`(Slip Opinion)
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` OCTOBER TERM, 2022
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`Syllabus
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`1
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` NOTE: Where it is feasible, a syllabus (headnote) will be released, as is
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` being done in connection with this case, at the time the opinion is issued.
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` The syllabus constitutes no part of the opinion of the Court but has been
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` prepared by the Reporter of Decisions for the convenience of the reader.
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` See United States v. Detroit Timber & Lumber Co., 200 U. S. 321, 337.
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`SUPREME COURT OF THE UNITED STATES
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` Syllabus
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` SACKETT ET UX. v. ENVIRONMENTAL PROTECTION
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` AGENCY ET AL.
`CERTIORARI TO THE UNITED STATES COURT OF APPEALS FOR
`
`THE NINTH CIRCUIT
` No. 21–454. Argued October 3, 2022—Decided May 25, 2023
`
`Petitioners Michael and Chantell Sackett purchased property near
`Priest Lake, Idaho, and began backfilling the lot with dirt to prepare
`for building a home. The Environmental Protection Agency informed
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`the Sacketts that their property contained wetlands and that their
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`backfilling violated the Clean Water Act, which prohibits discharging
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`pollutants into “the waters of the United States.” 33 U. S. C. §1362(7).
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`The EPA ordered the Sacketts to restore the site, threatening penalties
`of over $40,000 per day. The EPA classified the wetlands on the Sack-
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`etts’ lot as “waters of the United States” because they were near a ditch
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`that fed into a creek, which fed into Priest Lake, a navigable, intrastate
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`lake. The Sacketts sued, alleging that their property was not “waters
`of the United States.” The District Court entered summary judgment
`for the EPA. The Ninth Circuit affirmed, holding that the CWA covers
`wetlands with an ecologically significant nexus to traditional naviga-
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`ble waters and that the Sacketts’ wetlands satisfy that standard.
`Held: The CWA’s use of “waters” in §1362(7) refers only to “geo-
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`graphic[al] features that are described in ordinary parlance as
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`‘streams, oceans, rivers, and lakes’ ” and to adjacent wetlands that are
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`“indistinguishable” from those bodies of water due to a continuous sur-
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`face connection. Rapanos v. United States, 547 U. S. 715, 755, 742, 739
`(plurality opinion). To assert jurisdiction over an adjacent wetland un-
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`der the CWA, a party must establish “first, that the adjacent [body of
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`water constitutes] . . . ‘water[s] of the United States’ (i.e., a relatively
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`permanent body of water connected to traditional interstate navigable
`waters); and second, that the wetland has a continuous surface con-
`nection with that water, making it difficult to determine where the
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`‘water’ ends and the ‘wetland’ begins.” Ibid. Pp. 6–28.
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`2
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`SACKETT v. EPA
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`Syllabus
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`(a) The uncertain meaning of “the waters of the United States” has
`been a persistent problem, sparking decades of agency action and liti-
`gation. Resolving the CWA’s applicability to wetlands requires a re-
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`view of the history surrounding the interpretation of that phrase.
`Pp. 6–14.
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`(1) During the period relevant to this case, the two federal agen-
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`cies charged with enforcement of the CWA—the EPA and the Army
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`Corps of Engineers—similarly defined “the waters of the United
`States” broadly to encompass “[a]ll . . . waters” that “could affect inter-
`state or foreign commerce.” 40 CFR §230.3(s)(3). The agencies like-
`wise gave an expansive interpretation of wetlands adjacent to those
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`waters, defining “adjacent” to mean “bordering, contiguous, or neigh-
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`boring.” §203.3(b). In United States v. Riverside Bayview Homes, Inc.,
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`474 U. S. 121, the Court confronted the Corps’ assertion of authority
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`under the CWA over wetlands that “actually abut[ted] on a navigable
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`waterway.” Id., at 135. Although concerned that the wetlands fell
`outside “traditional notions of ‘waters,’ ” the Court deferred to the
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`Corps, reasoning that “the transition from water to solid ground is not
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`necessarily or even typically an abrupt one.” Id., 132–133. Following
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`Riverside Bayview, the agencies issued the “migratory bird rule,” ex-
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`tending CWA jurisdiction to any waters or wetlands that “are or would
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`be used as [a] habitat” by migratory birds or endangered species. 53
`Fed. Reg. 20765. The Court rejected the rule after the Corps sought to
`apply it to several isolated ponds located wholly within the State of
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`Illinois, holding that the CWA does not “exten[d] to ponds that are not
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`adjacent to open water.” Solid Waste Agency of Northern Cook Cty. v.
