Endangered Species Act

The Endangered Species Act of 1973 (ESA) is considered the most powerful environmental law in the United States — and one of the most controversial. Its core prohibition: it is illegal to "take" (harm, harass, pursue, hunt, shoot, wound, trap, or capture) a listed endangered species, or to authorize, fund, or carry out any federal action that would "jeopardize the continued existence" of a listed species or destroy its "critical habitat." These prohibitions apply not just to the federal government but to private landowners — making the ESA's reach into private property one of its most politically contested features. The U.S. Fish and Wildlife Service (for land/freshwater species) and NOAA Fisheries (for marine species) administer about 1,680 listed U.S. species and process over 75,000 formal and informal Section 7 consultations per year with other federal agencies on projects that might affect listed species. The ESA has prevented the extinction of dozens of species including the bald eagle, gray wolf, and grizzly bear; critics argue it imposes heavy economic costs on development, agriculture, and energy projects with unclear conservation benefits for already-imperiled species. Delisting and critical habitat decisions are a permanent flashpoint between conservation groups and industry.

Current Law (2026)

Legal Authority

• 16 U.S.C. § 1531 — Congressional findings and purposes (various species rendered extinct by economic growth; others in danger of extinction; purpose to conserve ecosystems upon which endangered and threatened species depend; policy to cooperate with states and foreign nations)
• 16 U.S.C. § 1532 — Definitions (endangered species: in danger of extinction throughout all or a significant portion of its range; threatened species: likely to become endangered within the foreseeable future; take: harass, harm, pursue, hunt, shoot, wound, kill, trap, capture, or collect; critical habitat: geographic areas essential for conservation)
• 16 U.S.C. § 1533 — Listing determinations (Secretary determines species status based solely on the best available scientific and commercial data; five listing factors: habitat destruction, overutilization, disease/predation, inadequacy of existing protections, other natural/manmade factors; 12-month finding and proposed rule; public comment; critical habitat designation required "to the maximum extent prudent and determinable")
• 16 U.S.C. § 1536 — Section 7 — Interagency cooperation (all federal agencies must ensure their actions are not likely to jeopardize the continued existence of listed species or destroy/adversely modify critical habitat; formal consultation with FWS/NMFS required; biological opinions; reasonable and prudent alternatives; incidental take statements; exemption process via "God Squad")
• 16 U.S.C. § 1538 — Section 9 — Prohibited acts (unlawful to import, export, take, possess, sell, or transport endangered species; "take" includes significant habitat modification that harms listed species; applies to all persons subject to U.S. jurisdiction; threatened species protections set by regulation)
• 16 U.S.C. § 1539 — Exceptions and Habitat Conservation Plans (Section 10 permits for incidental take by non-federal actors through Habitat Conservation Plans; scientific/enhancement permits; Safe Harbor Agreements for conservation actions on private land)
• 16 U.S.C. § 1540 — Penalties and enforcement (2026 inflation-adjusted civil penalties: up to $65,656 per knowing violation involving an endangered species, $31,441 for other knowing violations; criminal penalties for knowing violations up to $50,000 and 1 year imprisonment; citizen suits authorized)
• 16 U.S.C. § 1535 — Cooperation with states (cooperative agreements for conservation; federal funding; state permits)

Implementing Regulations (50 CFR)

• 50 CFR Part 17 — Endangered and threatened wildlife and plants (FWS):

  • § 17.11–17.12 — Lists of endangered and threatened wildlife and plants — the official designation list; species status, range, and critical habitat references
  • § 17.21–17.31 — Prohibitions: "take" prohibition for endangered species (§ 17.21); 4(d) rules specifying protections for threatened species that can be tailored to conservation needs (§ 17.31-17.32)
  • § 17.22–17.32 — Permits: incidental take permits (§ 17.22(b)) through Habitat Conservation Plans; scientific/enhancement permits; Safe Harbor Agreements
  • § 17.94–17.96 — Critical habitat designations — specific areas essential for conservation, mapped by geographic coordinates

• 50 CFR Part 402 — Interagency Cooperation — Endangered Species Act Section 7 (30 sections — the FWS/NMFS implementing regulations for ESA § 7, which requires all federal agencies to ensure their actions are not likely to jeopardize listed species or adversely modify critical habitat; 75,000+ consultations per year make this one of the most frequently used environmental regulations in the federal government):

