The Clean Water Act’s “Middle Instances” — When Indirect Discharges Need NPDES Permits Too

Environmental Update

Client Alert


For the past decade or so, the regulated community and federal courts alike struggled with the outer reaches of the Clean Water Act’s (CWA) point source permitting program. The core of the program — the National Pollutant Discharge Elimination System (NPDES) — is clear enough. Under the NPDES program, discharges from “point sources” to “navigable waters” (what qualifies as a “navigable water,” i.e., “water of the United States” presents another thorny question) require a NPDES permit.

But what about more attenuated discharges? Say a municipal wastewater facility collects, partially treats, and discharges wastewater into underground injection wells, which, through groundwater connections, carry the effluent roughly 2,500 feet into the Pacific Ocean. Groundwater is generally beyond the NPDES program’s reach; the Pacific Ocean is firmly within it. So, does the wastewater facility need a NPDES permit (because the groundwater conveys the effluent to a navigable water) or not (because the groundwater breaks the regulatory link)?

Before April, federal courts around the country would’ve applied different legal analyses — and, by extension, reached different permitting conclusions — to this same factual question. Some said the CWA applied so long as groundwater discharges created a “direct hydrological connection” to navigable waters. Others required permits if the pollutants were “fairly traceable” from the point source to the navigable water. And still others held that discharges to groundwater never required NPDES permits. Practically speaking, this meant federal courts in California, Virginia, and Tennessee all applied different legal rules to the same theoretical discharge, with very real consequences for permittees. Just a few months ago, the U.S. Supreme Court resolved this “circuit split.” But, in many ways, the Supreme Court left the regulated community with more questions than answers.

County of Maui v. Hawaii Wildlife Fund concerned the question posed above: Does the Hawaiian municipal wastewater facility require a NPDES permit to pump its partially treated effluent into groundwater that hydrologically reaches the Pacific Ocean? Sidestepping the specific question of whether that discharge required a NPDES permit, the Supreme Court answered with a resounding “maybe.” Though the court sent the particular issue back to the lower courts for further factual development, it did announce a new rule controlling whether any discharge triggers NPDES’ point source permitting requirements: The CWA requires NPDES permits “when there is a direct discharge from a point source into navigable waters or when there is the functional equivalent of a direct discharge.” What, then, is “the functional equivalent of a direct discharge?”

In a boon to lawyers everywhere, the Supreme Court eschewed a bright-line rule. Instead, it crafted a flexible, case-by-case analysis for permitting agencies, permittees, and courts to follow in these “middle instances.” Broadly speaking, the court said federal permits are necessary if a point source “directly deposits pollutants” into navigable water or “reaches the same result through roughly similar means.” Fortunately, the Supreme Court did get more specific: “Time and distance are obviously important.” And the court flagged the following non-exhaustive factors:

  • Transit time
  • Distance traveled
  • The nature of the material conveying the discharge
  • The degree of any pollutant dilution or transformation
  • The amount of pollutant ultimately reaching the navigable water relative to the amount initially discharged
  • The manner by or area in which the pollutant enters the navigable waters
  • The degree to which the pollutant, upon reaching navigable waters, retains its “specific identity”

That’s a lot to chew on. And it leaves us with few firm answers. But the Supreme Court did give us some useful guideposts. Most obviously, indirect discharges that reach navigable waters faster (in five minutes, rather than five years) and more directly (in 50 feet, rather than 50 miles) are likelier to require a NPDES permit. In the court’s eyes, these “time and distance” analyses “will be the most important factors in most cases.”

Of course, that’s little comfort for permittees facing the many “middle instance” discharges presenting closer calls. In those situations, permittees should work with their permitting authority and counsel to assess “functional equivalency.” Over time, this middle instance murkiness should fade away as regulators issue guidance and courts interpret County of Maui’s guidance. Indeed, we’re already tracking several post-County of Maui bellwether cases. But until then, permittees and project proponents should carefully consider whether indirect discharges — to groundwater or otherwise — now require state and federal permit coverage. And permittees and their regulators should also steel themselves for fresh challenges to existing “middle instance” discharges, which are sure to ensue.

A version of this article appeared in the September 2020 issue of the Florida Water Resources Journal.