Sixth Circuit Limits Reach of Clean Water Act to Groundwater Discharges, Creates Circuit Split on Proper Scope of CWA

David J. Oberly

Why It Matters

In recent years, the question of whether groundwater that migrates into federally protected navigable waters falls under the purview of the Clean Water Act (“CWA”) has been fiercely debated and heavily litigated across the country. To date, the Fourth and Ninth Circuits have both interpreted the CWA broadly, ruling that the CWA extends to reach groundwater discharges. Just recently, however, the Sixth Circuit in Kentucky Waterways Alliance v. Kentucky Utilities Company, No. 18-5115 (6th Cir. Sept. 24, 2018) and Tennessee Clean Water Network v. Tennessee Valley Authority, No. 17-6155 (6th Cir. Sept. 24, 2018) weighed in on the issue, and rejected the theory that pollutants reaching navigable waters as a result of passing through groundwater (or soil) are discharges that fall under the auspices of the CWA. The Sixth Circuit decisions are noteworthy, as they create a clear conflict among the federal circuit courts regarding the scope of the CWA and, more specifically, whether the Act reaches the issue of groundwater discharges, further increasing the likelihood that the United States Supreme Court will take up the matter to issue a decisive ruling on the proper scope of the CWA and provide a definitive resolution to this hotly contested issue of environmental law.

Factual & Procedural Background

In both Kentucky Waterways Alliance and Tennessee Clean Water Network, environmental groups filed citizen suits under the CWA, alleging that power plants violated the CWA by failing to acquire National Pollutant Discharge Elimination System (“NPDES”) permits for releases of pollutants from coal ash ponds into groundwater that subsequently migrated into navigable waters. In doing so, the plaintiffs argued that the groundwater was a point source, and that because pollutants migrated from the coal ash ponds through the groundwater (itself a point source) to navigable waters, the discharges fell under the purview of the CWA. In Kentucky Waterways Alliance, the district court granted the defendant’s motion to dismiss, holding that releases into groundwater were not discharges governed by the CWA. In Tennessee Clean Water Network, following a bench trial the district court held that the Tennessee Valley Authority’s coal ash ponds were illegally discharging to adjacent surface waters through hydrologically connected groundwater.

Discussion & Analysis

At issue on appeal was whether the discharge of pollutants into groundwater that subsequently migrate to navigable waters is regulated by the CWA. The CWA requires a permit to “discharge” “any pollutant.” The discharge of a pollutant is defined as “any addition of any pollutant to navigable waters from any point source.” A point source is a “discernible, confined and discrete conveyance.” These permits are issued pursuant to the CWA’s National Pollutant Discharge Elimination System. Therefore, in order to add a pollutant to the waters of the United States via a conveyance, a NPDES permit is required. A CWA claim has five elements: (1) a pollutant must be (2) added (3) to navigable waters (4) from (5) a point source.

The plaintiffs presented two arguments that the CWA extended to groundwater discharges. First, under the “point source” theory, the plaintiffs contended that groundwater (as well as the terrain that carries the groundwater) is a point source that deposits pollutants into navigable waters. This theory treats groundwater as if it were a pipe through which pollutants travel. Second, the plaintiffs urged the court to adopt the so-called “hydrological connection” theory. Under this theory, groundwater is not considered a point source, but rather a medium through which pollutants pass before being discharged into navigable waters, with the point sources being the coal ash ponds themselves.

The Sixth Circuit rejected both theories, finding instead that the CWA does not extend its reach to this form of pollution discharge that migrates from groundwater to navigable waters. In doing so, the court first addressed the point source theory. Here, the court concluded that groundwater is not a “point source” because it is not a “discernible, confined, or discrete conveyance.” In this regard, the court reasoned that by its very nature, groundwater is a “diffuse medium” that seeps in all directions, guided only by the general pull of gravity. Thus, it is neither confined nor discrete. In addition, groundwater is not discernible, as one cannot look at groundwater and discern its precise contours, as can be done with traditional point sources like pipes, ditches, or tunnels. Combined, the CWA’s text foreclosed any argument that groundwater (or the medium through which it flows) is a point source.