  • § 402.02 — Key definitions: "action area" means all areas to be affected directly or indirectly by the federal action and not merely the immediate area of the proposed action (e.g., a dam's action area includes the entire impounded reservoir and downstream reaches, not just the dam site); "effects of the action" means all consequences to listed species or critical habitat that are caused by the proposed action, including consequences caused by interrelated or interdependent activities; "jeopardize the continued existence" means to engage in action that reduces appreciably the likelihood of both survival and recovery of a listed species in the wild by reducing its reproduction, numbers, or distribution
  • § 402.03 — Applicability: Section 7 applies to all federal actions — including federal funding, permits, licenses, and authorizations; state and private actions that require any federal nexus (including permits, grants, or loans) trigger Section 7; the breadth of "federal action" means that virtually any project involving federal money, a federal permit (Clean Water Act § 404, FERC hydropower license, federal land use permit), or a federal agency decision is subject to Section 7 consultation
  • § 402.05 — Emergency consultation: where emergency circumstances require expedited action with significant potential effects on listed species, the Federal agency and FWS/NMFS may use a streamlined emergency consultation process; often used for post-disaster response (levee repairs after floods, fire suppression operations); emergency authorization may allow activities to proceed before formal consultation is complete, with post-emergency consultation following within 30 days
  • § 402.09 — Irreversible or irretrievable commitment of resources: after initiation of consultation, a federal agency may NOT make any irreversible or irretrievable commitment of resources that would foreclose the formulation or implementation of reasonable and prudent alternatives (RPAs) designed to avoid jeopardizing listed species; this is the most powerful interim protection in the consultation process — an agency cannot fully fund, permit, or construct a project while consultation is pending
  • § 402.12 — Biological assessments (BA): required before any federal action that the agency has determined "may affect" listed species, and mandatory for "major construction activities" (broadly interpreted); the action agency prepares the BA evaluating potential effects; FWS/NMFS may review and comment; the BA's conclusions (likely to adversely affect, may affect/not likely to adversely affect, or no effect) determine the consultation pathway; BA conclusions that an action is "not likely to adversely affect" can be confirmed by FWS/NMFS in a concurrence letter, allowing the project to proceed without formal consultation
  • § 402.13 — Informal consultation: used when the action agency believes its action "may affect but is not likely to adversely affect" listed species; FWS/NMFS reviews the BA and issues a written concurrence (or requests formal consultation); informal consultation ends when FWS/NMFS concurs in writing; most Section 7 consultations are informal — the "not likely to adversely affect" standard is the most commonly used exit ramp
  • § 402.14 — Formal consultation: initiated when a federal action "may affect" and is "likely to adversely affect" a listed species or critical habitat; FWS/NMFS has 90 days from initiation to complete the biological opinion (BiOp), with a 45-day extension on request (total maximum 135 days); the BiOp must include: (1) the status of the species and critical habitat; (2) the environmental baseline; (3) the effects of the action; (4) the cumulative effects; (5) a jeopardy/no-jeopardy determination; if jeopardy, FWS/NMFS must include reasonable and prudent alternatives (RPAs) — alternative actions the agency could take to avoid jeopardy; if no-jeopardy with incidental take, FWS/NMFS includes an Incidental Take Statement (ITS) specifying the amount of incidental take authorized and the reasonable and prudent measures to minimize take
  • § 402.16 — Reinitiation of consultation: required when new information reveals effects not previously considered, additional listing of species occurs, critical habitat is designated that may be affected, or the take authorized in the ITS is exceeded; reinitiation requirements mean that Section 7 compliance is ongoing, not a one-time event — agencies must monitor whether the conditions of their ITS are being exceeded and reinitiate if so; the reinitiation obligation is a significant ongoing compliance requirement for agencies with long-term operations (dam operations, ongoing forest management activities, maintained infrastructure)

  The Section 7 process is the primary mechanism for integrating ESA protections into federal decision-making. The 135-day statutory timeline is frequently exceeded in practice — complex projects can take years of extended consultation; agency-to-agency disputes (the "God Squad" provision allows a Cabinet-level committee to exempt a project from ESA requirements) are rare but exist. The Biden administration's 2019 and 2024 Part 402 rule amendments revised the definition of "effects of the action" and "destruction or adverse modification" following decades of litigation over whether future climate change effects must be included in Section 7 analyses. Recent rulemakings: 84 FR 45016 (August 2019) — definitional revisions; 74 FR 20423 (April 2009) — withdrawal of Bush-era rule amendments.

