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Connections to the Past: Understanding County of Maui v. Hawaii Wildlife Fund

by Taylor Wilson*

In April 2020, the Supreme Court handed down a decision that provides an answer to the ongoing debate over whether the Clean Water Act’s permitting requirements extend to pollution that travels through groundwater before reaching navigable waters. In County of Maui v. Hawaii Wildlife Fund, the Supreme Court held that the CWA requires “a permit if the addition of the pollutants through groundwater is the functional equivalent of a direct discharge from the point source into navigable waters.”[1] The rule handed down is vague, as the court itself admits.[2] However, its vagueness is a direct result of its many similarities to the EPA’s past guidance, and these similarities will ultimately better serve the purpose of the Clean Water Act. 

The Clean Water Act was enacted in 1972 to “restore and maintain the chemical, physical, and biological integrity of the Nation’s waters.”[3] This act prohibits the “discharge of any pollutant by any person” unless permission is granted by the National Pollutant Discharge Elimination System.[4]  “Discharge of any pollutant” is defined as “any addition of any pollutant to navigable waters from any point source.”[5]. “Navigable waters” are defined by the act as “waters of the United States.”[6] A “point source” is “any discernable, confined, and discrete conveyance” from which a pollutant could be discharged, such as a pipe or well.[7] Groundwater is not considered a navigable water, so discharge into groundwater does not inherently require a permit under the CWA. However, questions arise when a point source discharges pollutants into groundwater which then travel to a navigable water. Should a discharge into groundwater with a hydrological connection to navigable waters require a permit under the CWA? Does such a requirement reasonably fit into the legislative history and plain meaning of the CWA? [8] In response to a circuit split over these questions, the Supreme Court granted certiorari to County of Maui v. Hawaii Wildlife Fund.[9]

In County of Maui v. Hawaii Wildlife Fund¸ the county of Maui’s wastewater treatment facility collected sewage and, following partial treatment, pumped it into the ground through four injection wells.[10] The wastewater then travelled about half a mile through hydrologically connected groundwater and entered the Pacific Ocean.[11] Environmental groups brought the suit, alleging that the County of Maui was discharging a pollutant into the navigable waters of the United States without a permit.[12] The Supreme Court held the Clean Water Act requires “a permit if the addition of the pollutants through groundwater is the functional equivalent of a direct discharge from the point source into navigable waters.”[13]

There are two questions that are essential to the issue of hydrologically connected groundwater, both of which are addressed by the Supreme Court in County of Maui. First, under what theory can the EPA justify its jurisdiction over hydrologically connected groundwater under the CWA?[14]  Second, what standard of connectivity is sufficient between a navigable water and a point source for it to fall under the CWA? [15] (For example, should a permit be required when a pollutant enters navigable waters only after hundreds of years?) To the first question, the court articulates a theory which allows the EPA to exercise authority over hydrologically connected groundwater consistently with the plain meaning[16] and legislative history[17] of the CWA. To the second question, it set forth limits by which the courts and the EPA might determine when a specific case requires a NPDES permit under that jurisdiction.[18]

The Court theorized that the EPA can exercise jurisdiction over hydrologically connected groundwater when a discharge into it is the “functional equivalent” of a discharge into navigable water.[19] This “functional equivalent” theory might be better understood when compared to the EPA’s own prior theory of its jurisdiction over hydrologically connected groundwater.[20] Until April 2019 [21], the EPA took the position that hydrologically connected groundwater could be covered by the CWA.[22] This position was reiterated in 2001, when it stated that the CWA requires “NPDES permits for discharges to groundwater where there is a direct hydrological connection between groundwater and surface waters.”[23]The EPA goes on to explain that groundwaters are not themselves “waters of the United States,” but that “discharges to them are regulated because such discharges are effectively discharges to the directly connected surface waters.”[24] The EPA was primarily concerned with the end result; that the discharge into groundwater had the same effect as a discharge into surface water. The Supreme Court’s holding in County of Maui is similarly focused on the effect of the pollutant. Rather than holding that groundwater is itself a navigable water, the court held that it is covered when a discharge into groundwater serves the same function as a direct discharge into navigable waters. These similarities indicate that the Supreme Court’s “functional equivalent” theory was significantly influenced by the EPA’s past guidance.

