Carving out the Contours: The Clean Water Act and the Migration of Affected Groundwater to Waters of the United States

DRI: For the Defense

Authored Article

Author(s) , Andrew Bittner, Michelle S. Spak

The Supreme Court is expected to resolve whether the Clean Water Act governs the indirect discharge of pollutants that travel via groundwater to “waters of the United States.”

For over forty years, water pollution control in the United States has largely been governed by the 1972 amendments to the Federal Water Pollution Control Act. Commonly referred to collectively as the Clean Water Act, those amendments made it unlawful to discharge pollutants into “waters of the United States” without a National Pollutant Discharge Elimination System (NPDES) permit issued by the EPA or an authorized state. 33 U.S.C. §1342. Despite a substantial body of judicial and administrative interpretations of the Clean Water Act, the United States Supreme Court recently granted a petition for certiorari in a case involving releases of pollutants that reach jurisdictional surface waters indirectly through groundwater. The Supreme Court is expected to resolve whether the Clean Water Act governs the indirect discharge of pollutants that travel via groundwater to “waters of the United States.”

The Connection Between Groundwater and Surface Water

A fundamental understanding of the link between groundwater and surface water is rooted in our knowledge of the larger continuum of water movement on Earth. This continuum is known as the “hydrologic cycle.” The hydrologic cycle describes the constant transfer of water between different reservoirs. Such reservoirs include the atmosphere, surface waters (lakes, rivers, oceans, and streams), moisture in soils, groundwater, and polar ice caps. The physical link between any of these reservoirs is complex and often involves multiple processes. For example, after precipitation reaches the ground surface, water may either flow overland into a surface water body, may infiltrate into the soil and move downward into groundwater, may evaporate and return to the atmosphere, or may be taken up by plants and then transpired back into the atmosphere.

“Groundwater” is the term used to describe water beneath the Earth’s surface that is held within the pore space of soils and bedrock. Groundwater moves through the subsurface under gravitational and pressure forces, and its horizontal and vertical flow rates depend on numerous factors, including the geological setting and soil characteristics. Although it may only take a few days or up to several millennia, eventually all groundwater that has not evapotranspired, or withdrawn, will discharge into a surface water body.

While the connection between groundwater and surface water is established, whether the Clean Water Act regulates this relationship remains open to debate. The debate stems from the Clean Water Act’s prohibition against “point source” discharges of pollutants to “waters of the United States” without an NPDES permit. 33 U.S.C. §1342. The Clean Water Act defines a point source as a “discernible, confined and discrete conveyance, including but not limited to any pipe, ditch, channel, tunnel, conduit, well, discrete fissure, container, rolling stock, concentrated animal feeding operation, or vessel or other floating craft, from which pollutants are or may be discharged.” 33 U.S.C. §1362(14). Based on this definition, the NPDES program traditionally has been viewed as regulating only “end-of-pipe” discharges to a jurisdictional surface water body. Thus, discharges of hydrologically connected groundwater into surface water bodies have not been universally accepted as triggering NPDES permit requirements under the Clean Water Act.

Moreover, the regulation of discharges of hydrologically connected groundwater to surface water presents a number of site- specific challenges that do not fit within the current regulatory regime for the control of end-of-pipe discharges. Such an approach would require a clear and objective technical framework to establish what constitutes a “direct” hydrologic connection between groundwater and surface water requiring Clean Water Act compliance. Site- specific assessments of such hydraulic connections would be complicated since the connection between groundwater and surface waters may vary over time (both from season to season and year to year); may depend on the location of the source of groundwater relative to surface water, as well as the conditions and flowrates of the surface water; and may vary based on the nature of the transport mechanisms. In areas with multiple potential sources of groundwater impacts, identifying a site- specific source of pollution to a particular surface water body may also be challenging.

