Endangered Species Litigation and Associated Pesticide Limitations

Among other things, the Endangered Species Act (ESA) requires federal agencies to ensure that actions taken or permitted by the federal government will not jeopardize the continued existence of a listed species or result in adverse modification of its designed critical habitat.

The ESA also includes provisions that allow the public to bring suit in court against a federal agency when they believe a  listed species is not being adequately protected (called citizen suit provisions). Such suits maybe forced on a federal agency's action that invokes the obligations under ESA.

EPA has been subject to several lawsuits claiming that the Agency has failed to meet its ESA obligations. EPA has settled many of these lawsuits, resulting in the Agency agreeing to conduct scientific assessments and makes effects determinations for  numerous pesticides, including the effects of products containing any of:

  • 54 pesticide active ingredients to 26 species of listed salmon and steelhead.
  • 66 pesticide active ingredients to the California red-legged frog.
  • 59 pesticide active ingredients to 11 species in the greater San Francisco Bay area.

In order to assist the public in understanding certain other measures the courts have put in place, EPA developed interactive maps that depict certain court-ordered buffer areas, or no-use areas, around certain water bodies:

In addition to the assessments above, EPA has also examined the potential risks a pesticide may pose to a listed species and any designated critical habitat for the species. The conclusion is an "effects determination," also called a "biological evaluation" (BE). Some BEs have been completed as part of litigation, while others are pending. View these assessments and related documents.

EPA has completed nationwide assessments (BEs) for the following pesticides under the registration review program:

  • Chlorpyrifos.
  • Malathion.
  • Diazinon.
  • Carbaryl.
  • Methomyl.

In separate litigation, the National Marine Fisheries Service (NMFS) agreed to complete final biological opinions for chlorpyrifos, malathion and diazinon by December 2017 and for carbaryl and methomyl by December 2018. In 2017, NMFS issued a final biological opinion for chlorpyrifos, malathion and diazinon. In 2019, EPA requested to reinitiate formal consultation on these pesticide products to consider new information that was not available when NMFS issued its final biological opinion. In March 2022, as a result of EPA’s reinitiated consultation, NMFS completed a draft revised biological opinion for chlorpyrifos, malathion, and diazinon, took public comment on the draft, and finalized the biological opinion.

The biological opinion can be found at:

Biological Opinion for Pesticides: Chlorpyrifos, Diazinon, and Malathion

EPA and the Center for Biological Diversity have also agreed to an additional partial settlement agreement where EPA agreed to complete nationwide effects determinations on the following four pesticides:

  • Atrazine.
  • Simazine.
  • Propazine.
  • Glyphosate.

The agreement included schedules for completion of determinations and initiation of consultation for the four pesticides by 2020. EPA finalized biological evaluations, which include effects determinations, and initiated consultation for atrazine, simazine, and glyphosate in November 2021. Since the settlement agreement was approved by the Court, all propazine registrations in the United States have been terminated. See the announcement for more information.

Under a court-ordered settlement agreement in other litigation, EPA will complete BEs for flupyradifurone and bicyclopyrone by September 30, 2025, and benzovindiflupyr and halauxifen-methyl by September 30, 2027.

The registrants for these four pesticides, who are parties to this settlement, agreed to create a website with more information about certain listed species and the use of these four pesticides, available here [EXIT EPA]. 

Read the complete settlement agreement and other relevant information for Center for Biological Diversity, et al. v. EPA (D.C. Cir. Nos. 15-1054, 15-1176, 15-1389, 15-1462 and 16-1351):

For all of these nationwide effects determinations, EPA has used and built on the interim scientific approaches that were developed based on the April 2013 National Academy of Sciences (NAS) report recommendations.

Read information on the NAS report and EPA's implementation of it: 

Consistent with EPA's desire to conduct the business of the public in an open and transparent manner, the Agency makes available information on each lawsuit, orders issues by the courts, assessments and effects determinations made consistent with the outcome of litigation, and other relevant information. As future actions are taken, that information will be posted as well.

Information on Litigation Cases

Completed Cases Involving Only Effects Determinations

  • Natural Resources Defense Council (NRDC) v. EPA (effects of atrazine on 21 species)  Search EPA Archive 
  • Center for Biological Diversity (CBD) and Save Our Springs Alliance (SOSA) v. EPA (Case No: 1:04-Cv-00126-Ckk, 2004) (Barton Springs salamander)  Search EPA Archive
  • Californians for Alternatives to Toxics (CATs) v. EPA (Case No. C00-3150-CW, 2002) (effects of 18 pesticides on certain listed forest plants and salmonids) Search EPA Archive

Endangered Species

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Last updated on March 18, 2025