The Clean Water Act (CWA) imposes upon the federal government the responsibility for eliminating pollution from point sources by establishing federal restrictions on discharges of pollutants from these sources and enforcing them through a federal permit system. This federal permit system, the National Pollutant Discharge Elimination System (NPDES), is the chief mechanism for controlling discharges. No one may discharge a “pollutant” from a point source into the “navigable waters of the United States” (WOTUS) without a permit from the EPA.
The NPDES system only applies to discharges of pollutants into surface water. Discharges of contaminants into groundwater are not subject to the NPDES permit requirement, even if the groundwater is hydrologically connected to surface water.
In 2020, the U.S. Supreme Court in County of Maui v. Hawaii Wildlife Fund, 590 U.S. 165 (2020), addressed the question of whether the CWA requires a permit when pollutants that originate from a non-point source can be traced to reach navigable waters through mechanisms such as groundwater transport.
The Supreme Court ruled that such non-point discharges require a permit when they are the “functional equivalent of a direct discharge”. This decision means that even if pollutants travel through groundwater before reaching navigable waters, they still fall under the CWA’s jurisdiction if the discharge is functionally equivalent to a direct discharge. Recently, the Maryland Court of Appeals decided a case involving spray irrigation and applying the “Maui factors.”
Under the 1977 amendments to the CWA, agricultural irrigation return flows are not considered point sources and don’t require a discharge permit. What implications do the 2020 Supreme Court and the recent Maryland appellate court decisions have on the ag irrigation return flow exemption?
The County of Maui Decision
Hawaii Wildlife Fund v. County of Maui, No. 12-00198 SOM-KJM, 2020 U.S. Dist. LEXIS 259725 (D. Haw. Oct. 7, 2020), aff’d., No. 21-15207, 2022 U.S. App. LEXIS 15089 (9th Cir. Jun. 1, 2022).
In the County of Maui, the County operated a wastewater reclamation facility on the island of Maui. The facility collected “sewage from the surrounding area, partially treated it, and pumped the treated water through four wells hundreds of feet underground.” The effluent, which amounted to four million gallons each day, traveled a half mile or so through groundwater where, several environmental groups claimed, it was discharged into the Pacific Ocean. The Supreme Court held that an NPDES permit was required “when there is a direct discharge from a point source into navigable waters or when there is the functional equivalent of a direct discharge.”
The Supreme Court set forth a non-exhaustive list of seven factors to determine whether an indirect discharge falls under the jurisdiction of the Clean Water Act:
- Transit time;
- Distance traveled;
- The nature of the material through which the pollutant travels;
- The extent to which the pollutant is diluted or chemically changed as it travels;
- The amount of pollutant entering the navigable waters relative to the amount of the pollutant that leaves the point source;
- The manner by or area in which the pollutant enters the navigable waters;
- The degree to which the pollution (at that point) has maintained its specific identity.
The Supreme Court sent the case back to the Ninth Circuit for application of the factors. The Ninth Circuit then sent the case back to the trial court to apply the factors to the facts of the case. Ultimately, based on these factors, the trial court concluded that the County of Maui’s wastewater discharged into groundwater, which then reached the Pacific Ocean, required a permit. The Ninth Circuit affirmed this.
The Maryland Case
Chesapeake Bay Foundation, Inc., 264 Md. App. 107 (Md. Ct. App. Dec. 23, 2024).
In the recent Maryland case, the town of Trappe and the Trappe East Holdings Business Trust applied for a groundwater discharge permit from the Maryland Department of the Environment for a wastewater treatment facility that would dispose of treated effluent through spray irrigation onto crop fields. The permit included effluent limitations, requirements for a nutrient management plan, and conditions to ensure complete uptake of nutrients by vegetation, resulting in zero net discharge to groundwater or surface waters. The permit allowed the use of spray irrigation to discharge 100,000 gallons of treated wastewater per day onto Talbot County farm fields.
