Introduction

Congress established the Federal Water Pollution Control Act, also known as the Clean Water Act (CWA), to restore and protect the quality of the nation's surface waters.¹ The CWA protects "navigable waters," defined in the statute as "waters of the United States, including the territorial seas."² The scope of this term—waters of the United States, or WOTUS—determines which waters are federally regulated and has been the subject of debate for decades.³ The CWA does not define the term. Thus, in implementing the CWA, the Army Corps of Engineers (Corps) and the Environmental Protection Agency (EPA)—the two agencies that administer the statute—have defined the term in regulations.

For several decades, successive presidential administrations have struggled to interpret the term waters of the United States for the purpose of implementing various requirements of the CWA, and courts have been asked repeatedly to review the regulations and policy expressing those interpretations. Stakeholders have asked the various administrations and the courts to resolve issues involving scope, clarity, consistency, and predictability. Some stakeholders argue against any definition that would result in a broad scope of waters under federal jurisdiction and affect the interests of property owners, farmers, and others.⁴ Other stakeholders argue that a definition that results in too narrow of a scope of waters under federal jurisdiction would leave some hydrologically connected waters and aquatic habitats unprotected.⁵

The agencies' efforts to define WOTUS in regulation during both the Obama and Trump Administrations were mired in controversy and litigation. Many observers viewed the Obama Administration's 2015 Clean Water Rule as defining WOTUS too broadly, while many viewed the Trump Administration's 2020 Navigable Waters Protection Rule as defining WOTUS too narrowly. A federal district court vacated the Navigable Waters Protection Rule in September 2021, after which the Corps and EPA announced that they had halted implementation of the rule.⁶ The Biden Administration has signaled its intent to pursue an "enduring definition" that considers the implementation challenges presented by both of those rules. On December 7, 2021, the Corps and EPA published a proposed rule to revise the definition of WOTUS—the first of two separate rulemakings the agencies anticipate undertaking to establish a lasting definition.⁷

In light of these challenges, some observers argue that the statutory terms navigable waters and waters of the United States are too vague and should be more specifically defined by Congress or the courts. Others argue that the Corps and EPA, with their specific knowledge and expertise, are in the best position to determine the scope of the term. In January 2022, the Supreme Court agreed to review Sackett v. EPA, a long-running dispute regarding whether certain wetlands are WOTUS.⁸ Depending on the timing and scope of any decision in that case, the agencies may need to consider the Court's interpretation of the CWA in their regulations.

Actions by the courts, the Biden Administration, and Congress all have the potential to continue to alter the scope of federal jurisdiction under the CWA. This report examines the actions taken by the Obama, Trump, and Biden Administrations to define waters of the United States, along with related legislation and case law.

Recent History of WOTUS Regulations

Pre-2015 Rules and Guidance

For much of the past several decades, regulations promulgated by the Corps and EPA in 1986 and 1988, respectively, have been in effect.⁹ (These 1986 and 1988 regulations, as further interpreted by the courts and agencies, are hereinafter referred to as pre-2015 rules.) The agencies supplemented these regulations with interpretive guidance developed in response to two Supreme Court rulings. Specifically, in 2001 and 2006, the Supreme Court issued rulings pivotal to the definition of WOTUS—Solid Waste Agency of Northern Cook County v. U.S. Army Corps of Engineers and Rapanos v. United States.¹⁰ Both rulings interpreted the scope of the CWA more narrowly than the Corps and EPA had done previously in regulations and guidance, but Rapanos in particular created uncertainty about the intended scope of waters that are protected by the CWA. The Court's decision in Rapanos yielded three different opinions, none of which garnered a controlling majority for a single standard to govern future jurisdictional disputes. Instead, writing for a plurality of four Justices, Justice Scalia adopted a rule that "waters" in "waters of the United States" means only "relatively permanent, standing, or continuously flowing bodies of water" (i.e., streams, rivers, and lakes), and wetlands with a "continuous surface connection" to such waters.¹¹ Justice Kennedy, writing alone, concluded that a case-by-case test that considers ecological connection and requires a "significant nexus" between the water in question and traditional navigable waters was appropriate.¹² Justice Stevens, for the four dissenters, would have upheld the existing reach of Corps/EPA regulations.¹³ Because the 4-1-4 split in Rapanos did not produce a controlling majority opinion for a single jurisdictional test, lower courts have had to parse the various opinions to decide which definition to apply.¹⁴

In response to the rulings, the agencies developed guidance in 2003¹⁵ and 2008¹⁶ to help clarify how EPA regions and Corps districts should implement the Court's decisions. In the 2008 guidance issued by the Corps and EPA following Rapanos, the agencies organized CWA jurisdictional analysis into three categories:

• 1. waters and wetlands that were categorically WOTUS;
• 2. waters and wetlands that may be WOTUS on a case-by-case basis upon determining a "significant nexus" with a traditional navigable water; and
• 3. waters and wetlands that are categorically excluded from WOTUS.

However, the Corps and EPA acknowledged that their written guidance did not provide the public or agency staff with "the information needed to ensure timely, predictable, and consistent jurisdictional determinations."¹⁷ The agencies further acknowledged that case-by-case significant nexus determinations were resource- and time-intensive.¹⁸ Diverse stakeholders—including Members of Congress, states, the regulated community, and nongovernmental organizations—requested a formal rulemaking to revise the existing rules.¹⁹

2015 Clean Water Rule

In 2015, the Corps and EPA issued the Clean Water Rule, which redefined WOTUS in the agencies' regulations for the first time since the 1980s.²⁰ In publishing the 2015 Clean Water Rule, the agencies sought to reduce the universe of waters subject to case-by-case jurisdictional determinations.²¹ The 2015 Clean Water Rule retained aspects of the agencies' 2008 guidance, including a three-tiered jurisdictional analysis (i.e., categorically jurisdictional, jurisdictional on a case-by-case basis upon determining a "significant nexus," and categorically excluded).²² It also incorporated new features, such as definitions and criteria which established when certain waters were categorically WOTUS, subject to case-by-case significant nexus analysis, or categorically excluded.²³ Some of these changes expanded the set of waters that were categorically WOTUS.

For example, the 2015 Clean Water Rule newly defined tributaries.²⁴ Under the 2015 Clean Water Rule, tributaries were jurisdictional by rule if they had certain features that indicated flow (e.g., a bed and bank and an ordinary high water mark) and contributed flow directly or indirectly to a traditional navigable water, an interstate water, or the territorial seas.²⁵ Under the 2015 Clean Water Rule, a tributary could be perennial (i.e., flow year-round), intermittent (i.e., flow continuously only during certain times of year, such as seasonally), or ephemeral (i.e., flow only in response to precipitation events) as long as the criteria in the definition were met.²⁶ Under pre-2015 rules and guidance, tributaries were jurisdictional by rule if they were perennial or intermittent, while ephemeral tributaries were subject to significant nexus analysis.²⁷

Prior to 2015, waters and wetlands were jurisdictional if they were adjacent to certain regulated waters. The 2015 Clean Water Rule confirmed that such adjacent waters are categorically WOTUS and established numerical distance-based criteria to determine adjacency.²⁸ The rule defined adjacent to mean "bordering, contiguous, or neighboring" one of the aforementioned waters, consistent with the 1986 Corps regulations.²⁹ At the same time, the 2015 Clean Water Rule newly defined neighboring by setting limits for the purposes of determining adjacency.³⁰ Neighboring was defined to include waters (1) located within 100 feet of the ordinary high water mark (OHWM)³¹ of a traditional navigable water, interstate water, the territorial seas, jurisdictional tributary, or impoundment of these waters; (2) located in the 100-year floodplain and within 1,500 feet of the OHWM of a traditional navigable water, interstate water, the territorial seas, jurisdictional tributary, or impoundment of these waters; or (3) located 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 OHWM of the Great Lakes.³² (See Figure 1.) In addition, while the pre-2015 rules included adjacent wetlands as a category of WOTUS, the 2015 Rule created a new, broader category of WOTUS—adjacent waters—which included wetlands, ponds, lakes, oxbows, impoundments, and similar features.³³

Figure 1. Jurisdictional Waters Under the 2015 Clean Water Rule Not drawn to scale

Source: Prepared by CRS, from Army Corps of Engineers and EPA, "Clean Water Rule: Definition of 'Waters of the United States'; Final Rule," 80 Federal Register 37054, June 29, 2015. Notes: "Jurisdictional by Rule" waters were jurisdictional per se without case-specific evaluation. "Tributaries" and "adjacent waters" were jurisdictional by rule if they met the definitions established in the 2015 Clean Water Rule. Waters requiring case-specific evaluation would have been jurisdictional if there was a significant nexus to traditional navigable waters, interstate waters, or the territorial seas. An OHWM is defined in Corps and EPA regulations as the line on the shore established by the fluctuations of water and indicated by specific physical characteristics listed in those regulations (e.g., the natural line impressed on the bank, the presence of litter and debris). a. Case-specific evaluation for this subset of waters (waters within the 100-year floodplain, but beyond 1,500 feet from the OHWM) was limited to those waters within the 100-year floodplain of a traditional navigable water, interstate water, or the territorial seas.

