What was old is now new again as the United States Environmental Protection Agency (USEPA) and the United States Army Corps of Engineers (Corps) announced on September 3, 2021 a reversion to a pre-2015 definition of Waters of the United States (WOTUS) following a ruling by the United States District Court for Arizona, finding that the Trump-era Navigable Waters Protection Rule (NWPR) issued in 2020 was inconsistent with the federal Clean Water Act.

The NWPR was promulgated and meant to replace the Obama-era 2015 Clean Water Rule, which in turn was meant to replace and provide certainty regarding the definition of WOTUS following the United States Supreme Court’s decision in Rapanos v. United States, 547 U.S. 715 (2006), in which a split Court provided dueling definitions for what constituted WOTUS. 

A block of four justices led by Justice Scalia found that WOTUS was limited to navigable waters, those which directly contributed to navigable waters, and those which were a relatively permanent, standing, or continuous body of water, including wetlands. Justice Kennedy, who was the deciding fifth vote in the case with the Scalia block, defined WOTUS to include those traditional navigable waters and those waters which had a substantial nexus to a traditional navigable water. Justice Kennedy argued that a nexus exists where the wetland or waterbody, either by itself or in combination with other similar sites, significantly affects the physical, biological, and chemical integrity of the downstream navigable waterway.

Between 2006 and 2015 both USEPA and the Corps developed guidance setting forth its interpretation of Rapanos which concentrated on Justice Kennedy’s one-man opinion in support of the larger plurality of the Court. The result was general dissatisfaction amongst the regulated community due to a lack of certainty as to what constituted jurisdictional waters. We have now returned to this regime of uncertainty following the Arizona District Court’s ruling.

Adding to the uncertainty moving forward is the question of whether the Arizona District Court’s ruling applies nationwide or only in Arizona. Further, the court itself is weighing whether to resurrect the Obama-era rules, which had been removed by the Trump administration, or revert to the pre-Obama Rapanos regime. Even further, the Biden Administration has announced its intent to introduce a new rule vacating the NWPR, reinstating the Obama-era rule, and simultaneously developing a third WOTUS rule. Under any circumstance, there is significant uncertainty ahead with regard to the issue of WOTUS.