The Endangered Species Act Proposes to Change Its Stripes Yet Again

by Emily E. Moyes and Lauren C. Thomson¹

On November 21, 2025, the U.S. Fish and Wildlife Service (“FWS”) and National Oceanic and Atmospheric Administration (“NOAA”) proposed four rules for the implementation of the Endangered Species Act (“ESA”).² The proposed rules are a return to several changes previously promulgated by the first Trump Administration in 2019, which were largely reversed by the Biden Administration in 2024.³ The proposed rules repeal the “Blanket Rule,” clarify the process for excluding certain areas from designation as critical habitat, and refine key aspects of interagency cooperation and the designation of threatened species and critical habitat.

Repealing the Blanket Rule

The first proposed rule, proposed only by the FWS, repeals the Blanket Rule.⁴ The Blanket Rule extends the broad protections afforded to species that are classified as endangered to species that are also classified as threatened.⁵ This is the second time the Blanket Rule is set to be repealed, with the first time under the first Trump Administration in 2019.⁶ The proposed rule will apply to newly listed species, but will not remove blanket protections afforded to some currently listed species.⁷ Species that already have species-specific protections will not automatically require re-evaluation.⁸ However, FWS will have the discretion to revise and issue species-specific rules at any time it deems necessary and advisable for a threatened species.⁹ As of the date of this article, 148 species are afforded species-specific protections.¹⁰

Providing for the Exclusion of Critical Habitat

The second proposed rule, also from FWS, clarifies the process for excluding areas from being designated as critical habitat.¹¹ When designating an area as critical habitat under the ESA, the FWS must consider whether the benefits of excluding a particular area from designation would outweigh the benefits of designating the area as critical habitat.¹² The proposed rule adds triggers to begin the exclusion analysis, parameters for considering evidence that is presented, and additional factors to weigh in the balancing framework.¹³

Under the proposed rule, an exclusion analysis is triggered when the FWS Secretary receives credible information from a proponent of exclusion in support of the request, or at the Secretary’s own discretion.¹⁴ A two-factor test applies to determine if information is “credible”: (1) whether the proponents have provided factual information in support of the claimed impacts and (2) whether the claimed impacts are meaningful.¹⁵ When deciding to exclude an area under the proposed rule, FWS will “weigh [these] impacts relative to the conservation value of that particular area.”¹⁶

The proposed rule places new factors in the balance when determining if exclusion of critical habitat is appropriate. The proposed rule includes the consideration of national security impacts, economic impacts, and other relevant impacts.¹⁷ “Economic impacts” are defined as a non-exclusive list that includes considerations such as the economy of an area, jobs, and productivity.¹⁸ “Other relevant impacts” are defined by a non-exclusive list that includes impacts to states, local governments, and Tribes, and public health and safety requirements.¹⁹ Additionally, an exclusion analysis will take into account conservation plans, agreements, and partnerships, whether or not they include Section 10 “takings.”²⁰ Because these plans are designed to protect species, they will now be a factor weighing in favor of exclusion, as the Service asserts these plans appropriately reduce the regulatory burden of establishing critical habitat.²¹

Interagency Cooperation

The third proposed rule, jointly proposed by FWS and NOAA, modifies the consultation process between federal agencies.²² The consultation process requires agencies to consult with the Secretaries of the Interior and Commerce to ensure that any action authorized, funded, or carried out by such agencies is not likely to jeopardize the continued existence of endangered or threatened species, or result in the destruction or adverse modification of critical habitat of such species.²³ This rule proposes changes to key phrases that measure the impact of a federal action on a listed species and describes the actions taken to mitigate such impacts. These changes affect the following definitions: (1) “effects of the action,” (2) “reasonably certain to occur” (this phrase is used in the definition of “effects of an action”), (3) “environmental baseline,” and (4) “reasonable and prudent measures.”

