Yesterday the United States Environmental Protection Agency and the Corps of Engineers released a pre-publication, final version of a new rule defining the scope of “waters of the United States” under the Clean Water Act. This definition is key to the agencies’ jurisdiction under the National Pollutant Discharge Elimination System, Clean Water Act Section 404 permitting for discharge of dredge and fill materials, Oil Pollution Act coverage, and other federal water quality permitting, notification, and liability programs. The rule replaces 2008 guidance and 2011 draft guidance (later withdrawn) issued by the agencies in the aftermath of the U.S. Supreme Court’s plurality opinion in Rapanos v. United States and Carabell v. United States, 547 U.S. 715 (2006), in which Justice Kennedy articulated a “significant nexus” test for defining waters of the U.S. The rule will become effective sixty days after publication in the Federal Register. EPA and the Corps say the rule expands the scope of waters covered by these laws by only about 3%, but industry and development interests claim the expansion is much greater. Industry, development, and environmental interests have all threatened to seek judicial review of the new rule. EPA has posted information on the rule, including the text of the final rule.