`Army Corps of Engineers, 531 U. S. 159, 168 (SWANCC) (emphasis de-
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`leted). The agencies responded by instructing their field agents to de-
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`termine the scope of the CWA’s jurisdiction on a case-by-case basis.
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`Within a few years, the agencies had “interpreted their jurisdiction
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`over ‘the waters of the United States’ to cover 270-to-300 million acres”
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`of wetlands and “virtually any parcel of land containing a channel or
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`conduit . . . through which rainwater or drainage may occasionally or
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`intermittently flow.” Rapanos, 547 U. S., at 722 (plurality opinion).
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`Against that backdrop, the Court in Rapanos vacated a lower court
`decision that had held that the CWA covered wetlands near ditches
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`and drains that emptied into navigable waters several miles away. As
`to the rationale for vacating, however, no position in Rapanos com-
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`manded a majority of the Court. Four Justices concluded that the
`CWA’s coverage was limited to certain relatively permanent bodies of
`water connected to traditional interstate navigable waters and to wet-
`lands that are “as a practical matter indistinguishable” from those wa-
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`ters. Id., at 755 (emphasis deleted). Justice Kennedy, concurring only
`in the judgment, wrote that CWA jurisdiction over adjacent wetlands
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`Cite as: 598 U. S. ____ (2023)
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`Syllabus
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`requires a “significant nexus” between the wetland and its adjacent
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`navigable waters, which exists when “the wetlands, either alone or in
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`combination with similarly situated lands in the region, significantly
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`affect the chemical, physical, and biological integrity” of those waters.
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`Id., at 779–780. Following Rapanos, field agents brought nearly all
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`waters and wetlands under the risk of CWA jurisdiction by engaging
`in fact-intensive “significant-nexus” determinations that turned on a
`lengthy list of hydrological and ecological factors.
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`Under the agencies’ current rule, traditional navigable waters, in-
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`terstate waters, and the territorial seas, as well as their tributaries
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`and adjacent wetlands, are waters of the United States. See 88 Fed.
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`Reg. 3143. So too are any “[i]ntrastate lakes and ponds, streams, or
`wetlands” that either have a continuous surface connection to categor-
`ically included waters or have a significant nexus to interstate or tra-
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`ditional navigable waters. Id., at 3006, 3143. Finding a significant
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`nexus continues to require consideration of a list of open-ended factors.
`Ibid. Finally, the current rule returns to the agencies’ longstanding
`definition of “adjacent.” Ibid. Pp. 6–12.
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`(2) Landowners who even negligently discharge pollutants into
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`navigable waters without a permit potentially face severe criminal and
`civil penalties under the Act. As things currently stand, the agencies
`maintain that the significant-nexus test is sufficient to establish juris-
`diction over “adjacent” wetlands. By the EPA’s own admission, nearly
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`all waters and wetlands are potentially susceptible to regulation under
`this test, putting a staggering array of landowners at risk of criminal
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`prosecution for such mundane activities as moving dirt. Pp. 12–14.
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`(b) Next, the Court considers the extent of the CWA’s geographical
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`reach. Pp. 14–22.
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`(1) To make sense of Congress’s choice to define “navigable wa-
`ters” as “the waters of the United States,” the Court concludes that the
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`CWA’s use of “waters” encompasses “only those relatively permanent,
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`standing or continuously flowing bodies of water ‘forming geo-
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`graphic[al] features’ that are described in ordinary parlance as
`‘streams, oceans, rivers, and lakes.’ ” Rapanos, 547 U. S., at 739 (plu-
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`rality opinion). This reading follows from the CWA’s deliberate use of
`the plural “waters,” which refers to those bodies of water listed above,
`and also helps to align the meaning of “the waters of the United States”
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`with the defined term “navigable waters.” More broadly, this reading
`accords with how Congress has employed the term “waters” elsewhere
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`in the CWA—see, e.g., 33 U. S. C. §§1267(i)(2)(D), 1268(a)(3)(I)—and
`in other laws—see, e.g., 16 U. S. C. §§745, 4701(a)(7). This Court has
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`understood CWA’s use of “waters” in the same way. See, e.g., Riverside
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`Bayview, 474 U. S., at 133; SWANCC, 531 U. S., at 168–169, 172.