Even if a determination were made that there is a “direct” hydrologic connection between surface water and groundwater at a particular site that triggers the Clean Water Act, developing an NPDES permit for discharges of groundwater to surface water would present a number of additional challenges. Some structure would be required to determine appropriate effluent limits, points of compliance, mixing zones, discharge points, and monitoring requirements. For example, pollutant dispersion in groundwater may attenuate impacts and cause lateral spreading of contaminants so that discharges into a surface water body may occur over a broad area, rather than through a discrete point of discharge. Finally, many chemicals are subject to geochemical and microbially mediated reactions that affect their potential transport in groundwater and flux into surface waters. These reactions may sequester or degrade certain pollutants in groundwater, or both, before reaching a surface water body. Thus, apart from the physics of groundwater to surface water flow, there are multiple other contaminant transport processes that need to be considered to regulate groundwater discharges to surface water effectively.

The case that will be presented to the United States Supreme Court is not the first judicial assessments of Clean Water Act jurisdiction over groundwater discharges to surface waters. In Village of Oconomowoc Lake v. Dayton Hudson Corporation, 24 F.3d 962 (7th Cir. 1994), the Seventh Circuit affirmed a lower court’s dismissal of a claim under the Clean Water Act (CWA) that alleged that an artificial retention pond would act as a conduit for pollutants to enter groundwater and then to surface waters. The Seventh Circuit held, “Neither the Clean Water Act nor the EPA’s definition [of waters of the United States] asserts authority over ground waters, just because these may be hydrologically connected with surface waters.” Dayton Hudson Corp., 24 F.3d at 965. In his opinion, Judge Easterbrook recounted that “[t]he most concerted effort in Congress” to include groundwater under the regulatory requirements of the Clean Water Act “occurred in 1972.” Id. The Senate Committee on Public Works rejected the “proposals” but explained why: “Several bills pending before the Committee provided authority to establish Federally approved standards for groundwaters which permeate rock, soil, and other subsurface formations. Because the jurisdiction regarding groundwaters is so complex and varied from State to State, the Committee did not adopt this recommendation.” Id. (quoting S. Rep. No. 414, 92d Cong., 1st Sess. 73 (1972));see also Exxon Corp. v. Train, 554 F.2d 1310, 1325–29; Kelley v. Unites States, 618 F. Supp. 1103 (W.D. Mich. 1985); but see Idaho Rural Council v. Bosma, 143 F. Supp. 2d 1169 (D. Idaho 2001) (“the Court finds that the CWA extends federal jurisdiction over groundwater that is hydrologically connected to surface waters that are themselves waters of the United States”).

Current Circuit Split

The federal circuits have taken three approaches to “indirect discharges” of pollution that are transmitted by groundwater to the “waters of the United States.”

Fourth Circuit

In Upstate Forever v. Kinder Morgan Energy Partners, L.P., 887 F.3d 637 (4th Cir. 2018), the Fourth Circuit considered a CWA citizen-suit challenge relating to a discharge from a ruptured pipeline in South Carolina. The suit alleged that despite Kinder Morgan’s clean-up efforts and additional remedial measures overseen by South Carolina, unrecovered gasoline seeped into the groundwater and made its way into nearby navigable waters. Id. at 641. The district court originally dismissed the suit, finding that the challengers had not established a case for liability under the CWA based on this indirect discharge from a point source (the pipeline) to navigable waters. Id. at 644–45.

The Fourth Circuit, however, vacated and remanded. In the court’s view, “a discharge of a pollutant under the [CWA] need not be a discharge ‘directly’ to a navigable water from a point source.” Id. at 649. The court relied, in part, on Justice Scalia’s plurality opinion in Rapanos v. United States, 547 U.S. 715 (2006), which noted that the CWA prohibits the “addition of any pollutant to navigable waters,” not only discharges “directly to navigable waters.” Id. at 743 (citation omitted). In the Fourth Circuit’s view, Rapanos supports an interpretation of the CWA that prohibits indirect as well as direct discharges from point sources to navigable waters—limited by the requirement that the discharge be “sufficiently connected to navigable waters.” Id. at 651. This sufficient connection, in turn, requires alleging a “direct hydrological connection” between the point source and the jurisdictional waters. Id. The Fourth Circuit’s “direct hydrological connection” approach “necessarily is fact- specific,” and it involves weighing factors such as distance and “traceability of a pollutant in measurable quantities.” Id. at 652.

