Revised Endangered Species Act Regulations on the Horizon
The Trump administration recently announced four proposed rules that would modify the implementation of the Endangered Species Act (ESA). Many of these proposed rules would reinstate regulations from the first Trump administration that were subsequently rescinded by the Biden administration in 2024. Two of these rules were issued jointly by the U.S. Fish and Wildlife Service (USFWS) and the National Marine Fisheries Service (NMFS), sometimes referred to collectively as the “Services,” while the other two were issued solely by the USFWS. Below is a summary of the key changes under consideration.
1. Listing Endangered and Threatened Species and Designating Critical Habitat
The proposed rule pertaining to the listing of endangered and threatened species and designated critical habitat was jointly issued by the Services. To receive protection under the ESA, species must first be listed as either an endangered or threatened species. “Threatened species” are those “likely to become an endangered species within the foreseeable future throughout all or a significant portion of its range.”
Under the existing Biden-era regulations, a listing determination is to be made “without reference to possible economic or other impacts of such determination.” The proposed rule would remove this language from the regulations, allowing the Services to consider economic impacts from a listing determination. In addition, the Services need not identify the “foreseeable future” in terms of a specific period of time for purposes of listing a species as threatened. The proposed rule would restrict this timeframe, whereby “foreseeable future” extends only so far into the future as the Services can reasonably determine, based on the best scientific and commercial data available, that both the future threats and the species’ responses to those threats are likely to occur —not merely possible or anticipated to occur, as the Biden-era regulations currently require.
The proposed rule would also clarify standards for determining whether designating critical habitat may be considered “not prudent.” This rule would reinstate language clarifying that the designation of critical habitat may not be prudent when the only threats to a species’ habitat stem solely from causes that cannot be addressed by the actions identified in a Section 7 consultation. The proposed rule would also require the Services to first evaluate “occupied areas” before considering any “unoccupied areas” for critical habitat designation.
Because this proposed rule would essentially raise the bar for the Services’ listing determinations, it is possible this rule may result in fewer species receiving listing status under the ESA.
2. Interagency Cooperation (i.e., Section 7) Regulations
The proposed rule pertaining to the interagency cooperation regulations was also jointly issued by the Services. This proposed rule would govern the Section 7 consultation process, which requires the Services to ensure that any action authorized, funded, or carried out by any federal agency is not likely to jeopardize the continued existence of listed species or result in the destruction or adverse modification of critical habitat of such species. The proposed rule addresses definitions of “effects of the action,” “environmental baseline,” and “reasonable and prudent measures.”
Definition of “Effects of the Action”
The “effects of the action” establishes the scope of analysis for determining whether a federal agency action is likely to adversely affect listed species and includes “all consequences to listed species or critical habitat that are caused by the proposed action including the consequences of other activities that are caused by the proposed action.” The proposed rule would limit the effects to be considered during Section 7 consultation to those that are “reasonably certain to occur” and would not occur but for the proposed action, all in the context of whether an agency has statutory authority to prevent an effect from occurring.
Definition of “Environmental Baseline”
The proposed rules would establish a separate, stand-alone definition of “environmental baseline” used to evaluate impacts. Under this definition, the environmental baseline is the condition of the listed species or critical habitat in the action area without the consequences caused by the proposed action. The proposed rule would also add that the consequences to listed species or designated critical habitat from ongoing agency activities or existing agency facilities that are not within the agency’s discretion to modify are to be included in the environmental baseline.
Definition of “Reasonable and Prudent Measures”
The proposed rule would narrow the scope of reasonable and prudent measures (RPMs) that may be included in a Section 7 biological opinion by removing language from the Biden-era regulations that allows RPMs to include “offsets” for the impacts of incidental take, i.e., measures intended to compensate for the impacts of incidental take on listed species. The proposed rule removes references to “offset” and “mitigation,” and instead narrowly construes RPMs as requirements that “cannot alter the basic design, location, scope, duration, or timing of the action, and may involve only minor changes.”
