On March 25, 2014, the Environmental Protection Agency (EPA) and the U.S. Army Corps of Engineers (Corps) jointly proposed a rule defining the scope of waters protected under the Clean Water Act (CWA). The proposal would revise regulations that have been in place for more than 25 years. This book describes the proposed rule and includes a table comparing the existing regulatory language that defines “waters of the United States” with the proposal. In 2006, the Supreme Court decided Rapanos v. United States, the most recent and well-known of three Supreme Court decisions wrestling with the question of which wetlands are covered by the wetlands permitting program in the Clean Water Act. This book also provides background including the pre-Rapanos Supreme Court opinions, then moves on to Rapanos itself and the Corps/EPA guidance documents.