Ninth Circuit

Around the same time last spring, the Ninth Circuit decided the similar case of Hawai’i Wildlife Fund v. County of Maui, 886 F.3d 737 (9th Cir. 2018). The facts in County of Maui involved a challenge to discharges from wastewater treatment plant wells that eventually migrated to the Pacific Ocean. Id. at 742. The district court ruled that the county was liable for these discharges under the CWA, and the Ninth Circuit affirmed. Id. at 743. The Ninth Circuit rejected the county’s argument that a “discharge” occurs for purposes of the CWA only if the point source in question conveys the pollutants directly to navigable water. Instead, similar to the Fourth Circuit, the court concluded that “an indirect discharge from a point source to a navigable water suffices for CWA liability to attach.” Id. at 748. The court also relied on the same section of the Rapanos plurality decision that informed the Fourth Circuit’s analysis in Kinder Morgan. Id. Unlike the Fourth Circuit, however, in County of Maui, the Ninth Circuit described the test for indirect discharges covered by the CWA as whether “the pollutants are fairly traceable from the point source to a navigable water such that the discharge is the functional equivalent of a discharge into the navigable water,” and whether “the pollutant levels reaching navigable waters are more than de minimis.” Id. at 749.

Sixth Circuit

In the second half of 2018, the Sixth Circuit parted ways with both of the approaches of the Fourth and Ninth Circuits in a pair of similar decisions. First, the court considered Kentucky Waterways Alliance v. Kentucky Utilities Co., 905 F.3d 925 (6th Cir. 2018), which involved a challenge to power plant coal ash ponds. The Sixth Circuit rejected the plaintiffs’ argument that the plant could be liable under the CWA for discharges of coal ash pollutants from the pond that eventually reached navigable waters through groundwater migration. The court explained that “[t]he text and statutory context of the CWA” “make clear” that the statute does not reach these types of indirect discharges, and it expressly “disagree[d] with the decisions” in County of Maui and Kinder Morgan. Id. at 933. With respect to the Rapanos plurality, the court explained that the language that the Fourth and Ninth Circuits found key had “been taken out of context in an effort to expand the scope of the CWA well beyond what the Rapanos Court envisioned.” Id. at 936. Instead, Justice Scalia was referring only to the fact that pollutants can travel through multiple point sources before eventually reaching navigable waters, not that indirect discharges through nonpoint sources—such as groundwater—are sufficient for CWA liability. Id. The court explained that a discharge for purposes of the Clean Water Act occurs only if the pollutant is added to jurisdictional waters “by virtue of a point-source conveyance.” Id. at 934.

The Sixth Circuit doubled down on this approach in Tennessee Clean Water Network v. Tennessee Valley Authority, 905 F.3d 436 (2018), which also involved coal ash pond pollutants. The court reaffirmed its position that in contexts such as these, the pollutants “are not coming from a point source; they are coming from groundwater which is a nonpoint-source conveyance.” Id. at 444 (citation omitted). For this reason, the court reiterated that “[t]he CWA has no say over that conduct.” Id.

Certiorari Petitions

As noted above, two of these legal challenges made their way to the Supreme Court. Last fall, Kinder Morgan Energy Partners and the County of Maui filed petitions for certiorari, seeking review of the Fourth and Ninth Circuits’ decisions, respectively.

On December 3, 2018, the Supreme Court invited the views of the Solicitor General in both cases—but took the unusual step of setting a one-month deadline for these briefs. There is typically no deadline when the Supreme Court calls for the view of the Solicitor General in a case, and the Solicitor General often takes several months to file briefs in response to the Court’s invitation. The Supreme Court’s decision to accelerate that process signaled that the Court has a strong interest in these cases.

