On April 21, the United States Environmental Protection Agency (EPA) announced that the final step in the Trump Administration’s efforts to revise the definition of navigable waters under the Clean Water Act (CWA) is complete, and the final version of the Navigable Waters Protection Rule has been published in the Federal Register. The rule comes after a years-long battle over the Obama Administration’s 2015 Clean Water Rule that resulted in a regulatory patchwork in which the rule was in effect in only 22 states. The Trump Administration engaged in a two-step rule-making process to first repeal the Clean Water Rule and then issue this replacement rule.

The CWA prohibits discharges of pollutants from point sources into “navigable waters” and the Navigable Waters Protection Rule defines how far that prohibition extends under federal law. The rule retains jurisdiction over larger bodies of water (territorial seas, rivers, lakes) that are “navigable” in the traditional sense, as well as some smaller bodies of water that fell within the broader definition of the 2015 rule. But the rule scales back application of federal jurisdiction to more ephemeral bodies of water or those that lack a surface connection to traditional navigable waters. Remote wetlands and wetlands that are separated from surface water by artificial barriers are also excluded from jurisdiction under the Rule.

The rule goes into effect on June 22, 2020, and is likely to face challenges in courts nationwide. In 2018 in National Association of Manufacturers v. Department of Defense, 138 S.Ct. 617 (2018), the Supreme Court decided that the CWA jurisdictional rule must be challenged first in the various federal district courts, meaning that a ruling from the court on the Trump Administration’s rule, and a more final word on federal CWA jurisdiction, is still likely years away. In the meantime, the rule does not change the applicability of state laws that are more stringent—many states regulate isolated wetlands under their own permit programs—and regulated entities should ensure compliance with state obligations in addition to the new rule.