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. The two federal agencies responsible for administering the CWA—the U.S. Environmental Protection Agency (EPA) and U.S. Army Corps of Engineers (Corps) (the agencies)—introduced various regulations in hopes of clearly defining WOTUS, while the Supreme Court of the United States has interpreted the CWA’s scope.

Despite federal attempts to define WOTUS, its meaning remains unclear and pre-2015 regulations remain in effect that mostly derive from regulations implemented in the 1980s. WOTUS is currently under scrutiny as the Biden administration issued a proposed rule in December 2021 with a second rule forthcoming, and the Supreme Court case, Sackett v. EPA, scheduled for oral argument on October 3, 2022.

United States Supreme Court Legal Measures
The United States Supreme Court issued three decisions concerning “waters of the United States” to determine federal regulatory jurisdiction.

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.

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

In Rapanos v. United States (2006), a split decision resulted in two tests to define WOTUS. Under the first test, Justice Scalia 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, Justice Kennedy 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.

Agency Regulatory Measures
The agencies introduced a 2015 rule under the Obama administration to redefine WOTUS but legal challenges caused more than half of the states to implement the 1980s regulations. A 2019 rule introduced under the Trump administration repealed the 2015 rule and reinstated the 1980s regulations consistent with 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 rollback initiatives of the CWA under the Trump administration limited WOTUS protections. In August 2021, a federal court vacated and remanded the NWPR under Pascua Yaqui Tribe v. U.S. Environmental Protection Agency 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.

Current Status
In January 2021, the Biden administration issued Executive Order 13990 to direct EPA and Corps to review and act on WOTUS regulations. To resolve uncertainty surrounding WOTUS regulations most recently, the agencies, under the Biden administration, issued a proposed rule on December 7, 2021, to revise its definition through a two-step rulemaking process: (1) the proposed rule, if finalized, would restore pre-2015 protections; and (2) a second rule to build upon the regulatory foundation of the first rule. The proposed rule interprets “waters of the United States” as defined by 1986 regulations (e.g. traditional navigable waters, interstate waters, and the territorial seas) with certain amendments pursuant to Supreme Court holdings that incorporate the significant nexus test (e.g. impoundments, tributary, adjacent wetlands, other waters). The second rule is expected to reflect additional stakeholder engagement and environmental justice values. 

Simultaneously, the United States Supreme Court heard oral arguments on October 3, 2022, in Sackett v. EPA, to consider whether certain wetlands are WOTUS and thus subject to federal regulatory jurisdiction under the CWA. The plaintiff, Sackett, asserts the significant nexus test is inappropriate to consider a wetland as WOTUS and that the wetlands on their property are not WOTUS pursuant to the test identified by Justice Scalia. Read the oral argument transcript and listen to the audio here. 

The Biden administration’s proposed rule and the Supreme Court’s decision are both expected in 2023, presenting the potential for increased confusion surrounding WOTUS.

WOTUS and Landscape Architecture
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 that the current status of WOTUS leaves many water bodies unchecked for contaminants and pollution, providing uncertainty for many communities about having clean, healthy drinking and other water supplies. A clear WOTUS definition that is grounded in science is needed to ensure proper protection of our nation’s waters.

ASLA believes that a WOTUS definition should ensure healthy and safe drinking water, reduce adverse health consequences, bolster community tourism and recreation, facilitate placemaking for coastal communities, and more. ASLA’s Government Affairs team will continue to monitor WOTUS developments closely and work with allies and partners to promote a clear, consistent definition of waters of the United States that achieves these goals.

As ASLA continues to weigh in with policy makers on WOTUS, we want to learn about your experiences and thoughts about WOTUS. Please use this tool to tell us about your thoughts on the WOTUS rules and how it impacts your work.

Additional details and resources concerning "waters of the United States” can be found below:

U.S. Environmental Protection Agency: Waters of the United States. May 4, 2022.

Congressional Research Service, Redefining Waters of the United States: Recent Developments. July 8, 2022.

ASLA, The Murkiness of the Clean Water Act. September 4, 2018.

ASLA, ASLA Opposes Flawed Revision of the Definition of “Waters of the United States. April 16, 2019.

ASLA, ASLA Statement on Repeal of Waters of the United States (WOTUS) Rule. September 13, 2019.