The brief for the United States argued that the Court should grant the petition for certiorari in County of Maui, limited to the question of whether “discharge of a pollutant” under the CWA occurs when a pollutant is released from a point source, but only reaches navigable waters after migrating through groundwater. Br. for the United States as Amicus Curiae 1–2, Nos. 18-260 & 18-268 (Jan. 3, 2019). The brief also argued that the petition in Kinder Morgan should be held pending the Court’s disposition of the County of Maui petition because it does not present as clean a vehicle as the Ninth Circuit’s decision. Id. at 2, 15–17.

The Solicitor General’s brief pointed out that there is a clear division in the federal appellate courts over the CWA’s scope in cases of indirect discharges that migrate through groundwater to navigable waters—and that the Supreme Court should resolve this important question. In addition to the Fourth, Sixth, and Ninth Circuit decisions discussed above, the brief cites district court decisions around the country that have struggled with the proper interpretation of the CWA in the context of indirect discharges through groundwater. Id. at 13. The brief argued that the issue is important, because “[g]iven the potential breadth of [the CWA’s] provisions, and the ways in which groundwater may be connected to navigable waters, the question presented here has the potential to affect federal, state, and tribal regulatory efforts in innumerable circumstances nationwide.” Id. The brief also emphasizes the significant consequences for regulated parties in light of the Clean Water Act’s stringent civil and criminal penalty provisions. Id. at 13–14.

On February 19, 2019, the Supreme Court granted the petition in County of Maui, but limited its review to Question 1 presented by the petition: whether the CWA requires a permit when pollutants originate from a point source but are conveyed to navigable waters by a nonpoint source, such as groundwater. On March 19, 2019, the Court granted a motion of the parties to modify the briefing schedule in anticipation of the Court’s consideration of the matter during the October 2019 term.

Regardless of the Supreme Court’s decision, there will likely remain a number of issues that will have to be resolved in future cases involving groundwater to surface water connections. First, the County of Maui case presents a unique factual scenario in which a permitted underground injection well intersects a lava tube that allows groundwater to flow to the Pacific Ocean. If the Court’s decision is confined to the particular hydrogeological scenario, then the implication in other scenarios will have to be assessed in future litigation. Second, even if the Court’s decision is not limited to the facts of County of Maui, the unique characteristics of any particular groundwater to surface water connection may still play a role in the issue in future litigation. Third, the U.S. Environmental Protection Agency has indicated that it intends to issue guidance on groundwater to surface water connectivity before the Court takes up the case. The weight, if any, given to any such guidance in the Court’s opinion may also be instructive.

Clear Resource Conservation and Recovery Act (RCRA) Overlays Complicate the Hydrologic Connection Analysis

After the Fourth Circuit’s ruling in Kinder Morgan, 887 F.3d 637, the Fourth Circuit had another opportunity to consider whether the Clean Water Act allows liability for discharges to hydrologically connected groundwater. In Sierra Club v. Va. Elec & Power Co., 903 F.3d 403 (4th Cir. 2018) (Dominion), the Fourth Circuit analyzed whether discharges to groundwater from an ash basin that travel to surface water can create liability under the Clean Water Act. Despite recognizing the court’s recent holding in Kinder Morgan, in an opinion written by Judge Niemeyer, the Dominion panel distinguished the coal ash basins case, finding that the basins are not point sources regulated under the Clean Water Act. Id. at 411 (finding no point source where the diffuse seepage of arsenic was a generalized, site-wide condition and therefore could not be characterized as a discrete “point” and did not function as a conveyance).

In reaching that conclusion, the Dominion panel explained that such diffuse groundwater discharges are properly regulated under RCRA, 40 C.F.R. §§257.90–257.98. Dominion, 903 F.3d at 411–12.