While the Corps and EPA contended that their primary intent in the 2015 Clean Water Rule was to clarify (rather than enlarge) regulatory jurisdiction, some stakeholders and observers viewed it as an expansion of CWA jurisdiction.³⁴ Other stakeholders argued that it excluded too many waters from federal jurisdiction.³⁵ Following issuance of the 2015 Clean Water Rule, industry groups, more than half the states, and several environmental groups filed lawsuits challenging the rule in federal courts across the country.³⁶ Some district courts issued preliminary injunctions temporarily barring the 2015 Clean Water Rule from taking effect in certain states.³⁷ Other courts denied motions for preliminary injunctions.³⁸ Separately, the U.S. Court of Appeals for the Sixth Circuit issued a nationwide stay of the rule,³⁹ although the nationwide stay was lifted after the Supreme Court held that the Sixth Circuit lacked jurisdiction to hear challenges to the rule.⁴⁰ Two courts later remanded the 2015 Clean Water Rule to EPA and the Corps, concluding that it violated the Administrative Procedure Act (APA) and exceeded the agencies' statutory authority under the CWA.⁴¹

At the time the Trump Administration rescinded the 2015 Clean Water Rule, as discussed below, the rule was in effect in a patchwork of states that were not subject to a preliminary injunction or one of the remand orders.

2020 Navigable Waters Protection Rule

The Trump Administration described the 2015 Clean Water Rule as an example of federal "overreach" and took steps to rescind and revise it.⁴² On February 28, 2017, President Trump issued an executive order directing the Corps and EPA to review and rescind or revise the 2015 Clean Water Rule and to consider interpreting the statutory term "navigable waters" in a manner consistent with Justice Scalia's opinion in Rapanos.⁴³

The agencies responded to the executive order in a two-step process. In Step One, EPA and the Corps rescinded the 2015 Clean Water Rule and recodified the pre-2015 regulations.⁴⁴ Accordingly, the pre-2015 regulations and guidance were in effect beginning on the effective date of the Step One Rule (December 23, 2019), and until the agencies' redefinition of WOTUS went into effect.

On April 21, 2020, the Corps and EPA published a final Step Two Rule to redefine WOTUS, titled the Navigable Waters Protection Rule.⁴⁵ The rule went into effect on June 22, 2020, replacing the Step One Rule. Although it was immediately challenged, the Navigable Waters Protection Rule remained in effect in most jurisdictions until September 2021, when it was vacated by a federal district court. This report nonetheless discusses the Navigable Waters Protection Rule in some detail, because litigation is ongoing as of this writing, and because it is important background against which the Biden Administration is expected to take new actions (as described in more detail below).

Overall, the Navigable Waters Protection Rule narrowed the scope of waters and wetlands that were considered WOTUS and therefore fell under federal jurisdiction compared to both the 2015 Clean Water Rule and the pre-2015 rules. The Navigable Waters Protection Rule was structured to focus on relatively permanent bodies of water that provide surface flow to traditional navigable waters or the territorial seas in a typical year.⁴⁶ Thus, ephemeral features, including ephemeral tributaries, were categorically excluded from WOTUS, as were features that did not provide surface water flow in a typical year to certain jurisdictional waters.⁴⁷ Also, although the Navigable Waters Protection rule maintained tributaries and adjacent wetlands as categories of WOTUS that were jurisdictional by rule, the rule narrowed the definitions of those two terms in comparison to prior regulations.

Another of the rule's overarching changes was its elimination of case-by-case significant nexus determinations.⁴⁸ The rule instead established four categories of waters that were categorically WOTUS and specified which waters were categorically excluded.⁴⁹ An overview of these categories, including some of the changes from how such waters were considered under past regulations, is discussed below.

In addition to these changes, the Navigable Waters Protection Rule removed interstate waters, including interstate wetlands, as a separate category of WOTUS.⁵⁰ The pre-2015 rules and the 2015 Clean Water Rule had each included interstate waters as a separate category of WOTUS. Under the Navigable Waters Protection Rule, only those interstate waters that otherwise met the criteria for one of the four WOTUS categories under the rule remained jurisdictional.⁵¹

Jurisdictional Categories and Implementation Challenges

The precise categories the Corps and EPA have used to determine which waters are categorically WOTUS and which are excluded have not always overlapped neatly from one rule to the next. A full analysis of each regulatory framework's scheme for categorizing waters as WOTUS or not WOTUS is beyond the scope of this report. Instead, the following section uses the structure of the Navigable Waters Protection Rule—the most recently promulgated regulation—to discuss how the scope of included and excluded waters has changed, and for identification of selected challenges the Biden Administration could face in developing and implementing a new definition of WOTUS.

Waters That Are Categorically WOTUS

The Navigable Waters Protection Rule defined four categories of waters that were categorically WOTUS.⁵²

(1) Territorial Seas and Traditional Navigable Waters

Territorial seas and traditional navigable waters, which were jurisdictional by rule under the pre-2015 rules and guidance as well as the 2015 Clean Water Rule, were included as separate categories in those rules.⁵³ The Navigable Waters Protection Rule included territorial seas and traditional navigable waters as jurisdictional by rule, and it combined the two into one category rather than separate categories in an effort to streamline and simplify the definition of WOTUS.⁵⁴ The rule made no other substantive changes to these long-regulated categories of waters.⁵⁵

(2) Tributaries

Tributaries were included as a category of WOTUS under the pre-2015 rules and guidance as well as the 2015 Clean Water Rule, but the rules defined tributary differently. Under pre-2015 regulations, tributaries were jurisdictional by rule, but tributaries was not defined in regulation.⁵⁶ Under the 2008 guidance, relatively permanent tributaries—which the agencies defined as tributaries that flow year-round (i.e., perennial) or have continuous flow at least seasonally (i.e., intermittent)—were categorically WOTUS.⁵⁷ Tributaries that were not relatively permanent (i.e., ephemeral) were subject to a case-by-case significant nexus analysis to determine jurisdiction.⁵⁸

The 2015 Clean Water Rule newly provided a regulatory definition for tributaries. Under the 2015 Clean Water Rule, tributaries were jurisdictional by rule if they had certain features that were indicators of flow (e.g., a bed and bank and an ordinary high water mark) and contributed flow directly or indirectly to a traditional navigable water, an interstate water, or the territorial seas.⁵⁹ The tributary could be perennial, intermittent, or ephemeral as long as the criteria were met.

While the Navigable Waters Protection Rule included tributaries among waters that were categorically WOTUS, the rule narrowed the definition of tributary in comparison to prior regulations. Under the Navigable Waters Protection Rule, tributaries included rivers, streams, or similar naturally occurring surface water channels that contributed surface water flow to a territorial sea or traditional navigable water in a typical year.⁶⁰ To be jurisdictional, the tributary was required to be perennial or intermittent in a typical year.⁶¹ Ephemeral tributaries were categorically not WOTUS.⁶² Thus, under the Navigable Waters Protection Rule, fewer tributaries were considered WOTUS when compared to previous regulations and practice, when some ephemeral waters were considered WOTUS.

(3) Lakes, Ponds, and Impoundments of Jurisdictional Waters

Impoundments of jurisdictional waters were jurisdictional by rule and included as a separate category of WOTUS under both the pre-2015 rules and the 2015 Clean Water Rule.⁶³ Lakes and ponds were captured under other categories (e.g., traditional navigable waters, tributaries, adjacent waters, or impoundments) in prior regulations.⁶⁴

The Navigable Waters Protection Rule combined lakes, ponds, and impoundments of jurisdictional waters into a single category of WOTUS.⁶⁵ It also added flow or inundation requirements to this category of WOTUS, which narrowed the scope of jurisdictional waters compared to previous regulations and practice. Under the Navigable Waters Protection Rule, to be considered WOTUS, lakes, ponds, and impoundments of jurisdictional waters were required to either (1) contribute surface water flow in a typical year to a territorial sea or traditional navigable water or (2) be inundated by flooding from a traditional navigable water, territorial sea, jurisdictional tributary, or jurisdictional lake, pond, or impoundment in a typical year.⁶⁶ The flow/inundation requirements were a departure from past regulations and practice. The pre-2015 rules did not specify such requirements for impoundments of jurisdictional waters to be deemed WOTUS.⁶⁷ The preamble to the 2015 Clean Water Rule specified that impoundments of a jurisdictional water were WOTUS regardless of flow or inundation requirements.⁶⁸

(4) Adjacent Wetlands

Under pre-2015 rules, wetlands adjacent to jurisdictional waters were jurisdictional by rule.⁶⁹ EPA regulations did not define adjacent, but Corps regulations defined the term to mean "bordering, contiguous, or neighboring."⁷⁰ The Corps regulations also stated that "[w]etlands separated from other waters of the United States by man-made dikes or barriers, natural river berms, beach dunes and the like are 'adjacent wetlands.'"⁷¹ The 2008 guidance further provided that adjacency was established by (1) an unbroken surface or shallow subsurface connection to jurisdictional waters; (2) physical separation from jurisdictional waters by man-made dikes or barriers, natural river berms, beach dunes, or similar features; or (3) proximity to a jurisdictional water that supports an inference of ecological interconnection.⁷² According to the 2008 guidance, wetlands that were adjacent to traditional navigable waters and wetlands that abutted perennial or intermittent tributaries to such waters were categorically WOTUS.⁷³ Wetlands adjacent to ephemeral tributaries and wetlands adjacent to perennial or intermittent tributaries that did not directly abut them were subject to case-by-case significant nexus analysis to determine jurisdiction.⁷⁴

