Senator Mike Braun, Senator Joni Ernst, and Senator Chuck Grassley have introduced the Define WOTUS Act, which will codify a congressionally mandated definition of what constitutes WOTUS, or Waters of the United States. If passed, the bill would reassert Congressional responsibility to define this important term for farmers. The definition in the Define WOTUS Act also makes substantial improvements over various administrative attempts to define the term by clearly outlining what is, and is not, a federally regulated waterway.

It is time that Congress steps up to define WOTUS and end the regulatory whiplash.

“Regulations for what falls under ‘Waters of the U.S.’ have ping-ponged back and forth for years,” said Senator Braun. “Farmers and families need a reasonable, practical definition for WOTUS, and that’s why I’m introducing the Define WOTUS Act with my colleagues today.”

“Iowa farmers, landowners and developers care about the quality and health of their land, but multiple rules changes over the past several years have led to uncertainty and confusion. It’s time to put a stop to federal bureaucrats’ heavy-handed approach and create a clear, commonsense definition of WOTUS,” Grassley said.

“Vague and expanded regulations allow the Biden administration to tell Iowans what they can and can’t do on their own land. As over 46,000 Iowa small business owners brace for the impact of Biden’s WOTUS rule, I’m fighting to clarify what is and, most importantly, what is not a water of the U.S.,” said Senator Ernst.

The bill differs from EPA’s regulations under the Biden, Trump, and Obama Administrations in several important ways:

  • Wetlands: Unlike previous definitions, the bill restricts federal authority to wetlands that “abut.”
  • Ephemeral Waters: The bill restricts WOTUS to streams that flow at least 185 days a year—a common recommendation from agriculture stakeholders.
  • Exclusions: The bill includes more exclusions than previous rule—including an exclusion for snowpack melt requested by agriculture stakeholders as well as a new exclusion for drain tiling as a subsurface drainage system.
  • Beyond Visual Inspection: The bill also restricts waters that require more than a visual inspection to determine their federal status as not WOTUS. This is an important mechanism requested by many stakeholders to ensure that the definition is as predictable and uniformly implemented as possible. 


  • The U.S. Environmental Protection Agency (EPA) and U.S. Army Corps of Engineers (USACE) derive their authority to regulate waters of the United States (WOTUS) from the Federal Water Pollution Control Act Amendments of 1972. While the term “WOTUS” defines the scope of EPA’s jurisdiction (including multiple permitting programs, water quality standards, and enforcement mechanisms), the term was not clearly defined in statute—and still isn’t five decades later. 
  • Since the 2006 Supreme Court case Rapanos v. United States, WOTUS has been interpreted to include any waters with a “significant nexus” to navigable-in-fact waters, determined on a case-by-case basis. This case-by-case test can lead to contradicting determinations for the same tract of land by two bureaucrats from EPA. The post-Rapanos interpretation of WOTUS has been detrimental for American farmers and ranchers. 

Biden Administration Rulemaking: On December 30, 2022, EPA announced its Biden-era WOTUS rule. President Biden says his rule leans on a “pre-2015” interpretation of WOTUS and, therefore, should be exempt from the critiques levied against the Obama-era Clean Water Rule. However, the same fundamental concerns that led stakeholders to oppose the Clean Water rule (e.g., regulatory ambiguity under the “significant nexus” test, a reliance on case-by-case analysis, and regulation of ephemeral and intermittent flows) existed before the Obama Administration and persist under the Biden Administration.

Pending Supreme Court Decision: The Supreme Court is currently considering a case, Sackett v. EPA, which may strike down the “significant nexus” test, an underpinning of the Biden WOTUS rule. It is time that Congress steps up to define WOTUS and end the regulatory whiplash.