The Chesapeake Bay Foundation (CBF)and other parties challenged the permit, arguing it was the functional equivalent of a surface water discharge requiring an NPDES permit and did not ensure zero discharge of nutrients. The CBF argued that this method would increase pollution from the development and change in land use, potentially harming local waterways. The CBF claimed that the “Maui factors” established that the effluent discharged from the Facility required an NPDES permit because it would reach a creek in about 12 days after travelling approximately 1,159 feet, and that “dilution and ‘changed condition’ of nutrients in question is immaterial because the remaining [n]itrogen will enter surface waters despite the form it travels in.”
The Maryland Department of the Environment (MDE) argued that the spray irrigation method would result in “zero net discharge” of nitrogen and phosphorus pollution to local waterways, as the soil and vegetation would absorb the treated wastewater. The MDE also maintained that the permit met all regulatory requirements and that the spray irrigation system would not harm the environment.
The Talbot County Circuit Court dismissed CBF’s challenge, upholding MDE’s permit. The court reasoned that MDE’s assumption of “zero net discharge” of nitrogen and phosphorus pollution to local waterways was valid and dismissed the case. On appeal, the Maryland Court of Appeals affirmed the decision. (Chesapeake Bay Foundation, Inc., 264 Md. App. 107 (Md. Ct. App. Dec. 23, 2024).
The appellate court agreed with the MDE, concluding that the Department clearly considered the “Maui factors” and that the record supported the MDE’s findings and conclusions. The court found that the Department’s determination that the discharge was not the functional equivalent of a direct discharge to surface waters was supported by substantial evidence because the MDE considered the “Maui factors” and provided a detailed factual basis for its conclusion. The court also found that the MDE’s determination that the nutrient management plan would ensure 100 percent uptake of nutrients, as state law required, was supported by substantial evidence. The MDE evaluated the plan under its land application guidelines, considered related issues, and imposed monitoring and reporting requirements to ensure compliance. As a result, an NPDES permit was not required.
Impact on Agricultural Irrigation Activities
Both cases highlight the scrutiny given to agricultural practices and their impact on water quality. The County of Maui decision emphasizes that even indirect discharges of pollutants into navigable waters require permits, which could lead to stricter regulations for agricultural operations that use groundwater for irrigation.
Similarly, the Maryland case could result in more stringent controls on spray irrigation practices to prevent runoff pollution. This might include requirements for buffer zones, improved irrigation techniques, or best management practices to minimize the environmental impact.
Overall, these legal decisions underscore the importance of sustainable agricultural practices and the need for farmers to stay informed about regulatory changes that could affect their operations. By adopting environmentally friendly practices, farmers can help protect water quality while ensuring the long-term viability of their agricultural activities.
Until the Supreme Court’s 2023 decision in Sackett v. United States Environmental Protection Agency, 598 U.S. 651 (2023), it was believed that the Supreme Court’s opinion in the County of Maui case could have significant implications for the irrigation return flow exemption. However, the Sackett decision’s narrowing of the definition of WOTUS has narrowed the application of the County of Maui decision. By limiting the scope of waters protected under the CWA, the Sackett ruling may reduce the number of water bodies requiring permits for indirect pollutant discharges.
In any event, agricultural operations will likely need to manage their runoff carefully and consider the potential regulatory implications of various farming practices.
In particular, farming operations might be prudent to consider whether any of the following should be implemented:
- More efficient irrigation systems to minimize runoff and ensure that water is used more effectively. This could include drip irrigation, soil moisture sensors, and other technologies that reduce water waste.
- Establishing buffer zones and vegetation around water bodies to help filter “pollutants” before they reach navigable waters.
- Adoption of nutrient management practices, including the use of precision agriculture techniques that apply fertilizers more accurately and efficiently, to help prevent excess fertilizers from entering water bodies.
- Planting cover crops to reduce soil erosion and runoff and improve soil health (in areas of the country where this is possible!)
Conclusion
The agricultural irrigation return flow exemption remains an important exemption from the CWA discharge permit requirement. The “Maui factors” apply but have been limited in application by the Supreme Court’s 2023 Sackett decision.