Under the 2015 Clean Water Rule, as discussed above, the agencies similarly defined adjacent to mean "bordering, contiguous, or neighboring" one of the aforementioned waters.⁷⁵ However, the 2015 Clean Water Rule newly defined neighboring, which set new numeric standards for determining adjacency.⁷⁶ In addition, as discussed previously, the 2015 Clean Water Rule broadened the category to adjacent waters—including wetlands, ponds, lakes, oxbows, impoundments, and similar features.⁷⁷

The Navigable Waters Protection Rule included adjacent wetlands as WOTUS, but it narrowed the definition of what wetlands were considered adjacent compared to previous regulations and practice. Specifically, it limited the definition of adjacent wetlands to include only those wetlands that abutted or otherwise had a direct surface connection to other jurisdictional waters in a typical year, rather than allowing for a shallow subsurface connection or ecological interconnection to such waters. Under the Navigable Waters Protection Rule, adjacent wetlands included wetlands that (1) abutted a territorial sea or traditional navigable water, tributary, or a lake, pond, or impoundment of a jurisdictional water; (2) were inundated by flooding from one of the aforementioned waters in a typical year; (3) were physically separated from one of the aforementioned waters only by a natural berm, bank, dune, or similar natural feature; or (4) were physically separated from one of the aforementioned waters only by an artificial dike, barrier, or similar artificial structure so long as that structure allowed for a direct hydrological surface connection to the water in a typical year.⁷⁸

Waters and Features That Are Not WOTUS

Some waters or water features have been excluded from WOTUS in similar form in pre-2015 practice, the 2015 Clean Water Rule, and the Navigable Waters Protection Rule. While some of these exclusions were not listed in the pre-2015 rules, they were regularly applied in practice and then specifically added to the 2015 Clean Water Rule and Navigable Waters Protection Rule for clarity:⁷⁹

• groundwater, including groundwater drained through subsurface drainage systems;
• artificially irrigated areas that would revert to upland, or dry land, if artificial irrigation ceased; ⁸⁰
• artificial lakes and ponds that are not jurisdictional impoundments and that are constructed or excavated in upland, or dry land; ⁸¹
• water-filled depressions constructed or excavated in upland, or dry land, incidental to mining or construction activity, and pits excavated in upland for the purpose of obtaining fill, sand, or gravel;⁸²
• stormwater control features constructed or excavated in upland, or dry land, to convey, treat, infiltrate, or store stormwater runoff;⁸³
• groundwater recharge, water reuse, and wastewater recycling structures constructed or excavated in upland, or dry land;⁸⁴ and
• waste treatment systems.⁸⁵

The scope of some other excluded categories has changed over time, however. First, the 2015 Clean Water Rule (and pre-2015 practice) regulated ditches that met the definition of tributary and that were constructed in or relocated a tributary, and excluded other ditches.⁸⁶ The Navigable Waters Protection Rule considered ditches in a manner similar to previous regulations, but with a narrower scope. Ditches that were traditional navigable waters, or ditches that were constructed in or that relocated a tributary, or were constructed in an adjacent wetland as long as the ditch satisfied the flow conditions of the tributary definition, were all considered WOTUS.⁸⁷ Any ditches that did not meet these criteria were excluded from WOTUS.⁸⁸ Because the definition of tributary under the Navigable Waters Protection Rule was narrower than the 2015 Clean Water Rule's definition, however, fewer ditches were considered WOTUS under the Navigable Waters Protection Rule.

Second, while all three regulatory frameworks have excluded prior converted cropland, the scope of the term has changed over time. Corps and EPA regulations have excluded prior converted cropland since 1993, and the 2015 Clean Water Rule maintained the exclusion.⁸⁹ The preamble to the 1993 rule which added the exclusion to regulations included criteria for determining when prior converted cropland was considered abandoned and the exclusion ceased to apply.⁹⁰ Specifically, the 1993 rule's abandonment criteria required that an area be used for production of an agricultural commodity.⁹¹ The Navigable Waters Protection Rule retained the long-standing exclusion for prior converted cropland, but defined the term in regulations for the first time. The rule clarified the abandonment criteria and specified that an area would cease to be considered prior converted cropland for CWA purposes when both the prior converted cropland "is not used for, or in support of, agricultural purposes at least once in the immediately preceding five years" and the land reverts to wetland status, as defined in the rule.⁹² The term agricultural purposes was not defined by regulation, but some text in the preamble appeared to broaden the prior converted cropland exception for CWA purposes.

Additionally, the Navigable Waters Protection Rule added three new excluded categories: ephemeral features, diffuse stormwater runoff and directional sheet flow over upland, and waters not identified as categorically WOTUS.⁹³ As previously discussed, the Navigable Waters Protection Rule specified that ephemeral features, including ephemeral streams, swales, gullies, rills, and pools, were not WOTUS.⁹⁴ However, it clarified that a tributary, lake, pond, or impoundment of a jurisdictional water did not lose its jurisdictional status if it contributed surface water flow to a downstream jurisdictional water in a typical year through a channelized ephemeral feature.⁹⁵ In contrast, if an upstream water was connected to the downstream jurisdictional water only by diffuse stormwater runoff or directional sheet flow over upland, the upstream water was not jurisdictional under the Navigable Waters Protection Rule.⁹⁶ More broadly, the Navigable Waters Protection Rule added an exclusion for waters not identified as categorically WOTUS, thereby eliminating the category of waters subject to significant nexus analysis.

Implementation Challenges

In promulgating the Navigable Waters Protection Rule, the agencies pointed to its potential benefits in increased certainty over the Clean Water Rule and the pre-2015 regulations. The Navigable Waters Protection Rule, for instance, would have simplified most jurisdictional determinations and eliminated the fact-specific "significant nexus" standard which applied after Rapanos. Observers, however, claimed that these changes did not necessarily eliminate uncertainty, but only shifted it to new areas. The Navigable Waters Protection Rule depended upon new definitions or different applications for concepts such as typical year, perennial, intermittent, and ephemeral. Some observers argued that applying these terms to jurisdictional determinations (i.e., determinations as to whether particular water bodies are WOTUS) could be difficult. In addition, some observers argued that the removal of interstate waters as its own category of WOTUS could lead to implementation challenges.

"Typical Year"

The Navigable Waters Protection Rule defined the term typical year to mean "when precipitation and other climatic variables are within the normal periodic range (e.g., seasonally, annually) for the geographic area of the applicable aquatic resources based on a rolling thirty-year period." In the preamble to the rule, the agencies stated that under the final definition, "a typical year would generally not include times of drought or extreme flooding."⁹⁷

Some stakeholders, including scientists and environmental groups, argued that the typical year approach to the rule was concerning in light of climate change.⁹⁸ In their comments on the proposed rule, a coalition of scientific groups argued that the typical year approach "ignores the periodic and substantial connectivity that occurs during increasingly frequent atypical years resulting from climate change."⁹⁹ Some stakeholders also argued that it was unclear how a jurisdictional determination would be made if agencies were making such a determination when conditions did not reflect a typical year (either too wet or dry).¹⁰⁰ Further, some observed that a water body transitioning between protected and unprotected status in response to weather was not consistent with the agencies' stated objective to provide clarity and predictability through the new rule.¹⁰¹

As they had done under both the pre-2015 rules and the Clean Water Rule, the Corps and EPA signaled that they would rely in part on guidance beyond the text of the rule itself to guide implementation. Concurrent with the issuance of the Navigable Waters Protection Rule, the Corps and EPA published a fact sheet specific to the typical year concept.¹⁰² Responding to some stakeholder concerns, the agencies stated that using data from a shorter-than-30-year period could "potentially exaggerate the effects of short-term trends of drought or excessively rainy periods."¹⁰³ They also noted that during atypically wet or dry periods, it might be necessary to rely more heavily on data collected during "typical year" conditions, such as aerial photography or remote sensing imagery.¹⁰⁴

Differentiating Between Intermittent and Ephemeral

In the Navigable Waters Protection Rule, the Corps and EPA indicated that they included definitions of the terms perennial, intermittent, and ephemeral to ensure clarity.¹⁰⁵ The agencies defined perennial as surface water flowing continuously year-round; intermittent as flowing continuously during certain times of the year and more than in direct response to precipitation (e.g., seasonally when the groundwater table is elevated or when snowpack melts); and ephemeral as flowing or pooling only in direct response to precipitation (e.g., rain or snowfall).¹⁰⁶ However, some stakeholders expressed concerns regarding the challenges in differentiating between these concepts.

Some commenters on the proposed rule requested further clarification on the distinction between intermittent and ephemeral, noting concerns about various scenarios that could make the difference less certain. For example, some commenters requested clarification regarding whether streams that flow continuously during a rainy season, such as monsoon-driven streams, are considered intermittent. Others requested additional clarification on how to distinguish between melting snowfall (which under the rule could be considered ephemeral flow) versus melting snowpack (which could be considered the source of perennial or intermittent flow).¹⁰⁷ Some city and county stakeholders also noted that, in some parts of the country, the terms can be used interchangeably, especially in areas that experience a lot of rain.¹⁰⁸

Concurrent with the issuance of the Navigable Waters Protection Rule, the Corps and EPA published a fact sheet focused on implementing the Navigable Waters Protection Rule.¹⁰⁹ In the fact sheet, the agencies discussed some of best available sources of information that could be used to determine flow classification and jurisdiction.

