Waters of the United States (WOTUS)

Federal jurisdiction under the Clean Water Act (CWA) is limited to “Waters of the United States,” or WOTUS for short. The WOTUS definition indicates where the federal government can require permits to protect rivers, wetlands, lakes, estuaries, and other waterbodies from pollution.

The process for determining which waters meet the definition of  WOTUS was relatively stable until 2001. A U.S. Supreme Court decision that year (known as SWANCC) and a subsequent decision in 2006 (known as Rapanos) resulted in inconsistent application of CWA requirements and confusion among federal and state agencies about which waters were covered by the Act. Efforts to clarify the rulings through legislation and rulemakings resulted in a dramatic politicization and polarization of the concept, with clean water interests advocating for broad application, and some development, industrial, and agricultural interests wanting a very narrow definition.

On December 30, 2022, the Environmental Protection Agency released the “Revised Definition of ‘Waters of the United States’” rule to clarify the reach of the CWA. The rule restored long-standing water protections, leveraged science and the rule of law, and reversed devastating rollbacks in the Trump Administration’s WOTUS Rule. The rule went into effect March 20, 2023, however legal challenges of the rule and resulting court decisions halted implementation of the rule in several states.

On May 25, 2023, the US Supreme Court issued their ruling in the Sackett vs. EPA case. In this ruling, the Court severely reduced clean water safeguards by limiting CWA protections for wetlands to only those wetlands that have a continuous surface connection to traditional navigable waters. The ruling overturns decades of CWA interpretation and flies in the face of science showing the critical nature of wetlands in protecting clean water. The likely impact is that more than half of our nation’s remaining wetlands are now unprotected from destruction and pollution, which is ever more critical in the face of a changing climate.

On September 8, 2023, EPA published a final rule that codifies the Court’s decision.

What’s the Current WOTUS Definition?

Last updated 9/8/2023

Check EPA’s “Current Implementation of Waters of the United States” page for further information.

From 40 CFR Part 120.2, Waters of the United States means:

(1) Waters which are:

(i) Currently used, or were used in the past, or may be susceptible to use in interstate or foreign commerce, including all waters which are subject to the ebb and flow of the tide;
(ii) The territorial seas; or
(iii) Interstate waters

(2) Impoundments of waters otherwise defined as waters of the United States under this definition, other than impoundments of waters identified under paragraph (a)(5) of this section;

(3) Tributaries of waters identified in paragraph (a)(1) or (2) of this section that are relatively permanent, standing or continuously flowing bodies of water;

(4) Wetlands adjacent to the following waters:

(i) Waters identified in paragraph (a)(1) of this section; or
(ii) Relatively permanent, standing or continuously flowing bodies of water identified in paragraph (a)(2) or (a)(3) of this section and with a continuous surface connection to those waters;

(5) Intrastate lakes and ponds not identified in paragraphs (a)(1) through (4) of this section that are relatively permanent, standing or continuously flowing bodies of water with a continuous surface connection to the waters identified in paragraph (a)(1) or (a)(3) of this section.

Eight exclusions from the definition of “waters of the United States” are codified at paragraph (b), and key terms are defined at paragraph (c).

Redlined changes to 40 CFR Part 120.2 can be found here.

State Policy Perspective

For examples of how states are stepping up and clarifying what streams are protected from unpermitted pollution under their own laws or expanding their state jurisdiction to make sure critical headwater streams are protected, visit River Network’s State Policy Hub! It includes a section on Bolstering CWA Protections and features interviews with on-the-ground advocates, as well as state-level policy examples from across the country.