Decision concludes a permit is required if such discharges are the “functional equivalent” of a direct discharge to navigable waters.
By Janice Schneider, Maria Hoye, and Ethan Prall

On April 23, 2020, the Supreme Court of the United States issued an opinion in County of Maui, Hawai’i v. Hawai’i Wildlife Fund, holding that the Clean Water Act (CWA) requires a permit for certain discharges through groundwater. Specifically, a permit is required if there is a “direct discharge” from a point source to navigable waters, or if a given discharge is the “functional equivalent” of a direct discharge when that discharge passes through groundwater before reaching navigable waters.[1]
In establishing this new functional equivalence test, the Court rejected both the argument that allowing any regulation of discharges through groundwater would expand the CWA’s scope without warrant, and the contrary argument that every discharge that is “fairly traceable” from a point of discharge to navigable waters must be regulated under the CWA. When applying the test, the Court explained that several factors — most centrally, time and distance — are relevant to determining whether a discharge through groundwater is the functional equivalent of a direct discharge.
Over the past month, two US Courts of Appeals have rejected Clean Water Act (CWA) citizen suits seeking to hold power companies liable for discharges of pollutants from coal ash disposal facilities “through” groundwater to waters of the US. Although the Fourth Circuit accepted that discharges through groundwater could be the basis for liability, it held that the relevant ash piles and impoundments were not “point sources” for purposes of the CWA. The Sixth Circuit likewise held that the ash disposal facilities at issue were not point sources, but — contrary to the Fourth Circuit — also held that discharges through groundwater were not actionable under the Act. Collectively, these recent decisions stand as a significant new obstacle to citizen suits against owner/operators of coal ash impoundments. At the same time, the decisions deepen a circuit split on the so-called “groundwater conduit” theory of CWA liability, helping to tee the issue up for possible Supreme Court resolution. If the Court does take this question up, the outcome will be critically important for many industry sectors, including electric power, oil and gas, manufacturing, and mining companies, among others. The CWA imposes strict liability, and citizen suits based on groundwater conduit claims can result in extremely costly remedies — including large civil penalties and injunctive relief.
On February 26, for the first time ever, a federal district court has enjoined a California Proposition 65 warning requirement on First Amendment grounds. Under California’s Safe Drinking Water and Toxic Enforcement Act of 1986 — colloquially known as “Proposition 65” — the State listed the herbicide glyphosate, the most widely used herbicide in the world, as a chemical “known” to the