Collectively, these proposed changes are likely to result in a more limited review of impacts to listed species and critical habitat during the Section 7 process. These proposed changes are also likely to result in more restricted RPMs.
3. Regulations Pertaining to Threatened Species
The proposed rule pertaining to threatened species was issued solely by the USFWS. This rule pertains to what are known as “blanket rules” for protecting newly listed threatened species. Under “blanket rules,” when a species is listed as threatened, the “take” prohibitions applicable to endangered species automatically apply to the newly listed threatened species, unless the Service issues an alternative, species-specific rule. The proposed rule would remove this “blanket rule” option for protecting newly listed threatened species. Under the proposed rule, the USFWS must issue a “necessary and advisable” determination (including consideration of conservation and economic benefit) as to “protective regulations” for that species. The proposed rules would not change protections for currently listed threatened species that receive “blanket rule” protections.
This proposed change is likely to result in increased administrative burdens to establish protections for newly listed threatened species. The “blanket rule” approach provided automatic – and elevated – protections to threatened species as soon as they received their listing status. Without this approach, the USFWS will be required to process on a species-by-species basis rules for how newly listed threatened species are to be protected.
4. Regulations for Designating Critical Habitat
The proposed rule pertaining to the designation of critical habitat was issued solely by the USFWS. When the USFWS determines that a species warrants listing, it also designates “critical habitat” for that species. The proposed rule directs USFWS to designate critical habitat based on the “best scientific data available” and after considering the “economic, national security, and any other relevant impacts” of specifying any particular area as critical habitat. If the USFWS determines the benefits of exclusion outweigh the benefits of inclusion, the USFWS would exclude that area from critical habitat, so long as exclusion would not result in the extinction of the species.
The proposed rule provides a framework for this comparative weighing of impacts, referred to as an “exclusion analysis,” that includes a list of categories of potential “impacts” the USFWS should consider, as appropriate. For example, the proposed rule provides that economic impacts may include the economy of a particular area, productivity, and creation or elimination of jobs, opportunity costs potentially arising from critical habitat designation, and potential benefits from a designation, such as outdoor recreation or ecosystem services. The proposed rule also provides categories of “other relevant impacts” that the USFWS may consider, such as public health and safety, community interests, and the environment. The proposed rule also provides sideboards for when the USFWS should exercise its own discretion to potentially exclude an area from critical habitat, rather than in response to a request to exclude an area based on “credible information.”
By expanding the rationales upon which areas can be excluded from a critical habitat designation, this proposed rule is likely to result in an increase in “exclusion” determination, which in turn will result in a potential decrease in the overall areas designated as critical habitat for listed species.
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These proposed rules largely reinstate regulations from the first Trump administration, and so they are not novel or surprising, particularly in light of the second Trump administration’s recent efforts to roll back Biden-era environmental protections. That said, the proposed rules would result in significant changes in the Services’ approach to implementation of the ESA. The proposed rules were published on November 19, 2025, and a 30-day comment period began on November 21, 2025. The proposed rules would become effective only after this period has closed and the Services have addressed the comments. Given their scope, legal challenges to the proposed rules are almost certain.
For development in California, it’s important to note that the California legislature contemplated a potential “weakening” of federal ESA protections. If the proposed regulations are codified and withstand judicial scrutiny, then the delisting of species or other decrease in federal protections could trigger California state protections under Assembly Bill 1319, which was signed by Governor Newsom in 2025. Under AB 1319, for California native species that are not already listed under the California ESA, if federal ESA protections for those species are decreased, then those species may be identified by the California Department of Fish and Wildlife as a “provisional candidate species” under the California ESA. These “provisional candidate species” are treated as protected endangered and threatened species under the California ESA, which means that an incidental take permit under the California ESA would be required for the take of any such species.
If you have questions regarding any of these proposed regulations, please contact one of the authors.