The district court blurred two distinct forms of discharge that are separately regulated by Congress—diffuse discharges from solid waste and discharges from a point source—and concluded that any discharge from an identifiable source of coal ash, even that resulting from precipitation and groundwater seepage, is regulated by the Clean Water Act... The movement of pollutants, however, was not a function of the coal ash piles or ponds, but rather the result of a natural process of “precipitation percolat[ing] through the soil to the groundwater.” And that groundwater pollution from solid waste falls squarely within the regulatory scope of the RCRA. By contrast, the coal ash piles and ponds, from which arsenic diffusely seeped, can hardly be construed as discernible, confined, or discrete conveyances, as required by the Clean Water Act.

Id. at 412. The court likewise noted that the effluent limitation scheme at the heart of the Clean Water Act is “incompatible” with regulating groundwater. Id. at 411.

Indeed, this distinction between CWA and RCRA jurisdiction was likewise evident in the Sixth Circuit’s opinion in Kentucky Utilities, Ky. Waterways All. v. Ky. Utils. Co., 905 F.3d 925 (6th Cir. 2018). As discussed above, the Sixth Circuit rejected the hydrologic connection theory, thereby rejecting any theory of Clean Water Act liability relating to the coal ash basins at issue in that case. Id. at 938. Like the Fourth Circuit in Dominion, the Sixth Circuit was influenced by the fact that RCRA—and specifically the Coal Combustion Residuals Rule (CCR Rule) promulgated thereunder, 80 Fed. Reg. 21,302 (Apr. 17, 2015)—specifically addresses groundwater concerns at the facility, and if the Clean Water Act applied, it would eviscerate the applicability of the more- specific CCR Rule. Id. at 938.

The Sixth Circuit did not let Kentucky Utilities off the hook, however. The plaintiff there asserted an “imminent and substantial endangerment” citizen suit claim under RCRA. See 42 U.S.C. §6972(a)(1)(B). The lower court previously dismissed this claim for lack of jurisdiction, based on an ongoing state remedial plan. Ky. Waterways, 905 F.3d at 938. Perhaps recognizing the need for environmental groups to have a vehicle to take issues to federal court, the Sixth Circuit rejected Kentucky Utilities’ argument for abstention under Burford v. Sun Oil Co., 319 U.S. 315 (1943), finding that “applying Burford abstention… would be akin to grafting a new provision onto RCRA’s diligent prosecution bar.” Ky. Waterways, 905 F.3d at 939 (“Were we to abstain, we would effectively add a new component to that bar precluding citizen suits where a state is already trying to remedy the problem, regardless of the regulatory mechanism it is using.”).

Although the Sixth Circuit’s opinion in Kentucky Waterways was a victory for industry about the scope of the Clean Water Act, it was a loss insofar as it kept another door—RCRA—open for environmental groups to challenge the same issues. Indeed, environmental groups have repeatedly expressed concern that absent Clean Water Act jurisdiction, they would lack a viable means of federal enforcement. See Southern Envtl. Law Ctr., Comment on Clean Water Act Coverage of Discharges of Pollutants via a Direct Hydrologic Connection to Surface Water 18, Docket ID EPA-HQ-OW-2018-0063, (Apr, 18, 2018) (“A patchwork of state programs and narrowly focused regulatory schemes… cannot adequately make up for the crucial role the Clean Water Act plays in regulating these discharges. Moreover, relying on state regulatory programs to control these pollution sources would cut off citizen access to courts and undermine federal enforcement of federal law.”). And this narrative is heard regularly in Clean Water Act litigation involving coal ash basins. Whenever closure decisions are delegated to state solid-waste law, consistent with RCRA regulations, the environmental groups rely on the Clean Water Act to argue that as federal law, it trumps those decisions.

