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By: Sean Downey, Volume 106 Staff Member

With its grant of certiorari in Sackett v. EPA, the Supreme Court will take its fourth try at resolving a question that has vexed courts, agencies, lawyers, and landowners: what are “Waters of the United States (WOTUS)?”[1] The Clean Water Act (CWA) prohibits the discharge of pollutants into “navigable waters” without a permit.[2] For the purposes of the CWA, “navigable waters” is simply defined as “waters of the United States, including territorial seas.”[3] Since the CWA was enacted, the Supreme Court has addressed the meaning of WOTUS on three separate occasions and has obscured the meaning further each time. The decision in Sackett will have a far-reaching impact on environmental law and could significantly limit the federal government’s ability to protect the quality of the nation’s water and the integrity of aquatic ecosystems. To keep in accordance with the CWA’s text and purpose, the Court should reject the plurality’s reasoning from Rapanos v. United States, and instead adopt the reasoning of either Justice Kennedy’s concurrence or Justice Steven’s dissent.[4]


Since the CWA’s passage in 1972, both agencies and courts have grappled with defining the limits of WOTUS.[5] During this struggle to define the term, the Supreme Court ruled on the issue in three cases. While these cases are meant to provide guidance, they may have obscured WOTUS’ meaning further.

The first WOTUS case to reach the Supreme Court was United States v. Riverside Bayview Homes, Inc.[6] In its Chevronreview, the Court sought to determine “whether it is reasonable . . . for the [Army Corps of Engineers] to exercise jurisdiction over wetlands adjacent to but not regularly flooded by rivers, streams, and other hydrographic features more conventionally identifiable as ‘waters.’”[7] According to the Riverside Court, the wide spectrum of shallows, marshes, and mudflats that lie between open waters and dry land made the limit of “waters” far from obvious.[8] Though the statute and legislative history provided little guidance, the Court emphasized that Congress’ broad concern for the protection of water quality and aquatic ecosystems suggested that it was reasonable for the Corps to interpret the term “waters” to encompass wetlands adjacent to waters as conventionally defined.[9] Accordingly, the Court held that the Corps’ conclusion that wetlands adjacent to jurisdictional waters are inseparably bound up with WOTUS was not unreasonable.[10] Therefore, the Corps’ definition of WOTUS encompassing all wetlands adjacent to jurisdictional waters was a permissible interpretation of the act deserving of Chevron deference.[11]

Twenty-five years after Riverside was decided, the Court again interpreted WOTUS in Solid Waste Agency of Northern Cook County v. U.S. Army Corps of Engineers, commonly referred to as SWANCC.[12] SWANCC involved land previously used as a sand and gravel pit mine.[13] The excavation trenches on the land had become permanent and seasonal ponds that were visited by over 100 species of migratory birds.[14] The Corps initially concluded it had no jurisdiction over the site but reversed its determination after learning of the migratory bird populations observed at the site.[15] The Corps’ reversal was based on a regulation known as the Migratory Bird Rule, which extended the Corps’ § 404(a) jurisdiction to intrastate waters used as habitats for migratory birds.[16]

The SWANCC court stated that its holding in Riverside was based on “the significant nexus between the wetlands and ‘navigable waters.’”[17] The SWANCC court held the text of the CWA did not support the proposition that the Corps’ jurisdiction extended to ponds that are not adjacent to open water.[18] While in Riverside the Court concluded that the word “navigable” in the statute has limited effect, the SWANCC court held that the term at least shows that Congress intended the CWA’s jurisdictional waters to include waters that were or had been navigable in fact or which could reasonably be so made.[19] Furthermore, the Court noted that the Corps’ application of the Migratory Bird Rule raised constitutional questions over the line between state and federal jurisdiction.[20] Accordingly, the Court held that, even if it did agree with the Corps’ interpretation, it could not grant Chevron deference in the case because of the significant constitutional questions raised.[21]