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`The EPA’s insistence that “water” is “naturally read to encompass
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`4
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`SACKETT v. EPA
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`Syllabus
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`wetlands” because the “presence of water is ‘universally regarded as
`the most basic feature of wetlands’ ” proves too much. Brief for Re-
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`spondents 19. It is also tough to square with SWANCC’s exclusion of
`isolated ponds or Riverside Bayview’s extensive focus on the adjacency
`of wetlands to covered waters. Finally, it is difficult to see how the
`States’ “responsibilities and rights” in regulating water resources
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`would remain “primary” if the EPA had such broad jurisdiction.
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`§1251(b). Pp. 14–18.
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`(2) Statutory context shows that some wetlands nevertheless
`qualify as “waters of the United States.” Specifically, §1344(g)(1),
`which authorizes States to conduct certain permitting programs, spec-
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`ifies that discharges may be permitted into any waters of the United
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`States, except for traditional navigable waters, “including wetlands
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`adjacent thereto,” suggesting that at least some wetlands must qualify
`as “waters of the United States.” But §1344(g)(1) cannot define what
`wetlands the CWA regulates because it is not the operative provision
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`that defines the Act’s reach. Instead, the reference to adjacent wet-
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`lands in §1344(g)(1) must be harmonized with “the waters of the
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`United States,” which is the operative term that defines the CWA’s
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`reach. Because the “adjacent” wetlands in §1344(g)(1) are “includ[ed]”
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`within “waters of the United States,” these wetlands must qualify as
`“waters of the United States” in their own right, i.e., be indistinguish-
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`ably part of a body of water that itself constitutes “waters” under the
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`CWA. To hold otherwise would require implausibly concluding that
`Congress tucked an important expansion to the reach of the CWA into
`convoluted language in a relatively obscure provision concerning state
`permitting programs. Understanding the CWA to apply to wetlands
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`that are distinguishable from otherwise covered “waters of the United
`States” would substantially broaden §1362(7) to define “navigable wa-
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`ters” as “waters of the United States and adjacent wetlands.” But
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`§1344(g)(1)’s use of the term “including” makes clear that it does not
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`purport to do any such thing. It merely reflects Congress’s assumption
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`that certain “adjacent” wetlands are part of the “waters of the United
`States.”
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`To determine when a wetland is part of adjacent “waters of the
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`United States,” the Court agrees with the Rapanos plurality that the
`use of “waters” in §1362(7) may be fairly read to include only wetlands
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`that are “indistinguishable from waters of the United States.” This
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`occurs only when wetlands have “a continuous surface connection to
`bodies that are ‘waters of the United States’ in their own right, so that
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`there is no clear demarcation between ‘waters’ and wetlands.” 547
`U. S., at 742.
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`In sum, the CWA extends to only wetlands that are “as a practical
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`5
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` Cite as: 598 U. S. ____ (2023)
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` Syllabus
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`matter indistinguishable from waters of the United States.” This re-
`quires the party asserting jurisdiction to establish “first, that the ad-
`jacent [body of water constitutes] . . . ‘water[s] of the United States’
`(i.e., a relatively permanent body of water connected to traditional in-
`terstate navigable waters); and second, that the wetland has a contin-
`uous surface connection with that water, making it difficult to deter-
` mine where the ‘water’ ends and the ‘wetland’ begins.” Rapanos, 547
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`U. S., at 755, 742. Pp. 18–22.
`(c) The EPA asks the Court to defer to its most recent rule providing
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` that “adjacent wetlands are covered by the [CWA] if they ‘possess a
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`significant nexus to’ traditional navigable waters” and that wetlands
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` are “adjacent” when they are “neighboring” to covered waters. Brief
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` for Respondents 32, 20. For multiple reasons, the EPA’s position lacks
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`merit. Pp. 22–27.