Interstate Waters

Stakeholders also expressed concerns about changes in the Navigable Waters Protection Rule regarding interstate waters. The Navigable Waters Protection Rule removed interstate waters, including interstate wetlands, as a separate category of WOTUS.¹¹⁰ Although prior regulations—both the pre-2015 rules and the 2015 Clean Water Rule—included interstate waters as a separate category of WOTUS, the Corps and EPA asserted that "interstate waters without any surface water connection to traditional navigable waters or the territorial seas are not within the agencies' authority under the CWA."¹¹¹ The agencies nonetheless stated that any interstate waters that otherwise met the criteria for one of the four WOTUS categories under the rule would remain jurisdictional. While some stakeholders supported this change, others expressed concern that loss of interstate management of waters by federal agencies that no longer qualified as WOTUS could lead to complex interstate issues.¹¹² Specifically, some expressed concerns about resolving conflicts without federal assistance, as well as concerns about pollutants that could come from upstream waters.¹¹³

Stakeholder Responses and Litigation Regarding the Navigable Waters Protection Rule

The promulgation of the Navigable Waters Protection Rule prompted a range of reactions from a variety of stakeholders.

Industrial and agricultural groups that supported the Navigable Waters Protection Rule asserted, among other things, that it provided greater certainty and clarity and scaled back federal jurisdiction from the "significant expansion" under the 2015 Clean Water Rule to a more appropriate scope.¹¹⁴ Some of these groups, in comments filed in favor of the proposed Navigable Waters Protection Rule, explained that while they supported the rule, they also believed the agencies should further narrow jurisdiction by, for example, limiting how they define a traditional navigable water.¹¹⁵ Some states also supported the rule, asserting that they are most knowledgeable about their waters and are in the best position to manage them effectively.¹¹⁶

Other stakeholders, including environmental groups and some states, voiced strong opposition to the Navigable Waters Protection Rule. Some of these stakeholders expressed concern that the rule would "roll back" protections on many waters and could have a broad impact on water quality.¹¹⁷ Some states asserted, among other things, that the rule would result in loss of protection in some areas and uneven protections across states.¹¹⁸ Some further asserted that the changes could make it more challenging for some states to address pollution from upstream jurisdictions.¹¹⁹ Some also argued that the interconnectedness of water necessitates a minimum federal standard for most waters rather than a patchwork approach.¹²⁰ From a different perspective, some ranching groups opposed the Navigable Waters Protection Rule, arguing that the Corps and EPA defined navigable waters too broadly.¹²¹

EPA Science Advisory Board Commentary

In February 2020, EPA's Science Advisory Board (SAB), a federal advisory committee which was created in 1978 to provide scientific advice to EPA, finalized and transmitted a commentary on the proposed revised definition of WOTUS.¹²² The SAB had previously weighed in on the science of CWA jurisdiction in 2014. Specifically, the SAB conducted a technical review of a report prepared by EPA's Office of Research and Development synthesizing the peer-reviewed science on the relationship and downstream effects of waters (often referred to as the "Connectivity Report"), which provided much of the technical basis for the 2015 Clean Water Rule.¹²³ The SAB also reviewed the adequacy of the scientific and technical basis of the proposal for the Clean Water Rule. In providing comments on the Navigable Waters Protection Rule, the SAB thus opted to provide a "commentary" on the rule because the science had not changed, but the agencies' position on how to use the science to inform its policy decision had changed.¹²⁴

The SAB found that the proposed Navigable Waters Protection Rule "decreases protection for our Nation's waters" and concluded that it "does not incorporate best available science and as such we find that a scientific basis for the proposed Rule, and its consistency with the objectives of the Clean Water Act, is lacking."¹²⁵ The SAB highlighted several concerns about certain types of waters excluded from the definition of WOTUS in the proposed rule, as well as the basis for adopting a surface-water-based definition of WOTUS.¹²⁶ The SAB summarized these concerns by stating that the "current scientific understanding of surface and ground water … is not reflected in the proposed Rule. Specifically, the proposed definition of WOTUS excludes ground water, ephemeral streams, and wetlands which connect to navigable waters below the surface."¹²⁷ The SAB further stated that the agencies did not present new science to support the new definition, and therefore the proposed rule "lacks a scientific justification, while potentially introducing new risks to human and environmental health."¹²⁸

Litigation and the Biden Administration's Actions

States, environmental groups, tribes, and other stakeholders challenged the Navigable Waters Protection Rule in many separate cases.¹²⁹ On June 19, 2020, the U.S. District Court for the District of Colorado issued a preliminary injunction which barred the implementation of the Navigable Waters Protection Rule only in the state of Colorado.¹³⁰ However, on March 2, 2021, the U.S. Court of Appeals for the Tenth Circuit reversed and vacated the district court's decision, lifting the injunction and allowing the rule to take effect in Colorado.¹³¹

President Biden signaled interest in reconsidering the Navigable Waters Protection Rule immediately upon taking office. On January 20, 2021, President Biden issued an executive order (E.O. 13990) which revoked the Trump Administration's executive order directing the Corps and EPA to review and rescind or revise the Clean Water Rule.¹³² Although the Biden Administration's executive order did not itself rescind the Trump Administration's Navigable Waters Protection Rule, it also directed the heads of all agencies to "immediately review all existing regulations, orders, guidance documents, policies, and any other similar agency actions (agency actions) promulgated, issued, or adopted" during the Trump Administration "that are or may be inconsistent with, or present obstacles to, the policy set forth" in the order.¹³³ The executive order further stated "for any such actions identified by the agencies, the heads of agencies shall, as appropriate and consistent with applicable law, consider suspending, revising, or rescinding the agency actions."¹³⁴ In conjunction with the executive order, the Biden Administration included the Navigable Waters Protection Rule in a fact sheet listing more than 100 agency actions that heads of agencies were to review in accordance with the executive order.¹³⁵

In addition, on January 21, 2021, EPA sent a letter to the U.S. Department of Justice (DOJ) requesting that DOJ seek stays for pending litigation involving judicial review of EPA regulations issued during the Trump Administration.¹³⁶ In a number of cases, courts granted requests to stay challenges to the Navigable Waters Protection Rule while EPA reviewed the rule.¹³⁷

Also, in March 2021, EPA's Office of Inspector General published a report, with findings from a year-long performance audit, concluding that EPA failed to adhere to certain aspects of its internal process in promulgating selected rulemakings, including the Navigable Waters Protection Rule.¹³⁸

On June 9, 2021, the Corps and EPA announced their intent to revise the definition of WOTUS.¹³⁹ After reviewing the Navigable Waters Protection Rule pursuant to Executive Order 13990, the agencies "determined that the rule is significantly reducing clean water protections." For example, the agencies' review found "numerous clear and consistent indicators of a substantial reduction in waters covered under the [Navigable Waters Protection Rule] compared to previous rules and practice." Of particular concern to the agencies was the disproportionate impact in arid states. Corps data showed that in New Mexico and Arizona, almost all of the 1,538 streams assessed over a 10-month evaluation period while the Navigable Waters Protection Rule was in effect were found to be nonjurisdictional.¹⁴⁰ The agencies also noted that at least 333 projects that formerly required CWA Section 404 permits did not require them under the Navigable Waters Protection Rule.¹⁴¹

Accordingly, in their June 9 announcement, the agencies indicated that they (1) planned to initiate a new rulemaking process to restore the regulatory landscape as it existed prior to implementation of the 2015 Clean Water Rule; and (2) anticipated developing a new rule to define WOTUS through a process that would be informed by stakeholder engagement and the experience of implementing prior rules.¹⁴²

In conjunction with their June 9 announcement, the Corps and EPA began asking courts to remand the Navigable Waters Protection Rule while the agencies developed a new regulation.¹⁴³ The agencies argued that remand was appropriate to avoid potentially unnecessary litigation over aspects of the Navigable Waters Protection Rule that might change after WOTUS was redefined.¹⁴⁴ The agencies sought remand without vacatur, meaning that the Navigable Waters Protection Rule would have remained in effect pending the development of a new rule if their motions were granted.¹⁴⁵ Some groups opposed this aspect of the agencies' motion, arguing that courts should have vacated the Navigable Waters Protection Rule if they granted the remand request.¹⁴⁶

No court ruled on the merits of the Navigable Waters Protection Rule. Some courts granted the Corps and EPA's motion, remanding the rule but not vacating it.¹⁴⁷ On August 30, 2021, the U.S. District Court for the District of Arizona granted the agencies' request for voluntary remand in Pasqua Yaqui Tribe v. EPA, but it also vacated the rule.¹⁴⁸ While the court did not issue a ruling on the merits of the Navigable Waters Protection Rule, it found that both the plaintiffs and the United States had identified concerns with the rule that "involve fundamental, substantive flaws that cannot be cured without revising or replacing the [rule's] definition of [WOTUS]."¹⁴⁹ Additionally, the court found that remanding without vacatur "would risk serious environmental harm" in light of the reduction in waters considered to be WOTUS.¹⁵⁰ The court also found that vacatur and a return to the pre-2015 regulatory regime would not result in an unacceptable level of regulatory uncertainty. The district court's order did not specify what would take the place of the Navigable Waters Protection Rule following vacatur, nor did it specify whether the vacatur of the rule would apply nationwide or only in Arizona.¹⁵¹ In response to the order, however, the Corps and EPA announced that they had halted implementation of the Navigable Waters Protection Rule and would interpret WOTUS consistent with the pre-2015 regulatory regime until further notice.¹⁵²