• 50 CFR Part 424 — Listing of Endangered and Threatened Wildlife and Plants: the FWS/NMFS joint implementing regulations for ESA Section 4's listing and delisting procedures — the gateway through which species enter or exit ESA protection:

  • § 424.11 — Criteria for listing, delisting, and reclassification: a species may be listed if it is threatened or endangered due to any one or more of five statutory factors: (1) present or threatened destruction, modification, or curtailment of habitat or range — the most commonly cited listing factor; habitat loss accounts for the primary threat for roughly 85% of listed species; (2) overutilization for commercial, recreational, scientific, or educational purposes — commercial hunting, collecting, and trade; CITES-regulated commercial take falls here; (3) disease or predation — invasive species are a leading driver under this factor; chytrid fungus driving amphibian extinctions worldwide, avian malaria in Hawaiian birds; (4) inadequacy of existing regulatory mechanisms — the adequacy of existing federal and state law protection; if state law already protects the species, this factor weighs against listing; the adequacy analysis does NOT require proof that existing regulation has failed; (5) other natural or manmade factors affecting its continued existence — catch-all covering climate change, sea level rise, stochastic events for small populations, genetic isolation; climate change is increasingly invoked as a co-factor in listings; a single factor is sufficient — many species are listed primarily on habitat destruction alone
  • § 424.14 — Petitions to list, delist, or reclassify: any person may petition FWS or NMFS to add, remove, or reclassify a species; the petition must contain substantial scientific or commercial information indicating that listing may be warranted; FWS/NMFS must make a 90-day finding on whether the petition presents substantial information warranting a full review; if the 90-day finding is positive ("may be warranted"), FWS/NMFS conducts a status review and must issue a 12-month finding — either "warranted" (begin proposed listing), "not warranted," or "warranted but precluded" (listing is warranted but other listing actions have priority); the "warranted but precluded" finding places the species on the candidate list, where it awaits eventual listing when capacity allows; FWS's candidate list has historically contained 100–200 species; listing based on agency initiative (without a petition) is also authorized
  • § 424.17 — Critical habitat designation: when a species is listed, FWS/NMFS must designate critical habitat concurrently with the listing (or within one year if critical habitat is not then determinable); critical habitat consists of specific areas within the geographic area occupied by the species with features (physical or biological) essential to conservation, plus unoccupied areas when essential for conservation; the Secretary must consider the economic impact, national security impact, and other relevant impacts of designation and may exclude any area from critical habitat if the benefits of exclusion outweigh the benefits of designation — unless exclusion would cause extinction; the economic analysis under § 4(b)(2) looks at costs to federal agencies, private landowners, and project proponents that would result from additional Section 7 consultation requirements; exclusions based on economic impact have been used to remove development areas, military installations, and tribal lands from critical habitat designations; the economic analysis must be completed before the final rule — procedural challenge to incomplete economic analyses is a common litigation tool against critical habitat designations
  • § 424.20 — Emergency listings: if FWS/NMFS determines that an emergency poses a significant risk to the well-being of a species, it may publish emergency listing regulations that take effect immediately, without the standard proposed-rule notice-and-comment period; emergency listings are effective for 240 days and must be followed by a standard proposed rulemaking to make the listing permanent; emergency listings are rare — used when a population crash is discovered mid-cycle (disease outbreaks, sudden habitat destruction), not for slow-moving threats; during the 240-day emergency period, full ESA Section 7 and Section 9 protections apply

  The listing process is the most litigated area of the ESA. Major points of attack: (1) whether the five-factor analysis used the "best available science"; (2) whether the 90-day/12-month petition deadlines were met (FWS has been under multiple consent decrees for late findings); (3) whether the economic analysis for critical habitat designation was adequate; (4) whether the exclusion decision (§ 4(b)(2)) was arbitrary and capricious. The ESA's Section 4 listing timeline has never matched the agency's workload — the candidate list and petition backlogs reflect structural underfunding. Recent rulemakings: 84 FR 45020 (August 2019) — Trump administration revised the definition of "foreseeable future" for threatened species determinations; 88 FR 58982 (August 2023) — Biden administration restored "blanket 4(d) rule" automatic protections for threatened species that Trump had removed.

• 50 CFR Part 226 — NMFS Designated Critical Habitat (32 sections — NOAA Fisheries' (NMFS) specific critical habitat designations for marine and anadromous species under its jurisdiction; FWS uses 50 CFR Part 17 for its critical habitat designations while NMFS uses Part 226 for its separate list; together Parts 17 and 226 constitute the complete federal critical habitat registry):