Five years after SWANCC was decided, the most recent WOTUS case reached the Supreme Court. Rapanos v. United States involved 54 acres of wetlands with sometimes-saturated soil conditions 11 to 20 miles from the nearest body of navigable water.[22] Justice Scalia, writing for a plurality of the Court, stated that the CWA only granted jurisdiction over “waters,” which could not bear the expansive meaning the Corps gave it in applying to Rapanos’ wetlands.[23] According to Justice Scalia, “the waters” unambiguously referred to water “[a]s found in streams and bodies forming geographical features such as oceans, rivers, [and] lakes,” or “the flowing or moving masses, as of waves or floods, making up such streams or bodies,” not “transitory puddles or ephemeral flows of water.”[24] Based on this interpretation of the CWA, the plurality held that “only those wetlands with a continuous surface connection to bodies that are ‘waters of the United States’ in their own right, so that there is no clear demarcation between ‘waters’ and wetlands, are ‘adjacent to’ such waters and covered by the Act.”[25] Under the plurality’s holding, a wetland is only a water of the United States when (1) the adjacent channel contains a “water of the United States” and (2) the wetland has a continuous surface connection with that water.[26]

While Justice Scalia’s opinion in Rapanos garnered the most votes in its judgment, Justice Kennedy’s concurrence in the judgment has arguably been as influential, if not more. While Justice Kennedy concurred that the Court of Appeals used the improper standard in evaluating whether the wetlands were WOTUS, he roundly disagreed with the new test proposed by the plurality.[27] Instead, Kennedy adopted the SWANCC Court’s holding that to be WOTUS, a water or wetland must possess a “significant nexus” to waters that are or were navigable in fact or could reasonably be made so.[28] Under Kennedy’s test, the nexus must be assessed in terms of the statute’s goals and purposes to restore and maintain the chemical, physical, and biological integrity of the Nation’s waters.”[29] Accordingly, wetlands satisfy the “significant nexus test” if they significantly affect the chemical, physical, and biological integrity of other covered waters more readily understood as “navigable.”[30] Justice Kennedy concluded that while adjacency to a navigable-in-fact water establishes a wetland as WOTUS, a significant nexus between wetlands and a navigable-in-fact water must be established for wetlands to be WOTUS in other cases.[31]

Finally, the four remaining Justices joined in a dissent authored by Justice Stevens. Justice Stevens asserted the ambiguity of the phrase “waters of the United States,” combined with the Act’s broad purpose to protect water quality and aquatic ecosystems, made deference to the Corps’ approach appropriate.[32] Furthermore, Justice Stevens stated that “the inclusion of all identifiable tributaries that ultimately drain into large bodies of water within the mantle of federal protection is surely wise.”[33] Ultimately, the dissent’s preferred test would ask if a wetland has any “plausibly discernible relationship to any aspect of downstream water quality” and would hold the jurisdictional finding reasonable if such a relationship existed.[34] In the 15 years since the splintered Rapanos decision was handed down, lower courts and regulators have struggled to formulate a consistent test for categorizing bodies of water as WOTUS,[35] finally leading to the instant case.


After nearly two decades of continued uncertainty about the legal limits of WOTUS, the Supreme Court will soon take up a new case in which they will specifically address what test is appropriate for defining those limits.[36] In 2004, the Sacketts purchased a residential lot near Idaho’s Priest Lake intending to build a home on the property.[37] Shortly after the Sacketts began filling the “soggy” lot with sand and gravel, the EPA served them with a compliance order stating that the property contained wetlands protected under the CWA and that they needed to restore the property to its natural state.[38] Since the action’s commencement in 2008, the issue has been hotly litigated and reached the Supreme Court once already.[39] On their second trip to the Supreme Court, the Sacketts and the EPA will litigate one limited question: Whether the Ninth Circuit set forth the proper test for determining whether wetlands are “waters of the United States” under the CWA, 33 U.S.C. § 1362(7).[40]

In Sackett, the Ninth Circuit adopted Justice Kennedy’s “significant nexus” test based in part on previous Ninth Circuit precedent adopting the test in Northern California River Watch v. City of Healdsburg.[41] To reach this holding, the Sackett court applied the Supreme Court’s inquiry from Marks v. United States, which provides that the controlling holding of a fractured decision is “the narrowest ground to which a majority of Justices would assent if forced to choose in almost all cases.”[42] After evaluating Healdsburg in light of changes in Ninth Circuit jurisprudence on the application of Marks, the Sackett court concluded that Healdsburg remained the law of the circuit, and therefore the “significant nexus” test was the appropriate test to apply.[43]

