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 recognizes jurisdiction for three basic categories: Waters that are jurisdictional in all instances, waters that are excluded from jurisdiction, and a narrow category of waters subject to case-specific analysis to determine whether they are jurisdictional.
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 inconsistent analyses of the relationship between a particular stream, wetland, lake, or other water with downstream waters. The agencies have greatly reduced the extent of waters subject to this individual review by carefully incorporating the scientific literature and by utilizing agency expertise and experience to characterize 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 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 Start Printed Page 37058experience 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 types of jurisdictional waters, traditional navigable waters, interstate waters, and the territorial seas, are jurisdictional by rule in all cases. The fourth type of water, impoundments of jurisdictional waters, is also jurisdictional by rule in all cases. The next two types of waters, “tributaries” and “adjacent” waters, are jurisdictional by rule, as defined, because the science confirms that they have a significant nexus to traditional navigable waters, interstate waters, or territorial seas. For waters that are jurisdictional by rule, no additional analysis is required.
The final two types of jurisdictional waters are those waters found after a case-specific analysis to have a significant nexus to traditional navigable waters, interstate waters, or the territorial seas, either alone or in combination with similarly situated waters in the region. Justice Kennedy acknowledged the agencies could establish more specific regulations or establish a significant nexus on a case-by-case basis, Rapanos at 782, and for these waters the agencies will continue to assess significant nexus on a case-specific basis.
The major elements of the final rule are briefly summarized here.
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.
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 that contribute flow directly or indirectly to a traditional navigable water, an interstate water, or the territorial seas. The rule 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 only covers as tributaries those waters that science tells us provide chemical, physical, or biological functions to downstream waters and that meet the significant nexus standard. The agencies identify these functions in the definition of “significant nexus” at paragraph (c)(5). Features not meeting this legal and scientific test are not jurisdictional under this rule. The rule continues the current policy of regulating ditches that are constructed in tributaries or are relocated tributaries or, in certain circumstances drain wetlands, or that science clearly demonstrates are functioning as a tributary. These jurisdictional 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. Further, the rule explicitly excludes from the definition of “waters of the United States” erosional features, including gullies, rills, and ephemeral features such as ephemeral streams that do not have a bed and banks and ordinary high water mark.
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 this 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. However, it is important to note that “adjacent waters” do not include waters that are subject to established normal farming, silviculture, and ranching activities as those terms are used in Section 404(f) of the CWA.
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”:
(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, as defined in the rule.
(2) Waters located in whole or in part in the 100-year floodplain and 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, as defined in the rule (“floodplain waters”).
(3) Waters located in whole or in part within 1,500 feet of the high tide line of a traditional navigable water or the territorial seas and waters located within 1,500 feet of the ordinary high water mark of the Great Lakes.
The agencies emphasize that the rule has defined as “adjacent waters” those waters that currently available science demonstrates possess the requisite connection to downstream waters and function as a system to protect the chemical, physical, or biological integrity of those waters. The agencies also emphasize that the rule does not cover “adjacent waters” that are otherwise excluded. Further, the agencies recognize the establishment of bright line boundaries 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 specific circumstances 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” boundaries stated above where the science may 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 Start Printed Page 37059the 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 is based upon 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. Consistent with 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 function together.
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 function alike and are sufficiently close to function together in affecting downstream waters. These five types of waters are Prairie potholes, Carolina and Delmarva bays, pocosins, western vernal pools in California, and Texas coastal prairie wetlands. Consistent with 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 also provides that waters within the 100-year floodplain of a traditional navigable water, interstate water, or the territorial seas and 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, unless the water is excluded under paragraph (b) of the rule. The science available today does not establish that waters beyond those defined as “adjacent” should be jurisdictional as a category under the CWA, but the agencies' experience and expertise indicate that there are many waters within the 100-year floodplain of a traditional navigable water, interstate water, or the territorial seas or out to 4,000 feet where the science demonstrates that they have a significant effect on downstream waters.
In circumstances where waters within the 100-year floodplain of a traditional navigable water, interstate water, or the territorial seas or 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 function alike and are sufficiently close to function together in affecting 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 together to affect downstream water integrity. To provide greater clarity and transparency in determining what functions will be considered in determining what constitutes a significant nexus, the final rule lists specific functions that the agencies will consider.
In establishing both the 100-year floodplain and the 4,000 foot bright line boundaries for these case-specific significant nexus determinations in the rule, the agencies are carefully applying the available science. Consistent with the CWA, the agencies will work with the states in connection with the prevention, reduction and elimination of pollution from state waters. The agencies will work with states to more closely evaluate state-specific circumstances that may be present within their borders 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.
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 continue to be excluded. Ministerial changes are made for purposes of clarity, but these two exclusions remain substantively and operationally unchanged. The agencies add exclusions for waters and features previously identified as generally exempt (e.g., exclusion for certain ditches that are not located in or drain wetlands) in preamble language from Federal Register documents 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 ditches with ephemeral flow that are not a relocated tributary or excavated in a tributary, and ditches with intermittent flow that are not a relocated tributary, or excavated in a tributary, or drain wetlands. 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 the agencies' current 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. The CWA identifies the waters over which states may assume section 404 permitting jurisdiction. See CWA section 404(g)(1). The scope of waters Start Printed Page 37060that are subject to state and tribal permitting is a separate inquiry and must be based on the statutory language in CWA section 404. States administer approved CWA section 404 programs for “waters of the United States” within the state, except those waters remaining under Corps jurisdiction pursuant to CWA section 404(g)(1) as identified in a Memorandum of Agreement between the state and the Corps. 40 CFR 233.14; 40 CFR 233.70(c)(2); 40 CFR 233.71(d)(2). EPA has initiated a separate process to address how the EPA can best clarify assumable waters for dredged and fill material permit programs pursuant to the Clean Water Act section 404(g)(1). 80 FR 13539 (Mar. 16, 2015). 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.
