On March 10, 2010, the Center for Biological Diversity submitted a letter (PDF) on behalf of 50 conservation groups encouraging the Secretaries of the Department of the Interior and the Department of Commerce to adopt a radical new definition of “adverse modification of critical habitat.”  The proposed definition differs in two ways from the current regulatory definition; one uncontroversial and benign, while the other is likely to be controversial and far-reaching.

Currently, “adverse modification” is defined by regulation as “a direct or indirect alteration that appreciably diminishes the value of critical habitat for both the survival and recovery of a listed species.”  The groups would have “adverse modification of critical habitat” be defined as “a direct or indirect alteration that appreciably diminishes the value of any portion of any area of designated critical habitat for either the survival or recovery of a listed species,” with “appreciably diminishes” defined “as any action that would destroy or degrade any primary constituent element such that the habitat would be, measurably or perceptibly, of less value to the species.”  As explained below, the change to “either . . . or” would be benign; but the proposed addition of “any portion of any area” could dramatically alter the way the Services administer Section 7 of the ESA.

The change from “both the survival and recovery” to “either the survival or recovery” is benign, and likely to be uncontroversial because the Fish and Wildlife Service and National Marine Fisheries Service (the Services) have not been applying the current regulatory definition since late 2004, after the 9th Circuit held that it is invalid in Gifford Pinchot Task Force v. U.S. Fish and Wildlife Service, 378 F.3d 1059 (9th Cir. 2004).  In the wake of that opinion, the Fish and Wildlife Service issued guidance (PDF) in December 2004 directing the regions not to use the regulatory definition of “destruction or adverse modification,” but to rely on an analytic framework based on the language of the ESA itself, which requires that critical habitat be designated to achieve the twin goals of survival and conservation (i.e., recovery) of listed species.  Thus, under current practice, the Services will find "adverse modification" if the impacts of a proposed action on a species’ designated critical habitat would appreciably diminish the value of the habitat for either the survival or the recovery of the species.

In contrast, the proposed addition of “any portion of any area” represents a substantial change insofar as it could require the Services to find adverse modification whenever any action carried out, funded, or authorized by a federal agency would have an adverse impact on designated critical habitat.  This is the case because actions within the geographic area designated as critical habitat will — more often than not — appreciably diminish some “portion” of designated critical habitat.  For instance, certain species of trees are a primary constituent element of habitat for certain listed birds.  If an action with a federal nexus were to result in the destruction of one such tree in designated critical habitat, that would constitute an alteration that would appreciably diminish a “portion” of the bird’s designated critical habitat.

According to the letter, the addition of “any portion of any area” is needed “to avoid piecemeal destruction of critical habitat by precluding the argument that destruction of any particular area will not diminish the value of critical habitat as a whole.”  While no one reasonably could dispute that the Services have an obligation under the ESA to avoid “death by a thousand cuts,” the proposed definition could be interpreted to go well beyond preventing such an outcome, and would require an incidental take statement for every action with a federal nexus that would have any adverse effect on critical habitat.