  • § 226.201 — Hawaiian monk seal critical habitat: the near-extinct Hawaiian monk seal (fewer than 1,500 individuals remaining) has critical habitat designated around the Northwestern Hawaiian Islands and the main Hawaiian Islands; the designation protects feeding areas, resting beaches, and pupping habitat; Hawaiian monk seals are among the most endangered marine mammals in the United States and face pressures from human disturbance, prey depletion, and climate change
  • § 226.202 — Steller sea lion critical habitat: three major marine areas off Alaska designated (Gulf of Alaska, Bering Sea, Aleutian Islands) protecting critical foraging, breeding, and resting areas; Steller sea lion critical habitat overlaps with major commercial fisheries, making Section 7 consultations for fishing authorizations particularly complex
  • § 226.203 — North Atlantic right whale critical habitat: critical habitat designated in two areas — Cape Cod Bay (Massachusetts) as a feeding/nursery area and the southeast U.S. Atlantic coast (Georgia/Florida) as calving/nursing habitat; with fewer than 350 individuals remaining, North Atlantic right whale critical habitat designations have generated major conflicts with fishing (entanglement in lobster/crab gear) and vessel traffic (ship strikes)
  • §§ 226.204–226.209 — Pacific salmon and steelhead critical habitat: large sections of Pacific coast rivers and associated marine areas designated as critical habitat for Sacramento winter-run chinook salmon, Snake River species (sockeye, fall chinook, spring/summer chinook), Snake River steelhead, and several other ESA-listed salmon and steelhead runs; Pacific salmon critical habitat designations have been the basis for major dam relicensing controversies (Klamath River dams removed 2023-2024) and for water operation constraints on Bureau of Reclamation and Army Corps projects in the Columbia River basin
  • § 226.206 — Southern Resident killer whale critical habitat: Puget Sound, Strait of Juan de Fuca, and parts of the Pacific coast designated as critical habitat for the 73-individual Southern Resident orca population; critical habitat designation has affected port expansion projects, vessel speed limits, and fish stocking decisions in the Pacific Northwest

  NMFS critical habitat designations under Part 226 are legally binding — federal agencies must consult with NMFS before taking any action that may "destroy or adversely modify" the designated habitat; the adverse modification standard is separate from the "jeopardy" standard for the species itself, meaning an action can be prohibited under the critical habitat provision even if it wouldn't jeopardize the species overall; critical habitat has been the basis for some of the most contentious ESA litigation, including Gifford Pinchot Task Force v. USFWS establishing that critical habitat must provide "appreciable value" to conservation beyond what is provided by species protections. Recent rulemakings: 90 FR 38003 (2025) — updates to right whale critical habitat; 64 FR 14067 (1999) — Pacific salmonid critical habitat designation (foundational rule).

• 50 CFR Part 23 — Convention on International Trade in Endangered Species (CITES): FWS regulations implementing the 1973 Washington Convention, which regulates the international trade in listed species to prevent over-exploitation. CITES operates through a three-tier Appendix system that determines what documents are required for trade:

  • Appendix I — species threatened with extinction; commercial trade generally prohibited; export requires a permit from the exporting country AND an import permit from the importing country, both finding that trade will not be detrimental to the species and that the shipment is for non-commercial purposes (research, captive breeding, education); live animals must be prepared and shipped to minimize risk of injury, damage to health, or cruel treatment
  • Appendix II — species not yet threatened but could become so without trade controls; commercial trade is allowed but requires an export permit (or re-export certificate) from the exporting country, based on a "non-detriment finding" — the scientific authority of the exporting country must certify that export will not be detrimental to the survival of the species in the wild; no import permit required from the receiving country (though the U.S. requires its own import declaration)
  • Appendix III — species protected by at least one country that has asked other CITES Parties for assistance; requires an export certificate from the country that listed the species, or a certificate of origin from other countries
  • § 23.13 — Core prohibitions: it is unlawful for any U.S. person to import, export, re-export, or trade in any CITES-listed species without the required CITES documents; the prohibition covers whole specimens, parts, and derivatives (a carved elephant tusk, a leather handbag made from a CITES-listed python, or a cactus nursery pot from a wild-collected plant all fall within the prohibition); ESA enforcement (seizure, forfeiture, civil and criminal penalties) applies to CITES violations
  • § 23.15 — Personal effects and tourist souvenirs exemption: travelers may bring CITES-listed specimens as personal effects if: (a) the specimens were legally acquired; (b) the quantity is consistent with personal use (not commercial); and (c) the species is not subject to stricter national measures; critically: the personal effects exemption does NOT apply to Appendix I specimens imported into the U.S. — bringing back worked ivory, a macaw parrot, a live coral, or a monkey from abroad without CITES documents subjects the traveler to seizure and criminal prosecution even if the purchase was legal in the country of origin
  • § 23.20 — Document decision matrix: the specific CITES documents required (export permit, import permit, re-export certificate, certificate of origin, or CITES exemption document) depend on the Appendix level, the type of specimen (live animal, plant, dead animal, manufactured product), and the country of export; FWS publishes guidance on which documents are accepted at U.S. ports

  Practical scope: CITES covers over 38,000 species of animals and plants. Common enforcement situations: ivory (all commercial trade in elephant ivory banned unless pre-1976 "antique" with documentation); live parrots and exotic birds (CITES II or I); live reptiles and reptile skin products (many species CITES-listed); orchids (many species Appendix II, nursery-propagated exempt with phytosanitary certificate); cacti and succulents (wild-collected Appendix II; nursery-propagated generally exempt); coral (Appendix II; live coral and coral specimens require permits); shark fins (several species CITES-listed); tigers and big cat products (Appendix I). The U.S. has stricter-than-CITES rules for several species under the ESA.

