100 feet of the ordinary high water mark of a jurisdictional 
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water perform a myriad of critical chemical, physical, and biological functions associated with 

the downstream traditional navigable water, interstate water or the territorial seas and therefore 

the agencies have determined that they are “neighboring” and thus “waters of the United States. 

Waters within 100 feet of a jurisdictional water are often located within the riparian area and are 

often connected via surface and shallow subsurface hydrology to the water to which they are 

adjacent. While the SAB was clear that distance is not the only factor that influences connections 

and their effects downstream, due to their close proximity to jurisdictional waters, waters within 

100 feet are often located within a landscape position that allows for them to receive and process 

surface and shallow subsurface flows before they reach streams and rivers. These waters 

individually and collectively affect the integrity of downstream waters by acting primarily as 

sinks that retain floodwaters, sediments, nutrients, and contaminants that could otherwise 

negatively impact the condition or function of downstream waters. Wetlands and open waters 

within close proximity of jurisdictional waters improve water quality through assimilation, 

transformation, or sequestration of nutrients, sediment, and other pollutants that can affect the 

integrity of downstream traditional navigable waters, interstate waters, or the territorial seas. 

These waters, including wetlands, also provide important habitat for aquatic-associated species 

to forage, breed, and rest. 

In order to provide greater clarity and consistency and based on a review of the science 

and the agencies’ expertise and experience, the agencies identified a 100-foot threshold for 

neighboring waters to a traditional navigable water, interstate water, territorial sea, tributary or 

impoundment. Further, the agencies determined that there is a significant nexus with the 

downstream traditional navigable waters, interstate waters, or the territorial seas, and these 

adjacent waters are “waters of the United States.” With respect to provision of water quality 
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benefits downstream, non-floodplain waters within close proximity of the stream network often 

are able to have more water quality benefits than those located at a distance from the stream. 

Many studies indicate that the primary water quality and habitat benefits will generally occur 

within a several hundred foot zone of a water. In addition, the scientific literature indicates that 

to be effective contaminant removal needs to occur at a reasonable distance prior to entry into the 

downstream traditional navigable waters, interstate waters, or the territorial seas. Some studies 

also indicate that fish, amphibians (e.g., frogs, toads), reptiles (e.g., turtles), and small mammals 

(e.g., otters, beavers, etc.) will use at least a 100-foot zone for foraging, breeding, nesting, and 

other life cycle needs. 

Based on a review of the scientific literature and the agencies’ expertise and experience, 

there is clear evidence that the identified waters within 100 feet of the ordinary high water mark 

of a jurisdictional water, even when located outside the floodplain, perform critical processes and 

functions discussed in section III above. All waters within 100 feet of a jurisdictional water 

significantly affect the chemical, physical, or biological integrity of the waters to which they are 

adjacent, and those waters in turn significantly affect the chemical, physical, or biological 

integrity of the downstream traditional navigable waters, interstate waters, or the territorial seas. 

The agencies established a 100 foot threshold from the water’s lateral limit in the definition of 

neighboring because, based on the agencies’ expertise and experience implementing the CWA 

and in light of the science, the agencies concluded this was a reasonable and practical boundary 

within which to conclude the waters most clearly significantly affected the integrity of the (a)(1) 

through (a)(5) waters, and these adjacent waters are “waters of the United States.”

d. Floodplain waters within 1,500 feet
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As discussed in section III above, wetlands and open waters that are neighboring 

perform a myriad of critical chemical and biological functions associated with the downstream 

traditional navigable waters, interstate waters, or the territorial seas. The scientific literature 

supports that wetlands and open waters in floodplains are physically, chemically, and 

biologically connected to downstream traditional navigable waters, interstate waters, or the 

territorial seas and significantly affect the integrity of such waters. The Science Report concludes 

that wetlands and open waters located in “floodplains are physically, chemically and biologically 

integrated with rivers via functions that improve downstream water quality, including the 

temporary storage and deposition of channeling-forming sediment and woody debris, temporary 

storage of local ground water that supports baseflow in rivers, and transformation and transport 

of stored organic matter.” Science Report at ES-2 to ES-3. 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. 

For waters in the 100-year floodplain within 1,500 feet of the ordinary high water mark

of an (a)(1) through (a)(5) water, the agencies determine there is a significant nexus with the 

downstream traditional navigable waters, interstate waters, or the territorial seas and these areas 

are critical to protect “waters of the United States.” Based on a review of the scientific literature, 

the agencies’ technical expertise and experience, and the implementation value of drawing clear 

lines, the rule establishes a distance limit for floodplain waters to meet the definition of 

“neighboring” and thus to be “waters of the United States” by rule. This distance limitation was 

established in order to protect vitally important waters within a watershed while at the same time 
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providing a practical and implementable rule. The agencies are not determining that waters in 

the floodplain farther than 1,500 feet from the ordinary high water mark never have a significant 

nexus. Rather, the agencies are using their technical expertise to promulgate a practical rule that 

draws reasonable boundaries in order to protect the waters that most clearly have a significant 

nexus while minimizing uncertainty about the scope of “waters of the United States.” Because 

waters beyond these limits may have a significant nexus, the rule also establishes areas in which 

a case-specific significant nexus determination must be made. See section IV.H.

e. Waters within 1,500 feet of tidally-influenced traditional navigable waters 

or the territorial seas

Many tidally-influenced waters do not have floodplains, so the agencies include a 

separate provision within the definition of “neighboring” to protect the adjacent waters that have 

a significant nexus to tidally-influenced traditional navigable waters or the territorial seas. Under 

Riverside Bayview and Justice Kennedy’s opinion in Rapanos, waters adjacent to traditional 

navigable waters, including the territorial seas, are “waters of the United States.” Because the 

connection to a tidally-influenced traditional navigable water is so close, the 100-year floodplain 

is not as relevant to identifying connections to those traditional navigable waters, so the rule 

defines “neighboring” to include waters within 1,500 feet of the high tide line or the ordinary 

high water mark of an (a)(1) or (a)(3) water. Wetlands, ponds, lakes, oxbows, impoundments, 

and similar water features within 1,500 feet of an (a)(1) or (a)(3) water are physically-connected 

to such waters by surface and shallow subsurface flow. As demonstrated in section III above, 

these waters perform a myriad of critical chemical and biological functions associated with the 

nearby (a)(1) and (a)(3) waters to which they are adjacent. 
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These waters in combination significantly affect the integrity of the connected (a)(1) and 

(a)(3) waters (for example, the Great Lakes or territorial seas, respectively) by acting primarily 

as sinks that retain floodwaters, sediments, nutrients, and contaminants that could otherwise 

negatively impact the condition or function of those waters. Like floodplain waters, the 

scientific literature supports that wetlands and other similar waters within close proximity 

improve water quality through assimilation, transformation, or sequestration of nutrients, 

sediment, and other pollutants that can affect downstream water quality. These waters also 

provide important habitat for aquatic-associated species to forage, breed, and rest in. 

For example, wetlands dominated by grass-like vegetation that occur in depressional 

areas between sand dunes or beach ridges along the territorial seas and other tidally-influenced 

waters such as the Great Lakes shoreline are dependent upon these waters for their water source. 

The waters, including wetlands, generally form when water levels of the territorial seas fall or 

the Great Lakes drop, creating swales that support a diverse mix of wetland vegetation and many 

endangered and threatened species. Many studies demonstrate that these waters have been 

shown to act in concert with the rising and lowering of the tide and that the critical functions 

provided by these waters are similar and play an important role in maintaining the chemical, 

physical, or biological integrity of the nearby traditional navigable waters, interstate waters, or 

the territorial seas because of the hydrological and ecological connections to and interactions 

with those waters. 

Science demonstrates that distance is a factor in the connectivity and the strength of 

connectivity of wetlands and open waters to downstream waters. Thus, waters that are more 

distant generally have less opportunity to be connected to downstream waters. Wetlands and 

open waters closer to the stream network generally will have greater hydrologic and biological 
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connectivity than waters located farther from the same network. For instance, waters that are 

more closely proximate have a greater opportunity to contribute flow. Via their hydrologic 

connectivity, they also have chemical connectivity to and effects on downstream (a)(1) and (a)(3) 

waters and are more likely to impact water quality due to their close distance. Waters more 

closely located to (a)(1) and (a)(3) waters are also more likely to be biologically connected to 

such waters more frequently and by more species, including amphibians and other aquatic 

animals. Because traditional navigable waters are generally much larger in size than other 

jurisdictional waters, the agencies believe that a 1,500-foot threshold is a reasonable distance to 

capture most wetlands and open waters that are so closely linked to the (a)(1) and (a)(3) waters 

that they can properly be considered adjacent as neighboring waters.

Based on a review of the scientific literature and the agencies’ expertise and experience, 

there is clear evidence these waters, even when located outside the floodplain, perform critical 

processes and functions discussed in section III above. The agencies established a 1,500-foot 

threshold from the water’s lateral limit, which would be either the high tide line or the ordinary 

high water mark, in the definition of neighboring because, based on the agencies’ expertise and 

experience implementing the CWA and in light of the science, the agencies concluded this was a 

reasonable and practical boundary within which to conclude the waters most clearly significantly 

affected the integrity of the (a)(1) or (a)(3) waters, and these adjacent waters are “waters of the 

United States.” Waters located more than 1,500 feet and less than 4,000 feet from the lateral 

limit of an (a)(1) or (a)(3) water may still be determined to have a significant nexus on a casespecific basis under paragraph (a)(8) of the rule and a “water of the United States.” See section 

IV.H.
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H. Case-Specific Waters of the United States

The rule establishes two exclusive circumstances under which case-specific 

determinations will be made for whether a water has a “significant nexus” and is therefore a 

“water of the United States.” The proposed rule included a broad provision that allowed for a 

case-specific determination of significant nexus for any water that was not categorically 

jurisdictional or excluded. Many commenters expressed concern that such a broad opportunity 

for case-specific “waters of the United States” determinations would lead to too much 

uncertainty about the jurisdictional status of waters in broad areas throughout the country. The 

rule provides for case-specific determinations under more narrowly targeted circumstances based 

on the agencies’ assessment of the importance of certain specified waters to the chemical, 

physical, and biological integrity of traditional navigable waters, interstate waters, and the 

territorial seas.

First, the rule identifies at paragraph (a)(7) five subcategories of waters (prairie potholes, 

Carolina and Delmarva bays, pocosins, western vernal pools in California, and Texas coastal 

prairie wetlands) that the agencies have determined are “similarly situated” for purposes of a 

significant nexus determination. Second, the rule identifies at paragraph (a)(8) a specific 

circumstance under which waters will be subject to a case-specific significant nexus 

determination but for which the agencies have not made a “similarly situated” determination: 

waters within 4,000 feet of the high tide line or the ordinary high water mark of a traditional 

navigable water, interstate water, the territorial seas, impoundments, or tributaries, as defined. If 

any water meets the definition of “adjacent waters” it is jurisdictional under (a)(6) and no casespecific significant nexus is required – this includes waters within the five subcategories of 
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waters, or within 4,000 feet of an (a)(1) through (a)(5) water. Waters that do not fall within the 

six categorically jurisdictional waters identified in paragraph (a)(1) through (a)(6) of the rule or 

within these two case-specific provisions are not “waters of the United States.”

This section first discusses the five subcategories of waters that the agencies determine 

are “similarly situated” for purposes of a significant nexus determination; second, the 4,000-foot 

distance limitation under which waters will be subject to a case-specific significant nexus 

determination but for which the agencies have not made a “similarly situated” determination; 

third, the definition of “significant nexus” and how the case-specific significant nexus 

determinations will be made under these two provisions; and, finally, the revisions made to the 

rule with respect to case-specific determinations and major comments.

1. Waters Determined to Be “Similarly Situated” by Rule for which a CaseSpecific Significant Nexus Determinations is Required

a. Waters that have been determined to be “similarly situated” by rule

In the rule, paragraph (a)(7) specifies the subcategories of waters (prairie potholes, 

Carolina and Delmarva bays, pocosins, western vernal pools in California, and Texas coastal 

prairie wetlands) that, if they are not otherwise jurisdictional under (a)(1) through (a)(6), the 

agencies determine to be “similarly situated” by rule. The rationale for this determination is 

discussed above in Section III. Under paragraph (a)(7), prairie potholes, Carolina and Delmarva 

bays, pocosins, western vernal pools in California, and Texas coastal prairie wetlands are 
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jurisdictional when they have a significant nexus to a traditional navigable water, interstate 

water, or the territorial seas. Waters in these subcategories are not jurisdictional as a class under 

the rule. However, because the agencies determined that these subcategories of waters are 

“similarly situated,” the waters within the specified subcategories that are not otherwise 

jurisdictional under (a)(6) of the rule must be assessed in combination with all waters of a 

subcategory in the region identified by the watershed that drains to the nearest point of entry of a 

traditional navigable water, interstate water, or the territorial seas (point of entry watershed).

When performing a case-specific significant nexus evaluation for a water in the (a)(7) 

subcategories, the rule establishes which waters must, and must not, be considered in 

combination. The similarly situated waters identified in the subparagraphs will be combined 

with other waters in the same subparagraph located in a single point of entry watershed. For 

example, under (a)(7) only western vernal pools can be analyzed with other western vernal pools

in the same point of entry watershed. Waters identified in the subparagraphs that are otherwise 

jurisdictional under the rule cannot be considered in combination with (a)(7) waters for purposes 

of a case-specific significant nexus determination under (a)(7). Individual waters of the specified 

subcategories may be jurisdictional under other paragraphs of this rule (e.g., a prairie pothole 

that sits on a state border is an interstate water under (a)(2) or a western vernal pool that meets 

the definition of adjacent under (a)(6). Where those individual waters are jurisdictional under

(a)(1) through (a)(6) by rule, no case-specific significant nexus analysis is required. The rule 

also states that waters in (a)(7) shall not be combined with waters jurisdictional under (a)(6).

Essentially, while prairie potholes are an identified subcategory under (a)(7), that identification 

does not affect a prairie pothole that borders a covered tributary and is jurisdictional as an 

adjacent water under (a)(6). Additionally, a prairie pothole that is jurisdictional under (a)(6) 
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cannot be combined with prairie potholes that require a case-specific jurisdictional analysis 

under (a)(7) since adjacent waters have already been determined to have a significant nexus by 

rule. Finally, waters within the specified subcategories in (a)(7) are assessed under (a)(7) not 

under (a)(8); waters within the specified subcategories that are within the 4,000-foot distance 

limitation established for case-specific determinations under (a)(8) remain “similarly situated” 

waters under (a)(7). These similarly situated waters are evaluated in combination for their effect 

on the chemical, physical, or biological integrity of traditional navigable waters, interstate 

waters, or the territorial seas. Additional details about the case-specific significant nexus analysis 

are found in section 4 below. 

2. Waters Within 4,000 Foot Distance Limitation for which a Case-Specific 

Significant Nexus is Required

a. Waters within 4,000 Foot Distance Limitation

Paragraph (a)(8) in the rule specifies that a water that does not otherwise meet the 

definition of adjacency is evaluated on a case-specific basis for significant nexus under this 

paragraph where it is located within 4,000 feet of the high tide line or ordinary high water mark

of an (a)(1) through (a)(5) water. Although these waters are not considered similarly situated by 

rule, waters under this paragraph can be determined on a case-specific basis to be similarly 

situated. This is a change from the proposal which would have allowed for a significant nexus

determination for any water, anywhere in the landscape. Under the rule, the waters specified in 
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(a)(7) and waters that meet the distance limitation in (a)(8) are the only waters for which a casespecific significant nexus determination may be made. 

Only waters that are within the 4,000 foot distance limitation established in paragraph 

(a)(8) can be evaluated on a case-specific basis for significant nexus to a traditional navigable 

water, interstate water, or the territorial seas. If a portion of the water is located with 4,000 of the 

ordinary high water mark of an (a)(1) through (a)(5) water, the entire water will be considered to 

be within the distance threshold for (a)(8) and will undergo a case-specific significant nexus 

determination. Waters within the distance limitation must be evaluated on a case-specific basis 

for not only a significant nexus but also for a determination of whether such waters are similarly 

situated. Waters identified in paragraph (a)(8) may not be combined with waters identified in 

(a)(6) for purposes of the significant nexus analysis but may be combined with similarly situated 

waters located in the same point of entry watershed. If waters identified in (a)(8) also meet the 

definition of adjacency under paragraph (a)(6), they are jurisdictional as adjacent waters and do 

not need a case-specific significant nexus analysis. Waters identified in the subcategories in

(a)(7) are evaluated under (a)(7) only; the provisions of (a)(8), including the distance limitations 

in (a)(8), do not apply to (a)(7) waters. The significant nexus analysis for waters under (a)(8) 

will then consider the waters individually or, if it is determined that there are similarly situated 

waters, as a group of waters within a point of entry watershed for their effect on the chemical, 

physical, or biological integrity of traditional navigable waters, interstate waters, or the territorial 

seas.

b. Summary of Rationale for 4,000 Foot Distance Limitation
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The agencies establish a provision in the rule for case-specific significant nexus 

determinations because the agencies concluded that waters located within 4,000 feet of the 

ordinary high water mark of a traditional navigable water, an interstate water, the territorial seas, 

an impoundment, or a covered tributary can have significant chemical, physical, and biological 

connections to and effects on traditional navigable waters, interstate waters, or the territorial 

seas. The agencies establish a distance limit on case-specific significant nexus determinations 

because the Supreme Court has been clear that CWA jurisdiction is not without limit. Based on 

the agencies’ extensive experience, and applying the best available science, the agencies 

conclude that the 4,000 foot distance limit reasonably identifies the areas in which waters have 

been determined to have a significant nexus and appropriately establishes the limits of CWA 

jurisdiction under this case-specific provision. This approach also supports the goal of providing 

greater clarity to the public. The agencies decided that it is important to promulgate a rule that 

not only protects the most vital of our Nation’s waters, but one that is practical and provides 

sufficient limits so that the public reasonably understands where CWA jurisdiction ends. 

The agencies emphasize that they fully support efforts by States and tribes to protect 

under their own laws any additional waters, including locally special waters that may not be 

within the Federal interests of the CWA as the agencies have interpreted its scope in this rule. 

Indeed, the promulgation of this 4000 foot limit for purposes of a case-specific analysis of 

significant nexus does not foreclose states from acting consistent with their state authorities to 

establish protection for waters that fall outside of the protection of the CWA. In promulgating 

the 4,000-foot limit, the agencies have balanced protection and clarity, scientific uncertainties 

and regulatory experience, and established a line that is, in their judgment, reasonable and 

consistent with the statute and its goals and objectives.
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As noted above, since the Rapanos decision, the agencies have developed extensive 

experience making significant nexus determinations, and that experience and expertise has 

informed the judgment of the agencies. The agencies have made determinations in every state in 

the country, for a wide range of waters in a wide range of conditions. Based on this experience, 

and informed by the science that acknowledges the connectivity of waters lies on a continuum, 

the agencies are confident that the 4,000-foot limitation will protect the types of waters that have 

been determined to have a significant nexus on a case-specific basis.

The agencies conclusion to establish a case-specific significant nexus analysis for waters 

within 4,000 feet is based on a number of factors. These waters may be located within the 

floodplain of waters jurisdictional under (a)(1) through (a)(5). Section IV.G. and the Technical 

Support Document discuss the importance of floodplain waters on the chemical, physical, and 

biological integrity of downstream traditional navigable waters, interstate waters, or the 

territorial seas. For purposes of clarity and to provide regulatory certainty, the agencies decided 

to use distance limits with the 100-year floodplain to define adjacency for floodplain waters. 

Under the rule, the only floodplain waters that are specifically identified as being jurisdictional 

as adjacent are those located in whole or in part within the 100-year floodplain and not more than 

1,500 feet of the ordinary high water mark of jurisdictional waters. However, due to the many 

functions that floodplain wetlands and open waters provide to downstream water integrity, and 

based on the scientific literature, agency expertise and experience, and applicable caselaw, the 

rule calls for waters to be considered on a case-specific basis, either alone or in combination with 

other waters, where they are located within 4,000 feet of the high tide line or the ordinary high 

water mark of a water jurisdictional under (a)(1) through (a)(5), in part because such waters may 

be located within the floodplain. 
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Similarly, due to the many functions that waters located within 4,000 feet of the high tide 

line of a traditional navigable water or the territorial seas provide and their often close 

connections to the surrounding navigable in fact waters, science supports the agencies’ 

determination that such waters are rightfully evaluated on a case-specific basis for significant 

nexus to a traditional navigable water or the territorial seas. Waters within 4,000 feet of the 

ordinary high water mark of waters jurisdictional under (a)(1) through (a)(5) may fall within the 

riparian areas of such waters. As discussed in section IV.G., in response to comments regarding 

the uncertainty of the term “riparian area,” the agencies removed the term from the definition of 

neighboring. However, the agencies continue to recognize that science is clear that wetlands and 

open waters in riparian areas individually and cumulatively can have a significant effect on the 

chemical, physical, and biological integrity of downstream waters. Thus, the rule allows for a 

case-specific determination of significant nexus for waters located within 4,000 feet of the high 

tide line or the ordinary high water mark of waters jurisdictional under (a)(1) through (a)(5). 

The agencies have always recognized that adjacency is bounded by proximity, and the 

rule adds additional clarity to adjacency by bounding what can be considered neighboring. The

science is clear that a water’s proximity to downstream waters influences its impact on those 

waters. The Science Report states, “[s]patial proximity is one important determinant of the 

magnitude, frequency and duration of connections between wetlands and streams that will 

ultimately influence the fluxes of water, materials and biota between wetlands and downstream 

waters.” Science Report at ES-11. Generally, waters that are closer to a jurisdictional water are 

more likely to be connected to that water than waters that are farther away. A case-specific 

analysis for waters located within 4,000 feet of the high tide line or the ordinary high water mark

of a water jurisdictional under (a)(1) through (a)(5) allows such waters to be considered 
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jurisdictional only where they meet the significant nexus requirements. Even where not within a 

100-year floodplain, waters within 4,000 feet can have significant chemical, physical, and 

biological connections with traditional navigable waters, interstate waters, or the territorial seas. 

As noted previously, in response to comments concerned that there were no bounds in the 

proposed rule on how far a surface hydrologic connection could be, the agencies did not include 

surface hydrologic connections as its own factor for determining adjacency in the final rule. 

Such connections, however, are relevant in a case-specific significant nexus determination under 

(a)(8). For example, waters located within 4,000 feet of the high tide line or the ordinary high 

water mark of a water jurisdictional under (a)(1) through (a)(5) that contribute confined surface 

flow to a downstream water can have important hydrologic connections to and effects on that 

downstream water such as the attenuation and cycling of nutrients that would otherwise effect 

downstream water quality. 

The agencies’ decision to establish the case-specific provision at (a)(8), including the 

distance limitation, was also informed by the knowledge that waters located within 4,000 feet of 

the high tide line or the ordinary high water mark of a water jurisdictional under (a)(1) through 

(a)(5) can have a shallow subsurface connection to such a water. In order to provide the clarity 

and certainty that many commenters requested regarding adjacent waters, the rule does not 

define “neighboring” to include all waters with shallow subsurface connections. 

However, the agencies recognize that the science demonstrates that waters with a shallow 

subsurface connection to jurisdictional waters can have important effects on downstream waters. 

For purposes of a case-specific significant nexus analysis under the rule, a shallow subsurface 

hydrologic connection is lateral water flow over a restricting layer in the top soil horizons, or a 

shallow water table which fluctuates within the soil profile, sometimes rising to or near the 
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ground surface. In addition, water can move within confined man-made subsurface conveyance 

systems such as drain tiles and storm sewers, and in karst typography. Confined subsurface 

systems can move water, and potential contaminants, directly to surface waters directly and 

rapidly without the opportunity for nutrient or sediment reduction along the pathway. 

Shallow subsurface connections are distinct from deeper, regional groundwater 

connections, in that shallow subsurface connections move quickly through the soil and impact 

surface water directly within hours or days rather than the years it may take long pathways to 

reach surface waters. See Technical Support Document. Tools to assess shallow subsurface flow 

include reviewing the soils information from the NRCS Soil Survey, which is available for 

nearly every county in the United States. When assessing whether a water within 4,000 feet 

performs any of the functions identified in the rule’s definition of significant nexus, the 

significant nexus determination can consider whether shallow subsurface connections contribute 

to the type and strength of functions provided by a water or similarly situated waters. However, 

neither shallow subsurface connections nor any type of groundwater, shallow or deep, are 

themselves “waters of the United States.”

While the proposed rule did not set a distance threshold for case-specific waters to be 

evaluated for a significant nexus, the final rule does set a distance limit of 4,000 feet for waters 

that do not otherwise meet the requirements of (a)(1) through (a)(7). The agencies set this limit 

in order to provide clarity, predictability, and consistency, and in order to respond to comments 

requesting that case-specific evaluations be bounded. The Supreme Court decisions have been 

clear that the agencies have the authority, and responsibility, to determine the limits of CWA 

jurisdiction, and the agencies do so recognizing as noted above that spatial proximity is a key 

component of connectivity. Science Report at ES-11. Based on the agencies’ extensive 
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experience making case-specific significant nexus determinations across the country, it is the 

judgment of the agencies that the 4,000 foot distance limit reasonably identifies the areas in 

which waters have been determined to have a significant nexus and appropriately establishes the 

limits of CWA jurisdiction under this case-specific provision. 

For these reasons, the agencies decided to allow case-specific determinations of 

significant nexus for waters located within 4,000 feet of the high tide line or the ordinary high 

water mark of a traditional navigable water, an interstate water, the territorial seas, an 

impoundment, or a covered tributary. Under the rule, these waters are jurisdictional only where 

they individually or cumulatively (if it is determined that there are other similarly situated 

waters) have a significant nexus to traditional navigable waters, interstate waters, or the 

territorial seas. Additional scientific and policy rationale for including such waters as waters that 

can be evaluated on a case-specific basis can be find in the Technical Support Document.

3. Case-Specific Significant Nexus Determinations

Only waters identified in paragraphs (a)(7) or (a)(8) of the rule require a case-specific 

determination of significant nexus. This section discusses the definition of significant nexus in 

the rule and how the agencies will make case-specific significant nexus determinations under the 

rule.

a. Definition of Significant Nexus

Paragraph (c)(5) of the rule defines the term significant nexus to mean a significant effect 

(more than speculative or insubstantial) on the chemical, physical, or biological integrity of a 

traditional navigable water, interstate water, or the territorial seas. Waters, including wetlands, 
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are evaluated either alone, or in combination with other similarly situated waters in the region, 

based on the functions the evaluated waters perform. Functions to be considered for the purposes 

of determining significant nexus are sediment trapping, nutrient recycling, pollutant trapping 

transformation, filtering and transport, retention and attenuation of floodwaters, runoff storage, 

contribution of flow, export of organic matter, export of food resources, or provision of life-cycle 

dependent aquatic habitat (such as foraging, feeding, nesting, breeding, spawning, use as a 

nursery area) for species located in traditional navigable waters, interstate waters, or the 

territorial seas. 

The agencies definition of significant nexus is based upon the language in SWANCC and 

Rapanos. The definition is also consistent with current practice, where field staff evaluate the 

functions of the waters in question and the effects of these functions on downstream waters. In 

order to add clarity to the definition of significant nexus, the agencies have listed in the 

definition the functions that will be considered in a significant nexus analysis. These functions 

are consistent with the agencies’ scientific understanding of the functioning of aquatic 

ecosystems. A water does not need to perform all of the functions listed in paragraph (c)(5) in 

order to have a significant nexus. Depending upon the particular water and the functions it 

provides, if a water, either alone or in combination with similarly situated waters, performs just 

one function, and that function has a significant impact on the integrity of a traditional navigable 

water, interstate water, or the territorial seas, that water would have a significant nexus.

Case-specific determinations of significant nexus require (a)(7) or (a)(8) waters to be 

evaluated either alone, or in combination with other similarly situated waters in the region. In the 

rule, the agencies 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 
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of entry, or a single point of entry watershed. See Section III. In circumstances where the single 

point of entry watershed includes waters that are identified under (a)(7) and waters that are 

subject to analysis under (a)(8), those waters will be analyzed separately under the provisions of 

those paragraphs.

In a case-specific analysis of significant nexus, the agencies determine whether the water 

they are evaluating, in combination with other similarly situated waters in the region, has a 

significant effect on the chemical, physical, or biological integrity of the nearest traditional 

navigable water, interstate water, or the territorial seas. As noted previously, the agencies 

evaluate the listed functions in paragraph (c)(5) as part of that evaluation to determine if the 

water has an impact that is more than speculative or insubstantial. 

b. Conducting Case-Specific Significant Nexus Determinations Under (a)(7) 

and (a)(8)

The significant nexus analysis for waters assessed under (a)(7) and (a)(8) is a three-step 

process: first, the region for the significant nexus analysis must be identified – under the rule, it 

is the watershed which drains to the nearest traditional navigable water, interstate water or 

territorial sea; second, any similarly situated waters must be identified – under the rule, that is 

waters that function alike and are sufficiently close to function together in affecting downstream 

waters; and third, the waters are evaluated individually or in combination with any identified 

similarly situated waters in the single point of entry watershed to determine if they significantly 

impact the chemical, physical or biological integrity of the traditional navigable water, interstate 

water or the territorial seas. 

i. “In the Region” – the Point of Entry Watershed
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As discussed in Section III of the preamble and established in the definition of 

“significant nexus,” the region for purposes of a significant nexus analysis is the watershed that 

drains to the nearest traditional navigable water, interstate water, or the territorial seas. The first 

step of the analysis is to identify the point of entry watershed that the water being evaluated 

under (a)(7) or (a)(8) drains to. This point of entry approach identifies the nearest (a)(1) through 

(a)(3) that the water being evaluated and any similarly situated waters flow to and delineates the 

watershed of that nearest (a)(1) through (a)(3) water. The point of entry watershed is the area 

drained by the nearest (a)(1) through (a)(3) water and is typically defined by the topographic 

divides between one (a)(1) through (a)(3) water and another. 

Available mapping tools, such as those that are based on the NHD, topographic maps, 

and elevation data, can be used to demarcate boundaries of the single point of entry watershed. 