It is also worth noting the similarity between the Supreme Court’s theory of jurisdiction and the conduit theory which was used by the District of Hawaii when it heard the case.[25] The conduit theory finds EPA jurisdiction when groundwater serves as a conduit for pollution to reach surface water.[26] This “functional equivalent” theory appears to be rooted in the conduit theory. In fact, the phrase “functional equivalent” was used by the District of Hawaii to explain their reasoning when it heard the case and applied the conduit theory.[27] Like the District of Hawaii’s reasoning in Hawaii Wildlife Fundand the EPA’s pre-2019 position, the Supreme Court’s “functional equivalent” theory is focused on the destination of the pollutant, rather than its journey. 

The Supreme Court’s ruling on the standard of connectivity is also rooted in the EPA’s past guidance. The EPA previously asserted jurisdiction over hydrologically connected groundwater only on a case-by-case basis and applied a somewhat strict “direct hydrological connection” standard.[28] This standard required a consideration of factors such as time, distance, and geology, and stated that a general connection was insufficient.[29] In County of Maui, the court’s holding on the standard of connectivity declined to set forth a bright line rule but does set out limiting factors, some of which are notably similar to the “direct hydrological connection” standard.[30] Among the potentially significant factors, the court lists time and distance, the amount of pollutant, the extent of chemical change to the pollutant, and the area in which the pollutant has entered the water.[31] The presence of these specific factors indicate significant similarity to the EPA’s “direct hydrological connection” standard.

The Supreme Court rejected the Ninth Circuit’s “fairly traceable” standard for being overly broad, which further indicates that a general hydrological connection is not sufficient.[32] The Ninth Circuit held that a point source was covered by the CWA when a pollutant in a navigable water was “fairly traceable” to that point source. The Supreme Court deemed this standard to be overly broad because it would require a permit in circumstances when only a weak connection was present, such as a scenario in which a pollutant travels hundreds of miles to reach a navigable water. [33] The Supreme Court’s rejection of the “fairly traceable” standard, along with the articulation of specific relevant factors indicate that the court intends for the standard of connectivity to be something similar to the “direct hydrological connection” standard of the pre-2019 EPA.  

The Supreme Court’s holding in County of Maui shares significant similarities with the EPA’s past guidance in both its chosen theory of jurisdiction and its standard of connectivity. In the absence of an EPA that was willing to provide reasonable guidance on this issue, the Supreme Court was resourceful in deferring to the agency’s previous positions. Establishing a basis for the EPA’s jurisdiction over hydrologically connected groundwater leaves an opening for the EPA to make scientifically informed rules on the issue. While it may have been more administratively efficient for the Supreme Court to hand down a bright line rule, rules for connectivity created by experts on the subject will more effectively fulfill the Clean Water Act’s purpose.[34] And until the EPA creates those rules, these cases will be handled in a way that is consistent with the EPA’s past guidance. 

*Taylor Wilson is a Junior Editor with MJEAL. They grew up in Springfield, MO, and studied music education at the University of Arkansas. They can be reached at twilso@umich.edu


[1] County of Maui v. Hawaii Wildlife Fund, No. 18-260, slip op. at 1 (U.S. Apr. 23, 2020).

[2] Id. slip op. at 16. 

[3] Clean Water Act, 33 U.S.C. § 1251 (a)

[4] 33 USC §§ 1311(a), 1342 (a)(1)

[5] 33 USC § 1362(12)

[6] 33 USC § 1362 (7)

[7] 33 USC § 1362(14)

[8] Kaela Shiigi, Underground Pathways to Pollution: The Need for Better Guidance on Groundwater Hydrologically Connected to Surface Water, 46 Ecology L.Q. 519, 524 (2019).