• 50 CFR Part 453 — Endangered Species Committee Procedures: the regulations governing the "God Squad" — the seven-member Cabinet-level committee that can grant exemptions from ESA § 7(a)(2) (the jeopardy prohibition) when a federal project's benefits clearly outweigh the alternative of conserving the species. The Committee is composed of: the Secretary of Agriculture, the Secretary of the Army, the Chairman of the Council of Economic Advisers, the Administrator of EPA, the Secretary of the Interior (who chairs), the Administrator of NOAA, and one representative of each affected state (collectively casting one vote). Key provisions:

  • § 453.03 — Grant standard: the Committee may grant an exemption only if at least five of seven members concur, after finding on the record that: (1) there are no reasonable and prudent alternatives to the proposed action; (2) the benefits of the action clearly outweigh the benefits of alternative courses consistent with conservation; (3) the action is of regional or national significance; and (4) neither the federal agency nor the exemption applicant made any irreversible or irretrievable commitment of resources prohibited during consultation; even when granted, exemptions must include mitigation and enhancement measures (live propagation, transplantation, habitat acquisition) as conditions
  • § 453.04 — Information gathering: the Committee Chairman (Secretary of Interior) may invite public written submissions or hold public hearings when the Chairman or any four members determine such information is necessary; all hearings are open to the public; subpoenas may be issued for witnesses and documents under § 453.06
  • § 453.05 — Voting mechanics: five members constitute a quorum; only full members may vote (not their representatives); state members collectively share one vote, which they determine among themselves; all meetings and records are open to the public; the Chairman must publish Federal Register notice of all meetings, ordinarily at least 15 days in advance; the Committee must issue its final determination within 30 days of receiving the Secretary's report and record
  • § 453.06 — Additional powers: the Committee may subpoena witnesses and records, issue its own rules and orders, and delegate information-gathering authority to any member; these powers make the God Squad proceedings quasi-adjudicative

  The Endangered Species Committee has been invoked fewer than ten times since its 1978 creation. The most famous use was the 1992 exemption application for Bureau of Land Management timber sales in the Pacific Northwest — the "Spotted Owl War" — in which the Committee rejected the application despite intense political pressure. The Committee was also invoked during the 2001 Klamath River drought to examine dam operations affecting coho salmon, and has been considered during conflicts between western water projects and listed fish species. The combination of the five-vote supermajority requirement, the four-factor test, and the mandatory mitigation conditions make exemptions genuinely rare; the God Squad is primarily a political safety valve ensuring that the ESA cannot be used to block projects of overwhelming national significance, not a routine relief mechanism.

• 50 CFR Part 224 — Endangered Marine and Anadromous Species (NMFS): NOAA Fisheries' (NMFS) implementing regulations for ESA Section 9 take prohibitions and Section 10 permit requirements for marine and anadromous species under Commerce Department jurisdiction — most importantly whales, sea turtles, salmon, and other listed marine species. Part 224 is the operational counterpart to FWS's Part 17 for marine species. Key provisions:

  • § 224.101 — Enumeration: identifies the endangered marine and anadromous species under NMFS jurisdiction — including whales (North Atlantic right whale, blue whale, fin whale, humpback whale), sea turtles (leatherback, Kemp's ridley, hawksbill, green, loggerhead), and anadromous fish (certain Pacific salmon and steelhead Evolutionarily Significant Units); listing in this section triggers the full ESA § 9 take prohibitions for each named species
  • § 224.102 — Permit requirement: no person may take, import, export, or possess any endangered marine species listed in § 224.101 without an NMFS-issued ESA § 10(a)(1)(A) scientific permit or an incidental take permit; commercial fisheries may obtain incidental take authorizations through ESA § 7 consultation for activities regulated under fishery management plans
  • § 224.103 — Special prohibitions for endangered marine mammals, including approach restrictions for endangered humpback whales in Alaska: vessels and persons may not approach within specified distances of humpback whales in designated Alaska waters; the approach prohibition is designed to prevent harassment take — even non-injurious vessel approaches can constitute "harassment" under the MMPA and ESA when they disrupt feeding or social behavior
  • § 224.104 — Sea turtle protection requirements for shrimp fisheries: shrimp trawl vessels in the southeastern United States and Gulf of America must use Turtle Excluder Devices (TEDs) — mechanical devices installed in trawl nets that allow sea turtles to escape before drowning; TED requirements are among the most significant ongoing incidental take mitigation measures for any listed species; compliance is monitored by NOAA enforcement officers and coast guard inspections
  • § 224.105 — Speed restrictions to protect North Atlantic Right Whales (NARWs): vessels 65 feet (19.8 m) or longer must not exceed 10 knots in designated Seasonal Management Areas (SMAs) along the U.S. East Coast during periods when right whales aggregate for calving and feeding; SMAs are active from November through April in different geographic zones; the speed rule is one of the most contested endangered species measures — challenged by commercial shipping and fishing industries — because NARWs number approximately 350-360 individuals, making vessel strikes one of the primary threats to the species' survival

