On January 23, 2020, the EPA and the U.S. Army Corps of Engineers released the Navigable Waters Protection Rule (NWPR) which redefines “waters of the United States” (WOTUS). This new rule adopts a more limited definition of WOTUS that are subject to the Clean Water Act.  The NWPR defines WOTUS to include only four categories of waters: (1)  territorial seas and waters which are currently used, or were used in the past, or may be susceptible to use in interstate or foreign commerce, including waters which are subject to the ebb and flow of the tide; (2) tributaries; (3) lakes and ponds, and impoundments of jurisdictional waters; and (4) adjacent wetlands. The NWPR confirms that groundwater is not subject to regulation under the Clean Water Act, which means water features connected only by groundwater are also not subject to regulation.

The reduced scope in federal protections under the NWPR means that states will need to determine what waters within its boundaries are no longer covered and whether regulation adjustments are necessary.  Some states may need to decide whether to continue enforcing their existing regulations that go beyond the now contracted federal rules.  The NWPR will likely face multiple challenges in federal district courts.