` (1) The EPA’s interpretation is inconsistent with the CWA’s text
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` and structure and clashes with “background principles of construction”
`that apply to the interpretation of the relevant provisions. Bond v.
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`United States, 572 U. S. 844, 857. First, “exceedingly clear language”
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` is required if Congress wishes to alter the federal/state balance or the
`Government’s power over private property. United States Forest Ser-
`vice v. Cowpasture River Preservation Assn., 590 U. S. ___, ___. The
`Court has thus required a clear statement from Congress when deter-
`mining the scope of “the waters of the United States.” Second, the
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`EPA’s interpretation gives rise to serious vagueness concerns in light
`of the CWA’s criminal penalties, thus implicating the due process re-
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`quirement that penal statutes be defined “ ‘with sufficient definiteness
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`that ordinary people can understand what conduct is prohibited.’ ”
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`McDonnell v. United States, 579 U. S. 550, 576. Where penal statutes
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`could sweep broadly enough to render criminal a host of what might
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`otherwise be considered ordinary activities, the Court has been wary
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`about going beyond what “Congress certainly intended the statute to
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`cover.” Skilling v. United States, 561 U. S. 358, 404. Under these two
`principles, the judicial task when interpreting “the waters of the
`United States” is to ascertain whether clear congressional authoriza-
`tion exists for the EPA’s claimed power. Pp. 22–25.
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`(2) The EPA claims that Congress ratified the EPA’s regulatory
`definition of “adjacent” when it amended the CWA to include the ref-
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`erence to “adjacent” wetlands in §1344(g)(1). This argument fails for
`at least three reasons. First, the text of §§1362(7) and 1344(g) shows
`that “adjacent” cannot include wetlands that are merely nearby cov-
`ered waters. Second, EPA’s argument cannot be reconciled with this
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`Court’s repeated recognition that §1344(g)(1) “ ‘does not conclusively
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`determine the construction to be placed on . . . the relevant definition
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`of “navigable waters.” ’ ” SWANCC, 531 U. S., at 171. Third, the EPA
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`6
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`SACKETT v. EPA
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` Syllabus
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`falls short of establishing the sort of “overwhelming evidence of acqui-
`escence” necessary to support its argument in the face of Congress’s
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`failure to amend §1362(7). Finally, the EPA’s various policy argu-
`ments about the ecological consequences of a narrower definition of
`“adjacent” are rejected. Pp. 25–27.
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`8 F. 4th 1075, reversed and remanded.
`ALITO, J., delivered the opinion of the Court, in which ROBERTS, C. J.,
`and THOMAS, GORSUCH, and BARRETT, JJ., joined. THOMAS, J., filed a
`concurring opinion, in which GORSUCH, J., joined. KAGAN, J., filed an
`opinion concurring in the judgment, in which SOTOMAYOR and JACKSON,
`JJ., joined. KAVANAUGH, J., filed an opinion concurring in the judgment,
`in which SOTOMAYOR, KAGAN, and JACKSON, JJ., joined.
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` Cite as: 598 U. S. ____ (2023)
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`Opinion of the Court
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` NOTICE: This opinion is subject to formal revision before publication in the
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` United States Reports. Readers are requested to notify the Reporter of
` Decisions, Supreme Court of the United States, Washington, D. C. 20543,
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` pio@supremecourt.gov, of any typographical or other formal errors.
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`SUPREME COURT OF THE UNITED STATES
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`
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`_________________
`
` No. 21–454
`_________________
` MICHAEL SACKETT, ET UX., PETITIONERS v.
`ENVIRONMENTAL PROTECTION
`
` AGENCY, ET AL.
`ON WRIT OF CERTIORARI TO THE UNITED STATES COURT OF
`
`APPEALS FOR THE NINTH CIRCUIT
`[May 25, 2023]
`JUSTICE ALITO delivered the opinion of the Court.
`This case concerns a nagging question about the outer
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`reaches of the Clean Water Act (CWA), the principal federal
`law regulating water pollution in the United States.1 By all
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`accounts, the Act has been a great success. Before its en-
`actment in 1972, many of the Nation’s rivers, lakes, and
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`streams were severely polluted, and existing federal legis-
`lation had proved to be inadequate. Today, many formerly
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`fetid bodies of water are safe for the use and enjoyment of
`the people of this country.
