In mid-September, the U.S. Environmental Protection Agency and the Army Corps of Engineers jointly submitted a proposed rule to the White House Office of Management and Budget intended to clarify which waters and wetlands are protected under the Clean Water Act. The EPA announcement of the action along with supporting information can be found on the Agency’s website.

The proposed rule represents these agencies’ latest effort to clarify the scope of federal jurisdiction under the CWA and thereby resolve long standing uncertainty about which water bodies and activities are regulated by the law. The proposal, if adopted, would likely have its most significant impact on small streams and certain wetlands that would be determined to be hydrologically connected to and to have impacts on larger downstream waters. The draft rule is based on peer-reviewed science reflected in a draft report titled Connectivity of Streams and Wetlands to Downstream Waters. This document is a synthesis of scientific evidence on the connectivity of streams and wetlands assembled by EPA’s Office of Research and Development and can be viewed here. While the proposed rule is not yet available for public comment, the draft study is. Comments will be accepted until November 6, 2013, and a three- day public meeting will be held December 16 through 18, in Washington, D.C.

At least some observers believe that the proposed rule will not simply clarify CWA jurisdiction, but expand it. For example, see this from the Association of Water Agencies, and  this  from the Washington Post.

The Agencies’ action ultimately results from the U.S. Supreme Court decision Rapanos v. United States, 547 U.S. 715, 126 S.Ct. 2208 (2006). That plurality decision left some uncertainty with respect to the Court’s view of the scope of the CWA jurisdiction. The Court made clear that CWA jurisdiction includes, at least, traditional navigable waters, wetlands adjacent to those waters, non-navigable tributaries to traditional navigable waters where the tributary has at least continuous seasonal flow, and wetlands abutting such tributaries. However, this left open the question of jurisdiction regarding other waterbodies and the scope of that jurisdiction where applicable. Initially, EPA and Corps provided informal guidance on the scope of jurisdiction at least with respect to certain types of waters including non-navigable tributaries that are not relatively permanent; wetlands adjacent to such tributaries; and wetlands adjacent to but not directly abutting relatively permanent non-navigable tributaries. The proposed rule is intended to replace this informal guidance, and it may expand the scope of jurisdiction in the process.