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EPA Posts Draft Endangered Species Act Biological Opinion for Enlist Herbicide Products for Public Comment

Released on May 24, 2023

Today, the U.S. Environmental Protection Agency (EPA) is posting and seeking public comment on the U.S. Fish and Wildlife Service’s (FWS) draft biological opinion (BiOp) for Enlist products. Enlist One and Enlist Duo are two herbicides used to control weeds in genetically-modified corn, cotton, and soybean crops.

Under the Endangered Species Act (ESA), EPA must ensure that its actions, including pesticide registration actions, do not jeopardize federally threatened and endangered (listed) species, or adversely modify their designated critical habitats. When EPA determines in a biological evaluation (BE) that use of a pesticide product may affect these species or critical habitats, EPA must initiate consultation with FWS, the National Marine Fisheries Service, or both (the Services). In response, the Services may develop a BiOp that determines whether the pesticide is likely to jeopardize listed species or adversely modify their critical habitats and propose Reasonable and Prudent Alternatives and Reasonable and Prudent Measures to avoid jeopardy and minimize incidental take, respectively, of the listed species.

Background on Enlist Products

In January 2022, EPA completed a comprehensive ecological risk assessment for 2,4-D choline salt (2,4-D), an active ingredient in both Enlist products, and glyphosate dimethylammonium salt (glyphosate), an active ingredient in Enlist Duo. EPA also completed a BE for both Enlist products’ potential effects on listed species and their critical habitats, as well as an evaluation of mitigations that are already included on Enlist One and Enlist Duo labels to address listed species concerns. This evaluation was completed as part of EPA’s efforts to meet its obligations under the ESA. EPA determined in its BE that the use of Enlist One and Enlist Duo are “likely to adversely affect” (LAA) some listed species, but predicted that such use will not lead to jeopardy to listed species or to the adverse modification of critical habitats.

An LAA determination means that EPA reasonably expects that at least one individual of any listed species may be exposed to a chemical at a sufficient level to have an adverse effect. This is the case even if a listed species is almost recovered to a point where it may no longer need to be listed. The likely “take,” which includes unintentional harm or death, of even one individual of a species, is enough to trigger such a determination. As a result, there are often a high number of LAA determinations. An LAA determination, however, does not necessarily mean that a pesticide is putting a species in jeopardy.

EPA initiated consultation with FWS upon completion of the BE for Enlist products. During consultation with FWS, EPA provided additional analyses to support the BiOp. The conclusions of the 2022 BE identified 112 listed species and 38 critical habitats as LAA. During consultation, EPA considered additional lines of evidence (e.g., life-history, species distribution, likelihood and magnitude of plant effects, and impacts of required runoff mitigations) resulting in a revised determination that only 22 species and five designated critical habitats remained designated as LAA.

Draft Biological Opinion

The draft BiOp released today is the result of EPA’s consultation with FWS. The document contains preliminary findings from FWS that the use of Enlist products, as specified in the approved product labels, are not likely to jeopardize any listed species or adversely modify their critical habitats.

The draft BiOp describes measures to minimize potential exposure and effects to listed species and also accounts for measures that are included as part of the registration decision that are intended to ensure that Enlist products are not likely to jeopardize listed species or adversely modify critical habitats. It also includes actions EPA must take to minimize incidental take to listed species and critical habitats, such as the development of ESA educational materials, reporting of label compliance monitoring, and inclusion of label information about ecological incident reporting.

EPA is particularly interested in feedback on the feasibility of the conservation measures that are intended to further reduce movement of Enlist One and Enlist Duo off of treated fields after application.

Next Steps

After the 60-day public comment period, EPA will provide FWS with the comments for its consideration before it finalizes the BiOp. The issuance of the final BiOp is the last step in EPA’s formal consultation process with FWS. Once FWS issues its final BiOp, EPA will work with the registrants to implement it.

Click here to access the Enlist BiOp

Click here to submit a public comment to the docket

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Last updated on May 5, 2025
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