After disposing of the point source theory, the court then addressed the plaintiffs’ hydrological connection theory. Here, the court highlighted the fact that the CWA extends only to discharges “into” navigable waters from a point source. Thus, for a point source to discharge “into” navigable waters, it must dump directly into those navigable waters, as the phrase “into” leaves no room for intermediary mediums to carry the pollutants. Moreover, the court noted that the CWA addresses only pollutants that are added “to navigable waters from any point source.” Accordingly, the CWA requires two things in order for pollution to qualify as a “discharge of a pollutant”: (1) the pollutant must make its way into a navigable water (2) by virtue of a point-source conveyance. However, when pollutants are discharged into groundwater, and the groundwater then adds pollutants into navigable waters, the pollutants are not coming from a point source; rather, they are coming from the groundwater, which is a nonpoint-source conveyance. Because the CWA has no say over such conduct, the court also rejected the hydrological connection theory as a means to impose liability under the CWA.

In addition, the court also highlighted the fact that the CWA’s other provisions and corresponding federal environmental laws strengthened the court’s conclusion that the CWA did not extend to groundwater. Here, the court noted that Resource Conservation and Recovery Act (“RCRA”)—which is concerned with solid waste management—and the CWA are to be read as complementary statutes, as each is addressed at regulating different potential environmental hazards. Importantly, pursuant to RCRA, the Environmental Protection Agency (“EPA”) has issued a formal rule that specifically covers coal ash storage and treatment, known as the “CCR Rule.” The CCR Rule was designed to regulate, among other things, coal ash ponds. Importantly, the CCR Rule specifically addresses the disposal of coal ash as solid waste under RCRA. Thus, the CCR Rule, not the CWA, is the framework envisioned by Congress (by delegating rulemaking authority to the EPA through RCRA) to address the problem of groundwater contamination caused by coal ash impoundments. However, adopting the plaintiffs’ interpretation of the CWA would leave the CCR Rule virtually useless. As such—the court concluded—it would be improper to interpret the CWA in a way that would effectively nullify the CCR Rule and large portions of RCRA.


Kentucky Waterways Alliance and Tennessee Clean Water Network are significant wins for the regulated community, as these rulings articulate a much narrower interpretation of the CWA which allows companies to sidestep liability for discharges of pollution into groundwater that subsequently reaches federally protected navigable waters.

Importantly, the Sixth Circuit’s decisions are in direct conflict with previous decisions issued by the Fourth and Ninth Circuits on the issue of whether the CWA’s reach extends to groundwater discharges, which both held that a discharge of pollutants into groundwater that migrates to federally protected waters is prohibited under the CWA. Specifically, in Upstate Forever v. Kinder Morgan Energy Partners, No. 17-1640 (4th Cir. April 12, 2018), the Fourth Circuit held that a discrete discharge from a point source into navigable waters is not necessary for the CWA to apply where there is a direct hydrological connection between the navigable waters and the intervening groundwater. Likewise, in Hawai’i Wildlife Fund v. County of Maui, No. 15-17447 (9th Cir. Feb. 1, 2018), the Ninth Circuit held that a direct discharge to federally protected waters is not required for the CWA to apply where the discharge of pollutants is “fairly traceable” from the point source to a navigable water, such that the discharge is the functional equivalent of a discharge into navigable water.

Combined, a clear circuit split now exists as to whether the CWA reaches groundwater. The clear divergence of opinions that currently exists as to the proper scope of the CWA places significant pressure on the United States Supreme Court to address the issue and hand down a decisive ruling on whether the CWA encompasses groundwater discharges. At the time the Sixth Circuit issued its decisions, the nation’s highest Court was already considering a petition to review the Ninth Circuit’s decision in Hawai’i Wildlife Fund. The Sixth Circuit’s decisions make it substantially more likely that the Supreme Court will ultimately accept review of the matter at some point in the future to provide a definitive answer as to whether the CWA covers groundwater discharges which, in turn, will allow for consistent application of the law throughout the nation.

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