In July 2021, the Corps and EPA initiated the stakeholder engagement process. On July 30, 2021, the Corps and EPA signed a notice of public meeting dates and solicited preproposal feedback from interested stakeholders on defining WOTUS and implementing the definition.¹⁵³ The notice, published in the Federal Register on August 4, 2021, included a schedule for public meetings to take place in August 2021 and solicited written public comment on or before September 3, 2021.¹⁵⁴ The agencies specified several issues in the notice for which they were particularly interested in obtaining feedback, including implementation of the various prior and current regulatory regimes; regional, state, and tribal interests; science; environmental justice interests; climate implications; the scope of jurisdictional tributaries, jurisdictional ditches, and adjacency; and exclusions from the definition.¹⁵⁵

2021 Proposed Foundational Rule

On December 7, 2021, the Corps and EPA issued a proposed rule to revise the definition of WOTUS.¹⁵⁶ The proposed rule—which, if finalized, would restore pre-2015 protections—is the first step in an anticipated two-step rulemaking process. In the proposed rule, the agencies stated that they anticipate developing a second rule that builds upon the regulatory foundation of the first rule.¹⁵⁷

According to the agencies, their goal in proposing the Foundational Rule is to "return to the familiar and longstanding framework that will ensure Clean Water Act regulatory protections, informed by relevant Supreme Court decisions."¹⁵⁸ The 2021 Proposed Foundational Rule largely retains the following seven WOTUS categories from the pre-2015 regulations:¹⁵⁹

• 1. Traditional navigable waters
• 2. Interstate waters, including interstate wetlands
• 3. "Other waters"
• 4. Impoundments of jurisdictional waters
• 5. Tributaries
• 6. Territorial seas
• 7. Adjacent wetlands

The 2021 Proposed Foundational Rule retains three categories without changes from pre-2015 regulations. These include the traditional navigable waters, interstate waters, and territorial seas categories. The 2021 Proposed Foundational Rule also retains the impoundments of jurisdictional waters category with one change.¹⁶⁰ The pre-2015 regulations included impoundments of any WOTUS, but the 2021 Proposed Foundational Rule would exclude impoundments of waters determined to be jurisdictional under the "other waters" category. The agencies clarify that this change reflects their consideration of the jurisdictional concerns and limitations of SWANCC and Rapanos.¹⁶¹ Similarly, the agencies are proposing that the tributaries category not include tributaries of "other waters" and that the adjacent wetlands category not include wetlands adjacent to "other waters."¹⁶²

The remaining three categories—tributaries, adjacent wetlands, and other waters—reflect the definition of WOTUS from pre-2015 regulations, but propose to add language to reflect Supreme Court precedent. Specifically, the Foundational Rule would clarify that waters in those categories may meet either the relatively permanent standard¹⁶³ or the significant nexus standard¹⁶⁴ for purposes of determining jurisdiction. For example, a tributary in the 2021 Proposed Foundational Rule would be considered a WOTUS if it is a tributary of a traditional navigable water, interstate water, impoundment, or the territorial seas, and also meets either the relatively permanent or significant nexus standard.¹⁶⁵ Similarly, adjacent wetlands would be considered WOTUS if they are adjacent to traditional navigable waters, interstate waters, or the territorial seas; or if they are adjacent to jurisdictional impoundments or tributaries that meet the relatively permanent standard or significant nexus standard.¹⁶⁶ For the "other waters" category, the agencies are proposing to delete the provisions in the pre-2015 regulations referring to jurisdiction over waters "the use, degradation, or destruction of which could affect interstate or foreign commerce," and replace them with the relatively permanent and significant nexus standards.¹⁶⁷

The 2021 Proposed Foundational Rule also proposes to retain two long-standing pre-2015 exclusions from WOTUS: prior converted cropland and waste treatment systems.¹⁶⁸

Public Engagement

The Corps and EPA held a tribal roundtable and several virtual public hearings on the 2021 Proposed Foundational Rule in January 2022.¹⁶⁹ The 60-day public comment period closed, and the agencies set August 2022 as their target date for publishing a final rule.¹⁷⁰

The agencies also held 10 regionally focused roundtables between May and June 2022 to engage a variety of stakeholders and discuss experiences implementing the definition of WOTUS, including challenges and opportunities within their geographic areas.¹⁷¹ The agencies selected these roundtables through a nomination process.¹⁷²

SAB Review

Following the issuance of the 2021 Proposed Foundational Rule, EPA's SAB voted unanimously to review the science supporting the proposal.¹⁷³ In informing EPA of its intent to do so, EPA's SAB noted that the proposed rule involves "emerging environmental issues" that could benefit from a SAB review.¹⁷⁴ In May and June 2022, EPA's SAB held a public meeting to review the scientific and technical basis of the 2021 Proposed Foundational Rule, which included a discussion of the findings and recommendations included in a draft SAB work group report.¹⁷⁵ The SAB supported the agencies' return to the significant nexus standard and noted that the technical support document is supported by available scientific literature and technically accurate, but also provided some recommendations to EPA for improving aspects of its economic and environmental justice analyses to better support the rule.¹⁷⁶

Congressional Interest

Some Members of Congress have been critical of the Biden Administration's actions to date with respect to WOTUS. Some have been supportive of the Administration's intent to develop a new rule to replace the Navigable Waters Protection Rule, but criticized the Administration for not immediately repealing the rule.¹⁷⁷ Others criticized the Administration for not providing a sufficient period of time for stakeholder input, and asked the Corps and EPA to extend their public meeting schedule and public comment period to ensure meaningful input.¹⁷⁸ Some Members have also asked for greater transparency regarding the formation, intent, and execution of the regional stakeholder roundtables.¹⁷⁹

Sackett v. EPA

Separate from the current rulemaking process, a pending Supreme Court case could also affect the definition of WOTUS. On January 24, 2022, the Supreme Court agreed to review Sackett v. EPA, a case which raises the question whether certain wetlands are WOTUS and thus subject to protection under the CWA.¹⁸⁰ The petitioners, Chantell and Michael Sackett, own a parcel of land in Idaho, near Priest Lake and across the road from a wetlands complex that drains into an unnamed tributary of a creek that in turn feeds into the lake. The Sacketts' efforts to build on the parcel, which is across the road from the wetlands complex and about 30 feet from the unnamed tributary, have been the focus of a long-running dispute with the Corps and EPA.¹⁸¹ Most recently, the U.S. Court of Appeals for the Ninth Circuit upheld EPA's conclusion that the Sacketts' property contained WOTUS that were subject to federal jurisdiction under the CWA and relevant regulations.¹⁸²

Following the Supreme Court's ruling in Rapanos, lower courts have considered which Justice's opinion should apply in determining when wetlands are WOTUS based on their adjacency to other waters. Every court of appeals to consider the question has held either that Justice Kennedy's significant nexus standard is controlling, or that jurisdiction may be established under either Justice Kennedy's standard or Justice's Scalia's.¹⁸³ The Ninth Circuit's conclusion in Sackett was based on the application of Justice Kennedy's significant nexus test, which the court held in 2007 provided the controlling standard for cases within its circuit.¹⁸⁴

The Sacketts sought review of the Ninth Circuit's decision in the Supreme Court, urging the Court to revisit Rapanos and adopt Justice Scalia's plurality test.¹⁸⁵ The Supreme Court granted review, but specified that review would be limited to "whether the Ninth Circuit set forth the proper test for determining whether wetlands are 'waters of the United States' under the Clean Water Act."¹⁸⁶ Oral argument is scheduled for October 3, 2022.

The implications of the Supreme Court's decision in Sackett will depend on the scope of the Court's ruling. The Court could use this case as an opportunity to provide a majority opinion for a definition of WOTUS. The Court could engage in a de novo consideration of jurisdictional standards that were not articulated in Rapanos, or, more narrowly, it could consider whether one or both of the Rapanos tests provides a meaningful legal standard that can be applied. It is also unclear whether the Court will focus on the narrower question of when adjacent wetlands constitute WOTUS—the issue addressed in Rapanos—or address jurisdiction over other categories. Alternatively, the Court could articulate principles that could apply to the definition of WOTUS more broadly.

Some Members of Congress have called on the Biden Administration to pause its rulemaking efforts to await the Supreme Court's decision in Sackett.¹⁸⁷ EPA has indicated in testimony before House and Senate committees that it and the Corps intend to proceed with the rulemaking process while the case is pending.¹⁸⁸ If the Court opines on relevant statutory language before the Corps and EPA finalize a new definition of WOTUS, the agencies may need to consider the Court's interpretation in their regulations.