First, the phrase “effects of the action” is defined, in the proposed rule, as: “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. A consequence is caused by the proposed action if it would not occur but for the proposed action and it is reasonably certain to occur. Effects of the action may occur later in time and may include consequences occurring outside the immediate area involved in the action.”²⁴

This is a narrowing and tightening of the scope of the phrase, which is used in the context of determining the lead agency and the formal consultation process.²⁵ On March 30, 2026, the United States District Court for the Northern District of California vacated the current definition of “effects of the action” and reinstated the definition as it was before the first Trump Administration changed it in 2019.²⁶ Until a new definition is promulgated, the definition of “effects of the action” is “the direct and indirect effects of an action on the species or critical habitat, together with the effects of other activities that are interrelated or interdependent with that action.”²⁷

Second, within the definition of “effects of the action,” is the phrase “reasonably certain to occur.” The proposed rule defines this as well. For an activity to be “reasonably certain to occur” it must rest on “clear and substantial information” using the best scientific and commercial data available.²⁸ When evaluating whether activities caused by the proposed action or activities reviewed under cumulative effects are reasonably certain to occur, four non-exclusive factors are provided: (1) past experiences with similar activities, (2) existing plans for the activity, (3) legal, economic, and administrative requirements necessary for the activity to occur, and (4) the amount of governmental discretion to be exercised.²⁹

Third, the phrase “environmental baseline,” which is relevant to the formal consultation process, has been modified in the proposed rule to include a time element.³⁰ The environmental baseline determines the scope of the consultation by establishing a reference point from which to judge the proposed action. The proposed rule will limit the evaluation of this reference point to the state of the environment “at the time of the proposed action.”³¹

Fourth, the phrase “reasonable and prudent measures,” which is relevant to the context of the formal consultation process, especially as it relates to the development of incidental take statements, has been modified to more generally refer “to those actions the Director believes necessary or appropriate to minimize the impacts [of a federal action], i.e., the amount or extent, or incidental take.”³²

These changes have the collective effect of narrowing the view of the environment to its present state, limiting the effects of an action to be considered when determining the reasonable and prudent measures to apply, and granting FWS and NOAA greater discretion over what mitigation measures are reasonable and prudent.

Listing Threatened and Endangered Species and Designating Critical Habitat

The fourth rule, also proposed jointly by FWS and NOAA, modifies the process for listing threatened and endangered species and designating critical habitat.³³ Three significant changes have been made to the list of factors that determine whether a species should be listed, delisted, or reclassified.

First, listing, delisting, and reclassifying decisions under this section will now consider “possible economic or other impacts.”³⁴ Previously, these impacts were expressly prohibited from consideration when determining if a species is threatened or endangered.³⁵

Second, the phrase “foreseeable future,” which is relevant to the definition of “threatened species,” defined as those which are “likely to become endangered within the foreseeable future throughout all or a significant portion of their range,” has been amended. For over forty years, the Endangered Species Act functioned without a definition of this phrase. The first Trump Administration promulgated a definition for the term in 2019, and its scope was broadened by the Biden Administration in 2024.³⁶ Under the proposed rule, the foreseeable future will be defined as “only so far into the future as [FWS and NOAA] can reasonably determine that both the future threats and the species’ responses to those threats are likely.”³⁷

Third, the criteria for delisting a species will also revert to its 2019 form. Under the proposed rule, the reasons for delisting or reclassifying a species include: “(1) the species is extinct, (2) the species does not meet the definition of an endangered or a threatened species, and (3) the listed entity does not meet the definition of a species.”³⁸

Fourth, the rule proposes to change the criteria for designating critical habitat. The proposed rule’s designations prioritize areas that are occupied by a species over unoccupied areas.³⁹ The proposed rule provides additional ways in which the Secretary may determine that a critical habitat designation would not be prudent.⁴⁰ These situations, which are enumerated in the proposed rule, include areas that provide negligible conservation value, areas that present or threaten destruction, modification, or curtailment of a species, and more.⁴¹

Conclusion

Before the comment period closed on December 22, 2025, FWS and NOAA received more than 300,000 comments on each of the four proposed rules. The agencies must now consider and respond to the substance of these comments, before they publish final rules. To follow the rulemaking process, visit regulations.gov and enter the following docket numbers: Repeal of the Blanket Rule (Docket No. FWS-HQ-ES-2025-0044); Revisions to the Process for Excluding Critical Habitat (Docket No. FWS-HQ-ES-2025-0048); Revisions to the Process for Interagency Cooperation (Docket No. FWS-HQ-ES-2025-0044); Revisions to the Criteria for Listing, Delisting, and Reclassifying Species (Docket No. FWS-HQ-ES-2025-0039).