Applying the significant nexus test, the Sackett court decided that the EPA’s determination that the wetlands on the Sackett’s property were WOTUS was not arbitrary or capricious.[44] The court first noted that the Sackett’s property met the EPA’s adjacency test in place at the time, because they were adjacent to an unnamed, relatively permanent tributary that flowed into Kalispell Creek, which subsequently flowed into the nearby Priest Lake, a traditionally navigable water.[45] The EPA determined that the wetlands, in combination with other “similarly situated” wetlands, were important to maintaining Priest Lake’s high quality of water, fish, and wildlife.[46] Accordingly, the Sackett Court held that the “EPA reasonably determined that the Sacketts’ property contains wetlands that share a significant nexus with Priest Lake, such that the lot was regulable under the CWA and the relevant regulations.”[47]


Since Rapanos, the meaning of WOTUS has been uncertain, to say the least.[48] Most federal appellate courts that have taken up the WOTUS issue have adopted Justice Kennedy’s “significant nexus” test.[49] Moreover, no courts have adopted Justice Scalia’s test since Rapanos was decided.[50]

While adopting Justice Stevens’ broad interpretation of  WOTUS would likely best accomplish the CWA’s goal of protecting water quality and aquatic ecosystems,[51] it seems unlikely that the Court as currently composed would adopt a reading providing such broad deference to an administrative agency.[52] However, Justice Stevens opined that Justice Kennedy’s significant nexus test likely would not significantly diminish the number of wetlands covered by the CWA.[53] Accordingly, the best hope for retaining a CWA that accomplishes its purpose may be for the Court to adopt Justice Kennedy’s significant nexus test.

It is critical, however, that the Court does not adopt the reasoning of the Scalia plurality. The plurality approach places great importance on jurisdictional waters being “continuously present, fixed bodies of water.”[54] This approach is unsupported by the text and purpose of the CWA and could potentially strip 75% or more of rivers in the Western United States of their CWA protections, as they are non-perennial or intermittent.[55] The plurality test ignores the importance of intermittent and ephemeral streams in downstream water quality and the ecological importance of wetlands for many species.[56] Adopting the plurality’s approach would be counter to the CWA’s broad goal of protecting water quality and aquatic ecosystems. Therefore, the Sackett court should adopt either Justice Kennedy’s “significant nexus” test, or the dissent’s interpretation of WOTUS from Rapanos.


[1] Sackett v. EPA, 8 F.4th 1075 (9th Cir. 2021), cert. granted 142 S.Ct. 896 (Jan. 24, 2022).

[2] 33 U.S.C. § 1311(a) ([T]he discharge of any pollutant by any person shall be unlawful.”); id. § 1362(12) (“The term ‘discharge of a pollutant’ and the term ‘discharge of pollutants’ each means (A) any addition of any pollutant to navigable waters from any point source . . . .”).

[3] Id. § 1362(7).

[4] Rapanos v. United States, 547 U.S. 715 (2006).

[5] Sackett, 8 F.4th at 1079–80 (discussing the chronology of the Corps of Engineers’ interpretation of the phrase in its regulation).

[6] United States v. Riverside Bayview Homes, Inc., 474 U.S. 121 (1985).

[7] Id. at 131.

[8] Id. at 132.

[9] Id. at 133.

[10] Id. at 134.

[11] Id. at 135.

[12] Solid Waste Agency of N. Cook Cnty. v U.S. Army Corps of Eng’rs, 531 U.S. 159, 162 (2001).

[13] Id. at 163.

[14] Id. at 163–64.

[15] Id. at 164.

[16] Id. at 164 (quoting Final Rule for Regulatory Programs of the Corps of Engineers, 51 Fed. Reg. 41,217 (Nov. 13, 1986)) (“[I]n an attempt to ‘clarify’ the reach of its jurisdiction, the Corps stated that § 404(a) extends to instrastate [sic] waters: ‘a. Which are or would be used as habitat by birds protected by Migratory Bird Treaties; or b. Which are or would be used as habitat by other migratory birds which cross state lines; or c. Which are or would be used as habitat for endangered species; or d. Used to irrigate crops sold in interstate commerce.’”).

