One of the Supreme Court’s recurring environmental law topics is the scope of Clean Water Act (CWA) jurisdiction. Various aspects of CWA jurisdiction and implementation have been addressed over the years by the Court, including the meaning of “navigable waters” in U.S. v. Riverside Bayview Homes, Inc. (1985); Solid Waste Agency of N. Cook Cnty v. Army Corps of Eng’rs (2001); and Rapanos v. U.S. (2006), and judicial review of agency actions related to the applicability of the CWA dredge and fill permit program in Sackett v. EPA (2012) and U.S. Army Corps of Eng’rs v. Hawkes Co. (2016). Most recently, the Supreme Court heard oral argument on November 6 in County of Maui v. Hawai’i Wildlife Fund, et al., a case that addresses the applicability of the CWA’s prohibition on “point source” discharges to “navigable waters” to releases from point sources to groundwater. The Court granted certiorari to address whether releases from point sources that are carried to navigable waters by groundwater are regulated under the federal NPDES permit program or under state non-point source management programs.

 This case presents a fact pattern similar to those that have given rise to a number of other recent citizen suits, including a suit in Massachusetts claiming that the septic system of a resort located near navigable waters should have obtained a federal NPDES permit. As EPA explained in a recent (April 2019) interpretive notice addressing the applicability of the CWA to releases to groundwater, “[i]t is a fundamental principle of hydrology that many groundwaters and surface waters are linked through the hydrologic cycle.” As a result, waste water treatment systems such as septic tanks, leach fields, green infrastructure and stormwater management systems that slowly release effluent into the soil can lead to pollutants being dispersed and carried by groundwater to surface waters. As EPA explained, “neither EPA nor states have generally required NPDES permits for these types of activities.” Nevertheless, some lower courts have applied the CWA prohibition on point source discharges to navigable waters to require NPDES permits when groundwater is the medium that carries the point source release to navigable waters. The Supreme Court in County of Maui granted certiorari to address the growing confusion in this area of law. Reflecting the importance of this issue to municipal storm and waste water treatment systems and to green infrastructure, briefs in support of the County were filed by numerous municipalities and states, including the cities of New York and San Francisco, the National Association of Clean Water Agencies, the National League of Cities, the Association of California Water Agencies, the League of California Cities, the National Water Resources Association, the WateReuse Association and many others.

Confirming the confusion that has developed over the years regarding the applicability of the CWA NPDES permit program to point source releases to groundwater, the briefs in County of Maui offered a variety of jurisdictional tests for the Court’s consideration. The decision from the Ninth Circuit would require NPDES permitting for point source releases to groundwater in instances where pollutants that reach navigable waters are “fairly traceable” to the point source, as long as those pollutants reach surface waters in more than “de minimis” amounts. In the Supreme Court, Respondents did not defend this Ninth Circuit test but, rather, argued that CWA NPDES permitting should apply if (i) a release to groundwater was touched by a “point source” at some point along its route to navigable waters, (ii) the pollutant that found its way to surface waters was “fairly traceable” to the point source, and (iii) the presence of the pollutant in navigable waters was a “foreseeable” or “natural and probable consequence” of the release to groundwater.

In the ruling below, the Ninth Circuit rejected a test offered by EPA in the prior administration: NPDES permitting applies if the point source releases a pollutant to groundwater that has a “direct hydrological connection” to navigable waters. According to the Ninth Circuit, this test adds words to the statute. Nevertheless, some of Respondents’ amici continued to advance the “hydrological connection” test in their Supreme Court briefs. The United States government, for its part, offered a “bright line” test under which any release to groundwater is exempt from the NPDES permit program and would be subject to the nonpoint source management programs.

The County of Maui argued that the answer to this jurisdictional question is found in the definition of “point source” as a “discernible, confined and discrete conveyance.” Because a point source is defined as a conveyance, the County argued, the NPDES program can apply only where a point source is the thing that delivers the pollutant to navigable waters. Like the government, the County argued that this test preserves the line drawn by Congress in the CWA between federal point source and state nonpoint source regulation.

During oral argument, the Justices grappled with these various views of CWA jurisdiction. On one hand, Justice Sotomayor expressed concern about the adequacy of state nonpoint source regulation. If the line between point and nonpoint source programs is drawn as suggested by the County of Maui, Justice Sotomayor commented: “[B]ut that’s the problem, isn’t it? Because it presumes the states will regulate, and some states won’t.” On the other hand, Justice Alito expressed concern “whether any limiting principle…can be found in the text [that]…is workable and does not lead to absurd results.”

In the search for a workable line between the point and nonpoint source regulatory programs, Justice Breyer offered a test of his own: “[I]f it’s the functional equivalent of a direct discharge,” Justice Breyer posited, a release to groundwater could be regulated under the NPDES program. According to Justice Breyer, this test would “leave[] a lot of room for the EPA to write regulations, to decide what is the functional equivalent of a direct discharge.”

Ultimately, a majority of Justices seemed concerned with finding a test that is predictable and has a basis in the statute. Justice Gorsuch commented, “there are other regulations for nonpoint sources….you don’t want a subjective test…” defining when the different programs apply, “…you want an objective test.” He observed that for “septic tank[s]—and we might put in San Francisco’s green water treatment plants and a whole lot else—[it is] foreseeable [that releases are]…going to wind up in the waters of the United States.” He asked, “[w]hat…limiting principle do you have to offer the Court?”

Justice Breyer picked up on this line of questioning: “[V]irtually every little drop of rain that falls finds its way to the sea. And…that’s an overstatement but not by much. So it’s not just septic tanks…. [T]he brief…of the scientists [in support of Respondents] really convinced me …they can trace all kinds of things.” Justice Breyer continued, “I am worried about the 300 million people…suddenly discovering that they have to go apply for a permit [to] the EPA” for common activities like septic tanks that release pollutants to groundwater.

What then, is the best reading of the CWA? If both sides have a good textual argument, Justice Kavanaugh asked, “[w]hat then should we look at to help us decide how to interpret it?” Among relevant considerations, he suggested, are whether a given interpretation would result in a “massive increase in the permitting program,” in “uncertainty about when and whether you would need to get a permit,” and in “transforming the federal/state balance.”

It goes without saying that it is difficult to predict the outcome of a case from oral argument. What is clear, though, is that until there is resolution of how the jurisdictional line between the CWA NPDES permit program and state nonpoint source programs is drawn, state and municipal water management and regulatory agencies around the country will face continuing uncertainty, the diversion of regulatory resources and the potential for retroactive liability for choosing the wrong regulatory program.