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`There is, however, an unfortunate footnote to this success
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`story: the outer boundaries of the Act’s geographical reach
`have been uncertain from the start. The Act applies to “the
`waters of the United States,” but what does that phrase
`mean? Does the term encompass any backyard that is
`soggy enough for some minimum period of time? Does it
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`reach “mudflats, sandflats, wetlands, sloughs, prairie pot-
`holes, wet meadows, [or] playa lakes?”2 How about ditches,
`swimming pools, and puddles?
`——————
` 186 Stat. 816, as amended, 33 U. S. C. §1251 et seq.
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` 240 CFR §230.3(s)(3) (2008).
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` SACKETT v. EPA
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`Opinion of the Court
`For more than a half century, the agencies responsible for
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`enforcing the Act have wrestled with the problem and
`adopted varying interpretations. On three prior occasions,
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`this Court has tried to clarify the meaning of “the waters of
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`the United States.” But the problem persists. When we
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`last addressed the question 17 years ago, we were unable to
`agree on an opinion of the Court.3 Today, we return to the
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`problem and attempt to identify with greater clarity what
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`the Act means by “the waters of the United States.”
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`I
`A
`For most of this Nation’s history, the regulation of water
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`pollution was left almost entirely to the States and their
`subdivisions. The common law permitted aggrieved parties
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`to bring nuisance suits against polluters. But as industrial
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`production and population growth increased the quantity
`and toxicity of pollution, States gradually shifted to enforce-
`ment by regulatory agencies.4 Conversely, federal regula-
`tion was largely limited to ensuring that “traditional navi-
`gable waters”—that is, interstate waters that were either
`navigable in fact and used in commerce or readily suscepti-
`ble of being used in this way—remained free of impedi-
`ments. See, e.g., Rivers and Harbors Act of 1899, 30 Stat.
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`1151; see also United States v. Appalachian Elec. Power Co.,
`311 U. S. 377, 406–407 (1940); The Daniel Ball, 10 Wall.
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`557, 563 (1871).
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`Congress’s early efforts at directly regulating water pol-
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`lution were tepid. Although the Federal Water Pollution
`Control Act of 1948 allowed federal officials to seek judicial
`abatement of pollution in interstate waters, it imposed high
`——————
` 3See Rapanos v. United States, 547 U. S. 715 (2006). Neither party
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`contends that any opinion in Rapanos controls. We agree. See Nichols
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` v. United States, 511 U. S. 738, 745–746 (1994).
`4See N. Hines, Nor Any Drop To Drink: Public Regulation of Water
`Quality, 52 Iowa L. Rev. 186, 196–207 (1966).
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`Cite as: 598 U. S. ____ (2023)
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`Opinion of the Court
`hurdles, such as requiring the consent of the State where
`the pollution originated. See 62 Stat. 1156–1157. Despite
`repeated amendments over the next two decades, few ac-
`tions were brought under this framework.5
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`Congress eventually replaced this scheme in 1972 with
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`the CWA. See 86 Stat. 816. The Act prohibits “the dis-
`charge of any pollutant” into “navigable waters.” 33
`U. S. C. §§1311(a), 1362(12)(A). It broadly defines the term
`“‘pollutant’” to include not only contaminants like “chemi-
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`cal wastes,” but also more mundane materials like “rock,
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`sand,” and “cellar dirt.” §1362(6).