Potential Impacts of Revised WOTUS Definitions

The potential impacts of the Navigable Waters Protection Rule remain relevant even though the Biden Administration has indicated that it has halted implementation of the rule and has begun the process to rescind and replace it with a new definition of WOTUS. The agencies may consider the Navigable Waters Protection Rule and stakeholder comments on it when determining how to define WOTUS in a new regulatory action.

As the foregoing discussion of the controversy over WOTUS suggests, the Biden Administration's decisions about definitions will incorporate policy choices about the scope of waters that the CWA should address. Stakeholder comments about the final Navigable Waters Protection Rule reflected that policy issue, as observers highlighted potential impacts and challenges that could arise as the rule was implemented. Because the Navigable Waters Protection Rule narrowed the definition of WOTUS, CWA requirements and programs no longer applied to waters that were previously subject to CWA requirements but no longer qualified as WOTUS. The reductions in federal protection created by the rule and the potential impacts of the changes in scope were likely to differ among states. Likewise, if the Corps and EPA finalize a new definition of WOTUS that is broader than the one established in the Navigable Waters Protection Rule, more waters will be subject to CWA programs and requirements. The 2021 Proposed Foundational Rule, if finalized, would largely maintain the scope of WOTUS under the pre-2015 regulations and practice, which is broader than the scope in the Navigable Waters Protection Rule.

Changes in Federal Protection

In narrowing the scope of federal jurisdiction, the Navigable Waters Protection Rule protected fewer waters than were protected under prior regulations. One challenge in assessing any WOTUS definition is that the impacts and effects of particular definitions can be difficult to identify with precision. This section illustrates how that uncertainty was manifest in stakeholders' evaluations of the Navigable Waters Protection Rule, but similar questions arose under the 2015 Clean Water Rule—and are likely to continue in further rulemaking by the Biden Administration.

Using the Navigable Waters Protection Rule as an example, stakeholders held differing views regarding how many wetlands and streams would have been excluded from federal jurisdiction under that rule, as well as the degree to which such excluded waters could have been protected or managed under state laws and regulations.

Estimates of Changes in Jurisdiction

In evaluating the impact of the Navigable Waters Protection Rule, some attempted to estimate how many of the nation's wetlands and streams might be excluded from federal jurisdiction under the Navigable Waters Protection Rule. Many observers cited estimates prepared by EPA and Corps staff in 2017, and obtained through the Freedom of Information Act.¹⁸⁹ These estimates indicated that the proposed Navigable Waters Protection Rule would have excluded at least 18% of streams and 51% of wetlands nationwide from federal protection under the CWA.¹⁹⁰ The estimates were higher in the arid West, where 35% of all streams, comprising 39% of stream length, are ephemeral.¹⁹¹

However, in a fact sheet accompanying the issuance of the final Navigable Waters Protection Rule, the Corps and EPA dismissed the estimates and asserted that they were "highly unreliable and are based on stream and wetland datasets that were not created for regulatory purposes and which have significant limitations."¹⁹² The agencies also noted that prior administrations similarly did not use maps to estimate changes in jurisdiction when issuing 2003 and 2008 guidance from the SWANCC and Rapanos decisions, nor when the 2015 Clean Water Rule was promulgated.¹⁹³

The Corps and EPA addressed this issue again in their June 2021 press release announcing the Biden Administration's intent to revise the definition of WOTUS, as well as in the 2021 Proposed Foundational Rule. Based on a review of Corps data, the agencies found clear indicators of a substantial reduction in waters covered under the Navigable Waters Protection Rule compared to previous rules and practice, particularly in arid states.¹⁹⁴

Regional Differences in Jurisdictional Changes

Because the status of ephemeral and intermittent waters has been a significant issue in successive rulemakings, states where such waters are common may experience greater changes in federal jurisdiction from rule to rule. The Corps, EPA, and observers generally agree that the Navigable Waters Protection Rule excluded more waters from federal jurisdiction in some regions of the United States than others based on differences in climate. The arid West, for example, has many waterways that are dry for much of the year, but can experience high flows after storm events. Such waterways, under the Navigable Waters Protection Rule, would likely have been considered ephemeral and no longer under federal jurisdiction.¹⁹⁵ Other, wetter, regions of the United States may have had comparatively fewer waterbodies lose federal protection.¹⁹⁶

Ability of States to Address Reduced Federal Jurisdiction

Another significant question with respect to the Navigable Waters Protection Rule, and likely with any future rulemaking, is the balance between federal jurisdiction and state and local actions. Some observers argue that whatever changes resulted from reduced federal jurisdiction under the Navigable Waters Protection Rule (as compared to other historical or potential definitions of WOTUS) could be addressed, at least in part, by state and local programs and actions. States' abilities to manage waters that are not WOTUS may vary for reasons such as current state laws and regulations as well as differing permitting authority among states.

Differing State Laws and Regulations

In the preamble to the Navigable Waters Protection Rule, EPA noted that nothing in the rule or the CWA prevents states from protecting nonjurisdictional waters through their own actions.¹⁹⁷ Critics of broad assertion of federal jurisdiction over water resources point out that many states have authorities to regulate waters of their state, often beyond the scope of federal jurisdiction.¹⁹⁸ Other observers argue that many states effectively adopt the scope of federal CWA jurisdiction as a factor that determines their own agencies' authority to regulate waters.¹⁹⁹ The Corps and EPA compiled information on state authorities in developing the Navigable Waters Protection Rule. The agencies concluded that "approximately half or more of the states regulate at least some waters beyond the scope of federal CWA requirements,"²⁰⁰ but that many states face some constraints in their current authority to fill gaps. For example

• "There are some state laws that constrain the state's authority to regulate more broadly than the federal 'floor' set by the CWA in various respects."
• "Thirteen states have adopted laws that require their state regulations to parallel federal CWA regulations."
• "Some state laws limit the application of state regulations to certain industries, certain types of permits, or certain types of resources. Such requirements exist in six states."
• "Seven states have enacted requirements that no environmental state agencies can promulgate state regulations beyond what is required under federal regulations. These requirements include limits on geographic jurisdiction of state regulations to match CWA jurisdiction."
• "Twenty-four states have adopted laws that require extra steps or findings of benefits in order to impose state regulations beyond federal requirements."
• "Twenty-one states and the District of Columbia do not appear to have any laws that address state regulations outside the scope of CWA jurisdiction."²⁰¹

The prevalence of constraints and absence of protections broader than federal requirements in many states indicate that, in these states, there would be at least some time in which the Navigable Waters Protection Rule would reduce protections for waters with no countervailing state authority to regulate those waters. State legislators have the ability to alter their statutes or enact additional protections, irrespective of whether a new rule issued by the Biden Administration changes the universe of waters that are considered WOTUS. Addressing the changes, however, would require time and resources to take on these responsibilities and to develop effective programs.²⁰²

Differing Permitting Authority

The potential impacts of changes in federal jurisdiction in states may also vary depending upon whether the state or a federal agency (i.e., EPA or the Corps) is the CWA permitting authority. Specifically, if a state already has a permitting program established, that state may be able to address any reductions in coverage more easily than a state that does not have such a program because it has already established the legal, logistical, human resource, and financial infrastructure for permit program administration.

The CWA authorizes states to assume administration of the two key permitting programs under the statute—National Pollutant Discharge Elimination System (NPDES) permits under CWA Section 402 and dredge and fill permits under CWA Section 404.²⁰³ If states apply to EPA to administer either program and meet statutory criteria, then EPA must approve those states' assumption of their programs. Almost all states (with the exception of Massachusetts, New Hampshire, and New Mexico) have assumed administration of their CWA Section 402 NPDES permitting programs. In the three states that have not, EPA is the permitting authority. In contrast, three states (Florida, Michigan, and New Jersey) have assumed administration of their CWA Section 404 dredge and fill permitting programs. In the other 47 states, the Corps is the permitting authority.²⁰⁴ When a state assumes administration of its CWA Section 404 permitting program, its administration applies only to assumed waters, while the Corps continues to administer the CWA for retained waters.²⁰⁵

According to the Association of State Wetland Managers, interest in state assumption of the Section 404 program increased following the SWANCC and Rapanos rulings, which narrowed federal protections for certain waters.²⁰⁶ Many states have explored assumption, and some continue to pursue it.²⁰⁷ Many have explored but ultimately not pursued assumption, citing barriers such as lack of funding to administer a state program, uncertainty over the extent of waters that can be assumed, and significant modifications to state regulatory programs that would be necessary.²⁰⁸

Programmatic Impacts

Changes to the scope of waters subject to federal jurisdiction under the CWA also affect the applicability of CWA requirements and programs to many waters and wetlands. Affected provisions and programs include water quality standards, impaired waters, and total maximum daily loads; water quality certifications; CWA permitting programs; and other CWA and non-CWA programs. With respect to the Navigable Waters Protection Rule, some of the potential programmatic impacts were highlighted in stakeholder responses, the rule's preamble, and the Economic Analysis and Resource and Programmatic Assessment the Corps and EPA developed for the final rule.²⁰⁹

Water Quality Standards, Impaired Waters, and Total Maximum Daily Load Programs (CWA Section 303)

CWA Section 303(c) requires states to adopt water quality standards for WOTUS.²¹⁰ They may also adopt standards for additional surface waters if their own state laws allow them to do so.²¹¹ Water quality standards are the foundation for a number of CWA programs. They establish the water quality goals for waterbodies, including which designated uses the waterbody should support (e.g., recreation, fish consumption, public water supply) and the conditions in the water body necessary to support those uses (e.g., concentrations of pollutants).²¹² States are required to review their water quality standards at least once every three years, and EPA is required to review and approve or disapprove any new or revised standards for WOTUS.²¹³

To the extent that a definition of WOTUS narrows the scope of federal jurisdictional waters in comparison to prior regulations and practice, then states would not be required to maintain (or adopt new) water quality standards for excluded waters. States may or may not opt to continue to apply and enforce their water quality standards in such nonjurisdictional waters. If they decide to maintain or adopt water quality standards for nonjurisdictional waters, EPA would no longer be required to review them. As the Corps and EPA noted in the Navigable Waters Protection Rule Resource and Programmatic Assessment, "should they choose, states and tribes may apply standards under state or tribal law for waters that are not 'waters of the United States,' but they would not be in effect for CWA purposes."²¹⁴ In contrast, any new definition of WOTUS that broadens the scope of jurisdictional waters would require states to adopt water quality standards for those waters.

