On January 23, 2020, the U.S. Environmental Protection Agency
(EPA) and the Department of the Army finalized the new Navigable Waters Protection Rule narrowing the
scope of waters subject to federal regulation under the Clean Water
Act (CWA). The new rule replaces the 2015 Clean Water Rule’s
definition of “Waters of the United States” (WOTUS),
which was repealed by the Trump administration last fall. Among
other changes, the new rule restricts federal regulation to four
major categories of waters and limits protections for ephemeral
waterways and wetlands included in the 2015 Rule.
The federal government’s authority to issue pollutant
discharge permits under the CWA extends to all “Waters of the
United States,” a term left undefined in the statute. The
Obama administration’s 2015 Rule attempted to clarify the
definition of WOTUS after two Supreme Court decisions (SWANCC
v. Army Corps of Engineers and Rapanos v. United
States) created uncertainty around federal CWA