¹The authors would like to recognize Gabriel Murillo for his assistance with the preparation of this article.
²See generally 90 Fed. Reg. 52,587 (repeal of the Blanket Rule option for threatened species) (Nov. 21, 2025); 90 Fed. Reg. 52,592 (revisions to the considerations for excluding areas from critical habitat) (Nov. 21, 2025); 90 Fed. Reg. 52,600 (revisions to the interagency cooperation regulations) (Nov. 21, 2025); 90 Fed. Reg. 52,607 (revisions to the procedures and criteria for listing, reclassifying, and delisting species on the Lists of Endangered and Threatened Wildlife and Plants and designating critical habitat) (Nov. 21, 2025).
³E.g., 90 Fed. Reg. 52,607, 52,608.
⁴See generally 90 Fed. Reg. 52,587.
⁵50 C.F.R. §§ 17.31, 17.71 (2024).
⁶90 Fed. Reg. 52,587 (second Trump Administration, proposed repeal of the Blanket Rule); 84 Fed. Reg. 44,753 (Aug. 27, 2019) (first Trump Administration, repeal of the Blanket Rule); see 89 Fed. Reg. 23,919 (Apr. 5, 2024) (Biden Administration, reinstatement of the Blanket Rule).
⁷90 Fed. Reg. at 52,588-89.
⁸Id. at 52,589.
⁹Id.
¹⁰FWS, Species with 4d Rules, Environmental Conservation Online System, (last visited March 22, 2026) https://ecos.fws.gov/ecp/report/species-fourd.
¹¹See generally 90 Fed. Reg. 52,592.
¹²16 U.S.C. § 1533(b)(2) (2022).
¹³90 Fed. Reg. 52,592, 52,594 (to be codified at 50 C.F.R. § 17.90(a)).
¹⁴Id. at 52,595 (to be codified at 50 C.F.R. § 17.90(c)).
¹⁵Id.
¹⁶Id. at 52,599 (to be codified at 50 C.F.R. § 17.90(d)(2)).
¹⁷Id. (to be codified at 50 C.F.R. § 17.90(a)).
¹⁸Id.
¹⁹Id.
²⁰Id. (to be codified at 50 C.F.R. § 17.90(d)(3)-(4)).
²¹Id. at 52,596.
²²See generally 90 Fed. Reg. 52,600.
²³16 U.S.C. § 1536(a)(2) (1988).
²⁴90 Fed. Reg. at 52,606 (to be codified at 50 C.F.R. § 402.02 (effects of the action)).
²⁵50 C.F.R. § 402.07 (1986) (designation of lead agency); 50 C.F.R.
§ 402.14 (2024) (formal consultation process).
²⁶Ctr. for Biological Diversity v. U.S. Dep’t of the Interior, No. 24-cv-04651-JST, at *1, 417 (N.D. Cal. Mar. 30, 2026) (available at https://biologicaldiversity.org/programs/biodiversity/pdfs/62_Order-on-Cross-MSJs-and-Motion-for-Stay-on-Remand-3.30.26.pdf).
²⁷Id. at *41 (reinstating the previous definition of “effects of the action,” found at 50 C.F.R. § 402.02 (2018)).
²⁸Id. at 52,607 (to be codified at 50 C.F.R. § 402.17(a)).
²⁹Id.
³⁰Id. at 52,606 (to be codified at 50 C.F.R. § 402.02 (environmental baseline)); 50 C.F.R. § 402.14 (formal consultation process).
³¹Id.
³²Id. (to be codified at 50 C.F.R. § 402.02 (reasonable and prudent measures)); 50 C.F.R. § 402.14 (formal consultation process).
³³See generally 90 Fed. Reg. 52,607.
³⁴Id. at 52,609 (to be codified at 50 C.F.R. § 424.11(b)).
³⁵50 C.F.R. § 424.11(b) (2024) (a listing determination must be made “without reference to possible economic or other impacts”).
³⁶84 Fed. Reg. 45,020 (Aug. 27, 2019); 89 Fed. Reg. 24,300 (Apr. 5, 2024) (“The foreseeable future extends as far into the future as [FWS and NOAA] can make reasonable reliable predictions about the threats to the species and species’ responses to those threats.”).
³⁷90 Fed. Reg. at 52,614 (to be codified at 50 C.F.R. § 424.11(d)).
³⁸Id. at 52,610.
³⁹Id. at 52,612, 52,615 (to be codified at 50 C.F.R. § 424.12(b)(2)).
⁴⁰Id.
⁴¹Id.

Lauren Thomson is a Principal in the Firm’s Water, Compliance and Enforcement, and Litigation Practice Groups. Emily Moyes is an Associate in the Firm’s Water and Compliance and Enforcement Practice Groups. If you would like additional information or have questions related to these or other matters, please contact Lauren at 512.322.5858 or lthomson@lglawfirm.com, or Emily at 512.322.5841 or emoyes@lglawfirm.com.