Proposed Rule Would Narrow Scope of WOTUS

December 14, 2018
Kristine A. Tidgren

On December 11, 2018, the Environmental Protection Agency (EPA) and the U.S. Army Corps of Engineers proposed a revised definition for “waters of the United States” or WOTUS. This definition, if finalized, would determine which waters are subject to the jurisdiction of the federal Clean Water Act. As proposed, the rule would significantly narrow the scope of WOTUS, particularly in comparison to the 2015 Clean Water Rule.


WOTUS has been the subject of litigation and controversy since the final Clean Water Rule was unveiled on May 27, 2015. Because of the pending litigation, the 2015 rule is currently in effect in only 22 states. The rule is stayed for the remaining states because federal courts have determined that states challenging the rule were likely to succeed on the merits of their legal claims. In those states, a pre-2015 legal framework applies. Specifically, these states have alleged in their complaints that they are harmed because the Clean Water Rule expands the number of waters subject to federal jurisdiction, erodes states’ authority over their own waters, increases the burdens on the states to administer federal water quality programs, and undermines state sovereignty. For more background on the 2015 rule and the complex procedural saga it unleashed, click here.  

The 2018 proposed rule sets forth six specific categories of jurisdictional WOTUS, as compared to the 2015 rule’s eight categories. It also eliminates provisions and definitions that would subject isolated lakes, streams, and wetlands to federal jurisdiction.

Six Categories of WOTUS

The proposed rule identifies the following six categories of jurisdictional WOTUS:

1.Traditional Navigable Waters

The proposed rule incorporates territorial seas into the historical category of traditional navigable waters. This category includes waters that are currently used, or were used in the past, or may be susceptible to use in interstate or foreign commerce, including the territorial seas and waters which are subject to the ebb and flow of the tide.

Note: The proposed rule eliminates interstate waters as a separate category of jurisdictional water. Rather, the agencies propose that these waters are jurisdictional if they fall into the definition of another category.

2. Tributaries of Traditional Navigable Waters

The proposed rule significantly narrows the definition of the category “tributary.” It defines tributary as a river, stream, or similar naturally occurring surface water channel that contributes perennial or intermittent flow to a traditional navigable water "in a typical year" either directly or indirectly through other navigable water. The definition removes from jurisdiction streams that exist only after rain or snow fall.

Note: the proposed rule introduces a new term "typical year," which means within the normal range of precipitation over a rolling thirty-year period for a particular geographic area. Under this proposed definition, a typical year would generally not include times of drought or extreme flooding.

3. Ditches

Ditches are defined in the proposed rule as artificial channels used to convey water. They would be jurisdictional only if they are navigable, if they are constructed in a tributary (and meet the definition of a tributary), or if they are constructed in an adjacent wetland and satisfy the conditions of the "tributary" definition.

Note: Ditches constructed in the upland and ditches with only ephemeral flow would not be jurisdictional under the proposed rule. Ephemeral is defined to mean only in direct response to precipitation.

4. Lakes and Ponds

This category of jurisdictional water includes lakes and ponds that qualify as traditional navigable waters, those that contribute perennial or intermittent (not ephemeral) flow to a traditional navigable water, or those that are flooded by other jurisdictional water in a typical year. This is a new category of jurisdictional water. Under the 2015 rule, lakes and ponds were jurisdictional if they met other definitions, including that for broadly defined "neighboring" waters (which does not exist under the proposed rule).

5. Impoundments

Impoundments of other jurisdictional waters would remain jurisdictional under the proposed rule.

6. Adjacent Wetlands

The proposed rule would significantly reduce the number of wetlands subject to CWA jurisdiction. The proposed rule provides that wetlands “adjacent” to other jurisdictional waters would be jurisdictional. Adjacent wetlands must actually abut the jurisdictional waters or have a direct hydrological surface connection to the jurisdictional water in a typical year. Wetlands that are physically separated from jurisdictional waters by a berm, dike, or other barrier are not adjacent if they lack a direct hydrologic surface connection to a jurisdictional water in a typical year.

Specifically Excluded from WOTUS

The proposed rule would specifically exclude from the definition of WOTUS the following:

  • Waters or water features not specifically identified by the six categories set forth above
  • Groundwater, including groundwater drained through subsurface drainage systems
  • Ephemeral features and diffuse stormwater run-off, including directional sheet flow over upland
  • Ditches that are not identified in category three above
  • Prior converted cropland
  • Artificially irrigated areas, including fields flooded for rice or cranberry growing, that would revert to upland should application of irrigation water to that area cease
  • Artificial lakes and ponds constructed in upland (including water storage reservoirs, farm and stock watering ponds, and log cleaning ponds) which are not identified in categories four and five above
  • Water-filled depressions created in upland incidental to mining or construction activity, and pits excavated in upland for the purpose of obtaining fill, sand, or gravel
  • Stormwater control features excavated or constructed in upland to convey, treat, infiltrate or store stormwater run-off
  • Wastewater recycling structures constructed in upland, such as detention, retention and infiltration basins and ponds, and groundwater recharge basins
  • Waste treatment systems


The agencies released the following infographic to illustrate the reach of the proposed WOTUS rule.

Relation to Point Sources

The preamble to the proposed rule states that some waters that are excluded from the definition of WOTUS, such as ditches and ponds, could in some circumstances be point sources of pollution under the Clean Water Act. The agencies are specifically seeking comments on whether a ditch can be both a point source and a “water of the United States,” or whether these two categories as established by Congress are mutually exclusive. Although the proposed rule specifically states that groundwater itself, including that drained through sub-surface drainage tile, is not WOTUS, it does not answer the question of whether groundwater as a conduit for pollutants can lead to CWA liability. This is an issue that the agencies are separately considering. Certiorari petitions on this issue are pending before the U.S. Supreme Court. On Monday, December 3, 2018, the U.S. Supreme Court asked the U.S. Solicitor to file briefs in two pending cases expressing the views of the United States on or before January 4, 2019.

What’s Next?

As soon as the proposed rule is published in the federal register, the agencies will open a 60 day comment period. They hope to finalize the rule by the end of 2019. In the meantime, we continue to operate under the patchwork system of the 2015 rule for 22 states and the pre-2015 significant nexus framework for the rest.

CALT does not provide legal advice. Any information provided on this website is not intended to be a substitute for legal services from a competent professional. CALT's work is supported by fee-based seminars and generous private gifts. Any opinions, findings, conclusions or recommendations expressed in the material contained on this website do not necessarily reflect the views of Iowa State University.

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