About Waters of the United States

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What are "Waters of the United States"?

The 1972 amendments to the Clean Water Act established federal jurisdiction over “navigable waters,” defined in the Act as the “waters of the United States” (CWA Section 502(7)). Many Clean Water Act programs apply only to “waters of the United States.” EPA and the U.S. Department of the Army (Army) have defined “waters of the United States” in regulations since the 1970s. 

Current Implementation of “Waters of the United States”

On August 29, 2023, the U.S. Environmental Protection Agency (EPA) and Department of the Army (the agencies) issued a final rule to amend the final “Revised Definition of ‘Waters of the United States’” rule, published in the Federal Register on January 18, 2023. This final rule conforms the definition of “waters of the United States” to the U.S. Supreme Court’s May 25, 2023, decision in the case of Sackett v. Environmental Protection Agency. Parts of the January 2023 Rule are invalid under the Supreme Court’s interpretation of the Clean Water Act in the Sackett decision. Therefore, the agencies have amended key aspects of the regulatory text to conform it to the Court’s decision. The conforming rule, "Revised Definition of 'Waters of the United States'; Conforming," published in the Federal Register and became effective on September 8, 2023. 

In addition, due to ongoing litigation, the January 2023 Rule is not currently operative in certain states. The agencies are implementing the January 2023 Rule, as amended by the conforming rule, in 24 states, the District of Columbia, and the U.S. Territories. In the other 26 states, the agencies are interpreting "waters of the United States" consistent with the pre-2015 regulatory regime and the Supreme Court's decision in Sackett until further notice. Please visit the Rule Status page for additional information about the status of the January 2023 Rule, as amended, and litigation. 

If a state, Tribe, or an entity has specific questions about a pending jurisdictional determination or permit, please contact a local U.S. Army Corps of Engineers District office or EPA. 

Learn more about the agencies' current implementation of "waters of the United States."

History of "Waters of the United States"

Related Material

Clean Water Act Approved Jurisdictional Determinations

Army Corps of Engineers Website

Clean Water Act Summary

Other CWA Policies and Guidance

“Waters of the United States” is a threshold term in the Clean Water Act and establishes the geographic scope of federal jurisdiction under the Act. Clean Water Act programs, including Water Quality Standards, Total Maximum Daily Loads (TMDLs), and sections 311, 402, and 404 address “navigable waters,” defined in the statute as “the waters of the United States, including the territorial seas.”

The Clean Water Act does not define “waters of the United States.” Since the 1970s, EPA and the Department of the Army have defined “waters of the United States” by regulation. In the mid-1980s, both agencies promulgated a definition of “waters of the United States.”

Four Supreme Court decisions have addressed the definition of “waters of the United States.” In 1985, in United States v. Riverside Bayview Homes, Inc., the U.S. Supreme Court deferred to the Corps’ assertion of jurisdiction over wetlands adjacent to a traditional navigable water, stating that adjacent wetlands may be regulated as "waters of the United States" because they are ‘‘inseparably bound up’’ with navigable waters and ‘‘in the majority of cases’’ have ‘‘significant effects on water quality and the aquatic ecosystem’’ in those waters.

In Solid Waste Agency of Northern Cook County v. U.S. Army Corps of Engineers (SWANCC) in 2001, a 5-4 Court held that the use of "nonnavigable, isolated, intrastate waters" by migratory birds was not by itself a sufficient basis for the exercise of Federal authority under the Clean Water Act. SWANCC, 531 U.S. at 172. The Court noted that in Riverside Bayview, it had "found that Congress' concern for the protection of water quality and aquatic ecosystems indicated its intent to regulate wetlands 'inseparably bound up with the "waters" of the United States'" and that "[i]t was the significant nexus between the wetlands and 'navigable waters' that informed [the Court's] reading of the Clean Water Act" in that case. Id. at 167. In 2001 and again in 2003, the agencies developed guidance to address the definition of “waters of the United States” under the Clean Water Act following the SWANCC decision.

The Court also interpreted the term "waters of the United States" in Rapanos v. United States in 2006. A four-Justice plurality stated that "waters of the United States" ‘‘include[ ] only those relatively permanent, standing or continuously flowing bodies of water 'forming geographic features' that are described in ordinary parlance as 'streams[,] . . . oceans, rivers, [and] lakes,'" and "wetlands with a continuous surface connection" to a "relatively permanent body of water connected to traditional interstate navigable waters." In a concurring opinion, Justice Kennedy took a different approach, concluding that "to constitute 'navigable waters' under the Act, a water or wetland must possess a 'significant nexus' to waters that are or were navigable in fact or that could reasonably be so made." He stated that adjacent wetlands possess the requisite significant nexus if the wetlands "either alone or in combination with similarly situated lands in the region, significantly affect the chemical, physical, and biological integrity of other covered waters more readily understood as 'navigable.'" The four dissenting Justices, who would have affirmed the court of appeals' application of the agencies' existing regulation, concluded that the term "waters of the United States" encompasses all tributaries and wetlands that satisfy either the plurality's standard or Justice Kennedy's. Following Rapanos, in 2007 and again in 2008, the agencies developed additional guidance for implementing the "waters of the United States" definition.