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`The CWA is a potent weapon. It imposes what have been
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`described as “crushing” consequences “even for inadvertent
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`violations.” Army Corps of Engineers v. Hawkes Co., 578
`U. S. 590, 602 (2016) (Kennedy, J., concurring). Property
`owners who negligently discharge “pollutants” into covered
`waters may face severe criminal penalties including impris-
`onment. §1319(c). These penalties increase for knowing
`violations. Ibid. On the civil side, the CWA imposes over
`$60,000 in fines per day for each violation. See Note follow-
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`ing 28 U. S. C. §2461; 33 U. S. C. §1319(d); 88 Fed. Reg. 989
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`(2023) (to be codified in 40 CFR §19.4). And due to the Act’s
`5-year statute of limitations, 28 U. S. C. §2462, and expan-
`sive interpretations of the term “violation,” these civil pen-
`alties can be nearly as crushing as their criminal counter-
`parts, see, e.g., Borden Ranch Partnership v. United States
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`Army Corps of Engineers, 261 F. 3d 810, 813, 818 (CA9
`2001) (upholding Agency decision to count each of 348
`passes of a plow by a farmer through “jurisdictional” soil on
`his farm as a separate violation), aff ’d by an equally divided
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`Court, 537 U. S. 99 (2002) (per curiam).
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`The Environmental Protection Agency (EPA) and the
`——————
`5See Hearings on Activities of the Federal Water Pollution Control Ad-
`ministration before the Subcommittee on Air and Water Pollution of the
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`Senate Committee on Public Works, 90th Cong., 1st Sess., 674 (1967)
`(reporting only one abatement suit between 1948 and 1967).
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` SACKETT v. EPA
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`Opinion of the Court
`Army Corps of Engineers (Corps) jointly enforce the CWA.
`The EPA is tasked with policing violations after the fact,
`either by issuing orders demanding compliance or by bring-
`ing civil actions. §1319(a). The Act also authorizes private
`plaintiffs to sue to enforce its requirements. §1365(a). On
`the front end, both agencies are empowered to issue permits
`exempting activity that would otherwise be unlawful under
`the Act. Relevant here, the Corps controls permits for the
`discharge of dredged or fill material into covered waters.
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`See §1344(a). The costs of obtaining such a permit are “sig-
`nificant,” and both agencies have admitted that “the per-
`mitting process can be arduous, expensive, and long.”
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`Hawkes Co., 578 U. S., at 594–595, 601. Success is also far
`from guaranteed, as the Corps has asserted discretion to
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`grant or deny permits based on a long, nonexclusive list of
`factors that ends with a catchall mandate to consider “in
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`general, the needs and welfare of the people.” 33 CFR
`§320.4(a)(1) (2022).
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`Due to the CWA’s capacious definition of “pollutant,” its
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`low mens rea, and its severe penalties, regulated parties
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` have focused particular attention on the Act’s geographic
`scope. While its predecessor encompassed “interstate or
`navigable waters,” 33 U. S. C. §1160(a) (1970 ed.), the CWA
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`prohibits the discharge of pollutants into only “navigable
`waters,” which it defines as “the waters of the United
`States, including the territorial seas,” 33 U. S. C. §§1311(a),
`1362(7), (12)(A) (2018 ed.). The meaning of this definition
`is the persistent problem that we must address.
`B
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`Michael and Chantell Sackett have spent well over a dec-
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`ade navigating the CWA, and their voyage has been bumpy
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`and costly. In 2004, they purchased a small lot near Priest
`Lake, in Bonner County, Idaho. In preparation for building
`a modest home, they began backfilling their property with
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`Opinion of the Court
`dirt and rocks. A few months later, the EPA sent the Sack-
`etts a compliance order informing them that their backfill-
`ing violated the CWA because their property contained pro-
`tected wetlands. The EPA demanded that the Sacketts
`
`immediately “‘undertake activities to restore the Site’” pur-
`suant to a “‘Restoration Work Plan’” that it provided. Sack-
`ett v. EPA, 566 U. S. 120, 125 (2012). The order threatened
`the Sacketts with penalties of over $40,000 per day if they
`did not comply.
`
`At the time, the EPA interpreted “the waters of the
`United States” to include “[a]ll . . . waters” that “could affect
`interstate or foreign commerce,” as well as “[w]etlands ad-
`
`jacent” to those waters. 40 CFR §§230.3(s)(3), (7) (2008).
`
`“[A]djacent” was defined to mean not just “bordering” or
`
`“contiguous,” but also “neighboring.” §230.3(b). Agency
`guidance instructed officials to assert jurisdiction over wet-
`lands “adjacent” to non-navigable tributaries when those
`wetlands had “a significant nexus to a traditional navigable
`water.”6 A “significant nexus” was said to exist when “‘wet-
`lands, either alone or in combination with similarly situ-
`
`ated lands in the region, significantly affect the chemical,
`
`physical, and biological integrity’” of those waters. 2007
`Guidance 8 (emphasis added). In looking for evidence of a
`
`“significant nexus,” field agents were told to consider a wide
`
`range of open-ended hydrological and ecological factors.
