Originally published as a Schiff Hardin Environmental Update newsletter

The United States Environmental Protection Agency (USEPA) and the United States Army Corps of Engineers (USACE) proposed guidance earlier this month regarding the scope of waters regulated by the Clean Water Act (CWA). USEPA and the USACE stated that the purposes of the proposed guidance are to clarify which waters are subject to CWA jurisdiction, to provide clearer direction to field staff and to reduce uncertainty within the regulated community. If adopted, the guidance is expected to increase the number of waters that are protected under the CWA.

The proposed guidance would replace current CWA guidance documents adopted in response to two Supreme Court cases that addressed what it means to be “waters of the United States” under the CWA. Solid Waste Agency of Northern Cook County v. U.S. Army Corps of Engineers, 531 U.S. 159 (2001) (SWANCC) and Rapanos v. United States, 547 U.S. 715 (2006) (Rapanos). The holdings of both SWANCC and Rapanos served to limit the reach of CWA jurisdiction by excluding certain bodies of water. In Rapanos, four justices (one short of a majority) concluded that waters could be regulated under the CWA only if they were “relatively permanent, standing or flowing bodies of water.” In a concurring opinion, Justice Kennedy concluded that “waters of the United States” under the CWA includes wetlands that have a significant nexus to traditional navigable waters, if the wetlands “significantly affect the chemical, physical, and biological integrity of other covered waters more readily understood as navigable.”

Under the proposed guidance, the agencies would interpret the CWA as protecting traditional navigable waters; interstate waters; wetlands adjacent to either traditional navigable waters or interstate waters; non-navigable tributaries to traditional navigable waters that are relatively permanent (meaning they contain water at least seasonally); and wetlands that directly abut relatively permanent waters. The agencies would also interpret the CWA as protecting waters that have a “significant nexus” to traditional navigable waters or interstate waters. In accordance with Justice Kennedy’s opinion in Rapanos, a body of water would have a “significant nexus” if it significantly affects the chemical, physical, or biological integrity of traditional navigable waters or interstate waters. Examples of “significant nexus” waters would include: tributaries to traditional navigable waters or interstate waters; wetlands adjacent to jurisdictional tributaries to traditional navigable waters or interstate waters; and certain waters that fall under the “other waters” category of the CWA implementing regulations.

Unlike existing guidance, the proposed guidance specifically addresses the protection of interstate waters, clarifies that interstate waters are protected under the CWA (as are waters with a significant nexus to interstate waters), and addresses waters that only flow part of the year or that do not have a surface connection to traditional navigable or interstate waters.

The proposed guidance also presents the fact-specific analysis field agents should use to determine whether a “significant nexus” exists. More precisely, it instructs field agents to consider the following factors: (1) whether the waters are “similarly situated” with waters of the same resource type; (2) whether the waters fall within the same watershed; and (3) whether the waters alone or in combination with other similarly situated waters in the same watershed have an effect on the chemical, physical, or biological integrity of traditional navigable waters or interstate waters that is more than “speculative or insubstantial.” For the third factor, field agents are directed to look for indicators of hydrology, effects on water quality, and physical, chemical, and biological connections or functions to assess whether waters have more than speculative or insubstantial effect. The proposed guidance provides sediment trapping, nutrient recycling, pollutant trapping and filtering, retention or attenuation of flood waters, runoff storage, and provision of aquatic habitat as examples of water functions that might demonstrate a significant nexus.

In addition to this proposed guidance, USEPA and the USACE have stated that they will likely propose revisions to existing regulations to reflect similar changes. The agencies are seeking public comments regarding the proposed guidance by July 1, 2011. A copy of the proposed guidance can be found on USEPA’s Web site.