UPDATE: Since the court’s ruling was issued, EPA has announced on its website that both it and the U.S. Army Corps of Engineers will cease implementation of the NWPR and are instead interpreting WOTUS consistent with pre-2015 regulatory regime until further notice. To read EPA’s announcement, click here.

On August 30, 2021, a federal judge in the district of Arizona issued an order vacating the Navigable Waters Protection Rule (“NWPR”) and remanding the rule back to the Environmental Protection Agency (“EPA”) for further review. This decision represents the first time a court has vacated the NWPR which officially went into effect in June, 2020. EPA is currently in the process of reviewing the NWPR, and it is unclear how this recent decision will affect that effort.


The plaintiffs in Pasqua Yaqui Tribe v. U.S. Envtl. Prot. Agency, No. 4:20-cv-00266 (D. Ariz. 2021) was originally filed June 22, 2020 challenging the NWPR as contrary to the text and objectives of the Clean Water Act (“CWA”). The main objective of the CWA is to “restore and maintain the chemical, physical, and biological integrity of the Nation’s waters.” 33 U.S.C. § 1251. To accomplish that goal, the CWA prohibits the unpermitted discharge of any pollutant from a point source into “navigable waters.” The Act goes on to define “navigable waters” as “waters of the United States.”

The term “waters of the United States” (“WOTUS”) is central to the administration of the CWA because it determines which waterbodies receive CWA protection. However, the term is not defined in the text of the CWA. Since the CWA was passed in 1972, WOTUS has been defined by EPA through regulations. A full history of the regulatory definitions of WOTUS is available here. The NWPR is EPA’s latest effort to define WOTUS, narrowing the definition from EPA’s previous WOTUS rule which the Agency adopted in 2015. Under the NWPR, only six categories of waterbodies are included in the WOTUS definition. Additionally, several categories of waterbodies that were included in the 2015 rule were specifically excluded from the NWPR. For more information on the NWPR, see here. Among those waters excluded from CWA protection by the NWPR are ephemeral streams, and wetlands that do not have a direct surface connection with an otherwise protected waterbody.

The plaintiffs in Pasqua Yaqui Tribe v. U.S. Envtl. Prot. Agency are all federally recognized Native American tribes who rely on waters that lost CWA protections following adoption of the NWPR. In challenging the rule, the plaintiffs argued that the NWPR was contrary to the text of the CWA because it failed to protect waters that have “an effect on or connection to the physical, chemical, and biological integrity of downstream traditional navigable waters.” According to the plaintiffs, the CWA intends for WOTUS to be broadly defined so that it includes any waterways which have an effect on navigable waters. The NWPR failed to carry out the purpose of the CWA by excluding ephemeral streams, isolated wetlands, and other waters that do not share a surface connection with a protected waterbody.

When the Biden Administration took office in January, 2021, President Biden issued an Executive Order instructing agencies to review all agency actions taken between January 20, 2017 and January 20, 2021. Along with the Executive Order, the Biden Administration also released a non-exclusive list of agency actions that would receive particular review. The list included the NWPR. In response to the Executive Order, the EPA asked the Department of Justice to request stays for all pending litigation that were seeking judicial review of EPA regulations implemented during the Trump administration so that the Agency could begin to review those regulations and determine how to proceed. A stay was granted in Pasqua Yaqui Tribe v. U.S. Envtl. Prot. Agency, and when proceedings resumed, EPA filed a motion asking for voluntary remand of the NWPR without vacatur. In other words, EPA asked the court to send the NWPR back to EPA for review while still keeping the regulation in legal effect, thus ending the litigation.

While the plaintiffs agreed that the NWPR should be remanded to EPA for review, they opposed EPA’s request that remand be granted without vacatur. The plaintiffs argued that the court should remand and vacate the rule because vacatur is the appropriate remedy when an agency has committed serious errors that are likely to change the outcome of the regulation on remand, and leaving the regulation in effect would cause significant harm. Ultimately, the court found in favor of the plaintiffs and vacated the NWPR before remanding it to EPA.

The Court’s Decision

The issue presented to the court in Pasqua Yaqui Tribe v. U.S. Envtl. Prot. Agency was whether to remand the NWPR back to EPA while letting the regulation remain in legal effect, or to remand the NWPR back to EPA while also vacating the regulation so that it no longer was legally effective. After applying the standard that courts in the Ninth Circuit use to determine whether a remanded regulation should also be vacated, the court in Pasqua Yaqui Tribe v. U.S. Envtl. Prot. Agency determined that vacatur was appropriate.

