The U.S. Environmental Protection Agency (EPA) and the Department of the Army released a revised rule defining “waters of the United States” (WOTUS) on December 30, 2022. The rule aims to clarify inconsistencies over what United States waters are subject to federal protection. As such, the rule is founded on pre-2015 WOTUS definitions but is updated to reflect United States Supreme Court decisions, agency expertise, and scientific findings.

The revised WOTUS definition provides jurisdiction over waterbodies that Congress intended to protect under the Clean Water Act (CWA), including traditional navigable waters, territorial seas, and interstate waters. Additionally, the rule utilizes two standards for safeguarding other waters such as tributaries, adjacent wetlands, and additional waters; it accounts for the United States Supreme Court’s decision in Rapanos v. United States (2006). Specifically, the revised definition protects such United States waters if (1) if its relatively permanent such that the waterbodies are relatively permanent, standing, or continuously flowing or contains a continuous surface connection to such relatively permanent waters or (2) a significant nexus exists such that the waterbody (alone or in combination) significantly affects the chemical, physical, or biological integrity of traditional navigable waters, the territorial seas, or interstate waters.

In 2019, ASLA strongly objected to the previous administration’s proposed WOTUS rule because it left many water bodies unprotected, placing families and communities at risk from pollution. ASLA provided official comments to EPA and the Army Corps of Engineers urging the agencies to utilize current science to expand the types of water bodies that would be protected under the Clean Water Act.

ASLA is pleased that this rule considered ASLA’s recommendations and utilized “the best available science” to define WOTUS in a manner that will strengthen protections for varied waters across the nation. For example, this rule no longer defines adjacent wetlands as those solely with a hydrological surface connection; as summarized in the Fact Sheet, this rule defines adjacent wetlands as those that are next to, abutting, or near other jurisdictional waters or behind certain natural or constructed features, or meets the relatively permanent or significant nexus standard, or if the wetland is adjacent to a traditional navigable water, the territorial seas, or an interstate water. Additionally, this rule no longer exempts certain wetlands separated from other bodies of water by man-made barriers such as dikes and levees and are thus federally protected under CWA per this revised rule.

It should be noted, however, that CWA exclusions outlined in this revised rule include prior converted cropland, waste treatment systems, ditches, artificially irrigated areas, artificial lakes or ponds, artificial reflecting pools or swimming pools, waterfilled depressions, and certain swales and erosional features.

ASLA will continue to advocate for increased protection of our nation’s waters and landscape architecture opportunities to plan, design, and implement WOTUS protections. As ASLA continues to weigh in with policymakers on WOTUS, we want to learn about your experiences and thoughts. Please use this tool to tell us about your thoughts on the WOTUS rules and how it impacts your work.

The United States Supreme Court is expected to release its opinion in Sackett v. EPA—a “waters of the United States” case—this year which may, once again, present conflicts surrounding bodies of water covered under WOTUS.

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

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: WOTUS v. SCOTUS. October 3, 2022.

U.S. Environmental Protection Agency and Department of Defense: Revised Definition of "Waters of the United States", 88 Fed. Reg. 11. January 18, 2023.

U.S. Environmental Protection Agency and Department of the Army: Final Rule: Revised Definition of “Waters of the United States” Fact Sheet. December 2022.

U.S. Environmental Protection Agency: Waters of the United States. December 30, 2022.

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