As discussed in Section III and in the Technical Support Document, the single point of entry 

watershed represents the scientifically appropriate sized area for conducting a case-specific 

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 reasonable to evaluate all similarly situated waters in 

a smaller watershed. Under those circumstances, the agencies may demarcate catchments 

surrounding the water to be evaluated that, in combination, generally no smaller than a typical

10-digit hydrologic unit code (HUC-10) watershed in the same area. This combination of 

catchments would be used for conducting a significant nexus evaluation under (a)(7) or (a)(8) 

under those situations. The basis for such an approach in very large single point of entry 

watersheds in the arid West should be documented in the jurisdictional determination.

ii. Similarly Situated 
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Second, the agencies determine if the water or waters to be evaluated are similarly 

situated. The waters identified in (a)(7) are similarly situated by rule and shall be combined with 

other waters of the same subparagraph located in the same watershed that drains to the nearest 

(a)(1) through (a)(3) water with no need for a case-specific similarly situated finding. Under 

(a)(7), only waters of the same subparagraph in the point of entry watershed can be considered as 

similarly situated. For example, only pocosins may be evaluated with other pocosins in the same 

point of entry watershed. Pocosins in different point of entry watersheds cannot be combined, 

and pocosins cannot be combined with Carolina bays under (a)(7), even where they occur in the 

same point of entry watershed. 

Unlike waters evaluated under (a)(7), the waters specified at (a)(8) require a 

determination that they are similarly situated. Under this step, the agencies apply factors in the 

determination of when waters evaluated under (a)(8) should be considered either individually or 

in combination for purposes of a significant nexus analysis. A determination of “similarly 

situated” requires an evaluation of whether a group of waters in the region that meet the distance 

thresholds set out under (a)(8) 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. 

Similarly situated waters can be identified as sufficiently close together for purposes of 

this paragraph of the regulation when they are within a contiguous area of land with relatively 

homogeneous soils, vegetation, and landform (e.g., plain, mountain, valley, etc.). In general, it 

would be inappropriate, for example, to consider waters as “similarly situated” under (a)(8) if 

these waters are located in different landforms, have different elevation profiles, or have 

different soil and vegetation characteristics, unless the waters perform similar functions and are
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located sufficiently close to a “water of the United States” to allow them to consistently and 

collectively function together to affect a traditional navigable water, interstate water, or the 

territorial seas. In determining whether waters under (a)(8) are sufficiently close to each other the 

agencies will also consider hydrologic connectivity to each other or a jurisdictional water. 

In determining whether groups of waters under (a)(8) perform “similar functions” the 

agencies will consider functions such as habitat, water storage, sediment retention, and pollution 

sequestration. In addition, consideration of wetland/water type and landscape location are 

relevant for determining if the waters are similarly situated. For example, Texas coastal sand 

sheet wetlands that form a complex of wetlands with other wetlands of the same type on the 

landscape and are densely located may very well be similarly situated and considered in 

combination with other Texas coastal sand sheet wetlands in the same single point of entry 

watershed. However, under (a)(8), waters do not need to be of the same type (as they do in 

(a)(7)) to be considered similarly situated. As described above, waters are similarly situated 

under (a)(8) where they perform similar functions or are located sufficiently close to each other, 

regardless of type. The agencies will consider the hydrologic, geomorphic, and ecological 

characteristics and circumstances of the waters under consideration. Examples include: 

documentation of chemical, physical, and biological interactions of the similarly situated waters; 

aerial photography; USGS and state and local topographical or terrain maps and information; 

NRCS soil survey maps and data; other available geographic information systems (GIS) data; 

National Wetlands Inventory maps where wetlands meet the CWA definition; and state and local 

information. The evaluation will 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. 
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Only those waters that do not meet the requirements in (a)(1) through (a)(6) are to be 

considered in case-specific significant nexus determinations; subcategory waters that meet the 

provisions in (a)(1) through (a)(6) are per se jurisdictional without the need for a significant 

nexus determination. For example, waters that are identified under paragraph (a)(6) are adjacent 

and are not subject to a case-specific significant nexus evaluation under (a)(7) or (a)(8). Waters 

evaluated under (a)(7) cannot be combined with waters identified in paragraph (a)(6) or (a)(8), 

and waters evaluated under (a)(8) cannot be combined with waters identified in (a)(6) or (a)(7). 

For example, prairie potholes being evaluated under (a)(7) may not be combined with prairie 

potholes that are per se jurisdictional under (a)(6) that meet the definition of adjacent. When a 

water meets the specifications at both (a)(7) and (a)(8), it can only be evaluated under (a)(7). 

That is, for example, if a wetland is a Western vernal pool and is also within 4,000 feet of the 

ordinary high water mark of an (a)(5) water, it can only be assessed for significant nexus under 

(a)(7) in combination with other Western vernal pools in the point of entry watershed. Unlike 

(a)(8), there is no distance threshold for waters evaluated under (a)(7) – that is, waters in the 

(a)(7) subcategories that are more than 4,000 feet from the high tide line or the ordinary high 

water mark of an (a)(1) through (a)(5) water are to be included in combination in a significant 

nexus analysis. 

iii. Significant Nexus Analysis for (a)(7) and (a)(8) Waters

Third, the agencies evaluate waters individually or in combination with any identified 

similarly situated waters in the single point of entry watershed to determine if they significantly 

impact the chemical, physical, or biological integrity of the (a)(1) through (a)(3) water. For 

purposes of determining significant nexus under (a)(7), all waters of the specified subcategory 

are to be considered in combination in the point of entry watershed, as those waters are similarly 
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situated. For purposes of determining significant nexus under (a)(8), depending on the results of 

step two, a water within the distance limitation in paragraph (a)(8) is evaluated either alone or in 

combination with other similarly situated waters in the region. For example, in the case where 

the agencies have determined that a particular water under (a)(8) is not similarly situated, it is 

evaluated individually for significant nexus; the water cannot be aggregated if it is not similarly 

situated with other such waters. 

The analysis will include an evaluation of the functions listed in paragraph (c)(5) of the 

rule, which defines significant nexus. A water has a significant nexus when any single function 

or combination of functions performed by the water, alone or together with similarly situated 

waters in the region, contributes significantly to the chemical, physical, or biological integrity of 

the nearest (a)(1) through (a)(3) water. A water may be determined to have a significant nexus 

based on performing any of the following functions:sediment trapping, nutrient recycling, 

pollutant trapping, transformation, filtering, and transport, retention and attenuation of 

floodwaters, runoff storage, contribution of flow, export of organic matter, export of food 

resources, or provision of life cycle dependent aquatic habitat (such as foraging, feeding, nesting, 

breeding, spawning, or use as a nursery area) for species located in a water identified in 

paragraphs (a)(1) through (3) of this section.

For purposes of paragraph (c)(5)(I), a species is located in a water identified in (a)(1) 

through (a)(3) if such a water is typical type of habitat for at least part of the life cycle of the 

species. For example, amphibians and many reptiles can use (a)(1) through (a)(3) waters for part 

of their life cycle needs.

When evaluating a water individually or in combination with other similarly situated 

waters for the presence of a significant nexus to a traditional navigable water, interstate water, or 
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the territorial seas, a variety of factors will influence the chemical, physical, or biological 

connections the water has with the downstream traditional navigable water, interstate water, or 

the territorial seas, including distance from a jurisdictional water, the presence of surface or 

shallow subsurface hydrologic connections, and density of waters of the same type (if it has been 

concluded that such waters can be evaluated in combination). The likelihood of a significant 

connection is greater with increasing size and decreasing distance from the identified traditional 

navigable water, interstate water, or the territorial seas, as well as with increased density of the 

waters for such waters that can be considered in combination as similarly situated waters. In 

addition, the presence of a surface or shallow subsurface hydrologic connection can influence the 

impact that a water has with downstream waters. 

In many cases, the presence of a hydrologic connection increases the strength of the 

impact of the downstream traditional navigable water, interstate water, or the territorial seas. 

However, 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 floodwaters or pollutants that 

would otherwise flow downstream to the traditional navigable water, interstate water, or the 

territorial seas. See 547 U.S. at 775 (citations omitted) (J. Kennedy) (“it may be the absence of 

an interchange of waters prior to the dredge and fill activity that makes protection of the 

wetlands critical to the statutory scheme”). The Science Report concludes, “Some effects of nonfloodplain wetlands on downstream waters are due to their isolation, rather than their 

connectivity. Wetland ‘sink’ functions that trap materials and prevent their export to downstream 
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waters (e.g., sediment and entrained pollutant removal, water storage) result because of the 

wetland’s ability to isolate material fluxes.” Science Report at ES-4. 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. See Science 

Report and Technical Support Document. Even when they lack a surface hydrologic connection 

to downstream (a)(1) through (a)(3) waters, prairie potholes, for instance, cumulatively can store 

large volumes of water, impacting streamflow and reducing flooding downstream, and several 

studies have quantified the large storage capacity of prairie pothole complexes. This water 

storage function is estimated to hold tens of millions of cubic meters of water, including for 

example prairie potholes located in the watersheds of Devils Lake and the Red River of the 

North, which have both had a long history of flooding. Where prairie potholes lack a surface 

hydrologic connection, this water storage capacity is particularly effective in reducing 

downstream flooding and can have a significant effect on downstream (a)(1) through (a)(3) 

waters. Thus, even when lacking a surface hydrologic connection, a water can still have a 

significant effect on the chemical or the biological integrity of downstream traditional navigable 

waters, interstate waters, or the territorial seas.

The rule recognizes that not all waters have the 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.

Evidence of chemical connectivity and the effect on waters can be found by identifying 

the properties of the water in comparison to the identified traditional navigable water, interstate 
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water, or the territorial seas; 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 a traditional navigable water, interstate water, or 

the territorial seas. 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 traditional navigable waters, 

interstate waters, or the territorial seas 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 indicators 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 (a)(7) or (a)(8) water and the traditional navigable water, interstate water, or the territorial 

seas, 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 case-specific 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 case-specific water, and if so whether such dispersal extends to the 

tributary system or beyond or from the tributary system to the case-specific water. Factors 

influencing biological connectivity include species’ life history traits, species’ behavioral traits, 

dispersal range, population size, timing of dispersal, distance between the case-specific water 
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and a traditional navigable water, interstate water, or the territorial seas, 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 do not demonstrate a life cycle 

dependency on the identified aquatic resources and are not evidence of biological connectivity 

for purposes of this rule.

For practical administrative purposes, the rule does not require evaluation of all similarly 

situated waters under (a)(7) or (a)(8) when concluding that those waters have a significant nexus 

to a traditional navigable water, interstate water, or territorial sea. When a subset of similarly 

situated waters provides a sufficient science-based justification to conclude presence of a 

significant nexus, for efficiency purposes a significant nexus analysis need not unnecessarily 

require time and resources to locate and analyze all similarly situated waters in the entire point of 

entry watershed. For example, if a single Carolina bay or a group of Carolina bays in a portion of 

the point of entry watershed is determined to significantly affect the chemical, physical, or 

biological integrity of an (a)(1) through (a)(3) water, the analysis does not have to document all 

of the similarly situated Carolina bays in the watershed in order to conduct the significant nexus 

analysis. A conclusion that significant nexus is lacking may not be based on consideration of a 

subset of similarly situated waters because under the significant nexus standard the inquiry is 

how the similarly situated waters in combination affect the integrity of the downstream water. 

While the rule is clear that waters that are jurisdictional by rule cannot be combined with 

waters subject to a case-specific significant nexus analysis, the analysis may appropriately 

include the evaluation of functions of (a)(8) waters that reach covered waters through (a)(6)

waters without consideration of the functions contributed by those (a)(6) waters. The hydrologic 

connections between (a)(8) waters and a covered tributary and eventually to a traditional 
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navigable water, interstate water, or the territorial seas, can often occur through an adjacent 

water. This hydrologic connection is an appropriate part of the case-specific analysis as to 

whether the (a)(8) waters, alone or in combination with any similarly situated (a)(8) waters in the 

point of entry watershed, provide those functions downstream such that they significantly affect 

the chemical, physical or biological integrity of the traditional navigable water, interstate water, 

or the territorial seas. For example, when evaluating a wetland that is 2,500 feet from the

ordinary high water mark of an (a)(5) water and that has surface or shallow subsurface 

connections to downstream (a)(1) through (a)(3) waters via a wetland that is adjacent to an (a)(4) 

water, the existence of those connections is not ignored. However, while a water’s connections to 

the (a)(1) through (a)(3) water through (a)(5) through (a)(7) waters can be considered in the 

significant nexus analysis in order to determine whether the functions of the (a)(8) waters are 

provided downstream, only the functions of the water, along with any similarly situated waters, 

being evaluated under (a)(8) on downstream water integrity can be included in the significant 

nexus analysis.

The administrative record for a jurisdictional determination for a water under (a)(7) or 

(a)(8) will include available information supporting the determination. In addition to location and 

other descriptive information regarding the water at issue, the record will include an explanation 

of the rationale for the jurisdictional conclusion and a description of the information used. 

Relevant information can come from many sources, and need not always be specific to the water 

whose jurisdictional status is being evaluated. 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. In the case of (a)(8) waters, the administrative record will include the 
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rationale behind the similarly situated analysis, including an explanation of the data or 

information examined. 

The agencies expect that where waters are determined to be similarly situated in a single 

point of entry watershed, such similarly situated waters will often be found jurisdictional through 

the case-specific analysis of significant nexus. However, case-specific factors such as distance to 

the traditional navigable water, interstate water, or the territorial seas; density and/or number of 

similarly situated waters; individual and/or cumulative size of the similarly situated waters; soil 

permeability; climate; etc., may be considered in the determination, and there could be cases 

where even considering these waters in combination with similarly situated waters will not be 

sufficient for waters to have a significant nexus. 

Within a single point of entry watershed, over a period of time there will likely be 

multiple jurisdictional determinations. For (a)(7) waters, if a case-specific significant nexus 

determination has been made in the point of entry watershed, all waters in the subcategory in the 

point of entry watershed are jurisdictional. For (a)(8) waters, the case-specific significant nexus 

analyses must use information used in previous jurisdictional determinations, and if a significant 

nexus has been established for one water in the watershed, then other similarly situated waters in 

the watershed would also be found to have a significant nexus. This is because under Justice 

Kennedy’s test, similarly situated waters in the region should be evaluated together. A positive 

significant nexus determination would then apply to all similarly situated waters within the point 

of the watershed. A negative case-specific significant nexus evaluation under (a)(7) or (a)(8) of 

all similarly situated waters in the point of entry watershed applies to all similarly situated waters 

in that watershed. However, as noted above, a conclusion that significant nexus is lacking may 

not be based on consideration of a subset of similarly situated waters, because under the 
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significant nexus standard the inquiry is how the similarly situated waters in combination affect 

the integrity of the downstream water. The documentation for each case should be complete 

enough to support the specific jurisdictional determination, including an explanation of which 

waters were considered together as similarly situated and in the same region. 

4. Summary of Revisions to Case-Specific Determinations of “Waters of the 

United States” and Major Comments

a. Significant Nexus 

Some commenters stated concerns over the potential for inconsistent application of the 

significant nexus analysis in a jurisdictional determination. To address this concern within the 

regulatory framework, the agencies provide more detail regarding the definition of significant 

nexus in the rule and list the specific functions that will be considered in the analysis. This 

approach provides individual regulators who conduct the analysis clear and consistent 

parameters that they will consider during their review in making jurisdictional determinations 

and provides transparency to the regulated public over which factors will be considered. 

Overall, there was support for the concept of the single point of entry watershed as the 

interpretation of “in the region.” Several commenters supported the approach that the single 

point of entry watershed was an appropriate scale to use to measure effect on traditional 

navigable waters, interstate waters, or the territorial seas. Other commenters felt the single point 

of entry watershed was too small to capture all the benefits that waters that do not meet the 

definition of adjacency contribute. Some of the SAB panel members thought that because surface 

and ground-watershed units may not align, watersheds might be problematic for defining “in the 
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region.” These panel members suggested that a more scientifically justified approach would 

include surface and subsurface waters in a watershed delineation. The agencies have retained the 

single point of entry watershed from the proposed rule as the appropriate unit of analysis for 

significant nexus in the final rule as these watersheds are more easily understood and easier to 

delineate than those that map subsurface waters as the SAB suggested.

With respect to the agencies’ approach to “similarly situated waters,” commenters offered 

support for assessing waters in combination based on their type and function, particularly waters 

such as prairie potholes. Conversely, several commenters found that the ability to aggregate 

waters that do not meet the definition of adjacency is over-reaching and causes uncertainty to the 

regulated public. Some commenters also attributed uncertainty in which waters were regulated to 

subjectivity in review by Federal regulator(s). Similarly, some commenters were concerned that 

habitats eligible for protection were based on an individual analyst’s interpretation and wanted to 

know how the agencies would address consistency and potential bias. In response, the rule lists 

in paragraph (a)(7) a limited number of subcategories of waters where waters of the specified 

types have been determined by rule to be similarly situated for a significant nexus analysis. This 

will add consistency, predictability, and clarity, as the rule explicitly states that such waters are 

similarly situated for purposes of the significant nexus analysis. For waters identified under 

paragraph (a)(8), the agencies have established a 4,000 foot distance threshold for these waters 

and have established within the definition of significant nexus at (c)(5) criteria for determining 

whether waters are similarly situated and should therefore be analyzed in combination. Waters 

identified under (a)(8) are similarly situated when they function alike and are sufficiently close to 

function together in affecting downstream waters. The agencies have not determined that such 

waters are categorically similarly situated, so the agencies will base their case-specific 
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determinations of whether a particular water has any similarly situated waters on the available 

information and science. The rule also clarifies that (a)(8) waters cannot be considered similarly 

situated with adjacent waters, which are jurisdictional by rule, and (a)(7) waters, which have 

been determined to be similarly situated by rule. These parameters will reduce inconsistency in 

reviews and add clarity. 

Similarly, several commenters expressed concern that landowners would not know which 

water bodies on their property are subject to CWA jurisdiction due to aggregation, as waters on 

their property may be considered similarly situated with waters located off-site. While the rule 

does not eliminate the use of case-specific significant nexus analyses, the parameters placed on 

waters requiring a case-specific determination and the clearer definition of significant nexus 

address the concerns about uncertainty and inconsistencies in reviews. In particular, waters that 

are not either one of the five identified subcategories in (a)(7) or within the 4,000-foot threshold 

cannot be subject to a case-specific significant nexus analysis under the rule. In addition, owners 

with questions regarding jurisdiction of waters on their property may always consult their local 

Corps District, which is not a change from longstanding practice. 

b. Case-Specific Determinations

The rule provides more regulatory certainty by narrowing the scope of waters that can be 

assessed under a case-specific significant nexus evaluation as compared to the proposal. These 

changes still allow the scientific value of specific waters not covered in (a)(1) through (a)(6) to 

be evaluated on a case-specific basis. 

In the proposal, the agencies solicited comment regarding a variety of approaches to the 

“other waters” category. In addition, the agencies solicited comment on additional scientific 

research and data that might further inform decisions about “other waters.” In particular the 
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agencies solicited 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. One of these 

alternate approaches in the preamble to the proposed rule was to determine by rule that certain 

additional subcategories of waters would be jurisdictional rather than addressed with a casespecific basis for determining significant nexus. 

Many commenters expressed support for the agencies’ proposed approach to “other 

waters,” included additional references to support “other waters” being protected by rule, and 

supported the treatment of certain categories of waters as similarly situated (that is, evaluating 

them in combination with similarly situated waters for the purposes of the significant nexus 

analysis). Some suggested the agencies establish jurisdiction over “other waters” by rule and 

provided detailed information in support of their position. Other commenters suggested 

additional subcategories of “other waters” be considered as jurisdictional or as similarly situated 

by rule, such as playa lakes, kettle lakes, and woodland vernal pools. 

However, there was a concern raised by other commenters about what was termed 

regulatory overreach and uncertainty created by the “other waters” category. Some commenters 

stated that the “other waters” category would allow the agencies to regulate virtually any water. 

To address this concern, the rule places limits on which waters could be subject to a case-specific 

significant nexus determination, in recognition that case-specific analysis of significant nexus is 

resource-intensive and to reflect the consideration for the body of science that exists. As noted 

above, the agencies also establish by rule subcategories of waters that are “similarly situated” for 

the purposes of a significant nexus analysis because science supports that the subcategory waters 
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fall within a higher gradient of connectivity. By not determining that any one of the waters 

available for case-specific analysis is jurisdictional by rule, the agencies are recognizing the 

gradient of connectivity that exists and will assert jurisdiction only when that connection and the 

downstream effects are significant and more than speculative and insubstantial.

Waters are covered under the rule only where they are identified as jurisdictional in 

paragraphs (a)(1) through (a)(6), where they are not excluded under paragraph (b), or where they 

are within the limited number of subcategories listed in paragraphs (a)(7) and (a)(8) and have a 

case-specific significant nexus to a traditional navigable water, interstate water, or the territorial 

seas. These limits on jurisdiction reflect the case law and are in response to comments requesting 

greater regulatory certainty. Although some commenters suggested additional subcategories of 

waters for consideration, such as playa lakes and kettle lakes, the agencies at this time are not 

able to determine that the available science supports that the suggested additional subcategories 

of waters as a class have a significant nexus to traditional navigable waters, interstate waters, or 

the territorial seas. However, to be clear, under the rule, individual waters of the suggested 

additional subcategories are jurisdictional where they meet the requirements of (a)(1) through 

(a)(6) or (a)(8) (e.g., a playa lake that is an interstate water, a kettle lake that is an adjacent water, 

or a woodland vernal pool that is 2,000 feet from a jurisdictional tributary and is determined on a 

case-specific basis to have a significant nexus to a traditional navigable water, interstate water, or 

the territorial seas). 

In consideration of the variety of views of the commenters, the Science Report, the input 

from the SAB, and the developing state of the science, the agencies reasonably decided not to 

establish jurisdiction over all waters that do not meet the requirements of (a)(1) through (a)(6) by 

rule. Instead, the agencies established case-specific provisions for some specified waters at (a)(7) 
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and waters within a specific distance threshold at (a)(8). This approach strikes a balance between 

requests for bright lines and limited case-specific reviews with scientific support. 

I. Waters and Features that Are Not “Waters of the United States”

In the rule, the agencies identify a variety of waters and features that are not “waters of 

the United States.” Prior converted cropland and waste treatment systems have been excluded 

from this definition since 1992 and 1979, respectively, and they remain substantively and 

operationally unchanged. Only ministerial changes to delete an outdated cross reference are 

made to the exclusion for waste treatment systems. The agencies add exclusions for all waters 

and features identified as generally exempt in preamble language from Federal Register notices 

by the Corps on November 13, 1986, and by EPA on June 6, 1988. This is the first time these 

exclusions have been established by rule. In addition, under prior preamble guidance the 

agencies could determine that a particular feature generally considered nonjurisdictional was a 

“water of the United States.” The agencies do not retain that authority for features excluded

under the rule. The agencies for the first time also establish by rule that certain ditches are 

excluded from jurisdiction. The agencies add exclusions for groundwater and erosional features, 

as well as exclusions for some waters that were identified in public comments as possibly being 

found jurisdictional under proposed rule language where this was never the agencies’ intent. 

These exclusions reflect current agencies’ practice, and their inclusion in the rule furthers the 

agencies’ goal of providing greater clarity over what waters are and are not protected under the 

CWA. Under the rule, all waters and features identified in paragraph (b) as excluded will not be 
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“waters of the United States,” even if they otherwise fall within one of the categories in 

paragraphs (a)(1) through (a)(8). 

The exclusions reflect the agencies’ long-standing practice and technical judgment that 

certain waters and features are not subject to the CWA. The exclusions are also guided by 

Supreme Court cases. The significant nexus standard arises from the case law and is used to

interpret the terms of the CWA. Thus, a significant nexus determination is not a purely scientific 

inquiry, but rather is a determination by the agencies in light of the statutory language, the 

statute’s goals, objectives and policies, the case law, the relevant science, and the agencies’ 

technical expertise and experience. 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. The Supreme Court has 

recognized that clarifying the lines of jurisdiction is a difficult task: “Our common experience 

tells us that this is often no easy task: the transition from water to solid ground is not necessarily 

or even typically an abrupt one. Rather, between open waters and dry land may lie shallows, 

marshes, mudflats, swamps, bogs — in short, a huge array of areas that are not wholly aquatic 

but nevertheless fall far short of being dry land. Where on this continuum to find the limit of 

‘waters’ is far from obvious.” Riverside Bayview at 132-33. The exclusions reflect the agencies’ 

determinations of the lines of jurisdiction based on science, the case law and the agencies’

experience and expertise.

The existing exclusion for waste treatment systems moves to paragraph (b)(1) with no 

substantive changes. One ministerial change is the deletion of a cross-reference in the current 

language to an EPA regulation that no longer exists. Because the agencies are not addressing the 
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substance of the exclusion, the agencies do not 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, with the exception 

of deleting the cross-reference. 

Many commenters expressed concern about whether the agencies’ insertion of a comma 

following this ministerial change unintentionally narrowed the exclusion such that all excluded 

waste treatment systems must be designed to meet the requirements of the Clean Water Act. The 

commenters indicated concerns that waste treatment systems built before the Clean Water Act or 

primarily for purposes of other environmental laws could not be exempt. The agencies do not 

intend to change how the waste treatment exclusion is implemented and have deleted this 

proposed comma. Continuing current practice, any waste treatment system built in a “water of 

the United States” would need a section 404 permit to be constructed and a section 402 permit 

for discharges from the waste treatment system into “waters of United States.” 

A number of commenters suggested the agencies clarify how the waste treatment system 

exclusion is currently implemented. Many comments raised questions about stormwater systems 

and wastewater reuse and whether such facilities qualified under the waste treatment system 

exclusion as part of a complete waste treatment system. For clarity, the agencies have identified 

related exclusions in paragraph (b)(6). Many commenters also suggested making substantive 

changes to the existing exclusion for waste treatment systems. Because the agencies are not 

making any substantive changes to the waste treatment system and these comments are outside

the scope of the proposed rule, the final rule does not reflect changes suggested in public 

comments.
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The existing exclusion for prior converted cropland moves to paragraph (b)(2) of the rule 

and is unchanged. A number of commenters suggested changes to the existing exclusion for 

prior converted cropland. As with waste treatment systems, the preamble to the proposed rule 

indicated this rulemaking was not making changes to the exclusion for prior converted cropland. 

As a result, such comments are outside the scope of this rulemaking and the rule does not reflect 

changes suggested in public comments. The agencies will continue to implement this exclusion 

consistent with current policy and practice.

The agencies identify excluded ditches in paragraph (b)(3). Jurisdictional ditches are 

discussed at more detail in section IV.F. The rule excludes all ditches with ephemeral flow that 

are not excavated in or relocate a tributary. The rule also excludes roadside ditches with 

ephemeral or intermittent flow that drain a Federal, state, tribal, county or municipal roads, 

except where the ditch itself either is excavated in or relocates a covered tributary. Finally, 

ditches that do not connect to a traditional navigable water, interstate water, or territorial sea 

either directly or through another water are excluded, regardless of whether the flow is 

ephemeral, intermittent, or perennial. These ditch exclusions are clearer for the regulated public 

to identify and more straightforward for agency staff to implement than the proposed rule or 

current policies. The ditch exclusions do not affect the possible status of that ditch as a point 

source.

Many comments addressed ditches, and many of these comments are reflected in the 

approach to ditches articulated in the rule. The majority of commenters requested that the 

agencies’ ditch exclusion be clarified or broadened. Many commenters were confused by the 

term “uplands” and did not feel the term had a common understanding. Many expressed 
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concerns that all ditches would be jurisdictional under the proposed rule. Many groups especially 

called for exclusions of roadside ditches. 

The revised exclusions respond to these comments. The agencies have deleted the term 

“uplands” in response to the confusion the term created and have focused instead on flow. The 

flow regimes as used in the exclusions and described earlier have been used by the agencies 

consistently and are readily understood by field staff and the public. Deleting the term 

“uplands,” which was more subject to misinterpretation, from the exclusions will therefore 

improve clarity and simplify implementation. 

The agencies have also addressed roadside ditches in particular and have clearly 

identified which roadside ditches are excluded. The agencies have focused on roadside ditches 

for several years; in the 2008 Rapanos guidance the agencies stated they generally would not 

assert jurisdiction over “[d]itches (including roadside ditches) excavated wholly in and draining 

only uplands and that do not carry a relatively permanent flow of water.” Roadside ditches with 

ephemeral and intermittent flow that drain a Federal, state, tribal, county or municipal road are 

excluded, except where they channelize or relocate a covered tributary. A roadside ditch closely 

parallels a road and functions as an integral part of the roadway system to convey water away 

from the roadway, to preserve the structural stability of the roadway, and to enhance public 

safety. Federal, state, tribal, county and municipal roads are readily identifiable by maps and 

other public information so the Agencies expect implementation of this exclusion to be clear and 

straightforward. 

As discussed in Section IV.F.1., the definition of tributary includes natural, undisturbed 

waters and those that have been man-altered or constructed, but which science shows function as 

a tributary. In addition, natural streams and rivers that are altered or modified for purposes as 
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flood control, erosion control, and other reasons does not convert the tributary to a ditch. A 

stream or river that has been channelized or straightened because its natural sinuosity has been 

altered, cutting off the meanders, is not a ditch. A stream that has banks stabilized through use 

of concrete or rip-rap (e.g., rocks or stones) is not a ditch. The Los Angeles River, for example, 

is a “water of the United States” (and, indeed, a traditional navigable water) and remains a

“water of the United States” and is not a excluded under paragraph (b)(3) even where it has been 

ditched, channelized, concreted and runs alongside a road.

Where an excluded roadside or ephemeral ditch is excavated in or relocates a covered 

tributary, only the segment of the ditch actually excavated in or relocating the covered tributary 

would be considered jurisdictional. For example, an entire roadside ditch does not become 

subject to jurisdiction because a portion of it is excavated in or relocates a tributary. The 

opposite is also true though - a tributary does not lose its jurisdictional status for its entire length 

simply because a portion of it is excluded under paragraph (b)(3). This approach reasonably 

balances the exclusion with the need to ensure that covered tributaries, and the significant 

functions they provide, are preserved. A ditch that relocates a stream is not an excluded ditch 

under paragraph (b)(3) and a stream is relocated either when at least a portion of its original 

channel has been physically moved, or when the majority of its flow has been redirected. A 

ditch that is a relocated stream is distinguishable from a ditch that withdraws water from a stream 

without changing the stream’s aquatic character. The latter type of ditch may be excluded from 

jurisdiction where it meets the listed characteristics of excluded ditches under paragraph 

(b)(3). Agency staff can determine historical presence of tributaries using a variety of resources, 

such as USGS and state and local maps, historic aerial photographs, local surface water 
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management plans, street maintenance data, wetlands and conservation programs and plans, as 

well as functional assessments and monitoring efforts.

A number of commenters expressed concern that a ditch could be viewed as both a point 

source and a “water of the United States.” However, the approach that ditches can be considered 

both reflects the CWA itself as well as longstanding agency policy. 

