The Clean Water Act generally requires a federal permit for the discharge of pollutants “from any point source” to navigable waters. It is undisputed that permits are required for discharges of pollutants from point sources that proceed “directly” to regulated waters. But there is much disagreement over the extent to which indirect point-source discharges are regulated. In an attempt to clarify, the United States Supreme Court in County of Maui v. Hawaii Wildlife Fund ruled that permits are required not just for direct point-source discharges, but also for any point-source discharge that is the “functional equivalent” of a direct point-source discharge. Unfortunately, the Court did not define the term “functional equivalent,” other than to offer a non-exhaustive list of seven factors to consider (emphasizing time and distance), and to admonish lower courts to both respect the states’ traditional authority over water pollution and be mindful of avoiding decisions that would encourage evasion of the Act’s permitting requirements.

To pick up where County of Maui left off, this Article proposes the “hallmark” interpretation of the functional equivalent test. According to this approach, a pollutant discharge is the “functional equivalent” of a direct discharge (and therefore requires a permit) if it bears the hallmarks of a direct discharge—in other words, if the discharged pollutants still betray the traces of having been emitted from a “discernible, confined and discrete conveyance” (the statutory definition of “point source”). In contrast, if the pollutants lack those hallmarks, and thus are indistinguishable from pollutants added by nonpoint sources, then their discharge is not a regulated “functional equivalent.” This “hallmark” approach is consistent not only with County of Maui’s articulation of the functional equivalent rule, but also with the Court’s expectation of how that rule should be implemented. In support of the proposed hallmark analysis, the Article defines the reference point (“direct discharge”) and its functions, then explains how to determine whether the hallmarks of the pollutants at issue are equivalent to the hallmarks of a direct discharge. Finally, it cautions that, consistent with County of Maui’s admonition, the functional equivalent analysis must include a “perspective” check to prevent the Act from being used to undercut the states’ traditional authority over water quality, while also respecting Congress’ intent that certain point-source discharges be federally regulated.