States and federally-recognized tribes, consistent with the CWA, retain full authority to implement their own programs to more broadly and more fully protect the waters in their jurisdiction. Under section 510 of the CWA, unless expressly stated, nothing in the CWA precludes or denies the right of any state to establish more protective standards or limits than the Federal CWA. Congress has also provided roles for eligible Indian tribes to administer CWA programs over their reservations and expressed a preference for tribal regulation of surface water quality on Indian reservations to ensure compliance with the goals of the CWA. See 33 U.S.C. 1377; 56 FR 64876, 64878-79 (Dec. 12, 1991)). Tribes also have inherent sovereign authority to establish more protective standards or limits than the Federal CWA. Where appropriate, references to states in this document may also include eligible tribes. Many states and tribes, for example, regulate groundwater, and some others protect wetlands that are vital to their environment and economy but outside the 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 the 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
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 case law, 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, or 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 in which to evaluate waters 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 specific 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 the 100-year floodplain of a traditional navigable water, interstate water, or the territorial seas, or waters within 4,000 feet of the high tide line or ordinary high water mark of traditional navigable 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 scientific determination. 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 line boundaries 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 line boundaries 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.” Section 101(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.
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 Start Printed Page 37061to 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 No. 92-414). The Court also recognized that “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 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 “t 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 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' 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 Justice Kennedy's.” 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. (Emphasis in original.)
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 all recognize that the Act and the agencies must identify the scope of CWA jurisdiction “on this continuum to find the limit of `waters,' ” Riverside Bayview at 132, 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 peer-reviewed compilation and analysis of published peer-reviewed scientific literature summarizing the current scientific understanding of the Start Printed Page 37062connectivity 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 in the docket and at http://cfpub.epa.gov/ncea/cfm/record ... id=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. The final peer review report is available on the SAB Web site, 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 was comprised of more than 50 members from a variety of sectors including academia, non-profit organizations, foundations, 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 an 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). 78 FR 15012 (Mar. 8, 2013). 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 Web site 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-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 Web site. 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 Web site 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 covered tributaries, covered 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.
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 covered 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:Start Printed Page 37063
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 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 ES-2.
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 channel-forming 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 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. Science Report at ES-2 to ES-3.
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, 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 subsurface-water 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 ES-3.
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 ES-3 to ES-4.
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 Start Printed Page 37064ephemeral 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, transports pollutants, 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 ES-5 to ES-6.
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. The same SAB Panel 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 Web site 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 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 processes.” 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 semi-arid 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. The agencies did not make this change because this recommendation seemed to suggest that any hydrologic connection is sufficient for CWA jurisdiction. The definition of “tributary” in the rule better identifies tributaries that have a significant nexus to downstream traditional navigable waters, interstate waters, or the territorial seas. 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. The agencies have determined which waters are adjacent, and thus jurisdictional under the rule, based on both functional relationships and proximity because those factors identify the waters that have a strong influence on the chemical, physical, or biological integrity of traditional navigable waters, interstate waters, or the territorial seas. Section C. and IV.F below. The agencies' determination is informed by the science, and consideration of proximity is reasonable in interpreting the scope of adjacency.
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-by-case 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 agencies' identification of the areas within which a water is assessed on a case-specific basis for a significant nexus is informed by the science and the agencies' experience and technical expertise, and consideration of proximity is reasonable in interpreting the scope of the statute. The SAB also expressed support for language in one of the options discussed in the preamble to the proposed rule. 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 chemical, physical, 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 Start Printed Page 37065have 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 Conclusions
As noted earlier, 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 that provides additional legal and scientific discussion for issues raised in this rule, 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 “waters of the United States” and no additional analysis is required. The agencies also determined that additional waters may, on a case-specific basis, have a significant nexus to traditional navigable waters, interstate waters, and the territorial seas, either alone or in combination with similarly situated waters. The agencies' interpretation of the scope of “waters of the United States” is informed by the Science Report and the review and comments of the SAB. The rule reflects the judgment of the agencies in balancing the science, the agencies' expertise, and the regulatory goals of providing clarity to the public while protecting the environment and public health, consistent with the law.
Since the Rapanos decision, the agencies have gained 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 400,000 CWA jurisdictional determinations since 2008. Of those, more than 120,000 are case-specific significant nexus determinations. The agencies made determinations in every state in the country, from the arid West to the tropics of Hawaii, from the Appalachian Mountains in the East to the lush forests of the Northwest. With field staff located in 38 Corps District offices and 10 EPA regional offices, the agencies have almost a decade of nationwide experience in making significant nexus determinations. These individual jurisdictional determinations have been made 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 main part of the river below. 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.