  Part 224's North Atlantic Right Whale speed regulations represent the front line of ongoing ESA litigation. Environmental groups sought to strengthen the restrictions — broadening the geographic scope and extending the seasonal duration — while the maritime industry challenged whether vessel speed restrictions are within NMFS's ESA authority. NMFS published a revised speed rule in 2024 expanding the restrictions; the revised rule was stayed by courts in 2024-2025 following industry legal challenges. With only ~350 right whales surviving, each vessel strike or entanglement is biologically significant at the population level. No rulemakings pending in the absence of a final binding speed rule — the litigation-stayed 2024 rule and the pre-2024 baseline rule are both subject to ongoing proceedings.

• 50 CFR Part 222 — General Endangered and Threatened Marine Species (26 sections across 5 subparts — the NMFS framework regulations governing permit procedures, pre-Act certificates of exemption, experimental population designations, and observer requirements applicable to all NMFS-administered ESA permits for marine and anadromous species; authority: 16 U.S.C. §§ 1361, 1531; the administrative backbone behind Parts 223 and 224's specific take prohibitions and exemptions):

  • Subpart C — General Permit Procedures (§§ 222.301–222.312): the procedural rules governing all NMFS ESA permits — scientific research permits (ESA § 10(a)(1)(A)), incidental take permits (§ 10(a)(1)(B)), captive propagation permits, and enhancement permits; any permit authorizing take of marine ESA species must follow these procedures regardless of which specific Part 223 or 224 provision triggers the requirement; key provisions: permits are non-transferable (§ 222.305); permittees must submit activity reports within 90 days of permit expiration; NMFS may modify or revoke a permit if the permittee violates any condition or if new information shows the permitted activity is jeopardizing the species (§ 222.306); no permit takes effect until any applicable ESA § 7 interagency consultation is complete (§ 222.307)
  • Subpart E — Experimental Populations (§§ 222.501–222.504): the regulatory framework NMFS uses when reintroducing endangered or threatened marine species into historical habitat outside their current range as "experimental populations"; the designation is authorized by ESA § 10(j) and provides important flexibility: an experimental population may be classified as either essential (treated as endangered — full ESA protections apply) or non-essential (treated as threatened — section 7 obligations are narrowed; take is permitted if it does not appreciably reduce the likelihood of survival; jeopardy consultations apply only in National Park System and National Wildlife Refuge lands); the non-essential classification has made the Pacific salmon and Pacific lamprey reintroduction programs politically viable in areas where full endangered-species protections would have blocked water development; to designate an experimental population, NMFS must find (§ 222.502): (1) the species is listed; (2) the reintroduction is within the species' historical range (or a suitable area outside it if recovery requires it); (3) the experimental population is geographically separate from other wild populations of the same species; and (4) the introduction furthers conservation of the species; the designation is accomplished by rulemaking, not permit — each experimental population designation is its own Federal Register rulemaking with specific protective regulations tailored to the population's location and conservation needs

  Part 222's experimental population framework has been used for several significant marine and anadromous species reintroduction efforts, including Pacific salmon reintroductions above dams where fish passages are being constructed as part of dam removal projects. The non-essential designation allows reintroduced fish to interact with private water users and federal operators with less ESA friction than full endangered status would require — a policy choice that has enabled dam removals (including the Elwha River dam removal in Washington) by providing certainty to landowners and water users in the reintroduction area that they won't face new Section 9 take liability from returning populations.

• 50 CFR Part 81 — Conservation of Endangered and Threatened Species — Cooperation with the States (15 sections — FWS regulations implementing ESA Section 6, which authorizes cooperative agreements between FWS and state fish and wildlife agencies that have enacted adequate state endangered species programs; implementing 16 U.S.C. § 1535):

  Section 6 is the ESA's federalism channel: it allows the federal government to share both responsibility and funding with states that have their own conservation programs capable of managing listed species. Key provisions:

  • § 81.2 — Cooperation with the states: the Secretary of the Interior is authorized to enter cooperative agreements with any state whose program for the conservation of fish and wildlife is found to be "adequate and active"; the agreement designates the state as the primary manager of covered listed species within the state's borders, operating under federal backstop oversight; without a cooperative agreement, all ESA functions for listed species in a state remain with FWS, which is more resource-intensive for both the agency and the state
  • § 81.3 — Cooperative Agreement: before entering a cooperative agreement, FWS must determine that the state's program (a) uses professional fish and wildlife management staff, (b) provides for the conservation of resident species of fish and wildlife, (c) imposes penalties for violations at least as strict as ESA Section 11 penalties, (d) provides authority to acquire land or aquatic habitat for conservation, and (e) provides public participation in species and habitat decisions; the adequacy determination is a gateway condition — a state that lacks any of these elements cannot enter a cooperative agreement
  • § 81.4 — Allocation of funds: FWS allocates cooperative agreement funds semi-annually from amounts appropriated under ESA Section 6(i); funds are allocated among cooperating states based on a formula that accounts for total land and water area of each state, the proportion of that area in federal ownership, and the state's spending on its own fish and wildlife conservation programs; the cost-sharing structure requires states to match federal funds at a rate that increases with the federal share — states contributing more of their own resources receive a higher federal match; this formula is designed to reward state investment rather than simply rewarding large states
  • § 81.6 — Project Agreement: after a Cooperative Agreement is in place, FWS and the state execute project-specific agreements for individual conservation actions (surveys, habitat acquisition, captive propagation, research, recovery plan implementation); each project agreement specifies the scope of work, budget, federal and state cost shares, and deliverables; the project agreement is the financial instrument through which Section 6 funds flow to specific on-the-ground conservation activities
  • § 81.12 — Contracts: states may use their own procurement regulations when contracting for project services, provided they comply with applicable federal requirements (OMB Uniform Guidance for grants); this flexibility allows states to work with existing contractor relationships rather than navigating separate federal contracting rules

  The cooperative agreement program is the primary mechanism through which state wildlife agencies fund and staff conservation work for listed species on non-federal lands — which represent the vast majority of habitat for many listed species. FWS alone cannot practically manage recovery efforts for 1,700+ listed species across the country; cooperative agreements extend federal conservation resources through state wildlife agency infrastructure that already has on-the-ground staff, established landowner relationships, and local ecological knowledge. Annually, FWS distributes approximately $70–100 million in Section 6 grants through these cooperative agreements; recipient states typically administer habitat management, captive breeding programs (for fish and mussels especially), survey work to document population trends, and landowner assistance programs — all outside the federal bureaucracy.

• 50 CFR Part 13 — General Permit Procedures: FWS's uniform procedural rules governing all wildlife permits issued under subchapter B — covering applications, issuance, renewal, amendment, suspension, revocation, and general permit conditions. Part 13 is the procedural backbone for ESA Section 10 incidental take permits, Bald Eagle permits, Migratory Bird Treaty Act permits, CITES permits, Marine Mammal Protection Act scientific research permits, and all other FWS wildlife authorizations. It works alongside Part 222's equivalent rules for NMFS. Key provisions:

  • § 13.11 — Application: permits may only be issued to an applicant who has filed a formal written application using the Service's designated forms; no permit is issued in advance of a complete application except by written Director authorization in emergency circumstances (§ 13.4)
  • § 13.22 — Renewal: renewal applications must be filed at least 30 days before the permit expires; the applicant must certify that all information in the original application remains accurate, or provide updated information; FWS may renew a permit for the same or a shorter term than originally issued; no renewal extends a permit that has already expired — a lapsed permit requires a new application
  • § 13.27 — Suspension: FWS may suspend a permit if the permittee is not in compliance with permit conditions or applicable laws governing the permitted activity; suspension does not require the permittee to surrender the permit — it is a temporary pause that allows the permittee to demonstrate compliance before revocation is ordered
  • § 13.28 — Revocation: FWS may revoke a permit for (a) willful violation of any federal, state, or tribal wildlife law; (b) false statements in the permit application; (c) changed circumstances making the permitted activity no longer appropriate; or (d) failure to pay assessed civil penalties or criminal fines; revocation requires the permittee to immediately surrender the permit document (§ 13.49)
  • § 13.29 — Review: any person denied a permit or whose permit has been suspended or revoked may request reconsideration within the time specified in the denial notice; the initial decision is made by the FWS Regional Director; the Regional Director's decision may be further appealed to the FWS Director; the Director's decision is the final agency action, after which the applicant may seek federal court review
  • §§ 13.41–13.50 — Universal permit conditions: every FWS wildlife permit carries mandatory conditions regardless of the specific permit type — humane treatment of any live wildlife possessed under the permit (§ 13.41); permit specificity (activities must conform to terms stated on the permit face; § 13.42); permits may not be altered, erased, or mutilated (§ 13.43); permits must be displayed on request to FWS agents or any person relying on the permit's existence (§ 13.44); annual activity reports must be filed by March 31 for activities in the prior calendar year (§ 13.45); complete records of all permitted taking, possession, and trade must be maintained from permit issuance and made available for FWS inspection (§ 13.46–13.47); permittees accept full legal liability for activities conducted under the permit (§ 13.50)

How It Works

The ESA is widely considered the strongest wildlife protection law in the world. It operates through three main mechanisms: listing species, protecting them from "take," and requiring federal agencies to avoid jeopardizing their survival.