Excluding hydrologically connected groundwater from the purview of the Clean Water Act eliminates that argument. However, if courts require such claims to proceed under RCRA, industry will have more certainty than it does under the Clean Water Act and environmental groups will have a tougher time obtaining their preferred remedies. Unlike the CWA—which prohibits any unpermitted discharge without regard to particular levels of “pollutants” or to evidence of particular harm or risks—RCRA’s regulatory regime addresses levels of risk rather than absolutes. As such, even if a plaintiff proves an “imminent and substantial endangerment,” it does not follow that the only remedy can be source removal. As experience both under RCRA and Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) demonstrate, there are a suite of remedial methods that can address groundwater and abate a RCRA violation. Thus, environmental groups will continue to push for Clean Water Act jurisdiction over hydrologically connected groundwater, arguing that the only possible remedy is elimination of the allegedly unpermitted discharge by removal of the source.

Potential Regulatory Clarification of the Scope of CWA Liability

As the Ninth Circuit and some district courts seemed to be expanding the scope of the Clean Water Act to encompass hydrologically connected groundwater, in February 2018, the EPA requested comments on “whether pollutant discharges from point sources that reach jurisdictional surface waters via groundwater or other subsurface flow that has a direct hydrologic connection to the jurisdictional surface waters may be subject to Clean Water Act regulation.” Industry and environmental groups alike submitted comments. Industry’s comments emphasized the technical and practical difficulties of attempting to apply an end-of-pipe limit focused on effluent limitations to diffuse groundwater discharges that are not easily identified or quantified, let alone traced and sampled at a discharge point. See, e.g., Utility Solid Waste Activities Group, Comment on Clean Water Act Coverage of Discharges of Pollutants via a Direct Hydrologic Connection to Surface Water 6, Docket ID EPA-HQ-OW-2018-0063 (May 21, 2018). They also pointed out that the more- specific RCRA framework for monitoring and addressing groundwater contamination would be rendered meaningless because of a statutory exclusion in RCRA that expressly excludes from RCRA regulation “industrial discharges which are point sources subject to permits under [the Clean Water Act NPDES permitting program.]” Id. at 4. See also Utility Water Act Group, Comment on Clean Water Act Coverage of Discharges of Pollutants via a Direct Hydrologic Connection to Surface Water 87, Docket ID EPA-HQ-OW-2018-0063 (May 21, 2018).

Environmental groups, in contrast, relied on a plain-language argument. These groups claimed that the Clean Water Act does not require “direct” discharges “by” a point source into surface water, and characterized industry’s position as seeking a “loophole” in the Clean Water Act. Southern Envtl. Law Ctr., supra, at 7. The environmental groups ignore the impracticalities of permitting and monitoring diffuse seepage of pollutants through groundwater.


In April 2019, the EPA issued an Interpretive Statement that releases of pollutants to groundwater was categorically excluded from the permitting requirements of the Clean Water Act. The EPA also solicited additional public comments on the need for further clarity and regulatory certainty on this issue The Interpretative Statement recognizes that is not applicable in the states within the 9th or 4th Circuit. The EPA’s Interpretative Statement is also a change from the prior position of the prior administration in these cases. While the EPA’s Interpretative Statement is not binding, the timing was designed to provide the Supreme Court’s with the agency’s position when it considers the Maui case. It is likely that the EPA will initiate formal rulemaking after the Supreme Court’s decision. Whatever next step the EPA chooses to take, prolonged administrative litigation in the D.C. courts is certain and will include challenges to whether such actions are consistent with the Clean Water Act and the Administrative Procedures Act. Meanwhile, industry will continue to lack certainty regarding which regulatory framework applies, and courts will face ongoing challenges by environmental groups seeking to leverage the Clean Water Act’s questionable applicability and its available citizen suit remedies and to avoid the limitations of more specific groundwater rules. If these uncertainties are resolved and hydrologically connected groundwater is removed from Clean Water Act liability, industry should expect to see more federal RCRA claims and also anticipate that environmental groups will be more active at the state administrative level as they look to identify a new, consistent mechanism to influence permitting and remedial measures.

The original article, "Carving out the Contours: The Clean Water Act and the Migration of Affected Groundwater to Waters of the United States," first appeared in For the Defense on June 14, 2019.