EPA Proposes New WOTUS Rule to Clarify Clean Water Act's Scope

Posted on 2/15/2019 by Roger Marks

US EPA published a Notice of Proposed Rulemaking (NPRM) to re-define Waters of the United States (WOTUS) in the February 14 Federal Register (Vol 84, No. 31).

How EPA defines “waters of the US” is a critical piece of the Clean Water Act. The WOTUS definition determines which bodies of water are under the jurisdiction of EPA and the Army Corps of Engineers, i.e., which waters are subject to requirements for Spill Prevention Control and Countermeasure (SPCC) planning, oil spill notifications, NPDES permitting, stormwater discharge, dredge-and-fill, and other CWA programs.

EPA was directed by Executive Order to re-define Waters of the United States in a way that is more consistent with the Supreme Court decision in Rapanos v. United States.

Interested in the US EPA thought process and Supreme Court decisions that have impacted the Clean Water Act over the past few years? Check out our previous reporting on the WOTUS rulemaking process here. Below, we’ve outlined each category of waters covered by EPA’s latest proposal, and how EPA plans to regulate each one.

Navigable Waters and Territorial Seas

This term covers all navigable waters and territorial seas that are currently used, may be used, or were once used in interstate or foreign commerce. EPA will combine “navigable waters” and “territorial seas” into a single category. Otherwise, EPA proposes no changes to this category.

Interstate Waters

To clarify the regulations, EPA will eliminate “interstate waters” from the definition of WOTUS. In the past, Congress and the Supreme Court have referred to “interstate navigable waters” when evaluating the Clean Water Act. EPA takes this to mean that a water must be both “interstate” and “navigable” to be under CWA jurisdiction.

Because all “navigable waters” are already covered, EPA feels the “interstate waters” category can be eliminated. EPA stresses that the Agency “anticipates that most waters that would be deemed jurisdictional under the existing regulatory definition from the 1980s would likely remain jurisdictional under this proposal.”


EPA is not proposing any changes to the impoundment category. EPA does not “believe that one can denationalize national waters by exerting private control over them.”


EPA’s proposal retains tributaries as a category of jurisdictional waters subject to CWA. Covered tributaries will be subject to the Clean Water Act regardless of their local name (creek, bayou, branch, brook, run, etc.) or their size.

EPA’s proposed rule defines tributary as a river, stream or similar naturally occurring surface water that contributes perennial or intermittent flow to a traditional navigable water or territorial sea in a typical year either directly or indirectly through other jurisdictional waters (incl. tributaries, impoundments, and adjacent wetlands).

As proposed, “tributaries” do not include surface features that flow only in direct response to precipitation—ephemeral flows, dry washes, arroyos, and similar features. 


To provide more “clarity and predictability,” EPA is adding a new category for ditches and similar features. According to the proposal, a ditch is a jurisdictional water of the US if it is “an artificial channel used to convey water” and:
  1. Satisfies the conditions identified in paragraph (a)(1) of the proposal;
  2. Is constructed in a tributary as defined in paragraph (c)(11) ; or
  3. Is constructed in an adjacent wetland as defined in paragraph (c)(1).
EPA’s proposal will not impact the status of ditches as “point sources” under the Clean Water Act.  


EPA’s updated definition will include a category of WOTUS to include all adjacent wetlands to:
  • Traditional navigable waters (and territorial seas).
  • Tributaries to those waters.
  • Jurisdictional ditches.
  • Jurisdictional lakes and ponds.
  • Impoundments of otherwise jurisdictional waters.
EPA will maintain the longstanding regulatory definition of wetlands:
…those areas that are inundated or stranded by surface or ground water at a frequency and duration sufficient to support, and that under normal circumstances to support, a prevalence of vegetation typically adapted for life in saturated soil conditions. Wetlands include swamps, marshes, bogs, and similar areas.

Exclusions from the Definition of Waters of the United States

EPA also introduced eleven exclusions from the definition of WOTUS in the proposed rule, two of which already exist. The eleven exclusions from the definition of WOTUS are as follows:  
  • Groundwater, including groundwater drained through subsurface drainage systems
  • Ephemeral surface features
  • Diffuse stormwater run-off (such as directional sheet flow over upland)
  • All ditches except those identified above
  • Prior converted cropland, which have been excluded since 1993 and will remain excluded
  • Artificially irrigated areas
  • Artificial lakes and ponds constructed in upland not otherwise covered as jurisdictional (e.g., water storage reservoirs, farm and stock watering ponds, settling basins, and clearing ponds)
  • Pits excavated in upland for the purpose of obtaining fill, sand, or gravel.
  • Water-filled depressions created in upland incidental to mining or construction activity
  • Stormwater control features excavated or constructed in upland to convey, treat, infiltrate, or store stormwater run-off
  • Waste treatment system, which have been excluded since 1979 and will remain excluded

New Definitions in Clean Water Act Regulation

To clarify existing exclusions for waste treatment systems and prior converted cropland, EPA has for the first time defined the terms “prior converted cropland” and “waste treatment system” in the proposed rule.

Prior converted cropland means “any area that, prior to December 23, 1985, was drained or otherwise manipulated for the purpose, or having the effect, of making production of an agricultural product possible.”

Waste treatment system means all components, including lagoons and treatment ponds (such as settling or cooling ponds) designed to convey or retain, concentrate, settle, reduce, or remove pollutants, either actively or passively, from wastewater prior to discharge.

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Tags: Clean Water Act, EPA, new rules, SPCC Plans, WOTUS

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