• The U.S. Fish & Wildlife Service and National Marine Fisheries Service proposed four rules on November 19, 2025, significantly changing how agencies apply the Endangered Species Act.
• If finalized, these changes would affect how species are listed, whether threatened species enjoy the same protections as endangered species, how the agencies designate unoccupied critical habitat, and how agencies should evaluate impacts during the Section 7 consultation process.
• Foreseeing these federal changes, California recently enacted AB 1319 “to ensure no backsliding as a result of a decrease in endangered or threatened species protections by the federal government.”

Regulations implementing the Endangered Species Act (ESA) have experienced some whiplash over the years. After the Trump Administration finalized revised regulations in 2019, the Biden Administration changed course in 2024. Portions of the 2019 and 2024 rules are subject to pending litigation. Meanwhile, the U.S. Fish & Wildlife Service and National Marine Fisheries Service (both referred to as the “Services”) proposed several regulations for implementing the ESA. If implemented, the regulations would clarify when and how the ESA applies.

Many of the proposals, however, are not new. Some reinstate rules that the Biden Administration repealed. Others repeal regulations that the Biden Administration promulgated. These latest regulations thus reflect ongoing regulatory volleyball between administrations over how to implement the ESA.

Listing Species

Section 3(20) of the Act defines a “threatened species” as any species that is likely to become an endangered species within the foreseeable future throughout all or a significant portion of its range. The latest proposed regulations reinstate 2019 regulations that clarified the phrase, “foreseeable future,” as extending only as far as the Services can determine future threats and species’ responses to future threats.

Threatened Species

Another regulatory volley between administrations is the “blanket rule” regulation. As we have previously covered, the “blanket rule” intends to apply the same protections for “endangered species” to “threatened species.” The “blanket rule” was repealed in 2019, only to be reinstated in 2024. The latest proposal would, again, repeal the rule.

Designating Critical Habitat

The proposed regulations also explain that the Services should not designate critical habitat when the Section 7 consultation process cannot address threats to a listed species’ habitat.

They would also reestablish the process by which the Services may designate area unoccupied by listed species as “critical habitat.” As we have previously discussed, the Ninth Circuit has held that the Fish & Wildlife Service can designate unoccupied critical habitat only when designating occupied habitat would be inadequate to ensure the species’ conservation. Consistent with this ruling, the Services’ rule would require that they first consider whether designating only occupied areas as “critical habitat” would be “inadequate” for the species’ conservation.

The proposed regulations also explain how critical habitat designations should consider not just environmental impacts, but impacts to public health and safety, economic interests, and national security.

Section 7 Consultation

Issues over whether a species is listed as endangered or threatened, or whether an area is designated as “critical habitat,” often arise during the Section 7 consultation process. Under the ESA, an agency permitting a project involving, say, maintenance of a hydroelectric dam or repairs to a reservoir may need to consult the Services. The Services would evaluate the “effects of the action” proposed to determine whether the project may result in a “take” of a protected species. That process is referred to as a “Section 7 consultation.” The Services’ latest rule defines “effects of action” to apply a proximate cause standard for evaluating a project’s anticipated consequences. Those effects should be “reasonably certain to occur” and should be “caused by the proposed action.”

The proposed rule explains that this clarification intends to align the definition with the Supreme Court’s recent opinion in Seven County Infrastructure Coalition v. Eagle County, Colorado regarding a similar process under the National Environmental Policy Act. In that case, the Court explained that agencies should not evaluate a project’s effects over which the reviewing agencies lack discretionary authority to mitigate. Narrowing the scope of evaluation in this way can help focus and streamline permitting processes.

Lastly, the proposed regulations clarify the definition of “environmental baseline.” A project’s impacts are compared to past and ongoing human and natural impacts on species and their habitat. The species’ health at the time of the proposed action is the “environmental baseline.” Because issues over what this evaluation should include often arise, the Services propose the phrase to mean going forward that the agencies should rely on the “best available scientific information at the time of the proposed action.” As with its proposed rule for evaluating the “effects of action,” the rule would prevent an agency from evaluating conditions for an environmental baseline over which the agency has no discretion to prevent.

California’s Response (AB 1319)

Whether and how the ESA applies is a complex and often lengthy, contentious process. The Trump Administration’s latest volley in the repeal-reinstate-repeal process for ESA regulation illustrates this complexity.

These changes are no surprise in California. Governor Newsom recently signed into law AB 1319 “to ensure no backsliding” under the ESA when regulations change. Under the new law, the California Department of Fish & Wildlife must monitor federal actions to determine whether those actions would decrease protections for listed species. If the actions would decrease protections, then the Department may apply additional protections for these “provisional candidate species.”

Given these significant changes at the federal and state level, project proponents should stay apprised of these regulatory changes. If you have any questions about how these laws may affect your project, please contact our Environmental Law attorneys.