[9] County of Maui v. Hawaii Wildlife Fund, No. 18-260, slip op. at 4 (U.S. Apr. 23, 2020).

[10] Id. slip op. at 3.

[11] Id. 

[12] Id.

[13] Id. slip op. at 1. 

[14] Allison L. Kvien, Is Groundwater That Is Hydrologically Connected to Navigable Waters Covered under the CWA: Three Theories of Coverage & Alternative Remedies for Groundwater Pollution, 16 MINN. J.L. Sci. & TECH. 957, 960 (2015).

[15] See Shiigi, supra note 7, at 524. 

[16] See County of Maui, slip op. at 11 (Interpreting the word “from” in the phrase “from any point source” to mean an origin and inferring from this that water passing from a point source to a navigable body is not excluded from the CWA simply because it is being conveyed by groundwater).

[17] Id. at 7, 8 (Explaining that Congress intended for groundwater pollution to be regulated by the states and that the statute should not be interpreted to seriously interfere with the State’s ability to regulate it). Id. at 10, 13. (Asserting that disallowing that regulation of all groundwater by the EPA would create a loophole that would undermine the purpose of the CWA).

[18] Id. at 15, 16.

[19] County of Maui, slip op. at 1.

[20] Hawaii Wildlife Fund, 24 F.Supp. 3d at 995.

[21] See Interpretive Statement on Application of the Clean Water Act National Pollutant Discharge Elimination System Program to Releases of Pollutants From a Point Source to Groundwater, 84 Fed. Reg. 16,810, 16,810 (Apr. 23, 2019). In this interpretive statement, the EPA asserts that the CWA does not apply to any discharges directly into groundwater. 

[22] E.g. Kvien, supra note 13, at  959; see NPDES Permit Application Regulations for Storm Water Discharges, 55 Fed. Reg. 47990, 47997 (Dec. 2, 1990) (the EPA states that the rule can apply when discharges are made into groundwater that is hydrologically connected to navigable waters).; see alsoAmendments to the Water Quality Standards Regulations that Pertain to Standards on Indian Reservations, Final Rule56 Fed. Reg. No. 239, 64892 (Dec. 12, 1991) (Claiming that the EPA can exercise authority over groundwater pollution when there is a “direct hydrological connection between groundwaters and surface waters” in order to protect surface waters).

[23]National Pollutant Discharge Elimination System Permit Regulation and Effluent Limitations Guidelines and

Standards for Concentrated Animal Feeding Operations, 66 Fed. Reg. 2960, 3018 (proposed Jan. 12, 2001)

(codified at 40 C.F.R. pts. 122, 412)

[24] Id. 

[25] Hawaii Wildlife Fund v. County of Maui, 24 F.Supp. 3d 980, 998 (D. of Hawaii 2014), amended, by 881 F.3d. 754 (9th Cir. 2018).

[26]  Kvien, supra note 13, at 961; Hawaii Wildlife Fund, 24 F. Supp. 3d at 998 (“But when it is established that groundwater is a conduit for pollutants, liability may attach to a discharge into that groundwater even if the groundwater is not itself protected under the Act.”)

[27] Hawaii Wildlife Fund¸ 24 F.Supp. 3d at 994 (“. . . Plaintiffs may also prevail if they show that the discharge into the groundwater below the LWRF is functionally equivalent to a discharge into the ocean itself.”)

[28] 66 Fed. Reg. 2960, 3017; Accord Shiigi, supra note 2 at 529.

[29] Id.

[30] County of Maui, slip op. at 15. 

[31] Id. at 16.

[32] Id. at 5-7.

[33] County of Maui, slip op. at 6.

[34] See Shiigi, supra note 7, at 553

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