The agencies amended their regulations defining “waters of the United States” in 2015 in the Clean Water Rule: Definition of "Waters of the United States." 

The 2015 Clean Water Rule was repealed by the 2019 Rule, which reinstated the 1980s regulations, implemented consistent with the U.S. Supreme Court cases and applicable guidance.

The agencies replaced the 2019 Rule with the Navigable Waters Protection Rule (NWPR) in 2020. In light of the U.S. District Court for the District of Arizona's August 30, 2021 order vacating and remanding the Navigable Waters Protection Rule in the case of Pascua Yaqui Tribe v. U.S. Environmental Protection Agency, the agencies halted implementation of the NWPR nationwide and interpreted "waters of the United States" consistent with the pre-2015 regulatory regime.

The final "Revised Definition of 'Waters of the United States'" rule was published in the Federal Register on January 18, 2023, and the rule took effect on March 20, 2023.  The final rule was codified in the Code of Federal Regulations (CFR) in place of the vacated NWPR. However, the final rule is not currently operative in certain states due to litigation. 

On May 25, 2023, the Supreme Court decided Sackett v. Environmental Protection Agency. While the January 2023 Rule was not directly before the Court, the Court considered the jurisdictional standards set forth in that rule: the plurality standard and the significant nexus standard from the Court’s decision in Rapanos v. United States.  In Sackett, the Court “conclude[d] that the Rapanos plurality was correct: the [Clean Water Act]’s use of ‘waters’ encompasses ‘only those relatively permanent, standing or continuously flowing bodies of water “forming geographic[al] features” that are described in ordinary parlance as “streams, oceans, rivers, and lakes”’” (quoting Rapanos). The Court also “agree[d] with [the plurality’s] formulation of when wetlands are part of ‘the waters of the United States,’”: “when wetlands have ‘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’” (citing Rapanos). The Court concluded that the significant nexus standard is inconsistent with the Clean Water Act. 

On August 29, 2023, the agencies issued a final rule to amend the January 2023 Rule to conform to the Supreme Court's decision in Sackett. Parts of the January 2023 Rule are invalid under the Supreme Court’s interpretation of the Clean Water Act in the Sackett decision. Therefore, the agencies have amended key aspects of the regulatory text to conform it to the Court’s decision. The final conforming rule, "Revised Definition of 'Waters of the United States'; Conforming," became effective on September 8, 2023 upon publication in the Federal Register.

Please visit the Rule Status page for additional information about the status of the January 2023 Rule, as amended, and litigation. Find out more about the final conforming rule. 

Documents Used to Implement the Pre-2015 Definition of "Waters of the United States"

The agencies utilize the materials listed below in implementing the pre-2015 regulatory regime.  In light of litigation, the agencies are interpreting "waters of the United States" consistent with the pre-2015 regulatory regime in certain states until further notice. Additionally, the agencies are interpreting the phrase “waters of the United States” consistent with the Supreme Court’s decision in Sackett. Thus, certain aspects of the documents listed below may no longer be in effect. Please visit the Rule Status page for additional information about the status of the January 2023 Rule, as amended, and litigation.

Coordination Memorandum

  • September 2023 Joint Coordination Memorandum to the Field Between the U.S. Department of the Army, U.S. Army Corps of Engineers (Corps) and the U.S. Environmental Protection Agency (EPA) on the Pre-2015 Regulatory Regime: The purpose of this memo is to establish a process by which the Corps and EPA will coordinate on Clean Water Act geographic jurisdictional matters to ensure accurate and consistent implementation of the pre-2015 regulatory regime, where that regulatory regime is operative.

Rapanos v. United States & Carabell v. United States

In 2007 and again in 2008, the agencies developed guidance for implementing the above definition of "waters of the United States" under the Clean Water Act following the Rapanos v. United States, and Carabell v. United States Supreme Court decision.

Solid Waste Agency of Northern Cook County (SWANCC) v. United States

In 2001 and again in 2003, the agencies developed guidance to address the above definition of "waters of the United States" under the Clean Water Act following the SWANCC Supreme Court decision.

  • January 2003 Legal Memorandum discussing the scope of Clean Water Act jurisdiction in light of the SWANCC ruling and related court decisions.
  • January 2001 Legal Memorandum describing which aspects of the regulatory definition of "waters of the United States" are and are not affected by SWANCC. (This guidance was superseded by the 2003 guidance.)

Supreme Court Rulings Related to “Waters of the United States”

Waters of the United States

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Last updated on October 21, 2024