Hydrological Connectivity of Headwaters to Downstream Waters: Introduction to the Featured Collection

In January 2001, the U.S. Supreme Court issued a ruling in the case of Solid Waste Agency of Northern Cook County v. U.S. Army Corps of Engineers, 531 U.S. 159 (2001) (SWANCC). The SWANCC case presented the Court with two issues: (1) whether an isolated water could be considered part of the ‘‘waters of the United States,’’ protected under the Clean Water Act (CWA) – and thus subject to the U.S. Army Corps of Engineers’ (Corps) regulatory authority under Section 404 of the CWA – solely based on its use by migratory birds; and, if so, (2) whether Congress had the constitutional authority under the Commerce Clause to include these as waters of the United States. In particular, the Court considered the Corps’ Migratory Bird Rule – which deemed waters of the United States to include isolated intrastate waters that provide habitat for migratory birds. In a 5-4 decision, the Court found that the Migratory Bird Rule exceeded the Corps’ authority under the CWA [531 U.S., 159 (2001)], and held that the CWA is not intended to protect isolated, intrastate, non-navigable waters based solely on their use by migratory birds. While the Court’s decision did not create a bright line test for what Congress intended to regulate under the CWA, the Court’s reasoning implies that the CWA intended some ‘‘connection’’ to navigability, and that isolated waters need a ‘‘significant nexus’’ to navigable waters to be jurisdictional. The SWANCC decision has had profound implications on the legal status of so-called isolated waters – those lacking a surface water connection to other bodies of water. Furthermore, that decision affects all CWA programs – including Section 303 water quality standards, Section 311 oil spill prevention and cleanup, Section 401 water quality certification, and Section 402 pollution discharge permits – not just Section 404, which regulates the discharge of dredged or fill material into waters of the U.S, including wetlands. Initially following the SWANCC decision, much of the regulatory debate was focused on so-called isolated wetlands, while the debate in the courts focused on the jurisdictional status of tributaries, including headwater, intermittent and ephemeral streams. These case law and regulatory debates made apparent that the emerging issue is ‘‘what is the extent of the tributary system,’’ with a focus on headwater, intermittent and ephemeral streams and the connectivity, or ‘‘significant nexus,’’ of these waters to navigable waters. The Corps and the U.S. Environmental Protection Agency issued guidance in January 2003 indicating that field staff were to continue to assert jurisdiction over tributaries and their adjacent wetlands, and that formal headquarters approval should be obtained prior to asserting jurisdiction over isolated waters based solely on links to interstate commerce [68 Fed. Reg. 1995, 1998 (January 15, 2003)]. During that same time period, a significant majority of courts, including 17 appellate court decisions, concluded that SWANCC was narrowly focused