Courts in the Ninth Circuit will generally vacate a remanded regulation. Remand without vacatur will only occur in “limited circumstances,” such as when vacating the remanded rule would “risk environmental harm,” or if the agency to which the rule was remanded could ultimately adopt the same regulation after offering better reasoning or complying with procedural requirements.

Here, the court began by considering whether EPA would be able to effectively re-adopt the NWPR on remand by offering better reasoning or complying with procedural requirements. Upon review, the court concluded that EPA was unlikely to re-adopt the NWPR. In reaching that conclusion, the court cited both the plaintiffs’ arguments that the NWPR disregards established science and the advice of EPA’s own experts, as well as EPA’s own admission that it has “substantial concerns about certain aspects of the NWPR” that it plans to address. Because the court found that the concerns identified by both plaintiffs and EPA “are not mere procedural errors or problems that could be remedied through further explanation” the court found that EPA was unlikely to re-adopt the NWPR on remand which weighed in favor of vacating the regulation.

Next, the court considered whether vacating the NWPR could result in environmental harm. To reach its decision, the court reviewed jurisdictional determinations of waterbodies made by the U.S. Army Corps of Engineers since the NWPR took legal effect. Of 40,211 aquatic resources or water features reviewed, 76% were found to fall outside the jurisdiction of the CWA. In arid states like New Mexico and Arizona, nearly every one of the streams assessed under the NWPR were found to not fall under CWA protection. Citing these numbers, the court concluded that “remanding without vacatur would risk serious environmental harm.”

The court remanded the NWPR back to EPA with vacatur because it concluded that allowing the regulation to remain in legal effect would cause environmental harm, and that the EPA would be unable to resolve its concerns with the NWPR through additional explanation or by resolving procedural error.

Going Forward

Following the court’s decision, there are several questions about what the ultimate effect of the ruling will be. That includes questions on the jurisdictional scope of the court’s decision, what definition of WOTUS will control following vacatur, and what EPA will do next.

There is some question over whether the court’s decision applies nationwide, or if its applicability will be limited to a particular jurisdiction. Previously, when the 2015 WOTUS regulation was facing legal challenges, courts that issued preliminary injunctions preventing the rule from having legal effect did so on a jurisdiction-by-jurisdiction basis. In those cases, the district courts that granted preliminary injunctions declined to make those injunctions applicable nationwide because other district courts hearing similar challenges had chosen not to issue a preliminary injunction against the 2015 WOTUS rule. The courts that did issue injunctions chose to limit the scope of those injunctions to specific jurisdictions out of respect for the courts that did not issue injunctions.

Here, it is currently unclear whether the court’s decision in Pasqua Yaqui Tribe v. U.S. Envtl. Prot. Agency will apply nationwide or to a limited jurisdiction. The intent of the court may not be clear until it issues a mandate finalizing its decision, or some other order specifying the scope of its decision. However, it is worth noting that other district courts have issued rulings remanding the NWPR back to EPA without vacatur. Additionally, it remains unclear how EPA views the decision. Thus far, a spokesperson for EPA has declined to answer questions about the case, stating that EPA is in the process of reviewing the decision.

There is also some uncertainty over what definition of WOTUS will be in legal effect following vacatur of the NWPR. Generally, when a regulation is vacated, the legal landscape returns to the status quo that was in place before the vacated regulation was adopted. Before adopting the NWPR, EPA had issued a final regulation officially repealing the 2015 WOTUS rule. When EPA repealed the 2015 regulation, it also reinstated the previous regulatory definition of WOTUS which had been adopted by EPA in 1986. Therefore, if the NWPR is vacated, the 1986 regulations will likely be the controlling definition of WOTUS.

Finally, it is also unclear at this point whether EPA will choose to appeal the court’s decision to vacate the NWPR. EPA is currently in the process of developing a new WOTUS rule. That process will include two rulemakings, the first of which will “propose to restore the regulations defining ‘waters of the United States’ in place for decades until 2015,” followed by a second rule which will build off that regulatory foundation. It is therefore possible that EPA could choose not to appeal vacatur of the NWPR and instead choose to continue with its plan for drafting a new WOTUS rule. However, EPA specifically asked that the court remand the NWPR without vacatur, and EPA may choose to appeal the court’s decision not to grant that request. Additionally, several agricultural groups have intervened as defendants in the case and may also chose to appeal the ruling.


To read the court’s decision in Pasqua Yaqui Tribe v. U.S. Envtl. Prot. Agency, click here.

To read the plaintiff’s original complaint, click here.

To read the NWPR, click here.

To read the text of the CWA, click here.

To read more articles about WOTUS, click here.

For more National Agricultural Law Center resources on the CWA, click here.