The Supreme Court ruled, in a 6-3 decision, on Thursday, April 23, 2020, that the Clean Water Act (CWA) may apply to indirect discharge of waste into federally regulated rivers and oceans (Waters of the US) through groundwater. Requirements of the CWA have long regulated point source discharges into surface waters through the National Pollutant Discharge Elimination System (NPDES) permit program. Groundwater has never been considered a federal Water of the US (WOTUS), and regulation has been left to states for groundwater-to-surface-water discharges (GWSDs) through their respective State Disposal System (SDS) permits.
The Court concluded in The County of Maui v. Hawaii Wildlife Fund, No. 18-260, that pollutants traveling through navigable waters indirectly through groundwater is the “functional equivalent” of a direct discharge. The County of Maui owns and operates four injection wells at the Lahaina Wastewater Reclamation Facility, and the wells discharge about 3-5 million gallons of treated wastewater per day. The wastewater travels about a half mile through groundwater, to the Pacific Ocean. Plaintiffs argued that the County should have an NPDES permit for the discharge to the WOTUS (i.e. Pacific Ocean).
The Clean Water Act requires “point sources” of pollution to obtain permits for “any addition of any pollutant to navigable waters” and a failure to do so can result in daily fines of more than $50,000. Waste generators must have an NPDES permit from the issuing Agency ( in many cases the State Regulatory agency, but in some cases the US Environmental Protection Agency) when waste goes through a pipe from their source to a body of water (a point source). The Supreme Court decision affirmed that in certain circumstances, waste injected into underground wells may now be subject to federal CWA permitting. The Supreme Court articulated a qualitative standard under which NPDES permits will be necessary and remanded the case back to the 9th Circuit Court of Appeals for application of the standard.
The standard set by the Supreme Court says that the CWA applies and an NPDES permit is required when a discharge to groundwater is the “functional equivalent of a direct discharge.” The majority court opinion identified seven factors to be considered in determining a “functional equivalent of a direct discharge:”
- “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,” and
- “the degree to which the pollution (at that point) has maintained its specific identity.”
The court noted that time and distance are probably the most important factors, but in certain circumstances, other factors may be more important. This ruling stopped short of declaring that groundwater is a “Water of the US,” but it did acknowledge a regulatory link between groundwater and surface water.
This is not the first court challenge that argued that NPDES permits are required for GSWDs and addressed the scope of WOTUS. Similar suits have been heard in the 4th Circuit Federal Court of Appeals in Virginia and in the Minnesota State Court of Appeals. This is an emerging issue, and future permitting decisions and court cases will look to the recent ruling by the Supreme Court for guidance. An area of active concern is the movement of pollutants through groundwater from coal ash settling ponds, mining tailings dams, and leachate from landfills. In many cases, there will not be injection wells as in the Hawaiian case that serve as clear point sources. For ponds, basins and landfills, the movement of pollutants through groundwater is more diffuse. Facility operators and regulators will have to consider the seven factors defined by the Supreme Court to ascertain if the movement of pollutants in groundwater to surface water is the “functional equivalent of a direct discharge.”
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