The definition of WOTUS is also relevant to the identification and development of requirements for waters that are not achieving water quality standards (also known as "impaired waters"). CWA Section 303(d) requires states to identify any impaired waters on a biannual basis.²¹⁵ This list of impaired waters is also known as the 303(d) list. CWA Section 303(d) also requires that, for any impaired waters, states establish total maximum daily loads (TMDLs) for pollutants that prevent or are expected to prevent the attainment of water quality standards. A TMDL, essentially a "pollution diet" for a water body, is the maximum amount of a pollutant that a water body can receive and still meet water quality standards, allocated among the pollutant's sources (including a margin of safety).²¹⁶

In responding to the proposed and final Navigable Waters Protection Rule, some observers expressed concern that the narrower WOTUS definition may exclude some impaired waters and waters with established TMDLs.²¹⁷ The Corps and EPA acknowledged that the change in scope could affect existing and future 303(d) lists and TDML restoration plans, noting that states might not assess nonjurisdictional waters and may identify fewer waters as impaired and therefore develop fewer TDMLs.²¹⁸ They further acknowledged that "this could result in reduced protection for aquatic ecosystems if other mechanisms for restoration are not available or utilized."²¹⁹ The Corps and EPA also noted that states may be better "able to focus limited resources on assessing and developing TMDLs for more priority waters that otherwise might be delayed due to the need to assess all federal waters within state borders. The result may be greater ecological restoration of high priority resources earlier."²²⁰ To the extent that the Navigable Waters Protection Rule is replaced by the pre-2015 regulations or a broader definition of WOTUS, more waters will be subject to the protections afforded by inclusion on a 303(d) list, but states will again need to develop a greater number of TMDLs.

CWA Permitting Programs (CWA Sections 402 and 404)

CWA Section 301 prohibits the discharge of pollutants from any point source (i.e., a discrete conveyance, such as a pipe, ditch, etc.) to WOTUS without a permit.²²¹ For both of the CWA permitting programs—authorized under CWA Sections 402 and 404—the requirement for a permit is triggered when there is a discharge into a WOTUS. Consequently, the Navigable Waters Protection Rule reduced the scope of waters subject to CWA permitting.²²² However, the extent of the potential impacts of reduced federal jurisdiction on CWA permitting under CWA Sections 402 and 404 is not entirely certain and could vary across states based on how states address the changes (e.g., by modifying their regulatory programs). Further rulemaking on WOTUS may once again change the scope of waters subject to CWA permit requirements, though it is not yet certain how that scope would compare to the waters covered under prior regulatory definitions.

CWA Section 402 NPDES Permitting

Under CWA Section 402, the discharge of any pollutant from a point source into a WOTUS requires an NPDES permit.²²³ A narrower WOTUS definition, therefore, would reduce the number of point-source discharges that require a permit. The Corps and EPA have stated that some existing or new NPDES permits may still be needed even if a water that was jurisdictional under prior regulations is no longer jurisdictional.²²⁴ For example, under the Navigable Waters Protection Rule, discharges that travel through nonjurisdictional conveyances (such as an ephemeral stream), but reach WOTUS, would still have required a permit.²²⁵ However, in such cases, the permittee may have been able to request a modification to its permit to account for potential dilution of the pollutant that may have occurred before it reached jurisdictional waters.²²⁶ In contrast, under any potential new definition of WOTUS that expands the scope of jurisdictional waters, NPDES permits would be required for discharges to any waters that become jurisdictional.

CWA Section 404 Dredge and Fill Permitting

Under CWA Section 404, the discharge of dredged or fill material into WOTUS, including wetlands, requires a Section 404 permit.²²⁷ Such discharges may be associated with pipeline projects, water resource projects, mining projects, or other development. The Section 404 permitting process requires a permit applicant to demonstrate that they have taken steps to avoid impacts to wetlands, streams, and other aquatic resources; that potential impacts have been minimized; and that compensatory mitigation will be provided for all remaining unavoidable impacts.²²⁸

As with Section 402 NPDES permits, a broader definition of WOTUS would expand the scope of waters and wetlands that require Section 404 permits, and a narrower definition of WOTUS would reduce the scope. Accordingly, under the Navigable Waters Protection Rule, waters (including wetlands) that were previously considered jurisdictional, but no longer qualified as WOTUS, could be filled by developers and other project proponents without a Section 404 permit. In the Economic Analysis accompanying the Navigable Waters Protection Rule, the Corps and EPA acknowledged that absent any state or local programs to address such activities, developers or other project proponents might not take steps to avoid, minimize, or mitigate impacts in nonjurisdictional waters and wetlands.²²⁹ As mentioned previously, in the Corps and EPA's press release announcing their intent to revise the definition of WOTUS, the agencies stated that they were "aware of 333 projects that would have required Section 404 permitting prior to the Navigable Waters Protection Rule, but no longer do."²³⁰

In addition, stakeholders have observed that states considering the feasibility of assuming their CWA Section 404 permitting programs may have to adjust their analyses in light of any potential new definition of WOTUS. In a comment letter on the proposed Navigable Waters Protection Rule, the Association of Clean Water Agencies (ACWA) explained that "a narrowing of federal jurisdiction may impact [ACWA members'] evaluation of the efficiencies gained by assuming 404 programs as they may be assuming less waters."²³¹ This could ultimately impact the number of states that decide to pursue assumption of their CWA Section 404 programs.

Water Quality Certifications (CWA Section 401)

Changes to the definition of WOTUS also have an impact on the extent to which states and tribes may use CWA Section 401 water quality certifications to manage their waters. Under CWA Section 401, any applicant for a federal license or permit to conduct any activity that may result in any discharge into WOTUS shall provide the federal licensing or permitting agency a CWA Section 401 certification that the project will comply with applicable provisions of certain sections of the CWA, including state water quality standards.²³² CWA Section 401 provides states, certain tribes, and in certain circumstances, EPA (i.e., certifying authorities) the authority to grant, grant with conditions, deny, or waive certification of proposed federal licenses or permits that may result in a discharge into WOTUS. If a certifying authority denies certification, the federal licensing or permitting agency cannot issue the license or permit. If a certifying authority grants the certification with conditions, those conditions must become a term of the federal license or permit if one is issued. Consequently, some states view CWA Section 401 certification as a critical tool to manage and protect the quality of waters within their states.²³³ In addition, some states rely on CWA Section 401 water quality certification procedures to protect wetlands in lieu of assuming CWA Section 404 permitting authority, recognizing that they have the ability to affect the federal permit and to exercise some regulatory control over wetlands without the expense of establishing independent state programs.²³⁴

The authority of states and other certifying authorities under CWA Section 401 directly depends upon whether a permit issued by a federal agency under Sections 402 or 404 is required for waters within the states. The narrower scope of WOTUS under the Navigable Waters Protection Rule (or any future rule that narrows the scope of WOTUS) would have reduced the number of federal permits required, thereby affecting how often states exercised their CWA Section 401 authority.²³⁵ Under the Trump Administration, EPA published a final rule (the Section 401 Certification Rule) updating regulations on water quality certification on July 13, 2020.²³⁶ The rule included numerous changes to prior regulation and practice that narrowed the authority of certifying authorities when acting on Section 401 certification requests. (For further discussion of the rule and related policy issues, see CRS Report R46615, Clean Water Act Section 401: Overview and Recent Developments, by Laura Gatz and Kate R. Bowers.)

When considered together, the Navigable Waters Protection Rule and the Section 401 Certification Rule would likely have considerably narrowed states' ability to use water quality certification to manage their waters, for example by imposing conditions on federal project permitting. In addition to revising the definition of WOTUS, however, the Biden Administration has announced its intent to reconsider and revise the Section 401 Certification Rule.²³⁷ Accordingly, the interplay between the two sets of potential regulatory changes could have implications for the water quality certification process.

CWA Section 311

CWA Section 311 prohibits discharges of oil or hazardous substances in harmful quantities into or upon specified waters, including the navigable waters of the United States or adjoining shorelines, or waters of the contiguous zone.²³⁸ It also requires reporting spills of harmful quantities to the federal government and authorizes the federal government to respond to and enforce penalties for discharges into waters subject to CWA jurisdiction. Implementation of the CWA Section 311 program cannot be delegated to states or tribes, so the scope of the program is directly tied to the scope of WOTUS.