Paragraph (b)(4) of the rule identifies features and waters that the agencies have

identified as generally not “waters of the United States” in previous preambles or guidance 

documents. Codifying these longstanding practices supports the agencies’ goals of providing 

greater clarity, certainty, and predictability for the regulated public and the regulators. The 

Agencies’ 1986 and 1988 preambles indicated that these waters could be determined on a casespecific basis to be “waters of the United States.” The rule does not allow for this case-specific

analysis to be used to establish jurisdiction - these waters are categorically excluded from 

jurisdiction. Some of the exclusions have been modified slightly to address public comments and 

improve clarity. The following features are not “waters of the United States”:

• Artificially irrigated areas that would revert to dry land should application of irrigation 

water to that area cease

• Artificial lakes or ponds created by excavating and/or diking dry land and used primarily 

for such purposes as stock watering, irrigation, settling basins, or rice growing

• Artificial reflecting pools or swimming pools created by excavating and/or diking dry 

land

• Small ornamental waters created by excavating and/or diking dry land for primarily 

aesthetic reasons 
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• Water-filled depressions created in dry land incidental to mining or construction activity, 

including pits excavated for obtaining fill, sand or gravel that fill with water

• Non-wetland swales, erosional features, gullies, rills, and grassed waterways

• Puddles

Several of these exclusions use the phrase “dry land.” This phrase appears in the 1986 

and 1988 preambles, and the agencies believe the term is well understood based on the more than 

30 years of practice and implementation. But in keeping with the goal of providing greater 

clarity, the agencies clarify that “dry land” refers to areas of the geographic landscape that are 

not water features such as streams, rivers, wetlands, lakes, ponds and the like. However, it is 

important to note that a “water of the United States” is not considered “dry land” if it lacks water 

at a given time. Similarly, an area remains “dry land” even if it is wet after a rainfall event. 

In the exclusion for artificial lakes or ponds, the agencies have changed “exclusively” to 

“primarily” in describing the uses. Artificial lakes and ponds are often not used exclusively for 

one purpose and can have other beneficial purposes, such as animal habitat, water retention or 

recreation. The change to the exclusion reflects Agency practice and ensures that waters the 

agencies have historically not treated as jurisdictional do not become so because of another 

incidental beneficial use. The agencies have also added cooling ponds to the list of uses in the 

rule. The list of uses has always been illustrative rather than exhaustive, and this addition 

responds to many requests to clarify that cooling ponds created in dry land are excluded.

The rule includes several refinements to the exclusion for water-filled depressions created 

as a result of certain activities. In addition to construction activity, the agencies have also 

excluded water-filled depressions created in dry land incidental to mining activity. This change 
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is consistent with the agencies’ 1986 and 1988 preambles, which generally excluded pits 

excavated for obtaining fill, sand or gravel, and there is no need to distinguish between features 

based on whether they are created by construction or mining activity. A number of commenters 

indicated that these water-filled depressions created in dry land are often left on a site after 

construction or mining activity is complete in order to provide beneficial purposes, such as water 

retention, recreation, and animal habitat. The rule does not alter the agencies’ existing practice 

that these features could be found to be jurisdictional once the construction or mining activity is 

completed or abandoned and the water feature remains.

The agencies also here clarify their longstanding view that only the specific land being 

directly irrigated that would revert dry land should irrigation cease is exempt; it is not the case 

that all waters within watersheds where irrigation occurs are exempt.

The rule identifies all erosional features, including gullies and rills, as non-jurisdictional 

features. While the proposed rule specifically identified gullies and rills, the agencies intended 

that all erosional features would be excluded. The final rule makes this clear. Erosional features 

are not jurisdictional under the terms of paragraph (a) and the definitions in paragraph (c), 

especially the definition of tributary, and would be non-jurisdictional in any case. These features 

are specifically excluded in the rule to avoid confusion, because preceding guidance identified 

them as non-jurisdictional and many commenters stated these exclusions were important to 

maintain in the rule.

Tributaries can be distinguished from erosional features by the presence of bed and banks 

and an ordinary high water mark. Concentrated surface runoff can occur within erosional 

features without creating the permanent physical characteristics associated with bed and banks 

and ordinary high water mark. See Technical Support Document. It should be noted that some 
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ephemeral streams are colloquially called “gullies” or the like even when they exhibit a bed and 

banks and an ordinary high water mark; regardless of the name they are given locally, waters that 

meet the definition of tributary are not excluded erosional features.

The rule also excludes lawfully constructed grassed waterways. Grassed waterways are 

lawfully constructed for purposes of this rule either where they are on dry land and replace nonjurisdictional erosional features or, more commonly, where they have been lawfully converted 

from an intermittent or ephemeral stream under a CWA permit. Once converted to grassed 

waterways, these former streams segments no longer exhibit a bed and banks or ordinary high 

water mark and are excluded because they do not meet the definition of “tributary.” However, 

such conversion does not sever jurisdiction over the entire length of the tributary above and 

below the grassed waterway. Instead, the grassed waterway is considered a constructed break in 

the bed and banks and ordinary high water mark. This is reflected in the definition of tributary, 

which specifically addresses natural or man-made breaks in bed and banks and ordinary high 

water mark.

The final rule adds an exclusion for puddles. The proposed rule did not explicitly 

exclude puddles because the Agencies have never considered puddles to meet the minimum 

standard for being a “water of the United States,” and it is an inexact term. A puddle is 

commonly considered a very small, shallow, and highly transitory pool of water that forms on 

pavement or uplands during or immediately after a rainstorm or similar precipitation event. 

However, numerous commenters asked that the agencies expressly exclude them in a rule. The 

final rule does so.

The agencies include an exclusion for groundwater, including groundwater drained 

through subsurface drainage systems. As discussed in the preamble to the proposed rule, the 
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agencies have never interpreted “waters of the United States” to include groundwater. The 

exclusion does not apply to surface expressions of groundwater, as some commenters requested, 

such as where groundwater emerges on the surface and becomes baseflow in streams or spring 

fed ponds. 

The final rule includes a new exclusion in paragraph (b)(6) for stormwater control 

features constructed to convey, treat, or store stormwater that are created in dry land. This 

exclusion responds to numerous commenters who raised concerns that the proposed rule would 

adversely affect municipalities’ ability to operate and maintain their stormwater systems, and 

also to address confusion about the state of practice regarding jurisdiction of these features at the 

time the rule was proposed. 

The agencies’ longstanding practice is to view stormwater water control measures that 

are not built in “waters of the United States” as non-jurisdictional. Conversely, the agencies view 

some waters, such as channelized or piped streams, as jurisdictional currently even where used as 

part of a stormwater management system. Nothing in the proposed rule was intended to change 

that practice. Nonetheless, the agencies recognize that the proposed rule brought to light 

confusion about which stormwater control features are jurisdictional waters and which are not, 

and agree that it is appropriate to address this confusion by creating a specific exclusion in the 

final rule for stormwater controls features that are created in dry land. 

Many commenters, particularly municipalities and other public entities that operate storm 

sewer systems and stormwater management programs, expressed concern that various 

stormwater control measures—such as stormwater treatment systems, rain gardens, low impact 

development/green infrastructure, and flood control systems—could be considered “waters of the 

United States” under the proposed rule, either as part of a tributary system, an adjacent water, or 
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as a result of a case-specific significant nexus analysis. This exclusion should clarify the 

appropriate limits of jurisdiction relating to these systems. A key element of the exclusion is 

whether the feature or control system was built in dry land and whether it conveys, treats, or 

stores stormwater. Certain features, such as curbs and gutters, may be features of stormwater 

collection systems, but have never been considered “waters of the United States.” 

Stormwater control features have evolved considerably over the past several years, and 

their nomenclature is not consistent, so in order to avoid unintentionally limiting the exclusion, 

the agencies have not included a list of features in the rule. The rule is intended to exclude the 

diverse range of control features that are currently in place and may be developed in the future. 

Traditionally, stormwater controls were designed to direct runoff away from people and 

property as quickly as possible. Cities built systems to collect, convey, or store stormwater, using 

structures such as curbs, gutters, roads, and sewers. Often, cities used existing stream networks 

as part of the stormwater drainage network. Retention and detention stormwater ponds were built 

to store excess stormwater until it could be more safely released. 

Recently, treatment of stormwater has become more prevalent to remove harmful 

pollutants before the stormwater is discharged. Even more recently, cities have turned to green 

infrastructure, using existing natural features or creating new features that mimic natural 

hydrological processes that work to infiltrate or evapotranspirate precipitation, to manage 

stormwater at its source and keep it out of the conveyance system. These engineered components 

of stormwater management systems can address both water quantity and quality concerns, as 

well as provide other benefits to communities. This rule is designed to avoid disincentives to this 

environmentally beneficial trend in stormwater management practices.
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Paragraph (b)(7) of the rule clarifies that wastewater recycling structures created in dry 

land are excluded. This new exclusion clarifies the agencies’ current practice that such waters 

and water features used for water reuse and recycling are not jurisdictional when constructed in 

dry land. The agencies recognize the importance of water reuse and recycling, particularly in 

areas like California where water supplies can be limited and droughts can exacerbate supply 

issues. This exclusion responds to numerous commenters and encourages water reuse and 

conservation while still appropriately protecting the chemical, physical, and biological integrity 

of the nation’s water under CWA. 

The agencies specifically exclude constructed detention and retention basins created in 

dry land used for wastewater recycling as well as groundwater recharge basins and percolation 

ponds built for wastewater recycling. Many commenters noted the growing interest in and 

commitment to water recycling and reuse projects. Detention and retention basins can play an 

important role in capturing and storing water prior to beneficial reuse. Similarly, groundwater 

recharge basins and percolation ponds are becoming more prevalent tools for water reuse and 

recycling. These features are used to collect and store water which then infiltrates into 

groundwater via permeable soils. Though these features are often created in dry land, they are 

also often located in close proximity to tributaries or other larger bodies of water. The exclusion 

also covers water distributary structures that are built in dry land for water recycling. These 

features often connect or carry flow to other water recycling structures, for example a channel or 

canal that carries water to a percolation pond. The agencies have not considered these water

distributary systems jurisdictional where they do not have surface connections back into, and 

contribute flow to, “waters of the United States.” In contrast, the agencies have consistently 

regulated aqueducts and canals as “waters of the United States” where they serve as tributaries, 
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removing water from one part of the tributary network and moving it to another. The agencies 

have not in practice asserted jurisdiction over these types of features when created in dry land. 

The exclusion in paragraph (b)(7) codifies long-standing agency practice and encourages water 

management practices that the Agencies agree are important and beneficial.

It is important to note that while the waters listed in the exclusions are never “waters of 

the United States,” they can serve as a hydrologic connection that the agencies would consider 

under a case-specific significant nexus under paragraphs (a)(7) and (a)(8). For example, a 

wetland may be directly hydrologically connected to a covered tributary via flow through an 

excluded non-wetland swale. While the swale itself will always be excluded from jurisdiction, 

the connection of the wetland to the tributary is relevant for determining whether the wetland has 

a significant nexus to downstream traditional navigable waters, interstates waters, or the 

territorial seas. 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).

V. Economic Impacts 

This rule establishing the definition of “waters of the U.S.,” by itself, imposes no direct 

costs. The potential costs and benefits incurred as a result of this rule are considered indirect,

because the rule involves a definitional change to a term that is used in the implementation of 

CWA programs (i.e., sections 303, 305, 311, 401, 402, and 404). Entities currently are, and will 

continue to be, regulated under these programs that protect “waters of the United States” from 
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pollution and destruction. Each of these programs may subsequently impose direct or indirect 

costs as a result of implementation of their specific regulations. 

While the rule imposes no direct costs, the agencies prepared an economic analysis for 

informational purposes. In preparing the economic analysis to accompany the final rule, the 

agencies considered what should be the appropriate baseline for comparison. The existing 

regulations represent one appropriate baseline for comparison, and because the final rule is 

narrower in jurisdictional scope than the existing regulations, there would be no additional costs 

in comparison to this baseline. A comparison to field practice following the 2008 guidance is 

also an appropriate baseline, and the agencies believe that baseline is the most useful for 

purposes of evaluating the indirect costs and benefits associated with the policies in the final 

rule. 

To evaluate and estimate potential costs and benefits associated with this rule, the 

economic analysis utilizes available program data to estimate the extent to which assertion of 

jurisdiction might change under the associated final policies. The proposed rule analysis utilized 

CWA Section 404 jurisdictional determination and permit data from fiscal years 2009-2010 (post 

SWANCC and Rapanos), following issuance of program guidance in 2008 by the EPA and the 

Corps. The analysis for the final rule has been updated using data from fiscal years 2013-2014, 

providing a comparison to a more recent year of data, which responds to public comments. An 

estimate of how assertion of jurisdiction may change as a result of this rule, developed using 

updated data from fiscal years 2013-2014 jurisdictional determinations is applied to cost and 

benefit information for affected CWA programs. Additional updates to the economic analysis 

include a refined approach to calculating benefits from Section 404 compensatory mitigation, 

differentiating between emergent and forested wetlands, as well as sensitivity analyses reflecting 
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different assumptions of jurisdiction. The agencies’ analysis indicates that indirect incremental 

benefits exceed indirect incremental costs.

The agencies conducted this economic analysis to provide the public with information on 

the potential indirect costs and benefits associated with this definitional rule. The economic 

analysis was done for informational purposes only, and the final decisions on the scope of 

“waters of the United States” in this rulemaking are not based on consideration of the 

information or analysis in the economic analysis. The economic analysis fulfills the

requirements of Executive Orders 13563 and 12866. The economic analysis and an explanation 

for how indirect costs and benefits estimates were derived are documented in the Economic 

Analysis for the Clean Water Rule; Definition of “Waters of the United States” Under the Clean 

Water Act (Final Rule) and can be found in the accompanying docket. 

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

A. Executive Order 12866: Regulatory Planning and Review and Executive 

Order 13563: Improving Regulation and Regulatory Review

Under Executive Order 12866 (58 FR 51735, October 4, 1993), this action is a 

“significant regulatory action.” Accordingly, the EPA and the Corps submitted this action to the 

Office of Management and Budget (OMB) for review under Executive Orders 12866 and 13563 

(76 FR 3821, January 21, 2011) and any changes made in response to OMB recommendations 

have been documented in the docket for this action.
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In addition, the EPA and the Corps prepared an analysis of the potential costs and 

benefits associated with this action. This analysis is contained in Economic Analysis for the 

Clean Water Rule; Definition of “Waters of the United States” Under the Clean Water Act 

(Final Rule). 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 the 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.
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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 rule on small entities, we certify that this 

final 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 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 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 will not have a significant 

adverse economic impact on a substantial number of small entities, and therefore no regulatory 

flexibility analysis is required.

Today’s rule 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 
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United States, including the territorial seas” (33 U.S.C. 1362(7)), consistent with Supreme Court 

precedent. This question of CWA jurisdiction is 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 wide input from representatives of small 

entities while formulating the proposed and final 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, throughout the rule development, 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 prepared a report summarizing their small entity outreach, the results of this 

outreach, and how these results have informed the development of this rule. This report, Final 

Summary of the Discretionary Small Entity Outreach for the Revised Definition of Waters of the 

United States (Docket Id. No. EPA-HQ-OW-2011-0880-1927), is available in the docket.

D. Unfunded Mandates Reform Act
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This action does not contain any unfunded mandate under the regulatory provisions of 

Title II of the Unfunded Mandates Reform Act of 1995 (UMRA) (2 U.S.C. 1531-1538), and does 

not significantly or uniquely affect small governments. The action imposes no enforceable duty 

on any state, local, or tribal governments, or the private sector, and does not contain regulatory 

requirements that might significantly or uniquely affect small governments. The definition of 

“waters of the United States” applies broadly to CWA programs.

E. Executive Order 13132: Federalism

This rule does not have federalism implications. It 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. 

Keeping with the spirit of Executive Order 13132 and consistent with the agencies’

policy to promote communications with state and local governments, the agencies consulted with 

state and local officials throughout the process and solicited their comments on the proposed 

action and on the development of the rule. 

For this rule State and local governments were consulted at the onset of rule development 

in 2011, and following the publication of the proposed rule in 2014. In addition to engaging key 

organizations under federalism, the agencies sought feedback on this rule from a broad audience 

of stakeholders through extensive outreach to numerous State and local government 

organizations.

Early in the rulemaking process, EPA held two in-person meetings and two phone calls in 

the fall and winter of 2011. Organizations involved include the National Governors Association, 
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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. 

Additionally, the National Association of Clean Water Agencies and the Association of Clean 

Water Administrators were invited to participate. The agencies held many additional calls and 

meetings with state and local governments and their associations, in preparation for the 

development of a proposed rule. 

Similarly to the outreach conducted prior to the development of the rule, the agencies 

committed themselves to providing a transparent, comprehensive, and effective process for 

taking public comment on the proposed rule. As part of this consultation, EPA held a meeting 

on May 13, 2014 to seek technical input on the proposed rule from the largest national 

representative organizations for State and local governments. During this process the agencies 

also extended its focused outreach to include a series of meetings with the Local Government 

Advisory Committee, and the Environmental Council of States in conjunction with the 

Association of Clean Water Administrators and the Association of State Wetland Managers. In 

addition to engaging these key organizations under, the agencies sought additional feedback on 

the proposed rule through broader public outreach to state and local government organizations 

during the public comment period. 

During the consultation process, some participants expressed concern that the proposed 

changes may impose a resource burden on state and local governments. Some participants urged 

EPA to ensure that states are not unduly burdened by the regulatory revisions. 
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The agencies have prepared a report summarizing their voluntary consultation and 

extensive outreach to State, local, and county governments, the results of this outreach, and how 

these results have informed the development of today’s rule. This report, Final Summary of the 

Discretionary Consultation and Outreach to State, Local, and County Governments for the

Revised Definition of Waters of the United States (Docket Id. No. EPA-HQ-OW-2011-0880-

XXXX) is available in the docket for this 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), the 

agencies consulted with tribal officials throughout the rulemaking process to gain an 

understanding of tribal issues and solicited their comments on the proposed action and on the 

development of today’s rule. In the course of this consultation, EPA and the Corps jointly 

participated in aspects of the process.

The agencies began consultation with federally-recognized Indian tribes on the Clean 

Water Rule defining waters of the U.S. in October 2011. The consultation and coordination 
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process, including providing information on the development of an accompanying science report 

on the connectivity of streams and wetlands, continued, in stages, over a four year period, until 

the close of the public comment period on November 14, 2014. EPA invited tribes to provide 

written input on the rulemaking throughout both the tribal consultation process and public 

comment period.

EPA specifically consulted with tribal officials to gain an understanding of, and to 

address, the tribal implications of the proposed rule. In 2011, 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 three tribes during the initial consultation period.

EPA continued to provide status updates to the National Tribal Water Council and the 

National Tribal Caucus during 2012 through 2014. The final consultation event was completed 

on October 23, 2014 as a national teleconference with the Office of Water’s Deputy Assistant 

Administrator. Ultimately, EPA received an additional 23 letters from tribes/tribal affiliations by 

the completion of the consultation period. The comments indicate that Tribes, overall, support 

increased clarity of waters protected by the Clean Water Act, but some express concern with the 

consultation process and the burden of any expanded jurisdiction. The feedback received through 

consultation and written comments have been incorporated in today’s rule. 

The agencies have prepared a report summarizing their consultation with tribal nations, 

and how these results have informed the development of this rule. This report, Final Summary of 

Tribal Consultation for the Clean Water Rule: Definition of “Waters of the United States” Under 

the Clean Water Act; Final Rule (Docket Id. No. EPA-HQ-OW-2011-0880-XXXX), is available 

in the docket for this rule. 
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As required by section 7(a), EPA’s Tribal Consultation Official has certified that the 

requirements of the executive order have been met in a meaningful and timely manner. A copy 

of the certification is included in the docket for this action.

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

and Safety Risks

This action is not subject to Executive Order 13045 (62 FR 19885, April 23, 

1997) 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 No. 104-113, 12(d) (15 U.S.C. 272 note) directs federal agencies to use 

voluntary consensus standards in regulatory activities unless to do so would be inconsistent with 
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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 rule 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.) 12989 (59 FR 7729, 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 lowincome populations in the United States. 

The agencies have determined that the rule will not have disproportionately high and 

adverse human health or environmental effects on minority or low-income populations, because 

it does not adversely affect the level of protection provided to human health or the environment. 

The rule defines the scope of waters protected under the CWA. The increased clarity 

regarding the definition of “waters of the United States” is intended to benefit all regulators, 
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stakeholders, and interested parties. In addition, this rule is national in scope and, therefore, is 

not specific to a particular geographic area(s).

In the spirit of E.O. 12898, EPA and the Corps requested input from environmental 

justice stakeholders during the rule development process, through a series of stakeholder 

meetings between April-November 2014. On May 12, 2014, EPA held a focused teleconference

with non-traditional stakeholders, including environmental justice and faith-based stakeholders,

to solicit their individual input on the proposed rule. The agencies have used the feedback from 

public outreach as the source of early guidance and recommendations for refining the proposed 

rule. Stakeholder input received during public outreach events in combination with the written 

comments received during the public comment period have reshaped each of the definitions 

included in today’s rule, and incorporate increased clarity for regulators, stakeholders, and the 

regulated public to assist them in identifying waters as “waters of the United States.”

The agencies prepared a report summarizing their outreach to the environmental justice 

community, analysis of potential impacts, and how these results informed the development of the 

rule. This report, Environmental Justice Report for the Clean Water Rule: Definition of “Waters 

of the United States” Under the Clean Water Act; Final Rule (Docket Id. No. EPA-HQ-OW2011-0880-XXXX), is available in the docket for this rule. 

K. Congressional Review Act (CRA)

This action is subject to the CRA, and the agencies will submit a rule report to each 

House of the Congress and to the Comptroller General of the United States. This action is not a 

“major rule” as defined by 5 U.S.C. 804(2). 
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L. Environmental Documentation

The Corps has prepared a final environmental assessment and Findings of No Significant 

Impact in accordance with the National Environmental Policy Act (NEPA). The Corps has made 

a determination that the section 404 aspects of the 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) is not required. The rule provides for more efficient 

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.
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Clean Water Rule: Definition of “Waters of the United States” 

List of Subjects

33 CFR Part 328.3

Environmental protection, Administrative practice and procedure, Intergovernmental 

relations, Navigation, Water pollution control, Waterways.

40 CFR Part 110.1

Environmental protection, Water pollution control

40 CFR Part 112.2

Environmental protection, Water pollution control

40 CFR Part 116.3

Environmental protection, Water pollution control

40 CFR Part 117.1

Environmental protection, Water pollution control

40 CFR Part 122.2

Environmental protection, Water pollution control

40 CFR Part 230.3

Environmental protection, Water pollution control

40 CFR Part 232.2

Environmental protection, Water pollution control

40 CFR Part 300.5

Environmental protection, Water pollution control
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40 CFR Part 300 App. E

Environmental protection, Water pollution control

40 CFR Part 302.3 

Environmental protection, Water pollution control

40 CFR Part 401.11

Environmental protection, Water pollution control

Dated: Dated:

Gina McCarthy, Jo Ellen Darcy,

Administrator Assistant Secretary of the Army

Environmental Protection Agency. (Civil Works)

Department of the Army.
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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 

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

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

2. Section 328.3 is amended by removing the introductory text and revising subsections

(a), (b) and (c) to read as follows:

328.3 Definitions

(a) For purposes 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 otherwise identified as waters of the United States under 

this section;

(5) All tributaries, as defined in paragraph (c)(3) of this section, of waters identified in 

paragraphs (a)(1) through (3) of this section;

(6) All waters adjacent to a water identified in paragraphs (a)(1) through (5) of this 

section, including wetlands, ponds, lakes, oxbows, impoundments, and similar waters; 
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(7) All waters in paragraphs (A) through (E) of this paragraph where they are determined, 

on a case-specific basis, to have a significant nexus to a water identified in 

paragraphs (a)(1) through (3) of this section. The waters identified in each paragraph (A) 

through (E) of this paragraph are similarly situated and shall be combined, for purposes 

of a significant nexus analysis, in the watershed that drains to the nearest water identified 

in paragraphs (a)(1) through (3) of this section. Waters identified in this paragraph shall 

not be combined with waters identified in paragraph (a)(6) of this section when 

performing a significant nexus analysis. If waters identified in this paragraph are also an 

adjacent water under paragraph (a)(6), they are an adjacent water and no case specific 

significant nexus analysis is required.

(A) Prairie potholes. Prairie potholes are a complex of glacially formed wetlands, 

usually occurring in depressions that lack permanent natural outlets located in the 

upper Mid-west.

(B) Carolina bays and Delmarva bays. Carolina bays and Delmarva bays are 

ponded, depressional wetlands that occur along the Atlantic coastal plain.

(C) Pocosins. Pocosins are evergreen shrub and tree dominated wetlands found 

predominantly along the Central Atlantic coastal plain. 

(D) Western vernal pools. Western vernal pools are seasonal wetlands located in 

parts of California and associated with topographic depression, soils with poor 

drainage, mild, wet winters and hot, dry summers.

(E) Texas coastal prairie wetlands. Texas coastal prairie wetlands are freshwater 

wetlands that occur as a mosaic of depressions, ridges, intermound flats, and 

mima mound wetlands located along the Texas Gulf Coast.
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(8) All waters located within 4000 feet of the high tide line or ordinary high water mark 

of a water identified in paragraphs (a )(1) through (5) of this section where they are 

determined on a case-specific basis to have a significant nexus to a water identified in 

paragraphs (a)(1) through (3) of this section. The entire water is a water of the United 

States if a portion is located within 4000 feet of the high tide line or ordinary high water 

mark. Waters identified in this paragraph shall not be combined with waters identified in 

paragraph (a)(6) of this section when performing a significant nexus analysis. If waters 

identified in this paragraph are also an adjacent water under paragraph (a)(6), they are an 

adjacent water and no case specific significant nexus analysis is required.

(b) The following are not “waters of the United States” even where they otherwise meet the 

terms of paragraphs (a)(1) through (8) 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) The following ditches:

(A) Ephemeral ditches that are not a relocated tributary or excavated in a 

tributary.

(B) Ephemeral and intermittent roadside ditches that drain a Federal, state, tribal, 

county, or municipal road, and that are not a relocated tributary or excavated in a 

tributary.
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Page 181 of 186

(C) Ditches that do not flow, either directly or through another water, into a water 

identified in paragraphs (a)(1) through (3) of this section.

(4) The following features:

(A) Artificially irrigated areas that would revert to dry land should application of 

water to that area cease;

(B) Artificial lakes and ponds created in dry land and used primarily for uses such 

as stock watering, irrigation, settling basins, rice growing, or cooling ponds;

(C) Artificial reflecting pools or swimming pools created in dry land;

(D) Small ornamental waters created in dry land;

(E) Water-filled depressions created in dry land incidental to mining or 

construction activity, including pits excavated for obtaining fill, sand, or gravel 

that fill with water;

(F) Erosional features, including gullies, rills, and other ephemeral features that 

do not meet the definition of tributary, non-wetland swales, and lawfully 

constructed grassed waterways; and

(G) Puddles.

(5) Groundwater, including groundwater drained through subsurface drainage systems. 

(6) Stormwater control features constructed to convey, treat, or store stormwater that are 

created in dry land.

(7) Wastewater recycling structures created in dry land: detention and retention basins 

built for wastewater recycling, groundwater recharge basins, and percolation ponds 

built for wastewater recycling, and water distributary structures built for wastewater 

recycling.
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(c) Definitions—In this section, the following definitions apply:

(1) Adjacent. The term adjacent means bordering, contiguous, or neighboring a water 

identified in paragraphs (a)(1) through (5) of this section, including waters separated by 

constructed dikes or barriers, natural river berms, beach dunes and the like. For purposes 

of determining adjacency, a water that includes wetlands within or abutting its ordinary 

high water mark is considered a single water. Adjacency is not limited to waters located 

laterally to a water identified in paragraphs (a)(1) through (5) of this section. All waters 

that connect segments of a water identified in paragraphs (a)(1) through (5) or are located 

at the head of a water identified in paragraphs (a)(1) through (5) of this section and are 

bordering, contiguous, or neighboring such water, are adjacent. Waters subject to 

established, normal farming, silviculture, and ranching activities (33 USC § 1344(f)(1)) 

are not adjacent.

(2) Neighboring. The term neighboring means:

(A) all waters located within 100 feet of the ordinary high water mark of a water 

identified in paragraphs (a)(1) through(a)(5) of this section. The entire water is 

neighboring if a portion is located within 100 feet of the ordinary high water 

mark;

(B) all waters located within the 100 year floodplain of a water identified in 

paragraphs (a)(1) through (5) of this section and not more than 1500 feet of the 

ordinary high water mark of such water. The entire water is neighboring if a 

portion is located within 1500 feet of the ordinary high water mark and within the 

100 year floodplain; 
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Page 183 of 186

(C) all waters located within 1500 feet of the high tide line of a water identified in 

paragraphs (a)(1) or (a)(3) of this section, and all waters within 1500 feet of the 

ordinary high water mark of the Great Lakes. The entire water is neighboring if a 

portion is located with 1500 feet of the high tide line.

(3) Tributary and tributaries. The terms tributary and tributaries each mean a water that 

contributes flow, either directly or through another water (including an impoundment 

identified in paragraph (a)(4) of this section), to a water identified in paragraphs (a)(1) 

through (3) of this section that is characterized by the presence of the physical indicators 

of a bed and banks and an ordinary high water mark. These physical indicators 

demonstrate there is volume, frequency and duration of flow sufficient to create a bed 

and banks and an ordinary high water mark, and thus to qualify as a tributary. A tributary

can be a natural, man-altered, or man-made water and includes waters such as rivers, 

streams, canals, and ditches not excluded under paragraph (b) 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 constructed breaks (such as bridges, 

culverts, pipes, or dams), or one or more natural breaks (such as wetlands 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 water that otherwise qualifies as a tributary under this definition does not lose its status 

as a tributary if it contributes flow through a water of the United States that does not meet 

the definition of tributary or through a water excluded under paragraph (b) of this section, 

directly or through another water, to a water identified in paragraphs (a)(1) through (3) of 

this section.
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Page 184 of 186

(4) 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.

(5) 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, 

significantly affects the chemical, physical, or biological integrity of a water identified in 

paragraphs (a)(1) through (3) of this section. The term “in the region” means the 

watershed that drains to the nearest 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. Waters are similarly situated when they function alike and are sufficiently 

close to function together in affecting downstream waters. For purposes of determining 

whether or not a water has a significant nexus, the water’s effect on downstream (a)(1) 

through (3) waters shall be assessed by evaluating the aquatic functions identified in 

paragraphs (A) through (I) of this paragraph. A water has a significant nexus when any 

single function or combination of functions performed by the water, alone or together 

with similarly situated waters in the region, contributes significantly to the chemical, 

physical, or biological integrity of the nearest water identified in paragraphs (a)(1) 

through (3) of this section. Functions relevant to the significant nexus evaluation are the 

following: 

(A) sediment trapping, 
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Page 185 of 186

(B) nutrient recycling, 

(C) pollutant trapping, transformation, filtering, and transport, 

(D) retention and attenuation of flood waters, 

(E) runoff storage, 

(F) contribution of flow,

(G) export of organic matter, 

(H) export of food resources, or

(I) provision of life cycle dependent aquatic habitat (such as foraging, 

feeding, nesting, breeding, spawning, or use as a nursery area) for species 

located in a water identified in paragraphs (a)(1) through (3) of this 

section. 

