On Sept. 12, the U.S. Environmental Protection Agency (EPA) announced the final rule repealing the 2015 definition of “waters of the United States” (WOTUS) under the Clean Water Act. The revised rule is intended to increase predictability and stability in water pollution enforcement.

Since the Clean Water Act was originally enacted, there has been ambiguity as to what waters are under the federal government’s jurisdiction. The final rule repeals regulations from 2015 that significantly expanded the definition of WOTUS. After the publication of the 2015 rule, 31 states, including Wisconsin, challenged the EPA’s authority to enforce the broad rule. The U.S. Supreme Court ruled in early 2018 that the 2015 rule is subject to direct review in federal district courts. Since then, district courts have issued preliminary injunctions applying to 28 states overall, including Wisconsin.

EPA said its next step after the repeal is to implement a proposed new definition, which the agency released in December 2018. The proposed rule would narrow the definition of primary WOTUS to include only waters within the standard meaning of the term (e.g. oceans, streams, rivers, lakes, ponds, and wetlands).