A discussion of CWA Section 311 and the Oil Pollution Act's regulatory scheme is outside of the scope of this report. However, broadly speaking, a reduction in jurisdictional waters under the Navigable Waters Protection Rule, or any other potentially narrowed definition of WOTUS, may reduce the applicability of the CWA oil spill prevention, preparedness, and response programs and the associated Oil Spill Liability Trust Fund. For example, requirements to develop and implement certain spill prevention and preparedness plans depend on whether a facility poses a reasonable potential for a discharge to reach a water subject to CWA jurisdiction.²³⁹ If waters that could be affected by a spill from a facility are no longer considered jurisdictional under a narrowed definition of WOTUS, prevention and preparedness plans may no longer be required.²⁴⁰ In addition, the Oil Spill Liability Trust Fund—which is available to reimburse costs of assessing and responding to oil spills in waters subject to CWA jurisdiction—is not available for waters outside CWA jurisdiction.²⁴¹ Therefore, costs incurred by states or tribes to clean up spills in waters no longer considered jurisdictional, and costs related to business impacts associated with those spills, might not be reimbursed, and the responsible parties might not be subject to federal penalties.²⁴² In contrast, under any potential new definition of WOTUS that expands the scope of jurisdictional waters, the CWA Section 311 program would be applicable to those additional jurisdictional waters.

CWA Financial Assistance Programs

EPA administers a number of financial assistance programs under the CWA, including the Section 106 Water Pollution Control Grant Program, the Section 319 Nonpoint Source Management Grant Program, the Section 320 National Estuary Program, and various grant programs authorized under CWA Section 104(b)(3). Some stakeholders have expressed concern about the potential impacts of changes in CWA jurisdiction on various CWA financial assistance programs.²⁴³ In its Resource and Programmatic Assessment accompanying the Navigable Waters Protection Rule, however, the Corps and EPA concluded that they did not anticipate that the final rule would affect EPA's current CWA financial assistance programs, as the scope of these grant programs is not linked to CWA jurisdiction.²⁴⁴ For example, funds from some of these programs have long supported projects and efforts for waters that are not jurisdictional, such as groundwater.

CWA Enforcement

When a discharge of pollutants into WOTUS occurs without a permit (or other authorization or exemption) or in violation of a permit, the CWA provides for administrative, civil, and criminal enforcement actions.²⁴⁵ The enforcement authorities for each of the CWA permitting programs depend on whether a state has assumed the permitting. Both states and EPA are authorized to enforce NPDES permits in the 47 states that have assumed administration of their NPDES programs. In the three states where EPA is the permitting authority, EPA is authorized to enforce those permits. In the three states that have assumed their Section 404 permitting programs, the state, the Corps, and EPA are authorized to enforce permits. In the 47 states that have not assumed their Section 404 programs, the CWA authorizes the Corps and EPA to enforce permits.

Waters that are no longer considered WOTUS (whether under the Navigable Waters Protection Rule or any future rule that narrows the scope of WOTUS) would fall outside of the scope of the Corps and EPA's enforcement authorities under the CWA.²⁴⁶ If subsequent revisions expand the definition of WOTUS, any enforcement actions would likely be based on the rule that was in effect at the time of the discharge. However, as EPA and the Corps noted in the Navigable Waters Protection Rule Resource and Programmatic Assessment, "nothing in the revised definition of 'waters of the United States' affects the ability of states and tribes to apply and enforce independent authorities over aquatic resources under state or tribal law."²⁴⁷ As discussed in the permitting section above, the extent to which states are able or decide to permit waters that fall outside the scope of WOTUS (and enforce those permits) may vary across states.

Other Potential Program Impacts

In addition to these CWA programs, the Navigable Waters Protection Rule Resource and Programmatic Assessment also describes potential impacts on other EPA programs—including the Safe Drinking Water Act and the Resource Conservation and Recovery Act—as well as other federal programs, such as the National Environmental Policy Act, the Endangered Species Act, and the National Historic Preservation Act.²⁴⁸ These programs, and impacts on them from either the Navigable Waters Protection Rule or a revised definition of WOTUS, are outside the scope of this report.

Congressional Interest and Options

Considering the numerous court rulings, ongoing legal challenges, and issues that successive administrations have faced in defining the scope of WOTUS, some stakeholders have urged Congress to more specifically define the term through amendments to the CWA. Others argue that the Corps and EPA, with their specific knowledge and expertise, are in the best position to determine the scope of the term. Moving forward, Congress may oversee the Biden Administration's efforts to review and potentially revise the definition, or may consider introducing legislation that provides a definition of the term or expresses a clearer intent as to how Congress believes the term should be defined. In the 117^th and 116^th Congresses, some committees have held hearings and some Members have introduced legislation related to the scope of WOTUS.

117^th Congress

In the 117^th Congress, the Senate Environment and Public Works Committee and the House Transportation and Infrastructure Committee, Subcommittee on Water Resources and Environment, have held hearings which included discussion of the Biden Administration's plans to develop a new definition of WOTUS.²⁴⁹ While some Members have criticized the Corps and EPA's stated intent to rescind the Navigable Waters Protection Rule, others criticized the agencies for allowing the rule to remain in effect. In addition, some Members have introduced free-standing legislation related to the definition of WOTUS. Two of these bills would enact the Navigable Waters Protection Rule's definition of WOTUS into law. Other proposed legislation would amend the CWA to add a narrower definition of navigable waters. Because WOTUS is a statutory phrase that defines navigable waters, a different definition of the latter term could obviate the need to interpret the former, though it could introduce new interpretive questions.

• H.R. 2660, the "Withstanding Attempts to Encroach on our Resources (WATER) Act," would amend the CWA to codify the definition of WOTUS as revised under the Navigable Waters Protection Rule.
• H.Res. 318 and S.Res. 17 would express the sense of the House and Senate, respectively, that clean water is a national priority and that the Navigable Waters Protection Rule should not be withdrawn or vacated.
• H.R. 4570 and S. 2168, identical bills titled the "Define WOTUS Act of 2021," would amend the CWA to change the definition of navigable waters. The language, as introduced, would narrow the scope of waters subject to CWA jurisdiction in comparison to the Navigable Waters Protection Rule. It would also amend the CWA to make changes to the Corps process for making jurisdictional determinations.²⁵⁰
• H.R. 5849 and S. 2517, companion bills titled the "Defense of Environment and Property Act of 2021," would amend the CWA to change the definition of navigable waters. The language, as introduced, would narrow the scope of waters subject to CWA jurisdiction in comparison to the Navigable Waters Protection Rule. It would also prohibit the use of a significant nexus test; nullify the 1986 Corps Rule, 2008 Guidance, and any subsequent regulation or guidance that defines or interprets the terms navigable waters or WOTUS; and prohibit the Corps and EPA from promulgating any rules or issuing any guidance that expands or interprets the definition of navigable waters unless authorized by Congress. It would also amend the CWA to make changes to the Corps process for making jurisdictional determinations.²⁵¹
• S. 3456, the "Navigable Waters Protection Act of 2022" and S. 2567, the "Navigable Waters Protection Act of 2021," would codify the Navigable Waters Protection Rule's definition of WOTUS.
• S.Con.Res. 5, a concurrent budget resolution passed by the Senate and adopted by the House, included a provision that would allow for adjustments related to preserving the continued implementation of the categories of jurisdictional and excluded waters in the Navigable Waters Protection Rule. The amendment that added the provision (S.Amdt. 655) was agreed to by yea-nay vote (51-49).

116^th Congress

Multiple hearings in the 116^th Congress also discussed WOTUS.²⁵² During these hearings, some Members expressed support for the Trump Administration's efforts to more clearly and narrowly define WOTUS, while others opposed its efforts and expressed concern about the loss of protection for many waterways across the nation. In addition, some Members introduced free-standing legislation related to the definition of WOTUS. One of these bills would have prohibited implementation of the Navigable Waters Protection Rule and required the Corps and EPA to promulgate a new regulation. Other proposed legislation would have, among other things, repealed or nullified the 2015 Clean Water Rule and amended the CWA to add a narrower definition of navigable waters.

• H.R. 6745, the "Clean Water for All Act," would have nullified the Navigable Waters Protection Rule and prohibited the Corps and EPA from implementing or enforcing it. It would have also required the Corps and EPA to promulgate a regulation defining WOTUS within two years, subject to certain requirements laid out in the bill.
• H.R. 667, the "Regulatory Certainty for Navigable Waters Act," would have repealed the 2015 Clean Water Rule and amended the CWA by changing the definition of navigable waters. The language, as introduced, would have narrowed the scope of waters subject to CWA jurisdiction in comparison to the 2015 Clean Water Rule. It would have also amended the CWA to make changes to the Corps process for making jurisdictional determinations (i.e., determinations as to whether a water body is jurisdictional under the CWA).
• H.R. 2287, the "Federal Regulatory Certainty for Water Act," would have nullified the 2015 Clean Water Rule and amended the CWA by changing the definition of navigable waters. The language, as proposed, would have narrowed the scope of waters subject to CWA jurisdiction in comparison to the 2015 Clean Water Rule.