(6) Ordinary High Water Mark. The term ordinary high water mark means that line on 

the shore established by the fluctuations of water and indicated by physical characteristics 

such as a clear, natural line impressed on the bank, 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.

(7) High Tide Line. The term high tide line means the line of intersection of the land with 

the water's surface at the maximum height reached by a rising tide. The high tide line 

may be determined, in the absence of actual data, by a line of oil or scum along shore 

objects, a more or less continuous deposit of fine shell or debris on the foreshore or berm, 

other physical markings or characteristics, vegetation lines, tidal gages, or other suitable 

means that delineate the general height reached by a rising tide. The line encompasses 

spring high tides and other high tides that occur with periodic frequency but does not 
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Page 186 of 186

include storm surges in which there is a departure from the normal or predicted reach of 

the tide due to the piling up of water against a coast by strong winds such as those 

accompanying a hurricane or other intense storm.

***
Economic 

Analysis of 

the EPAArmy Clean 

Water Rule

April 27, 2015 

DRAFT FINAL

U.S. Environmental Protection 

Agency

U.S. Army Corps of Engineers
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1

Abt Associates provided technical support to U.S. EPA under contract EP-C-07-023.
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2

Table of Contents

Executive Summary........................................................................................................................ 4

Section 1: Introduction and Overview of the Clean Water Rule .................................................... 0

Section 2: Clean Water Act Regulatory Programs ......................................................................... 1

Section 3: Approach for the Economic Analysis............................................................................ 3

Section 4: Estimated Changes in Positive Jurisdictional Determinations ...................................... 5

Section 5: Clean Water Act Sections 303 and 305 ....................................................................... 12

Section 6: Estimate of Potential Clean Water Act Section 311 Oil Spill Prevention Program 

Costs and Benefits......................................................................................................................... 14

Section 7: Estimate of Potential Clean Water Act Section 401 Costs and Benefits..................... 16

Section 8: Estimate of Potential Clean Water Act Section 402 Costs and Benefits..................... 18

Section 402 Stormwater Permitting.......................................................................................... 20

Section 402 Concentrated Animal Feeding Operation Permitting ........................................... 24

Section 402 Pesticide General Permitting................................................................................. 26

Section 9: Estimate of Potential Clean Water Act Section 404 Costs and Benefits..................... 28

CWA Section 404 Compliance Costs....................................................................................... 28

Permit Application Costs...................................................................................................... 32

Compensatory Mitigation Costs ........................................................................................... 34

Wetland Mitigation Costs..................................................................................................... 35

Stream Mitigation Costs ....................................................................................................... 37

CWA Section 404 Benefits....................................................................................................... 38

Wetland Mitigation Benefits................................................................................................. 38

Valuation of Wetland Benefits.............................................................................................. 39

National Wetlands Inventory Approach to Benefits Transfer .............................................. 42

Aggregation of Benefits........................................................................................................ 44

Section 10: Summary of Estimated Indirect Costs and Benefits.................................................. 47

Section 11: Other Social Costs and Benefits ................................................................................ 49

Corps Administrative Costs...................................................................................................... 49

Section 12: Related Acts of Congress, Executive Orders, and Agency Initiatives....................... 52

Paperwork Reduction Act......................................................................................................... 52

Regulatory Flexibility Act ........................................................................................................ 52
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Unfunded Mandates Reform Act.............................................................................................. 53

Executive Order 13132: Federalism ......................................................................................... 54

Executive Order 13175: Consultation and Coordination with Indian Tribal Governments..... 55

Executive Order 13045: Protection of Children from Environmental Health and Safety Risks

................................................................................................................................................... 56

Executive Order 13211: Actions Concerning Regulations That Significantly Affect Energy 

Supply, Distribution, or Use ..................................................................................................... 56

Appendix A: Supplemental Cost Analysis Information ............................................................... 57

Appendix B: Supplemental Benefit Estimate Information ........................................................... 60

Summary of Wetland Benefits Studies Used to Generate WTP Estimates.............................. 60

Summary of Wetland Benefits Studies..................................................................................... 65

Procedure for Standardizing and Weighting WTP Values from Benefits Studies ................... 68

Appendix C: Sensitivity Analyses................................................................................................ 69
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Executive Summary

Key Background

The Environmental Protection Agency (EPA) and the U.S. Department of the Army

(Army) have prepared a final rule revising the definition of the regulatory term “waters of the 

United States.” This term identifies waters which are, and are not, subject to the Clean Water 

Act (CWA). The agencies have worked to develop this rule in light of the Act, science, Supreme 

Court decisions, public comments, and the agencies’ experience and technical expertise. 

The final rule includes eight categories of jurisdictional waters, maintains existing 

exemptions for certain categories of activities and waters, and adds additional exclusions for 

categories of waters that are never covered under the Act. The final rule does not establish 

regulatory requirements and, therefore, does not impose direct costs on any entity. Instead, it is a 

definitional rule that clarifies the scope of “waters of the United States.”

The agencies prepared this economic analysis to better understand the incremental costs 

and benefits that may result from any change in the number of positive jurisdictional 

determinations1 associated with CWA programs relying on the definition of “waters of the 

United States.” This summary describes the overall approach and presents the key results from 

the economic analysis.

Key Elements of the Analysis

Baseline for Comparison 

When determining which waters are covered by the CWA today, the agencies make 

jurisdictional determinations consistent with the law, existing regulations and policy, and the 

Supreme Court rulings in 2001 and 2006. This scope of waters currently covered by the CWA is 

considerably smaller than the scope of waters historically covered prior to the 2001 and 2006 

Supreme Court decisions. Based on the reduction in the scope of CWA jurisdiction, the agencies 

conclude that the new rule would impose no additional costs when compared to historic 

application of the regulation it replaces. 

For purposes of this economic analysis, however, the agencies evaluated costs and 

benefits associated with the difference in jurisdictional determinations between the new rule and 

current field practice, which is based on the 2008 EPA and Corps jurisdiction guidance. This 

 1 A “positive jurisdictional determination” is a decision to assert CWA jurisdiction over a particular water. The 

alternative is a “negative jurisdictional determination” which is a decision not to assert CWA jurisdiction over a 

particular water. It is important to note that the purpose of the economic analysis is not to estimate the change in the 

numbers of waters subject to jurisdiction.
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policy guidance has been implemented by the agencies since 2008 and reflects the Supreme 

Court decisions that limited assertion of CWA jurisdiction for some types of waters. Compared 

to this baseline, the agencies anticipate the new rule will result in an increase in the number of 

positive jurisdictional determinations and an associated increase in both costs and benefits that 

derive from the implementation of CWA programs.

Evaluation of Jurisdictional Determinations

To calculate costs and benefits to CWA programs, the agencies first estimated the 

potential changes to jurisdictional determinations due to the final rule. The agencies reviewed a 

sample of negative jurisdictional determinations (JDs) (i.e., determinations of no jurisdiction)

completed by the Corps in fiscal years 2013 and 2014 to assess whether or not the JD would 

change under the final rule.2

 It is important to emphasize that the economic analysis focuses 

exclusively on the costs and benefits associated with this change in negative to positive JDs,

rather than an analysis of how the scope of jurisdiction changes. Nationwide data do not exist on 

the areal extent of all waters covered by the CWA - the agencies generally only make 

jurisdictional determinations on a case-specific basis at the request of landowners. 

The agencies updated their economic analysis of the proposed rule, which relied upon 

data from FY09 and FY10, by reviewing more recent data from FY13 and FY14. This not only 

ensures that the most current data are used, but also responds to concerns raised in public 

comments that the FY09 and FY10 dataset used in the economic analysis for the proposed rule 

represented a period of decreased economic activity. JDs covering three categories of waters 

were reviewed – streams, wetlands, and other waters.

The agencies relied on certain conservative assumptions in their economic analysis that 

have the effect of consistently increasing the number of positive JDs that results from the new 

rule. Key assumptions and JD estimates include the following:

• For purposes of this analysis, the agencies assume that all waters in the stream and 

wetlands categories of the Corps JD data would be determined to be jurisdictional under 

the new rule, notwithstanding the limits on jurisdiction in the new rule.

• The agencies estimate that 17.1 percent of negative jurisdictional determinations for 

“other waters” will become positive under the new rule because they meet the definition 

of “adjacent.” Prior to the new rule, non-wetland adjacent waters were subject to a casespecific analysis because the definition of “adjacent” applied only to wetlands, not all 

waters.

• The agencies estimate that a total of 34.5 percent of the “other waters” JD category will 

change from negative to positive under the (a)(7) provision of the new rule. 

 2 The information available in the Corps ORM2 database does not allow the agencies to evaluate the percent of 

waters currently found to be jurisdictional that will not be under the final rule.
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• The agencies estimate that 5 percent of the remaining determinations in the “other 

waters” JD category will change from negative to positive under the (a)(8) provision of 

the new rule.

• Before estimating the overall change from negative to positive JDs, the agencies doubled 

the number of JDs in the “other waters” category, raising their representation in the total 

JD data from 6 percent to 11 percent to account for instances where landowners might 

not currently seek a jurisdictional determination and therefore are not represented in the 

data system. 

As a result of these assumptions and the estimates derived for all three categories of JDs in the 

FY13 and FY14 data, the agencies estimate that there will be an approximate 4.65 percent 

increase in positive jurisdictional determinations annually due to the new rule when compared 

with current field practice.

Costs and Benefits

It is important to note that a positive jurisdictional determination that a water is subject to 

the CWA is not equivalent to a new permit. Absent data to correlate positive jurisdiction to a 

new permit for purposes of estimating the costs and benefits of the rule, the agencies made the 

conservative assumption that the final rule could affect entities regulated under the CWA 

programs in direct proportion to this percentage change in positive jurisdictional determinations. 

To estimate annual costs and benefits, the agencies uniformly applied the 4.65 percent increment 

in jurisdiction to the total costs and benefits for the Sections 311, 401, 402 (stormwater, pesticide 

general permit, Confined Animal Feeding Operation permits) and 404 programs to account for 

an estimated increase in permitting and activities that would result. The agencies relied on 

existing annual administrative and compliance cost information, and updated cost figures to 2014 

dollars. 

A significant focus of the benefits analysis is on an anticipated increase in CWA 404 

permits that would result in ecological benefits from those permitted losses being offset through 

compensatory mitigation. The agencies estimate the potential benefits from CWA 404 

compensatory mitigation based upon a benefits transfer analysis using studies measuring 

willingness to pay for preservation of wetlands similar to the type likely to be protected by this 

rule. Updates to the final rule benefits analysis from the proposal analysis include making 

improvements by refining the approach to calculating benefits from Section 404 compensatory 

mitigation and differentiating between emergent and forested wetlands.
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Key Findings

Figure ES-1 presents a summary of the estimated indirect costs and benefits. There are 

several costs and benefits that the agencies were unable to monetize, including permitting time 

and project redesign costs under Section 404, as well as the benefits of Section 404 stream 

mitigation, benefits of the 402 pesticide general permit, and benefits of the 401 certification 

program. The agencies believe, however, that costs and benefits associated with each of these 

would be relatively small.

In addition, the agencies conducted a sensitivity analysis by changing certain assumptions 

in the initial estimate of increased positive jurisdictional determinations. This analysis may be 

found in Appendix C.

Key Conclusions

• The agencies’ analysis indicates that for all scenarios, indirect incremental benefits 

exceed indirect incremental costs by a ratio of up to 2:1.

• The “other waters” category represents the greatest potential for changes in jurisdictional 

determinations. 

• Indirect costs and benefits may be over-estimated because each newly jurisdictional 

water will not be affected by all CWA programs simultaneously, and a particular activity 

affecting a water may be exempt from permitting under the Clean Water Act. 
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8 

Figure ES- 1. Estimated Annual Indirect Costs and Benefits

Annual Costs

(FY14$ millions)

Annual Benefits

(FY14$ millions)

Low High Low High

CWA 402 CAFO Administration $0.3 $0.3 $6.2 $10.8 CWA 402 CAFO Implementation $9.9 $9.9

CWA 402 Stormwater 

Administration $0.5 $0.5 $47.5 $60.2 CWA 402 Stormwater 

Implementation $47.8 $59.6 

CWA 404 Permit Application $47.0 $80.3 $501.2 $501.2 CWA 404 Mitigation – Wetlands $90.1 $232.8

SUBTOTAL $195.7 $383.3 $554.9 $572.3

CWA 311 Compliance $12.7 $12.7 not quantified

CWA 401 Administration $1.3 $1.3 not quantified

CWA 402 Pesticide General Permit 

Implementation $5.4 $5.9 not quantified 

CWA 404 Mitigation – Streams $22.4 $44.4 not quantified

TOTAL $237.4 $447.6 $554.9 $572.3
Section 1: Introduction and Overview of the Clean Water

Rule

The U.S. Environmental Protection Agency (EPA) and U.S. Army Corps of Engineers 

(ACOE or Corps) conducted this economic analysis to provide the public with information on 

the potential indirect costs and benefits associated with the Final Clean Water Rule: Definition 

of “Waters of the United States” (hereafter referred to as the rule). The rule defines the scope of 

jurisdiction under the Clean Water Act for streams, wetlands, lakes, and other waters that form 

the foundation of the nation’s water resources. This rule, modifying the definition of “waters of 

the U.S.,” by itself imposes no direct costs. The potential costs and benefits incurred as a result 

of this rule are considered indirect, because the rule is a definitional change to a term that is used 

in the implementation of CWA programs (i.e., sections 303, 305, 311, 401, 402, and 404). 

Entities currently are, and will continue to be, subject to the provisions of these programs. Each 

of these programs may subsequently impose direct or indirect costs as a result of implementation 

of their specific provisions. While all of the costs and benefits associated with this rule are 

indirect, for readability throughout the rest of this document these indirect costs and indirect 

benefits are identified simply as costs and benefits.

On April 21, 2014, the EPA and the U.S. Army Corps of Engineers published a proposed

rule to reduce uncertainty about the scope of “waters of the United States” covered by Clean 

Water Act programs, that arose from interpretation of Supreme Court decisions in 2001 and 

2006. During the public comment period, which ran until November 14, 2014, over one million

comments were received. The agencies reviewed those comments in preparing this final rule.

[Stock language on rule changes, including discussion of expanded exclusions.]

In preparing this document (the Economic Analysis or EA), the agencies updated and 

revised the analyses completed for the proposal. The following sections describe Clean Water 

Act regulatory programs that will be affected by this rule, the approach used by the agencies to 

estimate a potential change in jurisdictional determinations based on the final rule, costs and 

benefits estimates associated with the final rule, and updates and enhancements to the analyses 

for the final EA. In addition, the agencies conducted a sensitivity analysis to determine the 

effects of different assumptions on the scope of jurisdiction and costs and benefits. For the main 

analysis and the sensitivity analysis, benefits exceed costs. 
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Section 2: Clean Water Act Regulatory Programs

The goal of the Clean Water Act (CWA) is to restore and maintain the chemical, 

physical, and biological integrity of the nation’s waters. To achieve that goal, the CWA

establishes a number of regulatory and non-regulatory programs that are designed to control 

pollution at its source and improve water quality. As a pollution prevention statute, the CWA 

extends beyond waters that are navigable in fact to include the headwater streams, lakes, and 

wetlands and other waters that contribute significantly to protect the integrity of navigable 

waters. The scope of waters that are specifically covered by CWA programs is all waters 

meeting the definition of “waters of the United States.” Any water that does not meet the 

definition of “waters of the U.S.” is not subject to the CWA. 

Figure 1 depicts the various CWA programs that are affected by the definition of “waters 

of the U.S.,” along with the government entities that may be responsible for administering the 

programs. Among its many provisions, the CWA calls for states and tribes to set standards for 

meeting water quality goals and developing plans to restore polluted waters (section 303); 

establishes oil spill prevention and clean-up programs (section 311); establishes state and tribal 

roles in certifying that federal permits will not violate water quality standards and other CWA 

requirements, as well as relevant state or tribal laws (section 401); requires permits for pollutant 

discharges (section 402); requires permits for the placement of dredged or fill material, (section 

404); and allows the federal government, states, tribes, and communities to enforce the law. 

The potential effects of this rule on each of these programs is discussed in greater detail 

in the sections that follow.
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Figure 1 - Affected Clean Water Act Programs

Navigable Waters: Waters of the United States,

Including Territorial Seas

303

•Water Quality 

Standards and 

TMDLS

•Involved in 

implementation:

•States

•Tribes

•USEPA

311

•Oil Spill 

Programs

•Involved in 

implementation:

•USEPA

•DHS

•DOI

•DOT

401

•State Certification

•Involved in 

implementation:

•States

•Tribes

•USEPA

402

•Pollutant 

Discharge 

Permits

•Involved in 

implementation:

•States

•Tribes

•USEPA

404

•Dredge and Fill 

Permits

•Involved in 

implementation:

•States

•Tribes

•USACE

•USEPA

As shown in Figure 1, states and tribes have a significant role in administering many 

CWA programs. This economic analysis does not account for the possibility that some states, as 

a matter of state law, may be considering a broader set of waters to be subject to a state’s 

implementation of certain CWA programs. Although the extent of a state’s CWA jurisdiction 

may not be smaller than the definition of waters of the U.S., states and tribes may elect to 

implement their water quality protection programs more broadly, according to a definition of 

“waters of the state” or “waters of the tribe.” Where individual states have elected to regulate 

waters more broadly, the estimated costs and benefits of this rule may be smaller than presented 

here (because states may already be asserting jurisdiction over waters for which this analysis 

presumed jurisdiction was not generally asserted in practice). 

The particulars of individual state laws and regulations vary greatly. A 2013 

Environmental Law Institute report estimated that approximately two-thirds of all states place 

some legal constraint on the authority of state and local government officials to adopt aquatic 

resource protections beyond the CWA definition of “waters of the U.S.” These may be 

straightforward stringency limitations, property-based limitations, or combinations of the two. 

The provisions may be partial limitations, affecting only some applications. The ELI report 

estimates that approximately half the states have some provisions that extend protections beyond 

“waters of the U.S.” Some of these provisions pre-date new stringency limitations and may not 

be retroactive.3

 

3 Environmental Law Institute. 2013. State Constraints: State-Imposed Limitation on the Authority of Agencies to 

Regulate Waters Beyond the Scope of the Federal Clean Water Act. Environmental Law Institute, Washington, DC.
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Section 3: Approach for the Economic Analysis

For this economic analysis, there are two potential baselines. The first potential baseline 

would use the EPA and Corps regulations it is written to replace. This rule will reduce the scope 

of waters subject to protection under the CWA compared to that baseline, because of changes in 

law that arise from Supreme Court decisions. The SWANCC (2001) and Rapanos (2006) 

Supreme Court decisions that altered the basis for assertion of CWA jurisdiction for some types 

of waters. The final rule is narrower in jurisdictional scope than the existing regulations, there 

would not be potential costs in comparison to this baseline. However, there is a second baseline 

founded in current field practice following the 2008 Guidance (see EPA and Corps guidance 

Clean Water Act Jurisdiction Following the U.S. Supreme Court’s Decision in Rapanos v. 

United States & Carabell v. United States, issued December 2, 2008), The agencies selected 

this second baseline for purposes of evaluating the costs and benefits associated with the final 

rule. This is because it is more in line with EPA and OMB guidance on selecting a baseline and 

reflects the expectations that most stakeholders are likely to hold 

To evaluate and estimate potential costs and benefits associated with this rule, the 

economic analysis utilizes available program data and documentation to estimate the extent to 

which assertion of jurisdiction might change under the final rule. The proposed rule analysis, 

which also estimated potential costs and benefits relative to current field practice, utilized CWA 

Section 404 jurisdictional determination and permit data from fiscal years 2009-2010, following 

issuance of program guidance in 2008 by the EPA and the Corps (post SWANCC and Rapanos). 

The analysis for the final rule has been updated using data from fiscal years 2013-2014, 

providing a comparison to more recent data, and responding to public comments expressing 

concern that the fiscal year 2009-2010 data represented a period of economic downturn. Using 

jurisdictional determination data from fiscal years 2013 and 2014, an estimate of how assertion 

of jurisdiction may change as a result of this rule is applied to cost and benefit information for 

affected CWA programs. Additional updates to the economic analysis include updated 

assumptions about the amount of compensatory mitigation occurring under CWA 404 general 

permits; a refined approach to calculating benefits from Section 404 compensatory mitigation, 

differentiating between emergent and forested wetlands; updated Section 404 wetland mitigation 

costs; and sensitivity analyses reflecting different assumptions of jurisdictional determinations 

and costs and benefits. The agencies’ analysis shows that incremental benefits always exceed 

incremental costs.

Uncertainties and Limitations

The economic analysis is necessarily based on available information and the resulting 

cost and benefit estimates correspondingly reflect available information. In estimating costs and 
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4

benefits from CWA programs under Section 311 and 401, regulator experience necessarily plays 

an important role, given a lack of complete information. The approach to estimating costs and 

benefits for each of these programs is presented in Sections 6 and 7, respectively. Additionally, 

costs and benefits estimated from potential increases in permitting in the CWA Section 402 

program, presented in Section 8, utilize data from economic analyses from the Section 402 final 

rule or the final permit that established the program. As a result, cost and benefit figures 

presented here are subject to the same limitations as those underlying analyses. Estimates of 

costs and benefits from Section 404 of the CWA are presented in Section 9. Since completion of 

the economic analysis at proposal the Corps of Engineers undertook significant efforts to 

complete quality assurance on 404 program data. This resulted in improvements in data 

availability and data quality, which in some instances revised previously-reported values. The 

estimate of benefits for newly-mitigated wetland impacts utilizes benefits transfer from stated 

preference willingness-to-pay (WTP) studies. Literature on WTP for wetlands similar to those 

likely to be protected by this rule is very limited, and was predominately published in the 1990s. 

Since that time, significant changes have been made in standard practices for this type of study, 

and thus the results presented here must be viewed accordingly. 

Recognizing these considerations, this analysis utilizes the best available information to 

assess the effects of the final rule on a variety of CWA programs and provide quantitative 

estimates for many potential impacts. The agencies took care throughout this document to 

describe the strengths and limitations of this analysis and encourage readers to treat the results 

with an appreciation of their limitations.
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5

Section 4: Estimated Changes in Positive Jurisdictional 

Determinations

To evaluate the extent to which assertion of CWA jurisdiction by EPA and the Corps 

may change as a result of this rule, EPA examined data records in the Corps’ ORM2 (Operation 

and Maintenance Business Information Link, Regulatory Module) database that documents 

Corps jurisdictional status decisions (jurisdictional determinations) associated with various 

aquatic resource types. The aquatic resource data records include the following categories: 

traditional navigable waters, relatively permanent waters, non-relatively permanent waters, 

wetlands associated with these categories; as well as uplands, impoundments, and isolated 

waters. The isolated waters category is used in the Corps’ ORM2 database to represent 

intrastate, non-navigable waters; including wetlands, lakes, ponds, streams, and ditches, that lack 

a direct surface connection to other waterways. These waters are hereafter referred to as “ORM2 

other waters.” It is important to emphasize that the ORM2 other waters group represents a more 

inclusive set of waters than would be determined to be subject to a case-specific analysis in the

final rule. The ORM2 other waters group includes many wetlands and some non-wetlands 

waters that could meet the definition of “adjacent” under the final rule as well as waters that are 

actually traditional navigable waters but that inconsistent practices following Rapanos may have 

incorrectly classified as other waters under current practice.

To examine how assertion of jurisdiction may change, the agencies reviewed negative 

jurisdictional determinations (JDs) for ORM2 other waters completed by the Corps in fiscal 

years 2013 and 2014 (i.e., determinations of no jurisdiction). Reviewing a more recent dataset 

from FY13 and FY14 responds to concerns raised in public comments that the FY09 and FY10 

dataset used in the proposal represented a period of decreased economic activity. As the agency 

that manages day-to-day implementation of the CWA section 404 program, the Corps conducts 

tens of thousands of JDs each year. For other federal CWA programs, EPA or the state (in the 

case of state-assumed programs) typically do not conduct JDs, with the exception of 

enforcement. Thus, most of the nation’s JDs for CWA purposes originate from the Corps.

Under current practice, JDs for waters determined to be “other waters” are required to be 

coordinated with EPA and Corps Headquarters, creating an organized set of JD files for review. 

JD files for positive JDs (i.e., determinations that waters are jurisdictional) are maintained by 

Corps District offices, and are not organized according to the regulatory provision under which a 

water is jurisdictional. As a result, reviewing how current positive JDs may become negative as 

a result of the final rule was determined to be outside the scope of this analysis. Analyzing only 

negative JDs allows for an estimation of only the potential increase in assertion of CWA 

jurisdiction, as viewed through the lens of CWA 404 activity during the baseline period of these 

fiscal years. The agencies recognize that the rule may result in some currently-jurisdictional 

waters being found to be non-jurisdictional.
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ORM2 aquatic resource records from FY13 and FY14 were placed into three groups: 

streams (ORM2 categories of traditionally navigable waters, relatively permanent waters, and 

non-relatively permanent waters), wetlands (associated with the various categories above of 

streams), and ORM2 other waters. These categories represent categories used in the agencies’ 

2008 guidance. Similar to the data from FY09 to FY10 that was evaluated in the economic 

analysis for the proposed rule, streams represented 65 percent of the total number of FY13 to 

FY14 records, wetlands represent 29 percent of the records, and other waters represent 6 percent

of the records.4 In the FY13 to FY14 baseline period, 93.2 percent of aquatic resource records 

were found jurisdictional where applicants sought a determination.

From this baseline level of jurisdictional determinations, the agencies estimate an overall 

percent change in positive jurisdictional determinations. The agencies begin by assuming that 

100 percent of the records classified as streams will meet the definition of tributary in the final 

rule, and 100 percent of the records classified as adjacent wetlands will meet the definition of 

adjacent in the final rule. In assuming 100 percent jurisdiction of streams and adjacent wetlands

the agencies are likely overestimating the number of positive jurisdictional determinations over 

these waters, because some of these streams and wetlands considered jurisdictional under current 

practice would not be under the final rule. Wetlands currently considered “adjacent” may be 

outside the applicable distance thresholds and non-jurisdictional. Similarly, all waters presently 

classified as streams may not meet the required physical characteristics under the final rule to be 

considered “tributary.” Note that waters that are currently found to be jurisdictional may also be 

subject to the expanded set of exclusions included in the final rule. For these and similar 

reasons, the agencies believe that positive jurisdictional determinations under the final rule will 

be less than assumed for the purposes of this economic analysis. 

The greatest change in current practice of CWA jurisdictional determinations is expected 

for waters currently known as “other waters,” and captured in the ORM2 other waters category. 

The final rule changes the existing regulation so that the basis of asserting jurisdiction for such 

waters is based on a significant nexus to a traditional navigable water, interstate water, or the 

territorial seas instead of based on a water’s ability to affect interstate or foreign commerce. As a 

result, this analysis reflects three potential ways that waters currently found non-jurisdictional as 

“other waters” could be determined to be jurisdictional: (1) a revised definition of adjacent 

waters, that includes physically proximate wetland and non-wetland waters, that under prior 

regulations were evaluated as “isolated,” (2) specific classes of waters determined to be similarly 

situated by (a)(7) in the final rule that today are subject to a case-specific significant nexus

evaluation, and (3) waters that are subject to a case-specific significant nexus analysis under 

(a)(8) and lie within 4,000 feet from the high tide line or ordinary high water mark of a 

traditionally navigable water, interstate water, territorial sea, jurisdictional impoundment of 

waters, or tributaries. 

 4 This other waters figure is consistent with the general estimate of the total proportion of “other waters” compared 

to the overall extent of wetlands and lakes (see e.g. Tiner (2003) and EPA (2014)).
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To determine how negative jurisdictional determinations may change for ORM2 other 

waters under the final rule, a team of EPA experts from across the country independently 

examined a random sample of 188 jurisdictional determination files previously generated with 

Corps headquarters during FY13 and FY14. A file may include more than one water. In total, 

these files represented over 782 individual waters in 32 states and were previously determined 

non-jurisdictional based on current regulations and guidance. Of the existing negative 

determinations for ORM2 other waters:

• 17.1 percent of negative jurisdictional determinations for ORM2 other waters were assumed 

to become positive jurisdictional determinations under the final rule because they meet the 

definition of adjacent waters and are not excluded under paragraph (b) of the rule. These 

waters fall within the 100-year floodplain and are within 1,500 feet of a stream mapped on 

the USGS’s National Hydrology Dataset (NHD). All waters within 300 feet of a stream 

mapped on the NHD are assumed to become adjacent waters. In the final rule, only waters 

that are within 100 feet of the ordinary high watermark of a non-tidally influenced traditional 

navigable water, interstate water, or a jurisdictional tributary are adjacent, so this 

overestimates waters that could become jurisdictional within this category.

o All of these waters are assumed to result in a positive jurisdictional determination for 

the purposes of the economic analysis.

• A total of 21.8 percent of the ORM2 other waters were assumed to fall within section (a)(7) 

of the final rule and not be excluded under paragraph (b) of the rule. These waters, where 

they do not meet the provisions of other paragraphs of the rule, are determined to be similarly 

situated by rule, though their jurisdiction would still need to be determined on a case-specific 

basis. 

o To estimate the likelihood that these waters could be found jurisdictional, EPA 

evaluated several factors in the areas where the five categories of waters are 

commonly found based on Dahl (2014), Moulton (2000), and Tiner (2003).

5

 Density 

of waters (i.e., their co-location with each other) and their proximity to the tributary 

system were key factors, with greater density and closer proximity generally 

capturing certain watersheds. In addition, chemical, physical, and biological features 

of each of the categories were factors, as were practical considerations such as the 

overall size and continuity of the area in which the category waters were located. 

EPA used data from the U.S. Fish and Wildlife Service’s National Wetland Inventory 

to evaluate the density of wetlands in the areas of interest. Given the high density of 

wetlands in certain watersheds where the category waters are commonly located, for 

the purposes of this analysis it is assumed that all of the waters of the selected 

 5 Dahl, T.E. 2014. Status and trends of prairie wetlands in the United States 1997 to 2009. U.S. Department of the 

Interior; Fish and Wildlife Service, Ecological Services, Washington, D.C. (67 pages).

