Issue Brief: Waters of the United States


The American Society of Landscape Architects (ASLA) believes that water quality is an essential component of ecosystem health and plays a critical role in community sustainability and public health. ASLA supports policies—like the Clean Water Act (CWA)—that protect our waters and communities nationwide and enhance environmental and public health, economic growth, and national security.


Water, one of our nation’s vital natural resources, supports public health, economic growth, and environmental protection, among other things. To safeguard the quality of “navigable waters,” more commonly known as “waters of the United States” (WOTUS), Congress enacted the Clean Water Act (CWA) in 1972. Since 1972, the quality of America’s rivers, lakes, streams, and other bodies of water has improved. However, continued efforts are needed to ensure that our waters remain safe and healthy.

The two federal agencies responsible for administering the CWA—the U.S. Environmental Protection Agency (EPA) and U.S. Army Corps of Engineers (USACE), collectively “the agencies”—introduced various regulations to try to clearly interpret the CWA and define WOTUS, while the Supreme Court of the United States has reviewed and determined the CWA’s scope for federal jurisdiction. The U.S. Congress has also intervened to try to clarify the scope of WOTUS.

For decades, the three branches of the federal government have been unable to agree on the authority of the federal government in regulating certain waters and in determining what bodies of water are governed by the CWA. Landscape architects have been greatly impacted by the lack of a clear definition of WOTUS, causing significant delays in project execution and completion. Further, the patchwork of governing case laws and regulations provides another layer of uncertainty for landscape architects working on projects where water bodies and site topography do not coincide with legal jurisdictional boundaries. The landscape architecture profession is also concerned WOTUS inconsistencies leave many water bodies unchecked for contaminants and pollution, providing uncertainty for many communities about access to clean, healthy drinking water and other water supplies. A clear WOTUS definition that is grounded in science is needed to ensure proper protection of our nation’s waters.

Bill Summary

United States Supreme Court Legal Measures

1985: In United States v. Riverside Bayview Homes, Inc. (1985), the Supreme Court determined adjacent wetlands may be regulated as “waters of the United States” because they are ‘‘inseparably bound up’’ with navigable waters and usually have ‘‘significant effects on water quality and the aquatic ecosystem’’ in those waters.

2001: The Supreme Court in Solid Waste Agency of Northern Cook County v. U.S. Army Corps of Engineers (2001) held CWA protections do not extend to isolated, abandoned pits with seasonal ponds.

2006: In Rapanos v. United States (2006), a split decision resulted in two tests to determine what is considered a WOTUS and thus subject to federal jurisdiction. Under the first test, the Court stated WOTUS refers only to relatively permanent, standing, or continuously flowing bodies of water and wetlands with a continuous surface connection to other relatively permanent waters. Under the second test, the Court utilized a “significant nexus” test to define WOTUS, stating wetlands should be considered WOTUS if the wetland or water at issue significantly impacts the chemical, physical, and biological integrity of a traditionally navigable waterbody.

2023: On May 25, 2023, in Sackett v. Environmental Protection Agency (2023) the Supreme Court held adjacent wetlands are only subject to CWA protections if it has a continuous surface connection with a WOTUS that is relatively permanent and connected to traditional interstate navigable waters such as a stream, ocean, river, or lake. Specifically, the court wrote that Clean Water Act jurisdiction extends only to wetlands that are "indistinguishable" from larger bodies of water by having a "continuous surface connection." The plaintiffs, Sackett, asserted the significant nexus test was inappropriate to consider a wetland as WOTUS and that the wetlands on their property are not WOTUS pursuant to the “relatively permanent” test in Rapanos. This ruling significantly weakens the CWA and will leave millions of acres of wetlands unprotected causing significant repercussions for water quality and flood control throughout the nation. For now, this ruling is the “law of the land,” and supersedes previous court rulings, the agencies’ actions, and congressional action.

Agency Regulatory Actions

2015: Under the Obama administration, the agencies introduced a 2015 rule to clarify that the federal government does have the authority to limit pollution into smaller bodies of water like wetlands, gullies, and more. However, legal challenges caused more than half of the states to implement the 1980s regulations.

2019: A 2019 rule introduced under the Trump administration repealed the 2015 rule and reinstated the 1980s regulations consistent with subsequent U.S. Supreme Court cases and applicable guidance. In 2020, also under the Trump administration, the agencies replaced the 2019 rule with the Navigable Waters Protection Rule (NWPR). Both Trump administration rules would roll back CWA protections. In August 2021, a federal court vacated and remanded the NWPR under Pascua Yaqui Tribe v. U.S. Environmental Protection Agency (2021) due to “fundamental, substantive flaws that cannot be cured without revising or replacing the NWPR’s definition” causing the agencies to no longer implement this rule.

2021: In January 2021, the Biden administration issued Executive Order 13990 to direct EPA and USACE to review and act on WOTUS regulations. The proposed rule stated the Biden administration also intends to issue a second rule to reflect additional stakeholder engagement and environmental justice values.

2023: In January 2023, the Biden administration issued a final rule defining “waters of the United States” to clarify inconsistencies over WOTUS regulations and what United States waters are subject to federal protection. The rule was founded on pre-2015 WOTUS definitions but updated to reflect previous United States Supreme Court decisions, agency expertise, scientific findings, and extensive public comments. The rule took effect in March 2023, however, provisions concerning wetland protections were invalidated due to the Supreme Court’s May 2023 decision in Sackett. 

In August 2023, EPA and USACE released a final rule amending the January 2023 definition of “waters of the United States” (WOTUS) to conform with the May 2023 United States Supreme Court’s decision in Sackett v. EPA. Specifically, the rule revised the January 2023 rule text that is invalid post-Sackett like references to the significant nexus standard, wetlands, and streams, as well as revised the definition of adjacent to mean “having a continuous surface connection.”

Congressional Action

2023: On February 2, 2023, Representative Sam Graves (MO) and Senator Shelley Moore Capito (WV) introduced H.J.Res. 27 and S.J.Res. 7, respectively, to overturn the Biden administration’s revised WOTUS definition. The measure(s) narrowly passed both chambers.

  • On March 9, 2023, the House of Representatives voted 227 - 198 in favor of H.J.Res. 27
  • On March 29, 2023, the Senate voted 53 - 43 in favor of H.J.Res. 27
  • On April 6, 2023, President Biden vetoed the measure
  • On April 18, 2023, the House of Representative failed to override the President’s veto of H.J.Res. 27 by a vote of 227-196, which left the Biden WOTUS Rule in place until the Supreme Court’s May 2023 decision in Sackett

Also, in March 2023, Representative Mary Miller (IL) and Senator Mike Braun (IN) introduced H.R. 1556 and S. 1022, the Define WOTUS Act, to modify which waters are subject to federal protections. No further action has been taken on these bills.


Roxanne Blackwell, 
Esq., Hon. ASLA,
Director of Federal
Government Affairs

Elizabeth Hebron,
Director of State
Government Affairs