Listing under Section 4 is a purely scientific determination: the Fish and Wildlife Service (terrestrial and freshwater species) or NMFS (marine) lists a species as "endangered" (in danger of extinction) or "threatened" (likely to become endangered) based solely on the best available scientific and commercial data — economic factors cannot be considered. The five listing criteria are habitat destruction, overutilization, disease or predation, inadequacy of existing regulatory mechanisms, and other manmade or natural factors. Once listed, the agency must designate "critical habitat" — geographic areas essential for conservation — where economic impacts can be considered. Section 7 imposes the broadest obligations: any federal action (permits, funding, construction, land management) that "may affect" a listed species triggers consultation with FWS or NMFS. Formal consultation produces a Biological Opinion that determines whether the action is likely to "jeopardize" the species or "destroy or adversely modify" critical habitat; if jeopardy is found, the agency must identify reasonable and prudent alternatives. If no jeopardy, an incidental take statement authorizes limited take with mandatory minimization measures. Section 7 affects virtually every major federal permitting decision — dams, highways, timber sales, water management, energy development, military operations.

Section 9 is the ESA's most powerful enforcement mechanism: it is unlawful for any person to "take" an endangered species, and "take" is defined broadly to include harass, harm, pursue, hunt, wound, kill, or collect. Critically, "harm" has been interpreted by regulation to include significant habitat modification that actually injures or kills listed wildlife — meaning private landowners can violate the ESA by destroying habitat on their own property. Threatened species receive protections through "4(d) rules" tailored to their conservation needs. Section 10 provides a release valve: non-federal actors who need to engage in activities that may incidentally take listed species can obtain an Incidental Take Permit through a Habitat Conservation Plan (HCP), committing to minimize and mitigate the take in exchange for a permit. HCPs range from simple single-species plans to massive multi-decade regional plans covering millions of acres. In the rare case where Section 7 consultation results in a jeopardy finding with no reasonable alternatives, a seven-member Endangered Species Committee (the "God Squad," composed of cabinet-level officials) can grant an exemption if the project's benefits clearly outweigh alternatives — an authority invoked only a handful of times in the ESA's history.

How It Affects You

State Variations

Pending Legislation

• S 3503 — Wildlife Road Crossing Program Reauthorization Act of 2025: authorizes $200M annually for wildlife crossings, makes program permanent. Status: Introduced.
• HR 6388 — Conservation Reserve Program Modernization Act: expands eligible land and changes payments to favor conservation buffers and wetlands. Status: Introduced.
• HR 3329 — Wildlife Corridors and USDA Conservation Programs Act: would set up a USDA-led program to map, designate, and conserve American wildlife corridors. Status: Introduced.

Recent Developments

• Ongoing regulatory revisions to ESA implementing regulations, including changes to the "blanket 4(d) rule" for threatened species, critical habitat designation process, and Section 7 consultation procedures
• The Supreme Court's decision in Sackett v. EPA (2023) on wetlands jurisdiction has implications for ESA habitat protections in wetland-dependent species. See NEPA for the environmental review framework that often runs alongside ESA consultation.
• Climate change is increasingly recognized as a listing factor, with species like the polar bear, coral species, and Joshua tree listed or petitioned based on climate impacts
• Conflicts between ESA protections and energy development (wind, solar, oil/gas) continue to intensify, particularly around sage-grouse habitat and desert tortoise in renewable energy zones
• In March 2026, APHIS announced its intention to request a revision and extension of the information collection for Endangered Species Regulations and Forfeiture Procedures under the Paperwork Reduction Act.
• In February 2026, the U.S. Fish and Wildlife Service, in response to a court order, removed the northern and southern distinct population segments of the lesser prairie-chicken from the endangered and threatened species list and initiated a new 12-month petition finding process for the species.
• In February 2026, NMFS completed a 12-month status review of the Washington Coast Chinook salmon ESU in response to a listing petition, evaluating whether the species warrants listing as threatened or endangered.
• In February 2026, NMFS issued a 90-day finding on two petitions to list the Atlantic horseshoe crab under the ESA and designate critical habitat, finding that the petitions presented substantial information warranting a status review.
• The U.S. Fish and Wildlife Service declined to remove grizzly bears from the endangered species list, maintaining federal protections despite state-level petitions for delisting in the Greater Yellowstone and Northern Continental Divide ecosystems.