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"Waters of the U.S." Rule Could Expand What Falls Under the Clean Water Act

June 8, 2015  |  Carolyn Berndt, National League of Cities

Last week, the U.S. Environmental Protection Agency (EPA) and the U.S. Army Corps of Engineers (Corps) released the final "waters of the U.S." rule to clarify which waters fall under federal jurisdiction of the Clean Water Act (CWA). The rule will be effective 60 days after publication in the Federal Register.

Under the final rule, "waters of the United States" means:


  1. All waters which are currently used, were used in the past, or may be susceptible to use in intestate or foreign commerce, including all waters which are subject to the ebb and flow of the tide; (commonly referred to as "traditional navigable waters")
  2. All interstate waters, including interstate wetlands;
  3. The territorial seas;
  4. All impoundments of waters otherwise identified as waters of the United States;
  5. All "tributaries" of waters identifed in 1-3 above;
  6. All waters "adjacent" to a water identified in 1-5 above, including wetlands, ponds, lakes, oxbows, impoundments, and similar waters;
  7. Waters including Prairie potholes, Caroline bays and Delmarva bays, Pocosins, Western vernal pools, and Texas coastal prairie wetlands where it is determined, on a case-specific basis, to have a "significant nexus" to a water identified in 1-3 above;
  8. All waters located within the 100-year floodplain of a water identified in 1-3 above and all waters located within 4000 feet of the high tide line or ordinary high water mark of a water identified in 1-5 above where they are determined on a case-specific basis to have a significant nexus to a water in 1-3 above.
The final rule includes definitions of "tributary," "adjacent," and "significant nexus," among others. This new definition of "waters of the U.S." has the potential to expand the number of waterbodies that are federally regulated under the CWA.

Among the most significant changes from the proposed rule is an exclusion for "stormwater control features constructed to convey, treat, or store stormwater that are created in dry land." The possibility that water conveyances, including but not limited to MS4s could meet the definition of a "tributary" under the proposed rule and thus be jurisdictional as a "waters of the U.S." was one of NLC's top concerns with the proposed rule.

While the language establishes a broad categorical exclusion, it does not apply to stormwater control features that were built on wet land or if the features are part of a traditionally navigable water, interstate waters or the territorial seas. For example, the exclusion may not apply to infrastructure in coastal or low-lying areas. Additionally, some features, such as channelized or piped streams, would be jurisdictional.

While the final rule does not include a specific exclusion for green infrastructure as NLC had requested, the preamble states, "this rule is designed to avoid disincentives to [the] environmentally beneficial trend in stormwater management practices"-using green infrastructure to manage stormwater at its source and keep it out of the conveyance system.

The exclusion for stormwater control features "is intended to address engineered stormwater control structures in municipal and urban environments-those that address runoff that occurs during and shortly after precipitation events; as a result stormwater features that convey runoff are expected to only carry ephemeral or intermittent flow."

The final rule also includes an exclusion for wastewater management systems, as NLC requested. The exclusion covers "wastewater recycling structures constructed in dry land; detention and retention basins built for wastewater recycling; groundwater recharge basins; percolation ponds built for wastewater recycling; and water distributary structures built for wastewater recycling." As with MS4s, the concern with the proposed rule was that water deliver and reuse facilities could be considered a "tributary" and therefore jurisdictional.

It is important to note that even if stormwater and wastewater infrastructure are not considered a "waters of the U.S.," they may still be regulated as a point source under the CWA Section 402 permit program.

NLC continues to review and analyze the final rule. This chart details a preliminary analysis covering NLC's specific concerns with the proposed rule. EPA will host a webinar on Thursday, June 11 from 1-2:30 p.m. EDT providing a broad overview of the final rule. You must register in advance to attend this webinar.