Moulton, D. W. and J. S. Jacob. 2000. Texas Coastal Wetlands Guidebook. Texas Sea Grant (66 pp).

Tiner, R.W. 2003. “Geographically Isolated Wetlands of the United States.” Wetlands 23(3): 494-516.
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8

categories that fall into these high density watersheds will result in a positive 

determination. This is because a significant nexus analysis that considers the 

aggregation of many similarly situated waters generally is anticipated to be more 

likely to have a significant nexus than that which considers fewer waters. Nine and a 

half (9.5) percent of the total ORM2 other waters are located in these high density 

watersheds, and were assumed to have a significant nexus and be determined as 

jurisdictional for the purposes of this analysis.

o The remaining 12.4 percent of ORM2 other waters that were identified as a special 

type are located in watersheds with less dense estimated wetland coverage. Given 

this lower density, for the purposes of the economic analysis it is assumed that half of 

these waters will be found to be jurisdictional under the rule, a total of 6.2 percent 

[=12.4%*0.5].

Using these assumptions, approximately 72 percent of the ORM2 other waters that fall under 

section (a)(7) are assumed to become jurisdictional. In the context of all ORM2 other waters, 

it is assumed that a total of 15.7 percent of the ORM2 other waters will become jurisdictional 

under (a)(7) of the final rule [=9.5%+6.2%].

• The remaining 33.1 percent of ORM2 other waters could be determined to be jurisdictional 

under paragraph (a)(8) of the final rule as they do not meet the criteria for adjacency, do not 

fall under paragraph (a)(7), and are not excluded under paragraph (b) of the final rule. 

Paragraph (a)(8) of the final rule allows for a case-specific significant nexus analysis for 

waters within 4,000 feet from the high tide line or ordinary high water mark of a traditionally 

navigable water, interstate water, territorial sea, jurisdictional impoundment, or water that 

meets the definition of tributary. Paragraph (a)(8) also allows waters to be aggregated with 

waters of the same type that are similarly situated for the purposes of a significant nexus 

analysis. Some of the waters that will be determined to be jurisdictional under this category 

are presently found to be jurisdictional as adjacent waters under current practice, based on 

their connections to currently jurisdictional waters. For the purposes of this economic 

analysis, the agencies assumed that 100 percent of wetlands currently considered adjacent 

will be determined to be jurisdictional; some of these currently adjacent waters may be 

outside the distance limits of adjacency in the final rule and as a result under the final rule 

will be determined to be jurisdictional under (a)(8), if found in a case-specific analysis to

have a significant nexus. Additionally, some waters that are presently determined to be 

jurisdictional but fall outside of the 4,000 foot limit under (a)(8) or that are determined to be 

jurisdictional as adjacent waters based on connections via confined surface flow or shallow 

subsurface flows will no longer be found jurisdictional under the final rule. These potential 

reductions in positive jurisdictional determinations are not quantified as part of this analysis. 

To calculate the percentage of ORM2 other waters that could found to be jurisdictional under 

paragraph (a)(8), the agencies used the procedure described in Section 11 of the economic

analysis that accompanied the proposal, examining information on the extent of isolated 

wetlands in a watershed and the likelihood of aggregation and a positive significant nexus 

analysis. This approach estimated that 5 percent of waters may be located in watersheds 

where a positive significant nexus evaluation with aggregation is likely (and estimates 
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9

beyond 10 percent of waters being found to have a significant nexus after aggregation do not 

represent realistic assumptions.) For the purposes of this analysis, the agencies assume that 5 

percent of the remaining ORM2 other waters not meeting an exclusion under paragraph (b) 

of the final rule will be found to be jurisdictional under (a)(8). This represents 1.7 percent of 

the total number of ORM2 other waters [33.1%*.05]. 

In total, the agencies estimate that 34.5 percent of the ORM2 other waters will be found to be 

jurisdictional under this final rule. This estimate is the sum of the 17.1 percent (adjacent waters), 

15.7 percent ((a)(7)), and 1.7 percent ((a)(8)) subsets of the ORM2 other waters category.

To estimate an overall potential change in positive jurisdictional determinations from 

current practice, an increase in assertion of jurisdiction in any category of waters (streams, 

wetlands, and ORM2 other waters) must be applied proportionally based on the size of that 

category relative to the total number of waters. Figure 2 presents the results of applying the 

assumptions above to the baseline set of ORM2 other waters.

Figure 2. Projected Change in Positive Jurisdictional Determinations, Using Original 

Number of ORM2 Other Waters Records.6

Number 

of ORM2 

Records 

(FY13-

14)

Percent of 

Total 

ORM2 

Records

Positive 

Jurisdictional 

Records 

(FY13-14)

Percent 

Positive 

Jurisdiction 

(FY13-14)

Projected 

Percent 

Positive 

Jurisdiction

Relative 

Contribution 

to Overall 

Change in 

Jurisdictional 

Waters

Streams 103,591 65% 102,894 99.3% 100.0% 0.44%

Wetlands 46,781 29% 46,273 98.9% 100.0% 0.32%

ORM2 

Other 

Waters

9,715 6% 0 0.0% 34.5% 2.09%

Total 160,087 100% 149,166 93.2% 96.0% 2.84%

Label A B C D E F

Formula A/Total(A) C/A (E-D)*B

The agencies also account for waters where landowners may have assumed their waters 

to be non-jurisdictional in the FY13-14 baseline period, and thus are not represented in the 

dataset. To do this, the agencies doubled the number of ORM2 other waters over the baseline 

period. In the analysis accompanying the proposed rule, this doubling was only applied to 

waters not meeting the definition of adjacency. This assumption reflects the belief that waters 

found to be adjacent are located on the landscape such that their current jurisdictional status is 

likely to be ambiguous and so a landowner would have sought a jurisdictional determination 

prior to any water disturbance activity. Public comments expressed concern with this 

 6 Calculations reflect rounding.
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10

assumption, and as a result in this analysis the agencies doubled the number of ORM2 other 

waters for all calculations. As a result of this doubling, ORM2 other waters represent 11 percent 

of the total number of ORM2 records. Figure 3 below shows how doubling the number of 

ORM2 other waters affects the estimated increase positive jurisdictional determinations.

Figure 3 - Projected Change in Jurisdictional Determinations, using 2x the Number of 

ORM2 Other Waters Records7

Number 

of ORM2 

Records 

(FY13-14)

Percent of 

Total 

ORM2 

Records

Positive 

Jurisdictional 

Records 

(FY13-14)

Percent 

Positive 

Jurisdiction 

(FY13-14)

Projected 

Percent 

Positive 

Jurisdiction

Relative 

Contribution 

to Overall 

Change in 

Jurisdictional 

Waters

Streams 103,591 61% 102,894 99.3% 100.0% 0.41%

Wetlands 46,781 28% 46,273 98.9% 100.0% 0.30%

ORM2 

Other 

Waters

19,430 11% 0 0.0% 34.5% 3.94%

Total 169,802 100% 149,166 87.8% 91.4% 4.65%

Label A B C D E F

Formula A/Total(A) C/A (E-D)*B

Based on these assumptions, the agencies estimate a 4.65 percent overall increase in 

positive jurisdictional determinations based on the final rule, utilizing the FY13 and FY14 

jurisdictional determination dataset. The agencies believe this represents the best estimate of the 

change in jurisdictional assertion under this rule and use this number as the primary estimated 

change in jurisdictional determinations to calculate potential incremental costs and benefits when 

applied to Clean Water Act programs. To the extent that the 4.65 percent is an overestimate of 

the increase in positive jurisdictional determinations, the costs and benefits are likewise 

overestimates. The costs and benefits of other jurisdictional determination scenarios are 

presented in Appendix C. 

It is important to note that by using this estimated increase in positive jurisdictional 

determinations as a proxy for increases in permitting across the various Clean Water Act 

programs the agencies are assuming that permits (or water quality certifications) will be 

requested for every water that is determined to be jurisdictional. This assumption is conservative 

because multiple CWA permits are not likely to be issued for every water projected to be 

determined jurisdictional. However, because the agencies do not know which entities will 

 7 Calculations reflect rounding.
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require CWA permits each year and for which newly-jurisdictional waters, the agencies apply 

this 4.65 percent universally.
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Section 5: Clean Water Act Sections 303 and 305 

CWA Section 303 includes development of state water quality standards, monitoring and 

assessment of water quality, and development of total maximum daily loads (TMDLs) for waters 

that are determined by the state to not meet applicable water quality standards.

States typically develop water quality standards for general categories of waters, 

including wetlands; in addition to creating site-specific standards and more generic standards that 

can apply broadly. State water quality standards have been in effect prior to and continuing after 

the SWANCC and Rapanos decisions. Therefore, requirements for state water quality standards 

to be consistent with the CWA (designated uses, criteria to protect those uses, antidegradation 

policies) will likely not require any changes as a result of this rule. What could change is 

whether or not those standards apply to a specific water. To the extent a state believes there are 

needs for water quality standards development for specific types of waters, those needs would 

exist with or without this rule. For example, several states have distinct designated use 

categories for different types of streams, such as New Mexico which has categories for 

ephemeral waters, intermittent waters, and perennial waters. Other states have expressed interest 

in, or are in the process of, further refining the designated use categories in their water quality 

standards, or making other modifications. These are ongoing practices for water quality 

standards development and revision that have occurred and will continue to regardless of 

changes to the Federal definition of waters of the U.S. The agencies do not project any 

additional costs relating to development or revision of water quality standards as a consequence 

of this rule.

CWA 305(b) requires a report from states that includes (among other items) a description 

of the water quality of all navigable waters in the state and an analysis of the extent to which 

they meet the 101(a)(2) goals of the Act. In practice, states typically have a set budget for these 

activities and make plans accordingly. Many states strive to be as comprehensive as possible and 

balance the needs to identify all impaired waters with probabilistic surveys designed to track 

general status and trends. To the extent that this rule may increase the coverage where a state 

would wish to apply its monitoring resources, states are likely to adjust sampling locations or 

sampling frequency without a net cost increase. If a state chooses to monitor a water whose 

jurisdictional status has been affected as a result of this rule in lieu of a monitoring site currently 

in use, there may be opportunity costs associated with this change as there would no longer be 

monitoring data from the old site.

States conduct assessments based on all existing and readily-available monitoring data. 

States are required to list waters that are impaired, but have discretion to prioritize this list for 

TMDL development, which may proceed over a period of several years under EPA policy. 

Monitoring, assessment, and TMDL development tend to occur in water segments where the 
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13

agencies assertion of jurisdiction is unlikely to change. Therefore, additional cost burdens for 

TMDL development are not anticipated from this action.8

 8 It is also worth noting that the development and application of a TMDL in a watershed setting is likely to reduce 

the need for additional controls in downstream waters. In watersheds where this rule clarifies jurisdiction it may 

reduce the cost of returning an impaired water to a condition of meeting water quality standards by allowing more 

efficient control of upstream and other watershed sources of pollution.
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Section 6: Estimate of Potential Clean Water Act Section 

311 Oil Spill Prevention Program Costs and Benefits

CWA Section 311 addresses oil spill prevention and preparedness, reporting obligations, 

and response planning. These requirements apply to facilities that produce or store oil products 

based on total volume. In particular, inland non-transportation oil facilities of a certain size that 

have potential to discharge to navigable waters must prepare and implement Spill Prevention, 

Control, and Countermeasure (SPCC) plans. Potential costs of this rule associated with CWA 

Section 311 include SPCC plan development and implementation for oil storage and production 

facilities. In its 2009 Regulatory Impact Analysis for the Final Amendments to the Oil Pollution 

Prevention Regulations, EPA developed compliance unit costs for SPCC-regulated facilities, 

including plan preparation and maintenance, secondary containment, integrity testing, drainage, 

monthly inspections, security, and training. There are four categories of production and storage 

facilities, with the great majority (more than 80 percent) comprising the lowest two categories in 

terms of capacity, and the lowest unit costs for compliance. The weighted average annual 

facility cost is $9,910 for production facilities (about 35% of total facilities) and $14,155 for 

storage facilities (values adjusted to 2014$ using CPI-U).

Information from EPA Regional Office program managers and enforcement specialists 

reveal that some potentially-regulated facilities believe that they are not covered by the 

applicable SPCC regulations because they do not have the potential to discharge to a water of the 

U.S. Although there is not corresponding jurisdictional determination information as available 

for the CWA 404 permit program, it is reasonable to assume that a broader assertion of CWA 

jurisdiction may affect some of these facilities. 

Each EPA Region has historically inspected approximately 100 facilities per year for 

compliance, totaling about 1,000 inspections nationwide per year, although in the past 5 years, 

the number of inspections has averaged about 700 per year. Upon closer inspection, some of 

these facilities that asserted non-jurisdiction conclude they do need to comply. Generally, less 

arid EPA Regions report that their facilities do not question CWA jurisdiction, whereas EPA 

Regions that include more arid (western) areas more frequently encounter this claim. Some EPA 

Regions report that a handful (one to five) facilities claim non-jurisdiction and that some of these 

facilities report there are a dozen others like them. One EPA Region reports that at least 20 

entities have asserted non-jurisdiction. Assuming that 100 inspected facilities per year could 

correctly claim non-jurisdiction, it is estimated that there could be ten times more facilities 

nationwide that could successfully make this claim, resulting in a total of 1,000 facilities each 

year. Assuming that none of these 1,000 facilities have incurred compliance costs (either for the 

SPCC rule or to meet self-imposed industry standards) and would now have to come into 

compliance given their proximity to a water determined to be jurisdictional under the final rule, 

these facilities are assumed to incur weighted average compliance costs described above. The 
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15

estimated 1,000 affected facilities are divided into 350 production facilities and 650 storage 

facilities, consisted with the breakdown of the regulated facilities from the 2009 SPCC rule. 

Applying weighted average unit costs of $9,910 for production facilities and $14,155 for storage 

facilities results in approximately $12.7 million per year in incremental compliance costs.

Benefits associated with a reduction in spills associated with compliance with the SPCC 

rule include avoided costs to regulated entities to respond to the event, fines and penalties and 

market loss. The public will benefit from avoided environmental impacts that can be measured 

through willingness to pay to prevent environmental damages from oil spills. Other benefits can 

include avoided impacts to commercial fishing, avoided closures of recreational sites, and 

shutting down of drinking water intakes. EPA assumes that the risk of a spill declines through 

compliance with the SPCC by these facilities that will now be subject to CWA jurisdiction, but is 

unable to quantify these benefit for this analysis.
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16

Section 7: Estimate of Potential Clean Water Act Section 

401 Costs and Benefits

Under Section 401 of the CWA, states, tribes, and interstate agencies have the authority 

to review federal permits or licenses that may result in a discharge to waters of the United States, 

and certify if they will meet applicable water quality standards, certain other provisions of CWA 

requirements, and appropriate state or tribal laws. States, tribes, and interstate agencies may also 

condition federal permits or licenses to ensure they will not violate those laws and requirements. 

Section 401 certification is commonly used to review CWA section 404 permits issued by the 

U.S. Army Corps of Engineers, CWA section 402 permits in the four states where EPA issues 

National Pollution Discharge Elimination System permits, Rivers and Harbors Act section 10 

permits, and Federal Energy Regulatory Commission licenses for non-federal hydroelectric 

dams. Because there is not a consistent level of effort across states to implement the 401 

certification program, based on program experience EPA estimates that a representative 

distribution of effort would be 25 states dedicating 0.5 FTE (full time employees) equivalent, 20 

states dedicating 10 FTE, and 5 states dedicating 20 FTE for CWA 401 implementation. This 

tallies to 312.5 FTE nationally. 

Section 401 certification program implementation involves prioritizing and reviewing 

permits and generally requires expertise in science, engineering, and economics along with the 

associated support staff, legal support, and management. To estimate potential costs to states, 

Bureau of Labor Statistics occupational employment and wage estimates from May 2013 were 

used, adjusted to reflect fully-loaded labor costs, and updated to 2014 values using the 

Employment Cost for Employee Compensation Index (See Figure 17 , Appendix A). Using this 

data, and assuming an even mix of scientists, engineers, economists, and managers employed by 

state government, the average fully-loaded hourly wage is $43.21 per hour. Assuming an eighthour work day, 5 days a week, and 52 weeks a year, this corresponds to an annual cost of 

$89,868 per employee. Multiplying this by a total of 312.5 FTE, this yields an annual estimate 

of current expenditures of approximately $28.1 million to implement this program for all federal 

permits. In order to estimate the incremental costs associated with the final rule, a 4.65 percent

increase in Clean Water Act Section 404 permits is estimated to result in projected incremental 

costs to states of approximately $1.3 million annually. 

Figure 4 summarizes Section 401 additional administrative cost information. As the vast 

majority of states have assumed implementation of Section 402 of the Clean Water Act, 

additional costs associated with potential growth in those programs is discussed in the following 

sections. States that have not assumed the Section 402 program have the opportunity to 

complete Section 401 certifications on these permits. However, the Section 402 programs most 

likely to be affected by this rule and thus examined in this analysis are typically implemented via 

existing statewide general permits, where a Section 401 certification already exists and 
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17

permittees simply submit a Notice of Intent. Therefore, while these permits may see increased 

usage, there will not be any additional Section 401 review burden for states that have not 

assumed the NPDES program, as these general permits already exist, with state Section 401 

certification.

Figure 4 - Estimated Additional CWA Section 401 Administrative Costs to States

FTE Amount 

for 401 Number of States Total FTE

Total Costs 

(2014$)

0.5 25 12.5 $1,123,351

10 20 200 $17,973,613

20 5 100 $8,986,807

Total: 312.5 $28,083,771

4.65% Incremental Increase: 14.5 $1,305,895

States may place additional restrictions on permits through their Section 401 authority, 

adding costs to permittees and environmental benefits. States can require permit conditions to 

protect water quality regardless of the scope of Clean Water Act jurisdiction. The costs and 

benefits associated with the conditions a state may place on a permit via Section 401 certification 

do not need to be added to the costs and benefits of this rule. States impose conditions on 

permits in watersheds where there are water quality concerns, which exist independently of this 

rule. Even in the absence of this rule, in watersheds where a state has water quality concerns it 

may impose additional permit conditions on permits issued within that watershed.
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Section 8: Estimate of Potential Clean Water Act Section 

402 Costs and Benefits

Section 402 of the CWA establishes the National Pollutant Discharge Elimination 

System (NPDES) program to provide for permits to point sources, with applicable 

requirements and conditions, to discharge pollutants to waters of the U.S. NPDES permits 

address the discharge of a pollutant, yet may reflect different statutory and regulatory

requirements depending on the type of point source and volume of discharge, and state water 

quality standards.

When evaluating potential impacts to NPDES permit costs associated with the final 

rule, EPA assumes that the decrease in waters that are jurisdictional associated with

implementation of the 2008 Guidance has not greatly affected the number of entities requiring 

individual CWA Section 402 permits, such as those issued for municipal wastewater treatment 

plants or industrial facilities. The EPA has not witnessed a large number of permit holders 

asserting they no longer required such a permit because of the non-jurisdictional status of a 

receiving water. While EPA is aware of occasional inquiries on this matter, no such inquiries 

have resulted in a permitting authority determining that a discharger no longer needed a 

permit. There are several potential explanations for this. First, the nature of a traditional 

discharge permit where a facility is seeking to have wastewater dispersed and carried away is 

different than a Section 404 permit where an entity is, for example, seeking to fill a portion of 

a natural waterway for development. As such, it is possible that a CWA 402-permitted 

discharger may have the effect of creating a permanent water where there once was an 

intermittent or ephemeral water because of continuous discharge (i.e., an “effluent-dependent” 

or “effluent-dominated” water). In these cases, jurisdiction may not come under question. 

Second, EPA has authorized most (46) states to operate the CWA Section 402 permitting 

program, and states assert jurisdiction over “waters of the state” which must be as inclusive as 

“waters of the U.S” but may be more expansive. In contrast, only two states (Michigan and 

New Jersey) have assumed the Section 404 program (to the extent it can be assumed for “nonnavigable” waters). Additionally, facilities may have invested the capital in treatment and 

simply be willing to continue operating under their permit and see no need to challenge 

jurisdictional status.

Permitting for construction and development stormwater, concentrated animal feeding 

operations (CAFOs), and pesticide application are three areas of CWA Section 402 

implementation where it is assumed there may be potential new costs associated with a change in 

the definition of “waters of the U.S.” This is because these activities relate to collection of 

stormwater runoff rather than disposal of domestic or industrial wastewater, and EPA and states 
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19

typically regulate them through CWA Section 402 general permits rather than individual permits. 

Entities engaged in actions requiring general permit coverage can submit a Notice of Intent 

(NOI) to the permitting authority to obtain coverage. Under the existing implementation of the 

scope of “waters of the U.S.”, many of these entities may not believe their discharge affects a 

protected water and may not have applied for permit coverage. Under the rule, a portion of these 

entities may be subject to an assertion of jurisdiction to a similar extent as those seeking Section 

404 permits. Construction-related stormwater discharges, CAFO discharges, and application of 

pesticides are more likely occur in similar locations as CWA Section 404 dredge and fill 

discharge with respect to proximity to “isolated waters,” small streams, and their adjacent 

wetlands. Thus there may be costs from this rule under these programs include implementing 

best management practices (BMPs) for regulated entities and administering permitting programs 

for government. The analysis here is derived from the estimates of direct costs for those rules.

The stormwater, CAFO, and pesticide general permit were finalized over a time period 

from 2003 to 2011. As such, these rules incorporated differing baselines of Clean Water Act 

jurisdiction in their analysis depending on if they were completed before or after the 2008 

Rapanos decision and corresponding 2008 Guidance. These differences are discussed in the 

sections that follow. All analyses going forward will include the new definition of “waters of the 

U. S.” established in this final rule as part of the baseline.
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20

Section 402 Stormwater Permitting 

Stormwater runoff is generated when precipitation from rain and snowmelt events flows 

over land or impervious surfaces and does not percolate into the ground. As the runoff flows 

over impervious surfaces (paved streets, parking lots, and building rooftops), it accumulates 

debris, chemicals, sediment or other pollutants that could adversely affect water quality if the 

runoff is discharged untreated. The primary method to control stormwater discharges is the use 

of best management practices (BMPs). In addition, most stormwater discharges have been 

designated as point sources by statute, regulations, or on a case-by-case basis and require 

coverage under a NPDES permit. The Stormwater program was implemented in two phases, 

with Phase I rule issued in 1990 and Phase II issued in 1999. The Stormwater program regulates 

construction sites, specific industrial sectors specified in the Phase I rule, and discharges from 

Municipal Separate Storm Sewer Systems (MS4s).

Stormwater runoff in cities and towns is commonly transported through MS4s, from 

which it is often discharged, untreated, into local waters. To prevent harmful pollutants from 

being washed or dumped into an MS4, operators must obtain a NPDES permit and develop a 

stormwater management program. The Stormwater Phase I rule, issued in 1990, requires 

medium and large cities or certain counties with populations of 100,000 or more to obtain 

NPDES permit coverage for their stormwater discharges. The Stormwater Phase II rule, issued 

in 1999, requires regulated small MS4s in urbanized areas, as well as small MS4s outside the 

urbanized areas that are designated by the permitting authority, to obtain NPDES permit 

coverage for their stormwater discharges. Generally, Phase I MS4s are covered by individual 

permits and Phase II MS4s are covered by a general permit. Each regulated MS4 is required to 

develop and implement a stormwater management program (SWMP) to reduce pollutant 

discharge from stormwater to the “maximum extent practicable” (MEP) and eliminate nonstormwater discharges. 

A MS4 may have several different outflows within its service area, and some may be to 

waters where CWA jurisdiction may not apply. However, in implementing a SWMP, operators 

likely implement BMPs uniformly across their area without regard to the specific location of a 

specific outfall, and thus the jurisdictional status of a portion of the receiving water would not 

matter in terms of costs. In addition, MS4 outfalls tend not to be in wetlands, which represent a 

large portion of the CWA Section 404 program aquatic resource records, and the waters where 

the greatest changes in assertion of CWA jurisdiction is expected under this rule. Thus, the true 

cost of the project impact is likely to be low. Any potential costs to MS4s resulting from 404 

permit requirements are captured in Section 9. With regard to 404 permits for MS4s, the 

agencies’ longstanding practice is to view stormwater control measures that are not built in 

“waters of the United States” as non-jurisdictional. Conversely, the agencies view some waters, 

such as channelized or piped streams, as jurisdictional currently even where used as part of a 

stormwater management system. The proposed rule brought to light confusion about which 
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21

stormwater control features are jurisdictional waters and which are not, and this confusion is 

addressed in the final rule via a specific exclusion for stormwater control features that are created 

in dry land.

Economic impacts to industrial facilities regulated under the EPA Phase I stormwater rule 

are also expected to be minimal. Most industrial sectors regulated under the Phase I stormwater 

rule are located in urbanized areas where newly-designated jurisdictional waters are not expected 

to exist. If any entities are currently discharging to a non-jurisdictional water, they are currently 

required to have a NPDES permit if their discharge later reaches a jurisdictional 

water. Regulated industrial sectors that could occur in areas where newly-designated

jurisdictional waters may occur (i.e., timber product facilities in SIC code 24; mining and oil and 

gas extraction and refining facilities in SIC codes 10-14; landfills; and air transportation facilities 

in SIC code 45) represent a minority of the regulated industrial stormwater universe (less than 30 

percent of facilities authorized to discharge under the EPA-issued Multi-Sector General Permit 

(MSGP) are in one of these sectors). Additionally, these types of facilities are generally large 

(the average acreage of facilities authorized to discharge under the EPA MSGP in these sectors is 

262 acres), and due to their scale it is expected that industrial facilities affected by the Phase I 

rule likely already discharge to, or their discharge reaches, a water of the U.S. Consequently, the 

majority of facilities in these sectors are presently covered under an existing NPDES permit and 

would not be newly-regulated under this rulemaking. Furthermore, nearly all oil and gas 

facilities qualify for an exemption from NPDES permitting and would not be affected by the 

rule. Section 402(l)(2) of the Clean Water Act (CWA) exempts from NPDES permitting 

“discharges of stormwater runoff from, oil and gas exploration, production, processing, or 

treatment operations or transmission facilities, composed entirely of flows which are from 

conveyances or systems of conveyances... which are not contaminated by contact with, or do not 

come into contact with, any... raw material, intermediate products, finished product, byproduct, 

or waste products located on the site of such operations.”

Stormwater runoff from construction activities can have a significant impact on water 

quality. As stormwater flows over a construction site, it can pick up pollutants like sediment, 

debris, and chemicals and transport these to a nearby storm sewer system or directly to a river, 

lake, or coastal water. Polluted stormwater runoff can harm or kill fish and other wildlife. 

Sedimentation can destroy aquatic habitat, and high volumes of runoff can cause stream bank 

erosion. Debris can clog waterways and potentially reach the ocean where it can kill marine 

wildlife and impact habitat.

The NPDES stormwater program requires certain construction site operators to obtain 

coverage under a NPDES permit for their stormwater discharges. The construction site operators 

subject to NPDES requirements are those engaged in clearing, grading, and excavating activities 

that disturb one acre or more; including smaller sites in a larger common plan of development or 

sale.
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22

To estimate potential incremental costs and benefits from the construction stormwater 

permitting program EPA used information from the Economic Analysis of Final Phase II Storm 

Water Rule.

9

 The Stormwater Phase II rule was promulgated prior to the two Supreme Court 

cases addressing CWA jurisdiction and nearly all waters that may have a change in their 

jurisdictional status as a result of implementation of the final Clean Water Rule were 

jurisdictional at that time. All costs associated with the Phase II Stormwater Rule were fully 

accounted for in the economic analysis that accompanied the Phase II rule and it would not be 

wrong to not explicitly include them here. However, this analysis identifies the component of 

the original stormwater costs and benefits that may be attributed to changing jurisdictional 

assertions. This is done by taking a 4.65 percent of the total costs and benefits calculated in the 

1999 Stormwater economic analysis. 

Since the issuance of the stormwater Phase II rule there has also been growth in the 

industry either through changes in the construction industry or changes in permitting levels 

resulting from the SWANCC and Rapanos decisions affecting CWA jurisdictional assertion. The 

1999 Economic analysis cites to 130,000 construction starts in 1994. EPA tracks NPDES permit 

numbers for reporting program performance under EPA’s Strategic Plan pursuant to the 

Government Performance and Results Act (GPRA).10 EPA’s 2011 reporting cites 169,000

construction sites with permit coverage; in 2014 164,000 covered construction sites were 

reported. For the purposes of this analysis growth is calculated from the higher level of 

permitting in 2011, which corresponds to 30 percent growth in the program. 

Figure 5 summarizes costs and benefits for construction and development stormwater 

permitting, with costs and benefits figures updated from 1998 to 2014 dollars using the CPI-U. 

Increases in administrative costs are estimated to total $360,000 annually. EPA has authorized 

most states to implement the NPDES stormwater permitting program, so these administrative 

costs accrue to states implementing the program. Costs to new permit-holders are estimated to 

range from $47.8 to $59.6 million annually. This cost estimate includes the costs of 

implementation of erosion and sediment controls and post-construction controls. Similarly, 

benefits are estimated to range from $47.5 to $60.2 million, which reflect public willingness-topay for water quality improvements achieved by the stormwater rule. 

 9 U.S. Environmental Protection Agency. 1999. Economic Analysis of Final Phase II Stormwater Rule. U.S. 

Environmental Protection Agency, Washington, D.C. 10 http://water.epa.gov/resource_performance/planning/index.cfm.
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23

Figure 5 - Estimated Annual CWA 402 Stormwater Permitting Impacts ($ millions)

Administrative 

Costs

Compliance

Costs

(low estimate)

Compliance

Costs

(high estimate)

Monetized 

Benefits

(low estimate)

Monetized 

Benefits 

(high 

estimate)

Original 

Rule 

Analysis

(1998$) $5.3 $545.0 $678.7 $540.5 $686.0

4.65% 

Component 

of 

Stormwater 

Program 

affected by

CWR $0.2 $25.3 $31.6 $25.1 $31.9

30% 

Program 

Growth $0.3 $32.9 $41.0 $32.7 $41.5

Total 

Incremental 

Change 

(2014$) $0.5 $47.8 $59.6 $47.5 $60.2
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24

Section 402 Concentrated Animal Feeding Operation Permitting

Facilities that meet the definition of Concentrated Animal Feeding Operations (CAFOs) 

under CWA regulations are point sources under the CWA and are regulated under the NPDES 

permitting program. Most current permit holders are covered under state-issued general permits, 

and thus administrative costs for implementing the program fall to states and CAFO operators. 