[17] Id. at 167.

[18] Id. at 168.

[19] Id. at 172.

[20] Id. at 173.

[21] Id. at 172–74.

[22] Rapanos v. United States, 547 U.S. 715, 719–21 (2006) (Scalia, J., plurality opinion).

[23] Id. at 731–32 (Scalia, J., plurality opinion).

[24] Id. at 732–34 (“All of these terms connote continuously present, fixed bodies of water, as opposed to ordinarily dry channels through which water occasionally or intermittently flows.”).

[25] Id. at 742.

[26] Id.

[27] Id. at 767–78 (Kennedy, J., concurring in the judgment) (discussing Justice Kennedy’s disagreements with the plurality’s opinion).

[28] Id. at 759.

[29] Id. at 779 (quoting 33 U.S.C. § 1251(a)).

[30] Id. at 780.

[31] Id. at 782.

[32] Id. at 792–99 (Stevens, J., dissenting).

[33] Id. at 804.

[34] Id. at 808–09; Adam Redder, Protecting America’s Wetlands Under Rapanos: Defining the Waters of the United States, 23 St. John’s J. Legal Comment. 293, 327–28 (2008) (describing the dissent in Rapanos).

[35] Bryan Moore, High Court’s Return To Wetlands Debate May Bring Clarity, Law360, [].

[36] Sackett v. EPA, 142 S.Ct. 896 (2022).

[37] Sackett v. EPA, 8 F.4th 1075, 1079 (9th Cir. 2021).

[38] Id.

[39] See id. at 1081–82 (describing the procedural history of the legal battle between the Sacketts and the EPA); see alsoSackett v. EPA, 566 U.S. 120, 121 (2012) (holding that the original compliance order in the Sackett litigation constituted “final agency action” subject to judicial review under the APA).

[40]  Sackett, 142 S.Ct. at 896; Sackett v. Environmental Protection Agency, SCOTUSblog, [] (detailing the proceedings and orders in Sackett since the petition for a writ of certiorari was filed).

[41] Sackett, 8 F.4th at 1088–89 (“In interpreting Rapanos to evaluate this argument, we are not writing on a blank slate. In Northern California River Watch . . . , we concluded that ‘Justice Kennedy’s concurrence provides the controlling rule of law’ from Rapanos.”) (quoting Northern California River Watch v. City of Healdsburg, 496 F.3d 993, 999 (2007)).

[42] Id. at 1088–89 (citing Healdsburg, 496 F.3d at 999 (2007)).

[43] Id. at 1089–91.

[44] Id. at 1092

[45] Id.

[46] Id. at 1093.

[47] Id.

[48] See, e.g., Moore, supra note 35 (“Over 15 years have elapsed since Rapanos was handed down, and in that time, the lower courts, regulators, and project stakeholders have struggled to distill a consistent, transparent standard from the court’s splintered holding”).

[49] Id.; see also United States v. Robison, 505 F.3d 1208, 1221–22 (2007) (holding that the significant nexus test is the narrowest because it imposes the least limitation on the scope of the CWA’s application); United States v. Gerke Excavating, Inc., 464 F.3d 723, 724 (2006) (holding that Justice Kennedy’s ground for decision was the narrowest under Marks and therefore is the controlling decision); Northern California River Watch v. City of Healdsburg, 496 F.3d 993, 999 (2007) (following Justice Kennedy’s test based on the Seventh Circuit’s reasoning in Gerke).

[50] Moore, supra note 35.

[51] United States v. Riverside Bayview Homes, Inc., 474 U.S. 121, 133 (1985).

[52] See, e.g., Noah Feldman, Gorsuch v. the Administrative State Is Really Heating Up, Bloomberg, January 15, 2022, [] (detailing a number of current Supreme Court Justices’ desire to curtail the power of the administrative state).

[53] Rapanos v. United States, 547 U.S. 715, 808 (2006) (Stevens, J., dissenting).

[54] Id. at 733 (Scalia, J., plurality opinion).

[55] Redder, supra note 34, at 335–36.

[56] Id. at 337–39.