On April 27, 2011, the Environmental Protection Agency (EPA) and the U.S. Army Corps of Engineers (ACOE) issued joint draft guidance seeking to clarify which wetlands are considered “waters of the United States” protected by the Clean Water Act (CWA). Although the U.S. federal government (typically through the EPA) has authority to regulate environmental matters in “waters of the United States,” the phrase has been the subject of significant debate and has been extensively litigated. This is particularly so in regard to small, isolated wetlands that do not appear to be navigable or connected to any other water body. The new draft guidance interprets the federal jurisdiction under the CWA more expansively than the existing guidance, which was published in 2008. For example, the new guidance explicitly describes interstate waters as categorically within federal jurisdiction and modifies the position of the EPA and the ACOE (together, the Agencies) concerning swales, erosional features and upland-draining ditches characterized by infrequent or low-volume flow. The proposed guidance also provides a more explicit and extensive list of waters over which the Agencies would generally not assert jurisdiction, thus providing greater certainty that activities affecting these waters would not trigger federal jurisdiction. For further information, please see the Draft Guidance.