EPA promulgated regulations for Concentrated Animal Feeding Operations (CAFOs) in 2003 

that expanded the number of operations covered by CAFO regulations and included requirements

for nutrient management plans for land application of manure from CAFOs. EPA revised this 

regulation in 2008 to reflect changes based on a Second Circuit Court decision. However, the 

basic cost and benefit information from the original economic analysis is useful for estimating 

potential impacts in a similar manner as above for stormwater.11 

In the Economic Analysis to support the 2003 CAFO rule EPA estimated a potential 

universe of 15,000 affected entities. The CAFO rule was finalized in February 2003, after 

issuance of the SWANCC Supreme Court decision in 2001. Therefore, estimates of the affected 

universe of CAFOs would reflect changes in jurisdictional assertion as a result of SWANCC. 

More recent permit data indicate that in 2011 7,318 entities held CAFO permits, and in 2014 

6,946 entities were permitted. These changes in permitting numbers may be the result of 

changes in size of the CAFO industry, or changes in jurisdictional assertion following the 

implementation of the agencies’ 2008 Guidance interpreting the Rapanos decision. These recent 

permit numbers remain significantly below the 15,000 entities projected to be affected in the 

2003 analysis, and so for this analysis the CAFO program size is decreased by 49 percent, to 

more accurately reflect the current universe. From this current program size, a 4.65 percent 

increment of the total costs and benefits is taken to account for an estimated increase in 

permitting resulting from changes in positive jurisdictional assertion from this rule. Lastly, costs 

presented in the 2003 analysis are updated from 2001 dollars to 2014 using the CPI-U, which 

accounts for inflation over this time period. 

Figure 6 summarizes the estimated costs and benefits associated with increased permit 

activity in the CAFO program due to an increase in Clean Water Act jurisdiction. Incremental 

costs to CAFO operators are estimated to total $9.9 million annually. Administrative costs, 

which accrue to states that have assumed the NPDES program, are estimated to total $270,000

annually. Using the benefits figures monetized in the original analysis provides estimated 

benefits ranging from $6.2 to $10.8 million annually. These benefits were calculated for large 

CAFOs only, which account for 85% of the implementation costs and 66% of administrative 

costs. Benefits for smaller CAFO operations were not calculated in the 2003 analysis. 

Monetized benefits are primarily from improved surface water quality (measured in terms of 

 11 National Pollutant Discharge Elimination System Permit Regulation and Effluent Limitation Guidelines and 

Standards for Concentrated Animal Feeding Operations (CAFOs), Final Rule. Federal Register 68 (12 February 

2003): 7176-7274.
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25

enhanced recreational value), reduced nitrates in private wells, reduced shellfish bed closures 

from pathogen contamination, and reduced fish kills from episodic events. EPA was not able to 

monetize a number of benefits categories, including human health and ecological benefits of 

reduced exposure to pollutants associated with CAFO manure; reduced eutrophication of coastal 

and estuarine waters due to both nutrients and runoff and deposition of ammonia volatized from 

CAFOs; reduced human illness due to pathogen exposure during recreational activities in 

estuaries and coastal waters; improvements in soil properties due to reduced over-application of 

manure, together with an increased acreage receiving manure applications at agronomic rates; 

reduced pathogen contamination in private drinking water wells, and reduced cost of commercial 

fertilizers for non-CAFO operations. 

Figure 6 - Estimated Annual CWA 402 CAFO Permitting Impacts ($ millions)

Administrative 

Costs

Compliance 

Costs

Monetized 

Benefits

(low estimate)

Monetized 

Benefits

(high estimate)

2003 Rule 

Analysis (2001$) $9.0 $326.0 $204.0 $355.0

49% Program 

Size Decrease $4.4 $159.7 $100.0 $174.0

4.65% Increment $0.2 $7.4 $4.6 $8.1

Total 

Incremental 

Change (2014$) $0.3 $9.9 $6.2 $10.8
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26

Section 402 Pesticide General Permitting

On October 31, 2011, EPA issued the final NPDES general permit for point source 

discharges to waters of the United States from the application of (1) biological pesticides, or (2) 

chemical pesticides that leave a residue. This permit, also known as the Pesticide General Permit 

(PGP), was developed in response to a decision by the Sixth Circuit Court of Appeals (National 

Cotton Council, et al. v. EPA). The Agency’s final PGP covers operators that apply pesticides 

that result in discharges from the following use patterns: (1) mosquito and other flying insect 

pest control; (2) weed and algae control; (3) animal pest control; and (4) forest canopy pest 

control. The permit requires the minimization of pesticide discharges through the use of pest 

management measures and monitoring for and reporting of any adverse incidents. The general 

permit provides coverage for discharges in the areas where EPA is the NPDES permitting 

authority. In the remaining areas (44 states and the U.S. Virgin Islands), which are not included 

in the PGP analysis, states are authorized to develop and issue the NPDES pesticide permits.

To estimate potential costs associated with an increase in CWA jurisdiction from 

pesticide general permits, EPA utilized the economic analysis completed to support the pesticide 

general permit.12 This analysis was completed in 2011, and so the baseline for the analysis 

incorporated any effects on jurisdiction resulting from SWANCC and Rapanos. The economic 

analysis focused on the 35,376 entities where EPA is the permitting authority. In other 

documentation EPA estimated approximately 365,000 entities could be affected nationwide once 

states developed and issued their own general permits for these discharges. The cost figures 

estimated in the original PGP analysis are scaled up to reflect this larger, nationwide universe, 

which inherently assumes that the costs of compliance will be similar in areas where EPA is not 

the permitting authority. States use the EPA PGP as a model, but they may deviate from the

EPA permit and in those circumstances the cost estimates presented here may not be 

representative. The estimated 4.65 percent increase in jurisdiction is applied to the cost figures 

from the original PGP analysis and then the number is scaled up to the entire potential universe 

size to estimate potential new costs and benefits resulting from this rule. After adjusting for 

inflation, costs range from $5.4 to $5.9 million. Figure 7 summarizes the process and estimated 

costs. The original PGP economic analysis did not estimate administrative costs to government 

entities nor did it quantify benefits, and these values are not estimated here.

 12 U.S. Environmental Protection Agency. 2011. Economic Analysis of the Pesticide General Permit (PGP) for 

Point Source Discharges from the Application of Pesticides. U.S. Environmental Protection Agency, Washington, 

D.C.
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27

Figure 7 - Estimated Annual CWA 402 PGP Impacts ($ millions)

Compliance Costs

(low estimate)

Compliance Costs

(high estimate)

Original PGP 

Estimates (2009$) $10.2 $11.2

4.65% Increment $0.5 $0.5

Scale Up to Total 

Potential Universe $4.9 $5.4

Total Incremental 

Change (2014$) $5.4 $5.9
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28

Section 9: Estimate of Potential Clean Water Act Section 

404 Costs and Benefits

Section 404 of the CWA establishes a program to regulate the discharge of dredged or fill 

material into waters of the United States, including wetlands. Activities in waters of the United 

States regulated under this program include fill for development, water resource projects (such as 

dams and levees), infrastructure development (such as highways and airports), and mining 

projects. Section 404 requires a permit before dredged or fill material may be discharged into 

waters of the United States, unless the activity is exempt from Section 404 regulation. Proposed 

activities are regulated through a permit review process. An individual permit is required where 

impacts are more than minimal.

Individual permit applications are reviewed by the U.S. Army Corps of Engineers, which 

evaluates applications under a public interest review, as well as the environmental criteria set 

forth in the CWA Section 404(b)(1) Guidelines. However, for most discharges that will have 

only minimal adverse effects, a general permit may be suitable. General permits are issued on a 

nationwide, regional, or State basis for particular categories of activities. The general permit 

process eliminates individual review and allows certain activities to proceed with little or no 

delay, provided that the general or specific conditions for the general permit are met. The great 

majority of discharges are authorized under a general permit.

An increase in assertion of CWA jurisdiction could produce costs of implementation of 

the Section 404 program as well as increased benefits. Regulated entities may face costs 

resulting from this rule through permit application costs, and associated compliance costs such as 

wetlands mitigation, stream mitigation, and project re-design and relocation expenses. There 

may also be program management costs and efficiencies associated with administering the 

Section 404 program. These costs are described in Section 11. 

Through clarifying jurisdiction, this rule may result in an increase in Section 404 permits

with associated costs. Ecological benefits will accrue from those permitted losses being offset 

through compensatory mitigation. These benefits are also presented in this section, based upon a 

benefits transfer analysis using studies measuring willingness to pay for preservation of wetlands 

similar to the type likely to be protected by this rule.

CWA Section 404 Compliance Costs

An increase in assertion of CWA jurisdiction could result in costs of implementation of 

the CWA 404 program: a greater number of development projects would impact jurisdictional 
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29

waters, thus requiring the sponsors of those additional projects to obtain and comply with CWA 

Section 404 permits. Figure 8 provides a descriptive overview of four types of CWA Section 

404 permitting costs the regulated community could face – permit application costs, permitting 

time costs, impact avoidance and minimization costs, and compensatory mitigation costs.

Figure 8 - Conceptual Overview of CWA Section 404 Permit Compliance Costs

Cost Category Description (costs vary considerably by permit type and by 

geographic region)

Permit 

Application Costs

Financial costs to finalize a permit application to a point that the Corps 

deems the application complete. Includes costs for delineation and survey 

of jurisdictional waters; preparing project area and impact drawings and 

maps; alternatives analysis that investigates opportunities to avoid and 

minimize project impacts (on-site alternatives in the case of general 

permits, both on- and off-site alternatives in the case of individual 

permits); developing a Corps-approved compensatory mitigation plan; 

submitting a completed application that includes all notification and other 

requirements. In general, permit application costs increase with the size of 

the project area, size of impacts to jurisdictional waters, the number of 

separate impact locations, and any actions needed to comply with other 

Federal laws before a permit can be issued (e.g., Endangered Species Act, 

National Historic Preservation Act). The cost of the alternatives analysis 

often dominates application costs for individual permits in the case of 

projects involving relatively large impacts to jurisdictional waters.

Permitting Time 

Costs

Potential financial and opportunity costs associated with any delay in 

project implementation resulting from the time it takes to secure a permit. 

In the case of private sector, for-profit development projects, time costs 

could include financial or opportunity costs of carrying development 

capital for longer periods of time. In the case of public sector projects, 

time costs could include opportunity costs of forgone public services and 

benefits from not proceeding with the project sooner rather than later.

Impact Avoidance 

and Minimization 

Costs

Potential financial and opportunity costs associated with project redesign 

that may be required in order to avoid and minimize impacts on 

jurisdictional waters. Opportunity costs could include foregone net returns 

to development in the case of private sector, for-profit development 

projects, or lower levels of public service provision and benefits in the 

case of public sector projects (e.g., road construction and maintenance, 

repair of flood control infrastructure, etc.).

Compensatory 

Mitigation Costs

Financial and opportunity costs to implement the Corps-approved 

compensatory mitigation plan that is written into the permit as a special 

condition. In the case of a mitigation plan that involves third-party 

mitigation providers (commercial mitigation banks or in-lieu fee 

programs), cost is driven by credit prices and the number of credits 

required. In the case of a permittee-responsible mitigation plan, this may 

include opportunity costs of reserving a portion of development project 
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30

lands for mitigation, and the financial costs of mitigation project 

implementation as well as mitigation monitoring, maintenance, and 

reporting until success criteria have been achieved. This could also 

include financial and opportunity costs of posting any required financial 

assurances for mitigation project success and/or providing any required 

endowment for long-term site management after mitigation success has 

been achieved.

The sponsors of projects subject to CWA Section 404 regulation incur costs to finalize a 

permit application (or a pre-construction notification in the case of general permits) that the 

Corps deems to be complete. Similarly, the sponsors of permitted projects also incur costs to 

implement compensatory mitigation actions required by permits to offset permitted impacts to 

jurisdictional waters. The analysis of incremental costs to the regulated community focused on 

the estimation of these two categories of compliance costs. Depending on circumstances, the 

sponsors of many private sector as well as public sector projects that are subject to Section 404 

permitting can also incur permitting time costs and/or impact avoidance and minimization costs. 

Permitting time costs include potential financial and opportunity costs associated with delays in 

project implementation resulting from the time it takes to secure a permit. Impact avoidance and 

minimization costs include potential financial and opportunity costs associated with permit 

requirements to redesign projects so as to avoid and minimize project impacts on jurisdictional 

waters to the extent practicable. The permit costs presented here include estimation of the costs 

of preparing a complete CWA Section 404 permit package, which includes an analysis of 

alternative to avoid and minimize impacts. However, the agencies recognize that there may be 

circumstances where specific individual permit applicants may be asked to do additional 

analyses or project redesign. The agencies recognize that these costs can be significant for 

affected permit applicants; however, these are very case-specific costs and lacking data to 

support a credible approach to estimating these costs, they are excluded from this analysis. 

The agencies utilize estimates of the number of additional permits and the average impact 

per permit to produce an estimate of additional acres of permitted impacts and associated costs 

that could result from this rule. In order to estimate the number of additional permits, a baseline 

level of activity must be established. The agencies examined data from ORM2 on the number of 

individual permits and general permit authorizations issued each fiscal year, from FY2009 to

FY2014. For the purposes of this analysis individual permits include standard permits and letters 

of permission while general permits include nationwide permits, programmatic general permits, 

and regional general permits. Permitting data records considered include permits issued under 

Clean Water Act Section 404. Data associated with permits issued under Sections 9 and 10 of 

the Rivers and Harbors Act of 1899; and Marine Protection, Research, and Sanctuaries Act 

Section 103 authority were excluded. Figure 9 shows a graph of the number of individual and 

general permits issued each year. Individual permit levels fluctuate between a low of 3,292 

permits issued in fiscal year 2014 and a high of 4,672 permits issued in fiscal year 2009. General 
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31

permit levels peak in fiscal year 2014 with 60,020 permits issued, while the minimum number of 

52,287 general permits were issued in fiscal year 2009.

Figure 9 – Individual 404 Permits (IP) and General 404 Permits (GP) Issued per Fiscal Year

In the proposed rule analysis, the agencies used a level of permitting based on permit

numbers from FY2010. Commenters expressed concern that this level of permitting activity was 

from a time of depressed economic activity. To be responsive to these comments, in this 

analysis the agencies formed the baseline level of permitting activity by independently selecting 

the maximum number of individual permits issued in a year (4,672 from fiscal year 2009) and 

the maximum number of general permits issued in a year (60,020 from fiscal year 2013). Figure 

10 provides a summary of this baseline level of activity. Separately selecting maximum numbers 

of issued general and individual permits creates a baseline level of permitting that actually has 

larger total permit numbers than ever actually occurred in an individual fiscal year from FY2009

to FY2014. This results in a potential over-estimate of impacts associated with an increase in

positive jurisdictional determinations, but addresses concerns that the analysis used a baseline 

level of economic activity more reflective of an economic downturn.

In order to estimate the potential additional impacted acreage of jurisdictional waters it is 

necessary to develop an estimate of the average impact per permit type. To develop this 

estimate, permanent impacts from FY2013 were considered, while excluding temporary 

0

10,000

20,000

30,000

40,000

50,000

60,000

70,000

FY09 FY10 FY11 FY12 FY13 FY14

Number of Permits

Fiscal Year

404 Permits Issued per Fiscal Year

IP

GP
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32

impacts13 as well as restoration and conversion activities. Records with non-zero values in the 

authorized area field were included (entries that contained just a linear feet impact value or null 

values were excluded). By dividing the total number of non-restoration permanent impacts by 

the total number of FY2013 permits of this type, we are able to calculate an average impact per 

permit, presented in Figure 10. This average impact per permit is then multiplied by the 

estimated increase in permits to produce an estimate of the total additional impacted acreage. 

Since issuance of the proposed rule, a data quality assurance effort was undertaken by the 

Corps. As a result, the average impact per permit reported here has been more thoroughly vetted 

than the value previously reported in the proposal analysis.

Figure 10 – Estimated Additional CWA Section 404 Permits and Impacts to Jurisdictional 

Waters

Permit 

Type

Maximum 

Number 

Permits Issues 

(FY09-14)

Estimated Additional 

Permits w/ Rule 

(Assuming 4.65% 

increase in jurisdiction)

FY13 Average 

Impact Per 

Permit 

(Acres)

Total 

Additional 

Impacts 

(Acres)

Individual 4,672 217 5.94 1,290

General 60,020 2,791 0.43 1,200

Total 64,692 3,008 2,491

Permit Application Costs

The agencies use two sets of estimates for permit application costs to calculate a range of 

incremental permit application costs associated with the estimated increase in permitting 

resulting from the final rule. These estimates of permitting costs were developed to calculate 

incremental permit application costs associated with the replacement of Nationwide Permit 26 

(NWP 26) with a suite of new and modified nationwide permits in the year 2000 (hereafter 

referred to as the “NWP replacement package”).

The Corps developed an estimate of permit costs as part of its analysis of the incremental 

costs of the NWP replacement package. This estimate relied on data and information obtained 

through informal phone interviews with Corps District staff and consulting firms from around 

the country that assist the regulated community in navigating the permitting process. The Corps 

asked interviewees to identify major components and component and total costs for finalizing a 

NWP 26 pre-construction notification and an individual permit application associated with a 

“typical” project involving up to three acres of impacts to jurisdictional waters. 

 13 For example, the Corps’ 2012 Nationwide Permit 33 provides that temporary structures, work, and discharges, 

including cofferdams; necessary for construction activities or access fills or dewatering of construction sites can be 

authorized if the fill is removed in its entirety and will have no more than minimal adverse effects on aquatic 

resources.
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33

The Corps analysis of unit permit application for the NWP replacement package 

explicitly notes that the cost estimates were developed for a “typical” project, and that individual 

permit (IP) application costs for some projects could be much higher than the estimates produced 

for the NWP replacement package (e.g., it noted that in the case of large projects, the costs for 

the alternatives analysis alone could be several times the Corps estimates of IP application costs 

for a typical project). Further, permit application costs can vary considerably by region, so the 

cost for a typical project in one region can be considerably different than the cost for a typical 

project in another region. Also, the Corps analysis of individual permit application costs for the 

NWP replacement package was limited to projects affecting up to three acres of jurisdictional 

waters, whereas this final rule could involve new permit application costs for projects involving 

significantly greater impacts to waters now determined to be jurisdictional (which is relevant 

since permit application costs generally increase as the impact size increases). For these reasons, 

in this analysis the agencies use the highest Corps estimates of unit permit application costs as a 

lower bound of estimated permit application costs associated with the final rule.

The NWP replacement analysis from the Corps estimated permit application costs for a 

pre-construction notification under NWP 26 could range from $3,000 - $10,000 and permit 

application costs for a standard or individual permit could range from $10,000 to $24,000. As 

discussed above, the high range of each of these costs was selected as a lower-bound permit 

application cost. The dollar figures were also adjusted for inflation from 1999$ to 2014$ using 

the CPI-U.

An estimate of NWP replacement costs was also commissioned by the National 

Association of Counties and the Foundation for Environmental and Economic Progress, whose 

members include large real estate development companies. This study, completed by David 

Sunding and David Zilberman, is hereafter referred to as the SZ study. The SZ study relied on a 

survey of 103 NWP and IP applications for which the project sponsors were asked to report the 

costs they incurred in preparing and finalizing the applications. Two-thirds of the applications in 

the survey sample involved projects in western states and the remainder involved applications in 

eastern or midwestern states. The sample involved a roughly equal mix of public sector and 

private sector development projects, including school construction, quarry expansion, sediment 

containment, home building, road improvements, and flood control.14 The analysis of the survey 

data found a statistically-significant positive relationship between the amount of permitted 

impacts on jurisdictional waters and the cost of preparing a NWP or an IP. The authors used the 

survey data to develop a relationship between impacts to jurisdictional waters (measured in 

acres) and the cost of preparing a NWP and an IP. For each permit type, the SZ study produced 

 14 These details on the projects included in the survey sample are reported in: D. Sunding and D. Zilberman. 2002. 

“The economics of environmental regulation by licensing: An assessment of recent changes in the wetland 

permitting process.” Natural Resources Journal. V. 42, Winter.
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34

an estimate of a fixed cost component plus another cost component that varied based on the 

amount of impact acres.15 

Figure 11 shows the unit application costs obtained from the two sources discussed 

above, and the estimated range of additional permit applications costs for individual and general 

permits based on the estimated increase in permits data from Figure 10. All cost figures are 

adjusted from 1999$ to 2014$ using the CPI-U.

Figure 11 - Estimated Annual Additional CWA Section 404 Permit Application Costs

Permit 

Type

Add’l 

Permits 

with 

Rule

FY13 

Avg. 

Impact 

per 

Permit 

(acres)

Unit Costs 

from 

Corps 

NWP 

Analysis 

(2014$)

Unit Costs from SZ 

Study (2014$)

Estimated 

Add’l Annual 

Permitting Cost

(2014$ millions)

Low

Estimated 

Add’l Annual 

Permitting 

Cost

(2014$ 

millions)

High

Individual 217 5.94 $34,100

$62,000 plus 

$16,800 per acre of 

impact $7.5 $13.7

General 2,791 0.43 $14,200

$23,900 plus 

$13,200 per acre of 

impact $39.9 $67.1

Total 3,008 $47.3 $80.8

Compensatory Mitigation Costs

A portion of costs to applicants will result from compensatory mitigation of wetlands and 

streams. The cost of compensatory mitigation depends upon land prices and the complexity of 

the work and varies substantially across and within states. Additionally, the scale of a project 

will affect costs as the amount of compensatory mitigation required is typically calculated as a 

multiple of acreage of wetlands or linear feet of streams to be filled.

To estimate state-specific per-acre costs of wetland mitigation and per linear foot 

estimates of stream mitigation, the Corps examined published studies and survey results, made 

phone inquiries to Corps Districts and mitigation banks, and researched web sites. A team of 

Corps experts developed a range of values for each state. These costs have been updated by the 

Corps since the proposal, where new data have become available. Costs for mitigation in 

estuarine environments, whose jurisdictional status likely will not be affected by this rule, are not 

 15 The range of NWP application costs in the survey was between $2,000 and $140,076; the median cost was 

$11,800, and the mean cost was $28,915. The range of IP application costs in the survey was between $7,000 and 

$1,530,000; the median cost was $155,000 and the mean cost was $271,596. (All estimates are presumed to reflect 

1999$) 
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35

included where explicitly identified by mitigation bank and in-lieu fee program fee schedules. 

Mitigation banks and in-lieu-fee programs almost always offer wetland mitigation credits for 

sale; however, stream mitigation markets are less robust. In reviewing in-lieu-fee program fee 

schedules, stream mitigation costs could be identified for ten in-lieu fee programs across the 

country. Stream mitigation continues to be a growing area of practice in the mitigation 

community, and an area where Corps Districts are also continuing to develop familiarity. Where 

new data were available, these were utilized. Where no new data were available, steam 

mitigation cost estimates from the proposed rule analysis were updated to 2014 dollars.

Mitigation costs vary widely, with nationwide average unit costs ranging from $41,572 to 

$111,985 per acre of wetlands mitigated and from $95 to $1,000 per linear foot of stream 

mitigation. There is more variation in unit costs per state, see Figure 18, Appendix A. Costs 

vary based on land acquisition costs, the nature of the work being done, demand for mitigation in 

the state, as well as other factors. The unit costs identified here, based on mitigation bank and 

in-lieu-fee program fee schedules represent fully-loaded unit costs and include the costs of land 

acquisition, construction work completed on site, monitoring for mitigation success, and longterm stewardship. In some cases, permittees may not purchase credits from a mitigation bank 

but rather complete a permittee-responsible mitigation project. The costs of this permitteeresponsible mitigation project may be lower than the purchase of credits, particularly in 

circumstances where a mitigation project is constructed on the same tract of land as the permitted 

impacts. In this circumstance new land would not have to be acquired, lowering the costs of the 

project. Therefore, the mitigation costs estimated here may be an overestimate. 

Wetland Mitigation Costs

To estimate wetlands mitigation costs the agencies assumed that all of the estimated 

additional acreage of impacts authorized under individual permits would require mitigation at a 

2:1 ratio, with two acres of mitigation required for every acre of impact. This ratio represents the 

reported average amount of mitigation required per acre of authorized impact from FY09 to 

FY13. In the analysis prepared for the proposed rule, the percentage of ORM2 other waters 

determined to be jurisdictional was embedded in the calculation for the amount of mitigation 

required, resulting in a ratio of 1.5 acres of mitigation per acre of impact. Directly applying the 

2:1 ratio uses a clearer approach utilizing existing permitting data.

For the additional acreage of impacts authorized under general permits, the agencies first 

assume that only half of these permits would require mitigation. As part of the analysis to 

support the most recent set of nationwide permits issued in 2012, the Corps estimated that only 

30,000 nationwide permit authorizations would require a pre-construction notification (PCN)16, 

as compared to 60,000 authorizations actually issued in 2012. A PCN is not required for 

activities that, in general, do not result in more than minimal adverse effects on the aquatic 

environment and mitigation is not required for these authorizations. As it was estimated in the 

 16 Reissuance of Nationwide Permits, 77 Federal Register 34 (February 21, 2012), pp 10184-10290.
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36

last nationwide permit package that only half of all permits would require a PCN, the agencies 

assume this half of the general permits would also require mitigation, assuming 2 acres of 

mitigation is required per acre of additional impact. 

Given an estimated increase in permitted losses of 1,290 acres authorized under 

individual permits, and 1,200 acres authorized under general permits from Figure 10, these 

assumptions can be used to calculate the total acreage of mitigation required, corresponding to 

3,781 new acres of mitigation. 

NNNNNN MMMMMMMMMMMMMMMMMMMMTTTTTTTTTT

= (2 ∗ 1,290 aaaa aa aa h oo oo IIII )

+(0.5 ∗ 2 ∗ 1,200 aaaa aa aa h oo oo GG )

This new level of required mitigation will compensate for newly-permitted wetland 

losses, resulting from an increase in assertion of CWA jurisdiction. This increased acreage of

mitigation is assigned by state based on the percentage of negative FY13-14 jurisdictional 

determinations for wetlands and “other waters” in that state:

NNNNNN MMMMMMMMMMMMMMMMMMMMSS SS

= 3,781 aaaa aa ∗ SS # NNNN NNNN WW WW OO h WW JJJJ

NN NN NN # NNNN NNNN WW WW OO h WW JJJJ

This approach results in more mitigation acres being assigned to states with many 

negative wetland or ORM2 other waters JDs, and thus likely to experience positive changes in 

jurisdictional assertion. Over the baseline period of FY13-14 Connecticut, Delaware, Maine, 

Michigan, New Hampshire, and Rhode Island had no negative JDs for wetlands or ORM2 other 

waters. However, the Agencies did not want to presume that the actual number of negative 

jurisdictional determinations in these states, and therefore requirements for mitigation acres, 

would be zero. As a result, these states were assumed to have one negative JD..

The estimated new mitigation on a state-by-state basis was then applied to state-specific 

low and high wetland mitigation costs to calculate an estimated increase in mitigation costs by 

state. Wetland mitigation costs have been updated from the proposal where additional data were 

available and all costs reflect 2014 dollars. Mitigation unit cost estimates are reported in 

Appendix B. Estimated increases in mitigation costs by state are added to form a nationwide 

estimated increase in wetland mitigation costs of $90.1 to $232.8 million. State-specific values 

appear in Appendix B.

TT WW WW MMMMMMMMMMMMMMMMMMMM CC = ∑ MMMMMMMMMMMMMMMMMMMM AA SS SS ∗ CC pp AA SS SS
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37

Stream Mitigation Costs

To calculate the costs of stream mitigation, the Corps provided data on jurisdictional 

determinations for streams by state over FY13-14. The Corps also provided an estimate of 590 

miles of stream mitigation from fiscal year 2013 to represent mitigation activity in the baseline 

period. The agencies believe it is a close approximation of required mitigation for FY13, and 

that it is consistent with the level of mitigation the Corps has estimated for the past 10 to 15 

years.

From this data on baseline levels of mitigation and positive and negative jurisdictional 

determinations over FY13-14 the agencies are first able to calculate, in the baseline period, linear 

feet of mitigation per positive stream jurisdictional determination. Then, using the data from 

Corps on the negative stream jurisdictional determinations, the agencies can calculate the statespecific increase in mitigation if all negative stream jurisdictional determinations became 

positive:

II SS SS MMMMMMMMMMMMMMMMMMMMSS SS = MMMMMMMMMMMMMMMMMMMM pp JJJJSS SS ∗ NNNN NNNN SS SS JJJJSS SS

This gives an increase in linear feet of stream mitigation by state, which is multiplied by 

state-specific data on mitigation costs per linear foot. The nationwide increase in stream 

mitigation is estimated to total 111,916 linear feet. Where data are available, state-specific unit 

cost estimates have been updated from the proposal. Unit cost estimates appear in Appendix B; 

all costs reflect 2014 dollars. Summing state-specific increases in stream mitigation costs across 

all states gives an overall estimated increase in stream mitigation costs of $22.4 to $44.4 million.

TT SS SS MMMMMMMMMMMMMMMMMMMM CC

= ∑ LL FF oo MMMMMMMMMMMM SS SS ∗ CC pp LL FF SS SS
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38

CWA Section 404 Benefits

In the absence of this rule and under current practices, these waters were found nonjurisdictional and impacts to these waters were not required to undergo the Section 404 

permitting process. The increase in Section 404 permits estimated to result from this rule 

represents impacts that will now be required to undergo the Section 404 mitigation sequence of 

avoiding and minimizing impacts to jurisdictional waters, and finally offsetting unavoidable 

impacts through compensatory mitigation. The permitting process may result in a lower acreage 

of wetlands being impacted through avoidance of the wetlands in the project design. Remaining

unavoidable losses will be offset via compensatory mitigation, and ecological benefits will 

accrue from the replacement of lost functions and services through compensatory mitigation. 

Benefits are calculated from the estimated new impacted acreage from all individual 

permits (1,290 acres) and half of general permits (0.5*1,200 acres), as mitigation is only 

assumed for half of general permits. In total, benefits are calculated from 1,890 acres of newlypermitted losses, now offset via mitigation. 

Mitigation is typically required to be “in-kind” (i.e., of the same wetland type) as the 

impact site. Benefits from stream mitigation are not quantified due to a lack of available data to 

allow for quantification or monetization of the ecosystem services performed by the small 

streams that may be affected by this rule. As only wetland benefits are monetized, the benefits 

figures reported here are likely to be an underestimate.

