The regulatory definition of "waters of the United States" (WOTUS), a key term in the Clean Water Act (CWA) establishing the scope of federal jurisdiction, once again is changing. The most recent definition, promulgated in the Navigable Waters Protection Rule (NWPR) (2020), eliminated the coverage of many water bodies. Following the June 9, 2021 joint announcement (previously discussed on this blog)[1] by the US Environmental Protection Agency (EPA) and the Army Corps of Engineers (together Agencies) that they intended to revise the WOTUS rule, additional significant developments have occurred.

On August 30, 2021, Judge Rosemary Márquez of the U.S. District Court for the District of Arizona struck down the NWPR.[2] Initially, it was unclear whether the ruling would apply nationally or only in the plaintiffs' state.[3] The Agencies, however, have adopted the former view, announcing that they "are interpreting 'waters of the United States' consistent with the pre-2015 regulatory regime until further notice."[4] Thus, at least for the time being, the definition of WOTUS has reverted to the 1986 regulatory definition, as interpreted by 2008 guidance.[5]

The Court's ruling potentially has the impact of accelerating the Agencies' rulemaking schedule, as they no longer must complete the process of repealing the 2020 NWPR.[6] Moreover, Judge Márquez has asked the parties for additional briefing on whether to strike down the 2019 Repeal Rule, which repealed the Clean Water Rule, including its definition of WOTUS, promulgated in 2015.[7]

The differences between a restored Clean Water Rule and a return to the pre-2015 status quo are complex. When promulgating the Clean Water Rule, the Agencies asserted that "[t]he scope of jurisdiction in this rule is narrower than that under the existing regulation," partly due to "important qualifiers on some existing categories such as tributaries."[8] The exact scope of WOTUS immediately prior to the Clean Water Rule was somewhat unclear, although it was narrower than the actual wording of the 1986 rule would imply because the rule was reinterpreted in the Agencies' 2008 guidance in light of Justice Anthony Kennedy's concurring opinion in the Supreme Court's decision in Rapanos v. United States (2006). The Agencies' guidance adopted Justice Kennedy's view[9] that "to constitute 'navigable waters' under the Act, a water or wetland must possess a 'significant nexus' to waters that are or were navigable in fact or that could reasonably be so made."[10]

In Pascua Yaqui Tribe, Judge Marquez held that Justice Kennedy's concurring opinion was the controlling opinion in Rapanos, citing Ninth Circuit precedent.[11] She also noted that the "Agencies published the NWPR notwithstanding feedback from the EPA Science Advisory Board that the NWPR conflicts with established science … and weakens protection of the nation's waters in contravention of the CWA's objectives."[12] The Court vacated and remanded the NWPR, which had been based on the plurality opinion in Rapanos, as "arbitrary and capricious" under the Administrative Procedure Act.[13]

Meanwhile, the period provided by the Agencies for public comment on a new WOTUS rule ended September 3, 2021,[14] and over 32,000 written comments were received.[15] As of September 22, 2021, the Agencies have not yet published a proposed new definition of WOTUS.