It wouldn’t be a change in Presidential administration without a change to the all-important definition of “Waters of the United States” (“WOTUS”) under the Clean Water Act. Last year, we updated you on Clean Water Act developments, including the then-new Trump administration WOTUS rule. The WOTUS rule defines which waters are subject to Clean Water Act jurisdiction—and which are not—so it has a meaningful impact on the reach of the Act. The Trump administration WOTUS rule, enacted in 2020, limited the waters that are considered WOTUS to include only territorial seas, traditionally navigable waters, certain surface waters that contribute surface flow to traditionally navigable waters, and wetlands that physically touch other jurisdictional waters. On August 30, 2021, a federal court in Arizona struck down the Trump WOTUS rule, citing the serious errors in enacting the rule, as well as the serious environmental harm that it has caused.

According to the Court, between June 22, 2020 and April 15, 2021, 76 percent of the 40,211 jurisdictional determinations of aquatic resources or water features made by the Army Corps of Engineers under the Trump WOTUS rule found the waters to be non-jurisdictional. The reduction was particularly significant in arid states, with nearly every stream assessed under the Trump WOTUS rule in New Mexico and Arizona falling outside Clean Water Act jurisdiction. The Court also cited concerns that the Trump WOTUS rule “disregards established science . . . .” The Court directed the Army Corps and the Environmental Protection Agency, the two agencies responsible for the WOTUS rule, to reconsider the rule (something the Biden administration had already prioritized), but it also vacated the Trump WOTUS rule, so it is no longer in effect.

So what are we left with? The Obama administration had enacted its own WOTUS rule, which was broader than the Trump WOTUS rule. However, the Obama WOTUS rule was repealed by the Trump administration, so unless that repeal is challenged, the Obama WOTUS rule will remain a thing of the past. Instead, the current definition of WOTUS will revert to a 1986 rule, which has been interpreted and re-interpreted by the courts, most notably by the Supreme Court in Rapanos v. United States, 547 U.S. 715 (2009). What does that mean? We could write a book about that, much less a blog post, but, at least temporarily, we will return to a regulatory definition that has been refined over the years by court decisions that essentially fall into some combination of the Trump WOTUS rule and the Obama WOTUS rule. Murky waters, indeed.