Non-navigable streams and adjacent wetlands: addressing science needs following the Supreme Court’s Rapanos decision

www.frontiersinecology.org © The Ecological Society of America T Clean Water Act (CWA) protects “navigable waters”, defined as “waters of the United States” (33 USC § 502[7]). Regulations by the US Environmental Protection Agency (EPA) and US Army Corps of Engineers (Corps) further define what are considered “waters of the US” (33 CFR § 328.3[a] and 40 CFR § 230.3[s]). Prior to 2001, any tributary to a navigable-infact water (including waters that are used in interstate or foreign commerce) and virtually all delineated wetlands (wetlands whose hydrology, soils, and vegetation meet regulatory requirements) were regarded as jurisdictional (ie considered a water of the US) under the CWA, because of their potential to serve as migratory bird habitat. Two Supreme Court cases changed this perspective. In Solid Waste Agency of Northern Cook County (SWANCC), the Court held that the presence of migratory birds was an insufficient sole basis for asserting CWA jurisdiction over isolated, intrastate, non-navigable waters (Solid Waste Agency of Northern Cook County v US Army Corps of Engineers 2001). However, the Court did not invalidate the regulations defining “waters of the US”. The reasoning in SWANCC could suggest that waters need some relationship with a navigable-in-fact body of water to be afforded protection under the CWA. By introducing the term “isolated” into the issue of CWA jurisdiction, SWANCC has encouraged research on the relative connectivity among wetlands and other waters (Leibowitz and Nadeau 2003). Five years after SWANCC, the Supreme Court explored CWA protections for tributaries and adjacent wetlands in Rapanos v United States and Carabell v United States (these two cases were consolidated into one decision, Rapanos v United States [2006]). In June of 2006, the Justices issued five opinions in Rapanos, with no single opinion commanding a majority. As a result, the scope of “waters of the US” will be determined by the interpretation of these decisions by the EPA, the Corps, and the courts. It is clear, however, that the Rapanos opinions establish new data and analytical requirements for determining whether a particular water is protected under the CWA. Justice Antonin Scalia (joined by three other Justices) opined that “waters of the US” extend beyond navigableREVIEWS REVIEWS REVIEWS