The federal government recently narrowed the definition of harm as it applies to the Endangered Species Act (ESA), but the effect is so far uncertain for infrastructure and development projects.

The U.S. Fish and Wildlife Service and the National Marine Fisheries Service have adopted a rule rescinding the regulatory definition of “harm” that applies to habitat used by endangered species. Starting in mid-September 2026, harm will be more narrowly defined as an action that directly injures or kills species protected under the ESA.

The controversial decision has triggered legal challenges that could take years to work through the courts. In the meantime, clients need guidance about how the new rule could affect their projects.

Until we learn more about how the rule change will be applied in coming months, we advise a business-as-usual approach during project planning and permitting that considers impacts on species, habitats, and ESA compliance. This approach helps minimize regulatory risk while legal disputes are resolved.

Here is what we know currently:

Existing permitted projects

The new definition of harm applies to projects going forward and does not affect permits issued before the change is scheduled to take effect September 14, 2026.

State wildlife regulations

State endangered species laws and wildlife regulations may continue to impose habitat-related restrictions even if the federal ESA requirements change.

Critical habitat and nesting birds

The federal rule change does not eliminate critical habitat designations or consultation requirements associated with them. Because the rule change does not pertain to the Migratory Bird Treaty Act or Bald and Golden Eagle Protection Act, nesting bird surveys still need to be completed.

Federal agency consultation (Section 7)

Section 7 evaluations of jeopardy, critical habitat analysis and review, habitat conservation plans, and incidental take will continue for projects involving federal permits, funding, or approval (federal nexus). Habitat impacts may be evaluated differently, but the consultation requirements remain.

Private project consultation (Section 10)

Section 10 consultations for land development, renewable energy, logging, railways, utility routing, and other private projects that lack a federal nexus will continue under the new rule. Habitat evaluations for incidental take permits will likely be evaluated based on direct take or mortality of endangered species, rather than modification of habitat.

Habitat conservation plans and conservation agreements will still need to demonstrate avoidance, minimization, and mitigation. Looking ahead, mitigation acreage requirements could be reduced, and loss of forest habitat may carry less weight in take determinations.

Managing risk

Though considerations based on habitat loss alone have shifted, habitat assessment or species-specific surveys remain good options to determine potential risk. Additionally, habitat conservation plans and incidental take permits remain valid options and provide ways to manage risk when take is likely to occur.

The bat example

Under the broader definition of harm, potential impacts tobat habitat often shaped ESA compliance. How might the same scenario change under the new rule?

If a developer planned to clear a large tract of forest, current permitting approaches would likely require habitat assessment, species surveys, tree-clearing restrictions during the active season for bats, an more.

If the new rule is finalized, analysis could focus more on whether protected bats are physically present, whether individual bats could be injured or killed, and whether roost trees actively hosting bats would be removed.

We will continue to monitor the changing regulatory landscape, and we are always available to help with questions.