`See id., at 7.
`
`
`According to the EPA, the “wetlands” on the Sacketts’ lot
`
`are “adjacent to” (in the sense that they are in the same
`neighborhood as) what it described as an “unnamed tribu-
`tary” on the other side of a 30-foot road. App. 33. That
`tributary feeds into a non-navigable creek, which, in turn,
`
`feeds into Priest Lake, an intrastate body of water that the
`
`
`
`——————
`6EPA & Corps, Clean Water Act Jurisdiction Following the U. S. Su-
`preme Court’s Decision in Rapanos v. United States & Carabell v. United
`States 7–11 (2007) (2007 Guidance).
`
`
`
`

`

`6
`
`
`
`
` SACKETT v. EPA
`
`Opinion of the Court
` EPA designated as traditionally navigable. To establish a
`
`
`significant nexus, the EPA lumped the Sacketts’ lot to-
`gether with the Kalispell Bay Fen, a large nearby wetland
`complex that the Agency regarded as “similarly situated.”
`
`According to the EPA, these properties, taken together,
`“significantly affect” the ecology of Priest Lake. Therefore,
`the EPA concluded, the Sacketts had illegally dumped soil
`and gravel onto “the waters of the United States.”
`The Sacketts filed suit under the Administrative Proce-
`
`dure Act, 5 U. S. C. §702 et seq., alleging that the EPA
`
`lacked jurisdiction because any wetlands on their property
`
`were not “waters of the United States.” The District Court
`
`initially dismissed the suit, reasoning that the compliance
`order was not a final agency action, but this Court ulti-
`mately held that the Sacketts could bring their suit under
`
`the APA. See Sackett, 566 U. S., at 131. After seven years
`
`of additional proceedings on remand, the District Court en-
`tered summary judgment for the EPA. 2019 WL 13026870
`(D Idaho, Mar. 31, 2019). The Ninth Circuit affirmed, hold-
`ing that the CWA covers adjacent wetlands with a signifi-
`cant nexus to traditional navigable waters and that the
`Sacketts’ lot satisfied that standard. 8 F. 4th 1075, 1091–
`1093 (2021).
`
`We granted certiorari to decide the proper test for deter-
`
`mining whether wetlands are “waters of the United States.”
`
`595 U. S. ___ (2022).
`
`
`II
`
`A
`In defining the meaning of “the waters of the United
`
`States,” we revisit what has been “a contentious and diffi-
`cult task.” National Assn. of Mfrs. v. Department of De-
`
`fense, 583 U. S. ___, ___ (2018) (slip op., at 1). The phrase
`has sparked decades of agency action and litigation. In or-
`der to resolve the CWA’s applicability to wetlands, we begin
`by reviewing this history.
`
`
`
`
`

`

`7
`
`
`
` Cite as: 598 U. S. ____ (2023)
`
`Opinion of the Court
`The EPA and the Corps initially promulgated different
`
` interpretations of “the waters of the United States.” The
`
`EPA defined its jurisdiction broadly to include, for example,
`intrastate lakes used by interstate travelers. 38 Fed. Reg.
`
`13529 (1973). Conversely, the Corps, consistent with its
`historical authority to regulate obstructions to navigation,
`
`asserted jurisdiction over only traditional navigable waters.
`
`39 Fed. Reg. 12119 (1974). But the Corps’ narrow definition
`did not last. It soon promulgated new, much broader defi-
`nitions designed to reach the outer limits of Congress’s com-
`merce power. See 42 Fed. Reg. 37144, and n. 2 (1977); 40
`Fed. Reg. 31324–31325 (1975).
`Eventually the EPA and Corps settled on materially iden-
`
`tical definitions. See 45 Fed. Reg. 33424 (1980); 47 Fed.
