Defining, Supporting, and Scoping an Impact-Based Approach to Maui’s “Functional Equivalence” Standard for Clean Water Act Permitting

In County of Maui v. Hawai’i Wildlife Fund, the Supreme Court held that“the statute requires a permit when there is a direct discharge from a pointsource into navigable waters or when there is the functional equivalent of adirect discharge.” The Court thus confirmed that some discharges traveling frompoint sources to navigable waters via intermediate nonnavigable and non-point-source “conduits” require permitting under the Clean Water Act. However, the meaning of “functional equivalence” was left ambiguous, and the Court’sproposed list of factors to determine functional equivalence was incomplete. Thisstandard and its attendant factors, if applied incorrectly, risk undermining thepurpose of the Clean Water Act. In this Note, I clarify that functional equivalenceshould be determined by the potential impact that an indirect point-sourcedischarge can have on a navigable water. This is consistent with the Clean WaterAct’s purpose and common-law origins and with judicial and regulatory history.The factors identified in County of Maui v. Hawai’i Wildlife Fund should be understood as indicia for determining an indirect discharge’s potential to impact navigable waters. Using the Clean Water Act’s public-nuisance and strict-liability roots, I also propose additional indicia that can determine whetherfunctional equivalence holds for the purposes of permitting under different discharge scenarios.