Wetland Mitigation Benefits

The agencies estimate the potential benefits from CWA Section 404 compensatory 

mitigation using a benefits transfer approach. Benefits transfer involves selecting study cases 

relevant to the policy case under consideration, and transferring values using a unit value or 

function-based approach. The major challenge with benefits transfer is that economic values for 

ecosystem services are context (resource/region/user) specific. Thus, it is best suited for 

transferring estimates between comparable contexts. For example, there is uncertainty involved 

in completing a benefits transfer where waters vary greatly in their functionality and relative 

value based on the relative scarcity, location within a watershed, and the degree of human 

impacts in their vicinity, as do the waters under consideration in this analysis. Inherent in this 

benefits transfer analysis is also the assumption that the wetlands whose functions are to be 

replaced by compensatory mitigation are of the same quality of functionality as the wetlands 

valued in the willingness-to-pay (WTP) studies. Also, the users of the services in the original 

valuation studies may not be comparable to users in other areas; that is, the WTP among service 

users in different areas could differ significantly. However, without knowing specifically where 

impacts will occur in the future, benefits transfer remains the only feasible option for quantifying 

potential benefits. Given these challenges, and the uncertainty as to specific sites that may be 
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39

affected by this proposed regulatory action, the benefits values presented in this analysis are 

most relevant for a national-level analysis. To produce a site-specific analysis there is ample 

opportunity for the methodology to be tailored to account for site-specific information. The type 

of analysis here would not be directly applicable to a site-specific evaluation.

The specific benefits transfer approach used in this analysis also relies on stated 

preference and aggregation of household level estimates of WTP. Stated preference studies elicit

“stated preferences” rather than revealed (or actual) preferences from observed behavior. Stated 

preference methods rely on surveys that assess respondents stated WTP for goods or services, 

such as ecosystem services provided by a natural landscape feature. In using the household-level 

WTP information, there are not always clear rules for aggregation (i.e., determining which 

households pay). For this analysis, the agencies attempt to make reasonable and credible 

choices, but it is important to recognize that there is uncertainty and limitations associated with 

the results.

Valuation of Wetland Benefits

For this economic analysis and the analysis supporting the proposed rule, the agencies 

sought out studies from the literature that provide value estimates for a suite of ecosystem 

services provided by a particular wetland or wetland complex as a whole (i.e., total resource 

values, including both use and nonuse values). Wetlands under consideration for their value may 

provide varying degrees of particular services, or may not provide a particular service at all. A 

strength of this approach is the values elicited implicitly account for the varying degree and 

interrelationships among of services provided,

17 assuming respondents are sufficiently informed. 

In conducting the literature search, the agencies focused on studies that assess wetlands 

similar to those expected to be incrementally protected under the final rule. The economic 

valuation literature includes a large volume of studies that estimate the value of preserving, 

protecting, restoring, replacing (mitigation), and increasing the size of wetlands, including 

several meta-analysis studies (e.g., Moeltner and Woodward 2007).

18 Many of these studies 

provide values for overseas, tidal, or coastal wetlands that do not well represent waters likely be 

incrementally protected by this rule. For example, tidal wetlands are valued highly for fishery 

habitat, which is typically not provided to the same degree by wetlands adjacent to small 

 17 The value of a bundle of services is generally not the same as the sum of values for individual services that 

comprise the bundle estimated separately. The independent valuation and then aggregation of multiple service 

values can introduce systemic bias in total value estimates because independent valuation does not account for the 

potential interdependence (e.g., complementarily) among services. Use of stated preference studies to estimate total 

values for all services collectively avoids this problem by estimating values for resource changes while considering 

the potential interdependence among individual resource services. 

18 Moeltner, K. and R. Woodward. 2007. Meta-Functional Benefit Transfer for Wetland Valuation: Making Most of 

Small Samples. UNR Joint Economics Working Paper 07-012. Paper presented at the W1133 Annual Meetings, 

Richmond, VA, March 28-30, 2007.
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40

tributaries or more isolated wetlands. Jurisdiction of tidal wetlands is not likely to change due to 

this rule.

Seeking only studies that value resources likely to be incrementally protected by this rule, 

the agencies identified 10 studies that provide 22 estimates of WTP to preserve wetlands that 

provide a suite of services expected to be similar to those provided by waters incrementally 

protected under the final rule. Given the limited scope of studies of interest, and the limited 

universe of wetlands valuation work generally, the relevant studies identified by the agencies are

predominately from the late 1980s and early 1990s. Since this time there have been 

methodological advances for studies of this kind, but as there are not more recent studies 

available, the effect of those advances are not reflected in these numbers. Some of these 

methodological improvements, such as techniques to remove hypothetical biases, have lowered 

WTP values. However, since the early 1990s there may also have also been other changes such 

as awareness of wetland services and changes in income that could increase WTP. Therefore, 

there is uncertainty as to whether the overall effect of these methodological improvements and 

other changes would result in an underestimate or overestimate of WTP. Clearly, it would be 

preferable to include more recent studies reflecting the current state of the art in stated preference 

analysis, but this was not possible as there are not relevant, more recent studies in the published 

literature.

These studies represent riverine or floodplain, forested, emergent, and depression or 

isolated wetlands in 12 states across the country. These studies are summarized in Appendix B

of this report. In preparing the benefits analysis for the final rule, the agencies reviewed the 

benefits studies and the WTP estimates utilized from those studies and have made a number of 

changes in application of the study results. These changes are described below.

Loomis et al. (1991) calculated willingness to pay for preservation of vernal pools in the 

San Joaquin Valley of California, presenting WTP figures for residents of CA within the San 

Joaquin Valley and outside the San Joaquin Valley, as well as an estimated statewide WTP. The 

study also presents WTP values for several different management scenarios (maintenance of 

current wetland levels, expansion of current levels, different management for contamination, and 

management to improve salmon populations). In the proposal, separate WTPs for the San 

Joaquin valley and outside the San Joaquin valley were used; in addition the WTP represented a 

program broader than just wetlands. For this analysis the agencies have chosen WTP values 

from this study that more closely match the policy context, utilizing only the statewide WTP 

value for maintenance of current wetland levels and the statewide WTP for expansion of wetland 

acreage. This ensures that benefits only for wetlands programs are captured, and also utilizes the 

lower, statewide WTP, capturing changes in WTP based on distance from the resource.

Azevedo et al. (2000) calculated household (HH) WTP for two projects in Iowa, one of 

which is a prairie pothole preservation program that would seek so acquire and preserve a total of 

40,000 acres of prairie potholes, acquired at a rate of 2,500 acres per year for 15 years. The 
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41

proposal benefits analysis attributed the WTP value for this program to a wetland size of 2,500 

acres, resulting in an erroneously high WTP per acre. For the final, we have taken the total size 

of the program (40,000 acres) and discounted those acres to the present at a 3% discount rate, 

assuming they are acquired over 15 years at a rate of 2,500 acres per year, thus describing the 

40,000 acres preserved over a 15 year period in terms of the amount of acres preserved at once 

that would result in a socially discounted equivalent level of services. This results in a present 

value project size of 32,345 acres.

Poor (1999) conducted a study of WTP for preservation of Nebraska’s flyway wetlands. 

The survey generating the WTP figures was completed in 1996. This was erroneously attributed 

to 1995$ in the proposal and has been corrected.

Whitehead and Blomquist (1991) presented six different figures of WTP for preservation 

of wetlands in Kentucky. Respondents were asked about three different wetland features, and 

asked their WTP given two different sets of information. The proposal used only three of these 

values, the final will incorporate all six values into the benefits analysis, capturing how different 

information affects WTP. 

Mullarky and Bishop (1999) asked respondents their WTP to preserve 110 acres of 

wetlands in Wisconsin via re-routing of a highway. Respondents were offered a polychotomouschoice format and indicated if they would “definitely yes”, “probably yes”, “not sure”, “probably 

no”, or “definitely no” be willing to pay the amount offered. In the proposal, only the mean of 

the “definitely yes” responses was utilized as a WTP figure. In the final, the mean of the 

“definitely yes” and “probably yes” responses will be used. When utilizing only the “definitely 

yes” responses, the inherent assumption is that all other respondents had zero WTP. By 

including the probably yes respondents, we are ascribing greater than zero WTP to respondents 

where we are relatively certain their WTP is not zero, because respondents had the option to 

indicate they were not willing to pay the proffered amount, and did not select this option. We are 

unable to adjust WTP based on the degree of certainty, so it is possible the WTP value associated 

with the “probably yes” responses is an over-estimate, but it is certainly not zero.

Lant and Tobin (1989) asked respondents their WTP for water quality improvements for 

rivers in Illinois and Iowa, and estimated the increase in wetland acreage in the floodplain 

necessary to achieve a higher level of water quality. In the final analysis, the WTP per acre will 

utilize the estimated necessary increased acreage of wetlands and the proportion of WTP for the 

water quality improvement being contemplated (i.e. an increase of 2,100 acres of wetlands would 

improve river quality by 0.55 points to “fair” (based on how respondents rated river quality). 

This represents 55 percent of the respondents’ WTP for water quality improvements from “poor” 

to “fair”. This study also reported WTP on a per person basis, but also provided statewide 

average household size at the time the study was completed. The individual WTP was adjusted 

to reflect household WTP based on these average household sizes.
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42

For this analysis, it is necessary to express WTP values on a “per acre” basis rather than a 

“per acre per year” basis to be comparable to the mitigation cost figures presented in this section. 

The cost figures for compensatory mitigation reflect the total one-time cost per acre to protect 

and maintain the services provided by a mitigation site into perpetuity. Thus benefits should be 

calculated as the total per acre value, not just the one-year per acre value. 

The agencies standardized WTP estimates across all studies in three ways: 1) household 

basis, 2) per acre basis, and 3) annual basis. For estimates reported as annual WTP for wetland 

preservation, the agencies derived the total present value over a period of 50 years using 3 

percent and 7 percent discount rates. The agencies calculated WTP on a per household per acre 

basis by dividing the per household WTP value by the size of valued wetlands reported in a 

particular study. Additional detail on the standardization process is available in Appendix B.

National Wetlands Inventory Approach to Benefits Transfer

Different types of wetlands perform different functions and may not be valued the same. 

In an effort to account for these differing values, a benefits transfer exercise was completing 

utilizing data from the National Wetlands Inventory (NWI).

19 NWI is the leading source for 

geospatial information on the potential and approximate extent of wetlands across the United 

States. Using data from the NWI, a GIS analysis was completed examining the acreage of 

digitally mapped wetland habitats on a county and state basis (NWI current as of February 4, 

2011). This analysis resulted in an estimate of the acreage of different categories of wetlands 

mapped in the NWI on a state level throughout the United States, where digital data are 

available. Note that this is likely an underestimate of actual wetland acreage, as at the time of 

the analysis digital NWI data were not available for portions of the United States and the NWI 

was not complete for other portions of the country. Additionally, at the time of the analysis, 

limited data were available in Alaska, Arkansas, Colorado, Kansas, Texas, and Utah, as 

approximately 75 percent or more of the wetlands in these states were not digitally mapped in the 

NWI. Digitization of the NWI is now complete for the conterminous United States, but parts of 

Alaska continue to have no NWI data. Additionally, the NWI does not capture all wetlands, as 

the data are derived from aerial photo-interpretation with varying limitations due to scale (NWI 

is at the 1:24,000 scale), photo quality, inventory techniques, vintage of the aerial photographs, 

and other factors. Consequently, the maps tend to show wetlands that are readily photointerpreted given consideration of photo and map scale, while missing certain forested wetlands 

that are not as easy to detect. Wetland features may also have changed since the date of the 

imagery and/or field work. There may be occasional differences in wetland boundaries or 

classifications between the information depicted on the map and the actual conditions on site. 

Note that the definition of wetland the NWI uses is broader than the Clean Water Act regulatory 

definition.

 19 U. S. Fish and Wildlife Service. Data current as of February 4, 2011. National Wetlands Inventory. U.S. 

Department of the Interior, Fish and Wildlife Service, Washington, D.C. http://www.fws.gov/wetlands/.
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43

The NWI classifies wetland and deepwater habitats by types, utilizing the U.S. Fish and 

Wildlife Cowardin Classification System as defined by Cowardin et al.,

20 as well as categorizing

wetlands in groups of similar classifications: Freshwater Forested and Shrub wetland, Freshwater 

Emergent wetland, Freshwater pond, Estuarine and Marine wetland, Riverine, Lakes, Estuarine 

and Marine Deepwater, and Other Freshwater wetland. In reviewing the projected jurisdictional 

changes associated with the policies in the final rule, EPA determined that the vast majority of 

wetlands that would become jurisdictional would fall into the NWI categories of Freshwater 

Forested/Shrub and Freshwater Emergent. Remaining incremental wetlands would be negligible. 

As described by the NWI section of the U.S. Fish and Wildlife Service website, a Freshwater 

Forested/Shrub wetland is a forested swamp wetland or shrub bog wetland. A Freshwater 

Emergent wetland is an herbaceous marsh, fen, swale, or wet meadow.

21

The state-level wetland acreage by NWI category from the GIS analysis was used to 

estimate the proportion of acres in each state that fall under Forested or Emergent wetlands. This 

proportion was then multiplied by the projected increase in impacted acreage of Forested and 

Emergent wetlands, now to be off-set via mitigation (see equation below). State-specific 

estimates of newly-impacted acres in each state was calculated using the same approach 

described above to estimate the state-specific increase in mitigation acreage. 

NNNNNN AA FF SS SS

= TT NNNNNN AA SS SS ∗ (

AA FF SS SS

AA FF SS SS + EE SS SS

)

NNNNNN AA EE SS SS

= TT NNNNNN AA SS SS ∗ (

AA EE SS SS

AA FF SS SS + EE SS SS

)

The benefits studies can also be divided into the NWI categories of Freshwater Forested 

or Freshwater Emergent. After examining the wetlands described or specified in each case study 

from the original literature search, it was determined that four studies, generating thirteen WTP 

values assess Freshwater Forested wetlands and six studies, generating nine WTP values assess

Freshwater Emergent Wetlands. WTP was calculated separately for each category by taking a 

geometric mean of the per-acre WTP values, weighted by the number of respondents in each 

study. As shown in Figure 12, WTP for Freshwater Forested/Shrub wetlands is approximately 

$0.04 per household per acre at a 7 percent discount rate and $0.06 per household per acre at 3

 20 Cowardin, L.M., V. Carter V., F.C. Golet, E.T. LaRoe. 1979. Classification of Wetlands and Deepwater Habitats 

of the United States. U.S. Fish and Wildlife Service Report No. FWS/OBS/-79/31.Washington, D.C. 21 U. S. Fish and Wildlife Service. May 22, 2013. Wetlands Mapper Legend Categories. National Wetlands 

Inventory. U.S. Department of the Interior, Fish and Wildlife Service. Retrieved August 5, 2013, from 

http://www.fws.gov/wetlands/Data/Mapper-Wetlands-Legend.html.
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44

percent. WTP for Freshwater Emergent wetlands is $0.004 per household per acre at 7 percent

and $0.005 per household per acre at 3 percent.

Figure 12. WTP per Household per acre ($/HH/acre) (2014$)

Freshwater 

Forested/Shrub

Freshwater 

Emergent

7% Discount Rate $0.04 $0.004

3% Discount Rate $0.06 $0.005

Aggregation of Benefits

The next step in a benefits analysis is to determine to whom benefits accrue. In the 

proposed rule analysis, benefits were determined to accrue across eight wetland regions in the 

contiguous United States identified by the USDA Economic Research service: Central Plains, 

Delta and Gulf, Mountain, Midwest, Northeast, Pacific, Prairie Potholes, and Southeast.22 

Alaska is not part of a wetland region and is treated separately. Accruing benefits on a regional 

scale assumes that all residents within that wetland region benefit from wetland losses within that 

region now being offset via compensatory mitigation. Three of the WTP studies used here 

surveyed respondents in multiple states. Thus, it may be appropriate to consider benefits at a 

regional level as wetlands provide services that affect downstream water quality and uses, 

including beyond state borders. However, aggregating benefits using the wetland regions 

requires ascribing benefits over a large geographic area and there are not data available to allow 

for examination of the effect distance from the resource being valued has on HH WTP for 

wetlands. 

Benefits from wetland losses now being compensated for via compensatory mitigation 

may also be assumed to accrue at the state level. This approach assumes that only residents 

within a state’s boundaries receive benefits from wetland losses offset within that state. This 

calculation for benefits may be overly conservative as wetlands can provide services and benefits 

to downstream waters beyond a state’s boundaries, but it serves as a useful point of comparison. 

Additionally, six of the WTP studies utilized in this analysis completed WTP surveys with a 

statewide geographic scope. For these studies, ascribing benefits only within state boundaries 

may represent the most appropriate benefits transfer exercise

There are no clear boundaries determining to whom benefits should accrue. Though both 

approaches are described above as appropriate, estimating mitigation benefits using both and 

presenting the results as a range would introduce more variation to the analysis than is warranted. 

That is, the WTP values are from studies that represent largely a mix of the state and regional

approaches. Applying the values at only the state level or only the regional level would ascribe 

 22 Heimlich, R.E., R. Claassen, K.D. Wiebe, D. Gadsby, and R.M. House. 1998. Wetlands and Agriculture: Private 

Interests and Public Benefits. AER-765, U.S. Department of Agriculture Economic Research Service, Washington, 

D.C.
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45

some values at the scale that would be less appropriate, and thus introduce additional variation

into the analysis. An additional reason that it is preferable to use a blended approach for the 

WTP estimates is that the WTP values from the studies represent both use and nonuse values. 

While we would expect the use values for a given household to be largely contained within the 

state where it is located, there is no reasonable justification for presuming that non-use values 

would only apply to wetlands contained within state boundaries. Instead, on a region by region 

basis, EPA has taken a blended approach, using the simple average of the WTP applied at the 

regional level and the weighted average WTP applied at the state level for the states in that 

region, and applied this blended WTP to the acreage estimated for that region.

Regional benefits for each wetland type were calculated using the following formula: 

RR FF /EE bb

= (NN NN oo HH h oo )

∗ (BB WW pp HHHH )

where Blended WTP per HH is the average of the WTPs per HH as applied at the state and 

regional levels, which also accounts for acreage of each wetland type in the region. The 

breakdown by region appears in Figure 13. In Figure 13, multiplying the number of households 

by the household willingness to pay for each wetland type ($/HH), yields the total WTP. Given 

that the WTP per HH per acre is an order of magnitude lower for emergent wetlands than 

forested wetlands, while there are roughly double the acres of emergent wetlands relative to 

forested wetlands, the household WTP for emergent wetlands in each region is smaller than the 

household WTP for forested wetlands. The agencies observe the largest differences in HH WTP 

by wetland type in regions such as the Midwest and Northeast, where there are significantly 

more forested acres than emergent acres expected to be found jurisdictional. Assuming a 3 

percent discount rate, this blended approach produces a primary benefits estimate of $501.2 

million.
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46

Figure 13. Estimated Annual Compensatory Mitigation Benefits - Blended Approach

(2014$).

Blended Approach - 3% Discount Rate

Region # Households 

Acres 

Emergent

Acres 

Forested

HH WTP 

Emergent

($/HH)

HH 

WTP 

Forested

($/HH) Total WTP

AK 258,058 1.0 0.7 0.005 0.041 $11,696

Central Plains 3,293,676 24.4 10.0 0.076 0.367 $1,458,757

Delta and Gulf 15,407,697 66.0 78.1 0.253 3.128 $52,086,199

Midwest 24,277,640 59.5 230.7 0.170 7.548 $187,371,142

Mountain 7,835,482 101.7 42.2 0.283 1.406 $13,241,121

Northeast 24,477,954 36.9 127.6 0.103 4.255 $106,679,257

Pacific 16,716,512 52.1 20.3 0.210 0.941 $19,236,590

Prairie Potholes 2,234,657 830.8 21.7 2.297 0.712 $6,723,890

Southeast 21,492,571 24.2 162.6 0.074 5.249 $114,405,313

Total $501,213,964

Blended Approach - 7%

Region # HH 

Acres 

Emergent

Acres 

Forested

HH WTP 

Emergent

($/HH)

HH WTP 

Forested

($/HH) Total WTP

AK 258,058 1.0 0.7 0.004 0.029 $8,393

Central Plains 3,293,676 24.4 10.0 0.072 0.342 $1,363,351

Delta and Gulf 15,407,697 66.0 78.1 0.233 2.853 $47,540,032

Midwest 24,277,640 59.5 230.7 0.165 7.225 $179,403,398

Mountain 7,835,482 101.7 42.2 0.276 1.340 $12,663,495

Northeast 24,477,954 36.9 127.6 0.100 4.053 $101,667,758

Pacific 16,716,512 52.1 20.3 0.192 0.832 $17,121,843

Prairie Potholes 2,234,657 830.8 21.7 2.239 0.681 $6,525,753

Southeast 21,492,571 24.2 162.6 0.071 5.042 $109,887,086

Total $476,181,110
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47

Section 10: Summary of Estimated Indirect Costs and 

Benefits

This rule is estimated to result in approximately a 4.65 percent increase in waters found 

jurisdictional under the Clean Water Act, when compared to a baseline of current practice over 

FY13 and FY14. Jurisdictional waters must not always be preserved in their natural state and 

never receive discharges of pollutants, but rather jurisdiction requires those seeking to discharge 

pollutants to receive a CWA permit and take required steps to ensure protection of water quality.

This analysis estimates potential increases in costs and benefits from CWA programs that 

may see increased permitting activity as a result of this rule, including CWA Sections 311; 401; 

402 CAFO, stormwater, and pesticide permits; and 404. 

Figure 14 displays a summary of these monetized costs and benefits. There are several costs 

and benefits that are unable to be monetized, including permitting time and project redesign costs 

under Section 404, as well as the benefits of Section 404 stream mitigation, benefits of the 402 

pesticide general permit, and benefits of the 401 certification program. A comparison of the 

monetized costs and benefits indicates that the benefits outweigh the costs.
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48

Figure 14. Estimated Annual Indirect Costs and Benefits.

Annual Costs

(FY14$ millions)

Annual Benefits

(FY14$ millions)

Low High Low High

CWA 402 CAFO Administration $0.3 $0.3 $6.2 $10.8 CWA 402 CAFO Implementation $9.9 $9.9

CWA 402 Stormwater 

Administration $0.5 $0.5 $47.5 $60.2 CWA 402 Stormwater 

Implementation $47.8 $59.6

CWA 404 Permit Application $47.0 $80.3 $501.2 $501.2 CWA 404 Mitigation – Wetlands $90.1 $232.8

SUBTOTAL $195.7 $383.3 $554.9 $572.3

CWA 311 Compliance $12.7 $12.7 not quantified

CWA 401 Administration $1.3 $1.3 not quantified

CWA 402 Pesticide General Permit 

Implementation $5.4 $5.9 not quantified

CWA 404 Mitigation – Streams $22.4 $44.4 not quantified

TOTAL $237.4 $447.6 $554.9 $572.3
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49

Section 11: Other Social Costs and Benefits

The changes in the definition of “Waters of the U.S.” under the Clean Water Act as a 

result of this rule will also affect federal government operations. In general, the agencies believe 

that the final rule will expedite the permit review process in the long-term by clarifying 

jurisdictional matters that have been time-consuming and cumbersome for field staff and the 

regulated community. However, with a projected increase in waters that will be jurisdictional 

when compared to the baseline, the agencies anticipate that there will be an increase in permit 

applications to be managed. The estimated incremental administrative costs to the Corps are 

described below.

Corps Administrative Costs

The Corps anticipates that it will incur additional administrative costs under the rule 

associated with the increased permitting workload. The Corps is typically, but not always, the 

permitting authority for CWA 404 permits. Sources of administrative costs include: responding 

to additional requests for jurisdictional determinations; an overall increase in workload-related 

tasks such as permit actions, consultations, and compliance and enforcement actions; and 

additional time to conduct significant nexus analyses. The Corps will also likely face additional 

costs to provide program management, training, and compliance oversight associated with 

administering the program, especially in the near term. Figure 15 briefly summarizes the 

principal cost categories for administering the CWA 404 program. 

Figure 15 - Overview of CWA 404 Administrative Costs

Cost Category Description (costs vary considerably by permit type and often by 

district)

Permitting Costs Costs associated with the time needed to review additional permits (which 

may be more complex due to a larger scope of review, reduction in the 

ability to avoid and minimize impacts, requiring more project 

modifications and additional mitigation) additional compliance and 

enforcement costs, additional mitigation plan reviews, effort to conduct 

additional agency consultations and coordination and possible increase in 

permit appeal requests and litigation costs. 

JD Review and 

Coordination 

Costs

Additional time needed to review additional JD requests, more 

coordination with Corps Headquarters for “other” (isolated) waters, 

additional time for District staff to prepare a significant nexus evaluation

for “other” waters. More appeals of approved JDs may occur.
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50

Automation Costs Additional costs for automating new JD forms, updating the permit 

tracking system (ORM2) to reflect needed data elements, updating user 

documentation.

Training Costs Additional costs for Corps districts to implement the new guidance/rule, 

includes webinars, field training, and outreach activities for the regulated 

public.23

The increase in waters that the agencies consider jurisdictional from the 2008 Guidance 

may result in an increase in requests for JDs. Some changes contained in the final rule, such as 

providing a definition of tributaries that are categorically jurisdictional, should reduce the 

administrative costs of establishing jurisdiction. If such changes balance the expected increase in 

JD requests, there would be no incremental change administrative costs related to jurisdictional 

determinations.

Because the agencies expect that most non-isolated waters will be jurisdictional under the 

policies under the proposed rule, applicants may find “preliminary JDs” (PJDs) more appealing. 

In a PJD a permit applicant elects to set aside the question of jurisdiction and voluntarily “opts 

in” to the permitting process and avoids a longer “approved JD” (AJD) process. In FY2010, 58 

percent of JDs were PJDs (42 percent were AJDs). PJDs are less time-consuming to document 

than AJDs, but permit application processing may require more information describing 

jurisdictional waters (e.g., to assess impacts and formulate compensatory mitigation 

requirements). Alternatively, some applicants may request an AJD as a means to potentially 

reduce mitigation requirements and associated costs. If more landowners elect to request AJDs, 

the workload and administrative costs will increase.

The agencies expect that permit applications will increase as the Corps determines that 

more waters are jurisdictional. This increase in permit activity may increase required 

consultations under the Endangered Species Act (ESA) and Section 106 of the National Historic 

Preservation Act. This could increase costs for other agencies, such as the Fish and Wildlife 

Service, NOAA Fisheries, Advisory Council on Historic Preservation, and Tribal and State 

Historic Preservation Officers. 

Figure 16 depicts the broad categories and specific tasks related to Corps administration 

of the CWA 404 program. To derive an estimate of the incremental administrative costs, the 

Corps identified how many hours per year are devoted to each task at the headquarters and 

district office level and translated this into dollars using average fully loaded salary rates for the 

needed personnel. Applying the incremental percentage increase in CWA 404 permits of 4.65

percent, the Corps estimates that their additional administrative costs will range from $XX to 

$XX million annually. 

 23 As the day-to-day permitting authority, the Corps will have primary responsibility for conducting outreach and 

training for industry and entities seeking permits. 
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51

Figure 16 - Categories of Cops CWA 404 Administrative Tasks

Category Tasks

Wetland Delineation and 

Jurisdictional Determination (JD)

Preliminary JD

Office/Desk JD

Field JD

Permit Related Tasks

Pre-Application Meetings

Standard Permit (SP) Processing Base

Letter of Permissions (LOP) 

Nationwide (NWP) Processing without a PreConstruction Notification (PCN)

NWP Processing with PCN

Regional/Programmatic (RGP/PGP) Processing 

without PCN (issued by Regulatory)

RGP/PGP Processing with PCN (issued by 

Regulatory)

Consultation

Endangered Species Act (ESA) Formal Consultation 

Process

ESA Informal Consultation Process

Historic Properties

Tribal

Environmental Impact Statement 

(EIS)

EIS as Lead

EIS as Cooperating Agency

Compliance Compliance

Resolution of Non-Compliance

Enforcement Unauthorized Activity
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52

Section 12: Related Acts of Congress, Executive Orders, 

and Agency Initiatives

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 the 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).

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 rule on small entities, I certify that this 

final 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). 
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53

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 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 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 will not have a significant 

adverse economic impact on a substantial number of small entities, and therefore no regulatory 

flexibility analysis is required.

Today’s rule 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 is 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 wide input from representatives of small 

entities while formulating the proposed and final 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, throughout the rule development, 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 prepared a report summarizing their small entity outreach, the results of this 

outreach, and how these results have informed the development of this rule. This report, Final 

Summary of the Discretionary Small Entity Outreach for the Revised Definition of Waters of the 

United States (Docket Id. No. EPA-HQ-OW-2011-0880-1927), is available in the docket. 

Unfunded Mandates Reform Act

This action does not contain any unfunded mandate under the regulatory provisions of 

Title II of the Unfunded Mandates Reform Act of 1995 (UMRA) (2 U.S.C. 1531-1538), and does 

not significantly or uniquely affect small governments. The action imposes no enforceable duty 
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54

on any state, local, or tribal governments, or the private sector, and does not contain regulatory 

requirements that might significantly or uniquely affect small governments. The definition of 

“waters of the United States” applies broadly to CWA programs.

Executive Order 13132: Federalism

This rule does not have federalism implications. It 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. 

Keeping with the spirit of Executive Order 13132 and consistent with the agencies’

policy to promote communications with state and local governments, the agencies consulted with 

state and local officials throughout the process and solicited their comments on the proposed 

action and on the development of the rule. 

For this rule State and local governments were consulted at the onset of rule development 

in 2011, and following the publication of the proposed rule in 2014. In addition to engaging key 

organizations under federalism, the agencies sought feedback on this rule from a broad audience 

of stakeholders through extensive outreach to numerous State and local government 

organizations.

Early in the rulemaking process, EPA held two 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. 

Additionally, the National Association of Clean Water Agencies and the Association of Clean 

Water Administrators were invited to participate. The agencies held many additional calls and 

meetings with state and local governments and their associations, in preparation for the 

development of a proposed rule.

Similarly to the outreach conducted prior to the development of the rule, the agencies 

committed themselves to providing a transparent, comprehensive, and effective process for 

taking public comment on the proposed rule. As part of this consultation, EPA held a meeting 

on May 13, 2014 to seek technical input on the proposed rule from the largest national 

representative organizations for State and local governments. During this process the agencies 

also extended its focused outreach to include a series of meetings with the Local Government 

Advisory Committee, and the Environmental Council of the States in conjunction with the 

Association of Clean Water Administrators and the Association of State Wetland Managers. In 
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55

addition to engaging these key organizations under, the agencies sought additional feedback on 

the proposed rule through broader public outreach to state and local government organizations 

during the public comment period.

During the consultation process, some participants expressed concern that the proposed 

changes may impose a resource burden on state and local governments. Some participants urged 

EPA to ensure that states are not unduly burdened by the regulatory revisions.