`
`Reg. 31810–31811 (1982). These broad definitions encom-
`passed “[a]ll . . . waters” that “could affect interstate or for-
`eign commerce.” 40 CFR §230.3(s)(3) (2008). So long as the
`potential for an interstate effect was present, the regulation
`extended the CWA to, for example, “intrastate lakes, rivers,
`streams (including intermittent streams), mudflats, sand-
`flats, wetlands, sloughs, prairie potholes, wet meadows,
`playa lakes, or natural ponds.” Ibid. The agencies likewise
`
` took an expansive view of the CWA’s coverage of wetlands
`
`“adjacent” to covered waters. §230.3(s)(7). As noted, they
`defined “adjacent” to mean “bordering, contiguous, or
`neighboring” and clarified that “adjacent” wetlands include
`those that are separated from covered waters “by man-
` made dikes or barriers, natural river berms, beach dunes
`
`and the like.” §230.3(b). They also specified that “wet-
`
`lands” is a technical term encompassing “those areas that
`
`are inundated or saturated by surface or ground water at a
`frequency and duration sufficient to support, and that un-
`der normal conditions do support, a prevalence of vegeta-
`
`tion typically adapted for life in saturated soil conditions.”
`§230.3(t). The Corps released what would become a 143-
`page manual to guide officers when they determine whether
`
`
`
`
`
`

`

`
`
`8
`
`
`
`SACKETT v. EPA
`
`Opinion of the Court
`
` property meets this definition.7
`This Court first construed the meaning of “the waters of
`
`the United States” in United States v. Riverside Bayview
`
`Homes, Inc., 474 U. S. 121 (1985). There, we were con-
`fronted with the Corps’ assertion of authority under the
`CWA over wetlands that “actually abut[ted] on a navigable
`waterway.” Id., at 135. Although we expressed concern
`
`
`that wetlands seemed to fall outside “traditional notions of
`
`‘waters,’” we nonetheless deferred to the Corps, reasoning
`that “the transition from water to solid ground is not neces-
`sarily or even typically an abrupt one.” Id., at 132–133.
`
`The agencies responded to Riverside Bayview by expand-
`ing their interpretations even further. Most notably, they
`issued the “migratory bird rule,” which extended jurisdic-
`
`tion to any waters or wetlands that “are or would be used
`
`as [a] habitat” by migratory birds or endangered species.
`
`See 53 Fed. Reg. 20765 (1988); 51 Fed. Reg. 41217 (1986).
`As the Corps would later admit, “nearly all waters were ju-
`
`risdictional under the migratory bird rule.”8
`In Solid Waste Agency of Northern Cook Cty. v. Army
`
`Corps of Engineers, 531 U. S. 159 (2001) (SWANCC), this
`
`Court rejected the migratory bird rule, which the Corps had
`
`used to assert jurisdiction over several isolated ponds lo-
`cated wholly within the State of Illinois. Disagreeing with
`the Corps’ argument that ecological interests supported its
`
`jurisdiction, we instead held that the CWA does not “ex-
`ten[d] to ponds that are not adjacent to open water.” Id., at
`
`168 (emphasis deleted).
`
`Days after our decision, the agencies issued guidance that
`
`
`——————
` 7See Corps, Wetlands Delineation Manual (Tech. Rep. Y–87–1, 1987)
`
`(Wetlands Delineation Manual); see also, e.g., Corps, Regional Supple-
`ment to the Corps of Engineers Wetland Delineation Manual: Alaska Re-
`
`
` gion (Version 2.0) (ERDC/EL Tr–07–24, 2007).
` 8GAO, Waters and Wetlands: Corps of Engineers Needs To Evaluate
`
`
`Its District Office Practices in Determining Jurisdiction 26 (GAO–04–
`297, 2004) (GAO Report).
`
`
`
`
`
`
`
`

`

`9
`
`
`
`
`
` Cite as: 598 U. S. ____ (2023)
`
`Opinion of the Court
`
`sought to minimize SWANCC’s impact. They took the view
`
`that this Court’s holding was “strictly limited to waters that
`are ‘nonnavigable, isolated, and intrastate’” and that “field
`staff should continue to exercise CWA jurisdiction to the
`full extent of their authority” for “any waters that fall out-
`
` side of that category.”9 The agencies never d