The agencies have prepared a report summarizing their voluntary consultation and 

extensive outreach to State, local, and county governments, the results of this outreach, and how 

these results have informed the development of today’s rule. This report, Final Summary of the 

Discretionary Consultation and Outreach to State, Local, and County Governments for the

Revised Definition of Waters of the United States (Docket Id. No. EPA-HQ-OW-2011-0880-

XXXX) is available in the docket for this rule.

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), the 

agencies consulted with tribal officials throughout the rulemaking process to gain an 

understanding of tribal issues and solicited their comments on the proposed action and on the 

development of today’s rule. In the course of this consultation, EPA and the Corps jointly 

participated in aspects of the process.

The agencies began consultation with federally-recognized Indian tribes on the Clean 

Water Rule defining waters of the U.S. in October 2011. The consultation and coordination 

process, including providing information on the development of an accompanying science report 

on the connectivity of streams and wetlands, continued, in stages, over a four year period, until 

the close of the public comment period on November 14, 2014. EPA invited tribes to provide 

written input on the rulemaking throughout both the tribal consultation process and public 

comment period.
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56

EPA specifically consulted with tribal officials to gain an understanding of, and to 

address, the tribal implications of the proposed rule. In 2011, 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 three tribes during the initial consultation period.

EPA continued to provide status updates to the National Tribal Water Council and the 

National Tribal Caucus during 2012 through 2014. The final consultation event was completed 

on October 23, 2014 as a national teleconference with the Office of Water’s Deputy Assistant 

Administrator. Ultimately, EPA received an additional 23 letters from tribes/tribal affiliations by 

the completion of the consultation period. The comments indicate that Tribes, overall, support 

increased clarity of waters protected by the Clean Water Act, but some express concern with the 

consultation process and the burden of any expanded jurisdiction. The feedback received through 

consultation and written comments have been incorporated in today’s rule. 

The agencies have prepared a report summarizing their consultation with tribal nations, 

and how these results have informed the development of this rule. This report, Final Summary of 

Tribal Consultation for the Clean Water Rule: Definition of “Waters of the United States” Under 

the Clean Water Act; Final Rule (Docket Id. No. EPA-HQ-OW-2011-0880-XXXX), is available 

in the docket for this rule. 

As required by section 7(a), EPA’s Tribal Consultation Official has certified that the 

requirements of the executive order have been met in a meaningful and timely manner. A copy 

of the certification is included in the docket for this action.

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.

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.
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57

Appendix A: Supplemental Cost Analysis Information

Figure 17. Occupational Employment and Wage Estimates.

Position Occupational 

Code1

Mean 

Hourly 

Wage1

Benefits 

Adjustment 

Factor3

Year 

Adjustment4

Total Hourly 

Adjusted 

Wage

Private Industry

Environmental Scientist 19-2041 $35.89

1.30 1.03

$47.96

Environmental Engineer 17-2081 $41.74 $55.77

Administrative Assistant 43-6011 $27.32 $36.51

Lawyer 23-1011 $66.41 $88.74

Economist 19-3011 $50.54 $67.53

Local Government

Environmental Scientist 19-2041 $30.27

1.35 1.02

$41.88

Environmental Engineer 17-2081 $37.58 $51.99

Administrative Assistant 43-6011 $25.09 $34.71

Lawyer 23-1011 $46.13 $63.82

Economist 19-3011 $36.35 $50.29

State Government

Environmental Scientist 19-2041 $28.50

1.35 1.02

$39.43

Environmental Engineer 17-2081 $35.26 $48.78

Administrative Assistant 43-6011 $21.42 $29.63

Lawyer 23-1011 $40.19 $55.60

Economist 19-3011 $30.78 $42.58

Federal Government

Environmental Scientist 19-2041 $46.93

1.31 1.03

$63.18

Environmental Engineer 17-2081 $46.91 $63.16

Administrative Assistant 43-6011 $27.322 $36.79

Lawyer 23-1011 $62.87 $84.65

Economist 19-3011 $53.54 $72.08

1. Occupational codes and mean hourly wage from BLS (2014). Bureau of Labor Statistics (BLS), United States 

Department of Labor. 2014. Occupational Employment and Wages, May 2013. 

http://www.bls.gov/oes/current/oes_nat.htm

2. Hourly mean wage for administrative assistants working in the federal government not calculated in the May 2013 

dataset. Hourly mean wage for private industry used for federal government rate.

3. Adjusted for benefits according to the Employment Cost for Employee Compensation Index for professional and 

related for private industry, local and state employees, and civilian workers. Average value across all three quarters 

of 2013. http://www.bls.gov/ncs/ect/

4. Escalated to 2014 dollars using the seasonally-adjusted Employment Cost Index for private industry (May 2013 

(Q2) =118.4, 2014 Q3=121.7), state and local employees (May 2013 (Q2) =121.0, 2014 Q3=124.0), and civilian 

workers (May 2013 (Q2) =118.9, 2014 Q3=122.2)
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58

Figure 18. State-Level Unit Cost Data and Incremental Increases in Wetland and Stream 

Mitigation.

State Increase 

in 

Wetland 

Mitigation 

(Acres)

Per Acre Unit Cost 

of Wetlands 

Mitigation

Increase in 

Stream 

Mitigation 

(Linear Feet)

Per Linear Foot 

Unit Cost of 

Stream 

Mitigation

Low High Low High

AK 3.4 $5,500 $55,000 23 $1,000 $1,000

AL 23.7 $10,524 $21,049 2,259 $380 $964

AR 23.7 $2,105 $5,262 54,862 $185 $343

AZ 36.3 $9,000 $23,000 1,000 $185 $343

CA 122.1 $18,500 $350,000 723 $185 $343

CO 25.2 $33,678 $105,245 14 $185 $343

CT 0.5 $124,000 $470,448 $185 $343

DE 0.5 $41,244 $41,244 $185 $343

FL 93.5 $35,000 $217,800 47 $185 $343

GA 13.6 $12,000 $136,000 $878 $975

IA 6.8 $15,787 $15,787 162 $185 $343

ID 1.9 $41,244 $41,244 348 $185 $343

IL 170.1 $41,244 $206,221 3,920 $185 $343

IN 55.7 $45,671 $91,341 11,316 $185 $343

KS 33.9 $52,622 $52,622 714 $185 $343

KY 14.5 $30,000 $30,000 7,916 $170 $396

LA 6.3 $15,787 $64,600 44 $185 $343

MA 1.9 $124,000 $621,166 $100 $343

MD 7.3 $12,917 $68,109 $294 $688

ME 0.5 $254,390 $377,230 $185 $343

MI 0.5 $40,000 $80,000 $185 $343

MN 34.9 $9,294 $76,443 33 $185 $343

MO 4.4 $15,787 $26,311 62 $95 $387

MS 2.9 $3,157 $26,311 86 $185 $343

MT 89.6 $41,244 $41,244 793 $185 $343

NC 22.8 $25,874 $69,736 25 $289 $381

ND 1441.9 $15,787 $15,787 201 $185 $343

NE 32.5 $15,787 $15,787 148 $185 $343

NH 0.5 $92,042 $128,330 $185 $343

NJ 4.8 $82,489 $412,443 $185 $343

NM 0.5 $42,098 $63,147 $185 $343

NV 179.7 $56,711 $67,022 98 $185 $343

NY 145.3 $50,000 $94,000 249 $310 $420

OH 289.7 $15,787 $15,787 8,247 $185 $343
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59

State Increase 

in 

Wetland 

Mitigation 

(Acres)

Per Acre Unit Cost 

of Wetlands 

Mitigation

Increase in 

Stream 

Mitigation 

(Linear Feet)

Per Linear Foot 

Unit Cost of 

Stream 

Mitigation

Low High Low High

OK 2.4 $12,000 $72,000 1,038 $240 $450

OR 18.9 $54,500 $125,170 $185 $343

PA 57.7 $12,000 $15,000 1,039 $185 $343

RI 0.5 $124,000 $160,000 $185 $343

SC 144.9 $26,311 $105,245 972 $79 $217

SD 166.7 $15,787 $15,787 331 $185 $343

TN 18.9 $25,000 $25,000 69 $54 $240

TX 236.4 $15,000 $45,000 5,837 $80 $220

UT 37.3 $56,711 $67,022 $185 $343

VA 75.1 $16,000 $140,000 $300 $977

VT 1.5 $110,000 $132,000 $185 $343

WA 3.9 $34,677 $318,546 48 $185 $343

WI 10.7 $58,000 $61,000 10 $185 $343

WV 108.0 $30,000 $64,000 9,279 $400 $869

WY 6.8 $15,787 $15,787 $185 $343

Total 3,781 111,916 
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60

Appendix B: Supplemental Benefit Estimate Information

Summary of Wetland Benefits Studies Used to Generate WTP Estimates

Study Location NWI 

Category

Study 

Area 

(acres)

Survey 

Population

Response 

Rate

WTP 

Value 

from 

Study 

(2014$)1

WTP 

Description

Standardized 

One-Time 

WTP per 

Acre2

Azevedo 

et al 

(2000)

IA Emergent 7,000 and 

32,3453

Random sample 

of Iowa residents 

statewide, 

additional 

random sample 

of a targeted 

group of 

hunters/anglers

58.1%4 $13.75-

$34.37

Iowa residents' 

one-time WTP to 

preserve and 

restore wetlands 

through the 

Prairie Pothole 

Joint Venture 

and Iowa River 

Corridor Project

$0.0011-

$0.0020

Blomquist 

and 

Whitehead 

(1998)

KY, IN, 

TN, IL, 

MO

Forested/Shrub 500 Random dialing 

of households in 

Western 

Kentucky and 

nearby areas of 

Indiana, 

Tennessee, 

Illinois and 

Missouri from 

phone directories

66.7% $3.06-

$20.30

Household

annual WTP for 

four wetlands 

with differing 

characteristics in 

western 

Kentucky

$0.1575-

$1.0447
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61

Study Location NWI 

Category

Study 

Area 

(acres)

Survey 

Population

Response 

Rate

WTP 

Value 

from 

Study 

(2014$)1

WTP 

Description

Standardized 

One-Time 

WTP per 

Acre2

Dillman et 

al (1993)

SC Forested/Shrub 2,500 Random sample 

of South 

Carolina 

households 

statewide

21% $28.25 South Carolina 

households’ onetime WTP for 

preservation of 

one of three 

2,500 acre 

wetlands in the 

Francis Biedler 

forest of South 

Carolina

$0.0113

Johnson 

and 

Linder 

(1986)

SD Emergent 1,307,187 One percent 

random sample 

of a targeted 

group, South 

Dakota anglers 

and hunters 

statewide

61% $626.18 South Dakota 

hunters’ onetime WTP for 

wetlands 

statewide for 

hunting. 

Majority of 

hunting wetlands 

are located in the 

eastern part of 

the state.

$0.0005

Lant and 

Tobin 

(1989)

IA, IL Forested/Shrub 2,109 and 

1,1085

In-person 

interviews with 

residents of 

towns near the 

three rivers 

examined.

Not 

reported.

$46.30-

$104.22

Annual WTP to 

improve water 

quality in two 

different river 

basins.

$0.3029-

$2.4203
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62

Study Location NWI 

Category

Study 

Area 

(acres)

Survey 

Population

Response 

Rate

WTP 

Value 

from 

Study 

(2014$)1

WTP 

Description

Standardized 

One-Time 

WTP per 

Acre2

Loomis et 

al. (1991)

CA Emergent 85,000 

and 

125,0006

Random sample 

of households in 

San Joaquin 

Valley and 

throughout 

California

51% $267.68-

$441.49

Annual 

California 

statewide 

household WTP 

to protect and 

restore San 

Joaquin Valley 

wetlands.

$0.0435-

$0.0909

Mullarky 

and 

Bishop 

(1999)

WI Emergent 110 Random sample 

of Wisconsin 

residents 

statewide

43.5% $19.44-

$34.20

Annual WTP for 

a hypothetical 

rerouting of a 

highway 

expansion that 

would preserve 

110 acres of 

wetlands in 

Wisconsin

$2.4389-

$8.0003

Poor 

(1999)

NE Emergent 41,000 Random 

statewide sample 

of Nebraska 

households

46% $31.76 Annual WTP to 

increase the area 

of wetlands in 

Nebraska’s 

rainwater basin

wetland region

by an average of 

41.000 acres

$0.0107-

$0.0199
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63

Study Location NWI 

Category

Study 

Area 

(acres)

Survey 

Population

Response 

Rate

WTP 

Value 

from 

Study 

(2014$)1

WTP 

Description

Standardized 

One-Time 

WTP per 

Acre2

Roberts 

and Leitch 

(1997)

MN, SD Emergent 5,000 Minnesota and 

South Dakota 

households 

within a 30-mile 

radius of Mud 

Lake

62% $9.34 Annual value to 

households to 

households of 

Mud Lake, a 

managed 

lacustrine 

wetland on the 

border of 

Minnesota and 

South Dakota

$0.0258-

$0.0480

Whitehead 

and 

Blomquist 

(1991)

KY Forested 5,000 Random cluster 

sample of 

Western 

Kentucky 

households from 

phone directories

31% $9.72-

$31.71

Kentucky 

households’ 

annual WTP for 

preservation of 

Clear Creek 

wetland, a large 

natural wetland 

with hardwood 

trees, standing 

water, and nonwoody 

vegetation.

$0.0268-

$0.1632
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64

Study Location NWI 

Category

Study 

Area 

(acres)

Survey 

Population

Response 

Rate

WTP 

Value 

from 

Study 

(2014$)1

WTP 

Description

Standardized 

One-Time 

WTP per 

Acre2

1. If frequency of payment not specified, EPA assumed WTP is in terms of a one-time payment. Figures updated to 2014$ 

using CPI-U.

2. For estimates reported as annual WTP, the agencies derived the total present value over a period of 50 years using 3 percent 

and 7 percent discount rates.

3. Azevedo et all present WTP for two different study areas, sized 7,000 acres and a project to preserve a total of 40,000 acres 

of prairie potholes over 15 years, at a rate of 2,500 acres per year. This figure was discounted at a 3% rate, to develop a 

project size of 32,345

4. 58.1% represents average overall response rate for Azevedo et al. The response rate for Iowa River Corridor survey (study 

area 7,000 acres) was 56.5%. The response rate for the Prairie Pothole version of the survey (study area 32,345 acres) was

58.9%.

5. Lant and Tobin (1989) estimate the increase in wetland acreage in the riparian corridor to achieve water quality 

improvements in two different river basins. It is estimated an increase of 2,109 acres of wetlands would achieve the valued 

water quality improvements in the Edwards River basin and 1,108 new acres of wetlands would achieve the valued water 

quality improvements in the South Skunk River.

6. Loomis et al. present statewide WTP values to preserve existing wetlands of 85,000 acres and also for a program with a total 

size of 125,000 acres that would preserve the original 85,000 acres plus restore an additional 40,000 acres. 
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65

Summary of Wetland Benefits Studies

Azevedo, C., J.A. Herriges, and C.L. Kling. 2000. Iowa Wetlands: Perceptions and Values. 

Center for Agricultural and Rural Development. Staff Report 00-SR 91.

Azevedo et al. (2000) conducted a survey to understand how residents of Iowa value wetlands, 

specifically with regard to the following functions: wildlife viewing, fishing, biking, hiking, 

waterfowl and upland hunting. The 5-part survey collected information regarding wetland 

visitation patterns, perceived benefits and costs associated with wetlands, socioeconomic 

characteristics of respondents, and their WTP for preservation of existing wetlands and 

restoration of additional wetlands via two specific programs: the Prairie Pothole Joint Venture 

(PP) and the Iowa River Corridor Project (IRCP). The authors used contingent valuation to 

evaluate WTP for restoring additional wetlands through PP and ICRP. Results indicated that 

approximately 50% of Iowans would pay $25 in support of PP and less than $10 for ICRP (2000 

dollars).

Blomquist, G.C. and J.C. Whitehead. 1998. Resource Quality Information and Validity of 

Willingness to Pay in Contingent Valuation. Resource and Energy Economics 20: 179-196.

Blomquist and Whitehead (1998) conducted a contingent valuation study to estimate the value of 

four wetlands in Western Kentucky with differing characteristics. One was a freshwater marsh, 

one was a temporarily flooded bottomland hardwood forest, one was a seasonally flooded 

bottomland hardwood forest, and one was a bald cypress swamp. Wetland functions included 

flood control, water quality improvements, and wildlife production/habitat. WTP ranged from 

$1.69 (1990 dollars) for Flat Creek, a freshwater marsh, to $11.21 (1990 dollars) for Cypress 

Creek, a cypress swamp.

Dillman, B., L.J. Beran, and D.D. Hook. 1993. Nonmarket Valuation of Freshwater Wetlands: 

The Francis Beidler Forest. South Carolina Water Resources Research Institute, Clemson 

University.

Dillman et al. (1993) estimated the WTP for preservation of 2,500 acres of wetlands in the 

Francis Biedler forest of South Carolina using dichotomous choice contingent valuation method. 

The study examined three types of wetland: frequently flooded bottomland (cypress-tupelo 

swamp), infrequently flooded bottomland hardwood forest, and non-bottomland pine plantation 

with hardwood runners. These wetlands served the following functions: flood control, wildlife 

habitat, recreational activities, water supply, and aesthetic value. The mean WTP estimated was 

$16.74 (1993 dollars) per household (ranging from $6.82 for infrequently flooded bottomland 

hardwood forests to $19.57 for pine plantations with scattered hardwood runners).
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66

Johnson, C.W. and R.L. Linder. 1986. An Economic Valuation of South Dakota Wetlands as a 

Recreation Resource for Resident Hunters. Landscape Journal 5(1): 33-38.

Johnson and Linder (1986) conducted a contingent valuation study to estimate the value of 

wetlands in South Dakota as a recreational resource for resident hunters. The study examined 

wetlands statewide, the majority of which are located in the eastern part of the state. Their results 

indicated that the total value for waterfowl, upland, big game, and predator hunting in South 

Dakota wetlands in 1986 dollars was $34 million, and that the average total per user value of 

wetlands was $289.90 for a single hunting season.

Lant, C.L. and G.A. Tobin. 1989. "The Economic Value of Riparian Corridors in Cornbelt 

Floodplains: A Research Framework". Professional Geographer 41(3): 337-49.

Lant and Tobin (1989) studied willingness to pay higher state sales tax to improve water quality 

of riparian corridors in Iowa and Illinois. The study examined three river corridors utilizing faceto-face interviews: the Edwards River in Illinois, the South Skunk River in Iowa, and the 

Wapsipinicon River in Iowa. A necessary increase in wetland acreage in the Riparian corridor to 

achieve water quality improvements was estimated. WTP per person for improvement of quality 

in the Edwards River to that in the South Skunk was $8.85 per year (1989$), and value per 

person for improvement of quality in the South Skunk River to that in the Wapsipinicon was 

$20.37 per year (1989$). The study also reported a state mean average household size of 2.74 

and 2.68 individuals per household in Illinois and Iowa respectively. This study had a very small 

sample size.

Loomis, J., M. Hanemann, B. Kanninen and T. Wegge. 1991. "Willingness to Pay to Protect 

Wetlands and Reduce Wildlife Contamination from Agricultural Drainage." In A. Dinar and D. 

Zilberman (eds.), The Economics and management of Water and Drainage in Agriculture. 

Boston, Massachusetts: Kluwer Academic Publishers, pp. 411-445.

Loomis et al. (1991) studied California residents’ willingness to pay additional taxes to preserve 

and restore wetlands in California’s San Joaquin Valley. The study’s focus was wetlands as a 

habitat for migratory birds. The study found that average statewide annual household willingness 

to pay for a program to prevent further destruction of an existing 85,000 acres of wetlands was 

$154, and the mean statewide willingness to pay for a program including both maintenance of 

existing acreage plus the restoration of an additional 40,000 acres was $254 (1990 dollars). The 

study also examined a program to reduce and prevent further pollution of wildlife habitat in the 

region, and to increase Chinook salmon populations.
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67

Mullarkey, D.J. and R.C. Bishop. 1999. Sensitivity to Scope: Evidence from a CVM Study of 

Wetlands. Presented at the Annual Meeting of the American Agricultural Economics 

Association, Nashville, TN, August 8-11, 1999.

Mullarkey and Bishop (1999) conducted a study of WTP for a hypothetical rerouting of a 

highway expansion that would preserve 110 acres of wetlands in Wisconsin. The wetlands in 

question provide a range of services including flood control, water purification, bird/wildlife 

habitat, and for a portion of the affected wetlands, fish habitat. The study reported six estimates 

of WTP ranging from $13.68 to $57.83 (1999 dollars) depending upon whether respondents were 

informed that mitigation would be taking place if the wetland were destroyed and the degree of 

certainty respondents expressed in their answers.

Poor, P.J. 1999. The Value of Additional Central Flyway Wetlands: The Case of Nebraska’s 

Rainwater Basin Wetlands. Journal of Agricultural and Resource Economics 24: 253-265.

Poor (1999) examined WTP to increase the area of wetlands in Nebraska’s rainwater basin by an 

average of 41,000 acres across multiple survey versions. The basin is a large complex of 34,000 

wetland acres, and a plan is already in place to create an additional 25,000 wetland acres. 

Wetland services in this study included flood control, water quality improvement, wildlife 

production and habitat, and bird watching/hiking. Median and mean household WTP were $4.17 

and $21.05 (1996 dollars), respectively.

Roberts, L.A. and J.A. Leitch. 1997. Economic Valuation of Some Wetland Outputs of Mud 

Lake, Minnesota-South Dakota. North Dakota Agricultural Experiment Station. Agricultural 

Economics Report No. 381.

Roberts and Leitch (1997) conducted a contingent valuation study of the value of Mud Lake, a 

managed lacustrine wetland on the border of Minnesota and South Dakota. This study used a 

discrete choice survey to determine use, option/bequest, and existence values for Mud Lake. Use 

values, defined as WTP for management for water related recreation and fish/wildlife habitat 

ranged from $22,699 to more than $44,736 (1997 dollars) for all respondents in the sample. 

Option/bequest values ranged from $25,795 to more than $52,750 (1997 dollars) for all 

respondents in the sample. Existence values ranged from $18,508 to more than $40,451 (1997 

dollars) for all respondents in the sample. Total overall median willingness to pay for the sample 

was estimated to be $102,000 (1997 dollars).

Whitehead, J.C. and G.C. Blomquist. 1991. Measuring Contingent Values for Wetlands: Effects 

of Information about Related Environmental Goods. Water Resources Research 27: 2523-2531.
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68

Whitehead and Blomquist (1991) utilized contingent valuation to examine Kentucky residents’ 

WTP for preservation of the Clear Creek wetland, a large natural wetland with hardwood trees, 

standing water, and non-woody vegetation. The wetland provides a range of services including 

water quality maintenance, fish and wildlife habitat, flood and sediment control, groundwater 

recharge, biological productivity and outdoor recreation. The study used three different survey 

versions consisting of two WTP questions each, with the difference in each case reflecting a 

difference in information presented about the wetland quality that would result if Clear Creek is 

not preserved. WTP values ranged from $5.09 to $16.61 (1991 dollars) under the scenario 

discussing preservation and reclamation of Clear Creek itself, and from $3.75 to $8.13 (1991 

dollars) under scenarios discussing preservation of other wetlands concurrent with reclamation of 

Clear Creek. 

Procedure for Standardizing and Weighting WTP Values from 

Benefits Studies

WTP estimates were standardized across studies as follows:

1. For WTP values reported as an annual value, the agencies derived the total present value 

over a period of 50 years using 3 percent and 7 percent discount rates.

2. In a few studies WTP values were reported for individuals as opposed to per household. 

In such cases, the agencies applied the individual value as if it were representative of the 

household value, with the exception of Lant and Tobin (1989), which explicitly stated the 

average household size at the time the study was completed. Where an individual was 

assumed to represent the household value, for studies where the average household size 

was actually greater than one, this leads to an underestimate of benefits. 

3. WTP per household per acre was calculated using the reported size of the wetlands 

valued in the studies. 

Standardized WTP values were sorted by NWI Category, and an overall WTP value was 

calculated using a geometric mean, weighted by the number of respondents per survey (a study 

may have more than one survey). In circumstances where multiple WTP values were extracted 

from a one survey, the total weight assigned to that survey was divided amongst the observations 

utilized.
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69

Appendix C: Sensitivity Analyses

This sensitivity analyses examines how overall costs and benefits are affected by changes 

in the jurisdictional assumptions that drive calculations throughout the analysis. The results of 

the different scenarios examined are presented below in Figure 19. The figure first presents the 

primary jurisdictional scenario used throughout the document and described in detail in Section 

4, and briefly discussed here. In the primary scenario, it is assumed that 100 percent of wetlands 

and 100 percent of streams are jurisdictional. Waters currently classified as other waters can 

become jurisdictional as adjacent waters, an (a)(7) special type of water found jurisdictional 

through a case-specific analysis, or an (a)(8) water within 4,000 feet of an ordinary high water 

mark of a traditionally navigable water, interstate water, territorial sea, tributary, or 

impoundment of waters.

An analysis of jurisdictional determination files for currently non-jurisdictional ORM2 

other waters found that:

• 17.1 percent would be determined to be jurisdictional as adjacent waters.

• 21.8 percent are the special categories of waters identified in (a)(7) of the final rule. Nine 

and a half (9.5) percent of these special categories are located in watersheds with a high 

density of wetlands, and all of these waters were assumed to become jurisdictional. The 

remaining 12.4 percent of these special types of waters are located in less dense watersheds,

and half were assumed to be determined as jurisdictional. Overall, 15.7 of other waters are 

estimated to change from negative determinations to positive jurisdictional determinations

under (a)(7) in the final rule [9.5%+(12.4%*0.5)]. 

• The remaining 33.1 percent of ORM2 other waters may be determined to be jurisdictional 

under paragraph (a)(8) of the final rule. Five percent of these waters are assumed to be

determined jurisdictional, which represents 1.7 percent of the total number of ORM2 other 

waters [33.1%*.05].

In total, these assumptions result in an estimate that 34.5 percent of the ORM2 other 

waters would receive a positive jurisdictional determination under this rule. Additionally, in the 

primary jurisdictional scenario, the number of other waters records are doubled for all 

calculations.

To estimate the overall percent change in positive jurisdictional determinations, an 

increase in positive determinations in any category of waters (wetland, streams, or ORM2 other 

waters) must be applied proportionally based on the size of that category relative to the total 

number of other waters. Figure 3 shows this calculation in the primary scenario, resulting in a 

4.65 percent change in positive jurisdictional determinations. This corresponds to costs ranging 

from $237.4 to $447.6 million and benefits ranging from $554.9 to $572.3 million, as calculated 

throughout the document. These cost and benefits figures are presented below in Figure 19, as 

the primary scenario.
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70

Section 4 also presents a scenario where the number of “other waters” is not doubled at 

all, corresponding to an overall 2.84 percent change in positive jurisdictional determinations, as 

calculated in Figure 2. Using these assumptions, costs range from $158.6 to $295.6 million, with 

benefits of $338.9 to $349.5 million. This jurisdictional scenario is presented in Figure 19 as 

scenario A.

Another scenario to consider is if the number of ORM2 other waters records was doubled 

only for the purposes of calculating waters that would be determined to be jurisdictional under 

(a)(7) and (a)(8) provisions. This approach to doubling is similar to the approach used in the 

economic analysis accompanying the proposed rule, where doubling was only utilized for the 

calculations for ORM2 other waters not becoming jurisdictional as adjacent. This scenario 

corresponds to an overall increase in positive jurisdictional determinations of 3.67 percent, 

presented in scenario B below. Corresponding costs range from $194.8 to $365.3 million with 

benefits of $437.9 to $451.7 million.

It is also useful to examine how jurisdiction is affected if it is assumed that all waters 

identified in our random sample as a special type of water under (a)(7) would be determined to 

be jurisdictional, rather than adjusting for the likelihood of a positive case-specific jurisdictional 

determination based on density. Assuming that all 21.8 percent of (a)(7) waters are determined 

to be jurisdictional and returning to the approach to doubling ORM2 other waters for all 

calculations as done in the primary scenario, we calculate a projected increase in percent positive 

jurisdictional determinations for ORM2 other waters of 40.7 percent [=17.1%+21.8%+1.7%]. 

As summarized in scenario C below, when weighted appropriately, this corresponds to an overall 

increase of positive determinations of 5.36 percent and costs range from $268.3 to $507.2

million. Benefits range from $639.6 to $659.6million.

Changes in assumptions regarding (a)(8) waters can also be considered. Returning to the 

same assumptions about (a)(7) waters as in the primary scenario, scenario D below examines 

how the calculations are affected if it is assumed that 10 percent of the waters under (a)(7) are 

assumed to be determined jurisdictional. This corresponds to a 36.1 increase in projected percent 

of positive jurisdictional determinations for ORM2 other waters, corresponding to an overall 

increase in positive determinations of 4.84 percent. This is presented as scenario D below, and 

costs and benefits range from $245.7 to $463.6 million and $593.0 to $611.1 million 

respectively. 

Scenario E combines the assumptions from scenarios C and D. In scenario E, all (a)(7) 

and 10 percent of (a)(8) waters are assumed to be determined jurisdictional. In this scenario, 

42.3 percent of all ORM2 other waters are projected to be determined jurisdictional, 

corresponding to an overall 5.55 percent increase in jurisdictional determinations. Associated 

costs range from $276.6 million to $523.2 million, with benefits ranging from $662.3-to $683.0 

million.
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71

It is important to recognize that in all scenarios benefits outweigh the costs because, as 

the number of waters that are protected under the Clean Water Act increases, benefits rise along 

with costs. Some scenarios show higher costs and benefits than the primary scenario, while 

others result in lower costs and benefits; however, the agencies believe that the primary scenario 

represents the most likely change in jurisdictional assertion as a result of this rule. 

Figure 19. Sensitivity Analysis

Scenario Change in 

Jurisdictional 

Assumptions from 

Primary Scenario

Overall Percent 

Change in 

Jurisdictional 

Waters

Costs

(2014$ 

millions)

Benefits

(2014$ 

millions)

Primary 4.65% $237.4-$447.6 $554.9-$572.3

A No doubling of ORM2 

other waters records.

2.84% $158.6-$295.6 $338.9-$349.5

B Doubling of ORM2 

other waters only 

applied to waters 

becoming jurisdictional 

under (a)(7) and (a)(8), 

similar to proposal 

analysis

3.67% $194.8-$365.3 $437.9-$451.7

C All (a)(7) waters 

jurisdictional

5.36% $268.3-$507.2 $639.6-$659.6

D 10% of (a)(8) waters 

jurisdictional

4.84% $245.7-$463.6 $577.6-$595.6

E All (a)(7) waters 

become jurisdictional, 

10% of (a)(8) waters 

jurisdictional

5.55% $276.6-$523.2 $662.3-$683.0